Brain & Head
Understanding Pain ChartThis visual and textual overview of pain provides and easy to understand tool designed for patient interaction with their health professional. Defines pain and the types of pain and lists symptoms for each. Simplifies “How Pain Works” into 3 comprehensible steps. Provides a pain scale and a sample human figure so patients can provide their health professional information about the level and location of pain. Provides brief mention of prevention tips and to consult health professional for a tailored treatment plan. Size is 20" W by 26" H.
Understanding Stroke Chart, 2nd EditionRedesigned for easier comprehension, this latest edition provides essential information regarding stroke. Explains and illustrates stroke, including the two main types: ischaemic and haemorrhagic. For ischaemic stroke, shows common sites of plaque formation, formation of a thrombus and embolus. For haemorrhagic strokes, illustrates brain with intracerebral haemorrhage and ateriovenous malformation (AVM). Shows Circle of Willis with aneurysm and cross-section of brain with subarachnoid hemorrhage, arterioles and microaneurysm. Also provides illustration of the brain and discusses it's functional areas & their roles in the body. Describes events leading to a stroke. Lists risk factors and common neurological deficits after stroke. Size is 20" W by 26" H.
Anatomy of the Brain ChartShows base and right side views of arteries of the brain as well as venous sinuses. Illustrates cerebral hemispheres, lobes of the brain, cross-section of meninges & venous sinuses, typical nerve cell, typical glial cells, and circulation of cerebrospinal fluid. Size is 20" W by 26" H.
The Brain Anatomical ChartShows cranial nerves and vessles in the base of brain. Also provides lateral and sagittal section views of the arteries of the brain. Illustrates lobes, limbic system, ventricles of the brain, coronal section, Circle of Willis, circulation of cerebrospinal fluid (CSF), somatotopic organization of the cerebrum and meninges of the brain. Size is 20" W by 26" H.
Understanding Sleep Disorders ChartDefines sleep and the sleep-wake cycle. Explains why the body needs sleep. Describes the role of the Suprachiasmatic Nucleus (SCN) of the brain in sleep and wake regulation. Provides graphs and descriptions of the five phases of sleep. Covers common sleep disorders such as Insomnia, Obstructive Sleep Apnea, Restless Legs Syndrome (RLS) and Narcolepsy. Includes tips for a good night’s sleep. Size is 20" W by 26" H.
Understanding Alzheimers ChartDiscusses the aging brain and dementia, providing an overview of Alzheimer's Disease (AD). Illustrates affected areas of the brain and the abnormal cellular structures involved with AD: granulovacuolar degeneration, neurofibrillary tangles and amyloid plaques. Discusses the stages of Alzheimer's Disease and shows the physical changes in the brain cortex caused by AD. Illustrates and defines the role of neurotransmitters as messengers. Size is 20" W by 26" H.
Understanding Epilepsy ChartDefines epilepsy, discusses causes and illustrates how the brain works. Defines seizures including the phases of a seizure. Discusses the symptoms and what to do if someone has a seizure. Shows brain activity for generalized and partial seizures and defines the main forms of these types of seizures. Discusses diagnosing epilepsy and the various tests used in the process. Size is 20" W by 26" H.
Dermatomes ChartDefines dermatomes and illustrates cutaneous areas of peripheral nerve innervation, development of dermatomes and dematomes in extremities. Size is 20" W by 26" H.
Spinal Nerves ChartIllustrates spinal nerves, cranial nerves and diagrams the portion of the thoracic spinal cord with spinal nerves. Also shows spinal cord segments, cutaneous distribution of spinal nerves and dermal segmentation. Size is 20" W by 26" H.
Autonomic Nervous System ChartShows autonomic nervous system, including sympathetic and parasympathetic nerves. Size is 20" W by 26" H.
Nervous System ChartClassic illustrations by Peter Bachin. Illustrates nerves in the body, brain, midbrain, medulla oblongata and spinal cord. Also shows spinal meninges, intercostal nerves and sagittal section of female pelvis. Size is 20" W by 26" H.
Understanding Parkinson's Disease ChartDefines Parkinson's Disease (PD) and how your body moves. Shows various views of the brain (highlighting the motor cortex), the role of neurotranmitters, and the lower levels of dopamine associated with PD. Discusses medical and surgical management techniques and lists symptoms. Size is 20" W by 26" H.
Whiplash Injuries of the Head and Neck ChartDefines whiplash and shows hyperflexion, hyperextension, spinal ligaments, ligament damage, muscle injury and spinal cord injury. Size is 20" W by 26" H.
Head and Neck ChartCenter illustration shows muscles, veins, nerves and arteries of the head and neck. Chart also shows bones, deep muscles and sensory nerves, internal carotid and vertebral arteries and deep structures. Illustrates horizonal and median sections. Size is 20" W by 26" H.
Migraines and Headache ChartDeveloped in conjunction with the Diamond Headache Clinic, the first comprehensive private headache clinic in the world. Details what vascular, tension, and organic headaches are, and the real differences among them. Also discusses the pathways of a migraine, and lists a comprehensive headache diagnostic guide. Size is 20" W by 26" H.
Understanding Depression ChartThis chart defines depression and three main types of this serious medical condition. Also listed are signs and symptoms of major depression, risk factors, suicide warning signs and treatment options. Includes illustrations of the role of neurotransmitters, the areas of the brain affected by depression, and the Hypothalamic-Pituitary Adrenal axis. Size is 20" W by 26" H.
Anatomy of the Brain Study GuideThis folding study guide takes our most popular anatomical images and puts them in a durable, portable format-perfect for the on-the-go student. Guide shows numbered anatomical structures and contains answers that can be concealed for easy self-testing and memorisation. Write-on, wipe-off laminated surface. This quick reference covers:
Nerves, arteries, vessels, ventricles and cells Limbic system and coronal section Midbrain, medulla oblongata and spinal cord Meninges and venous sinuses Lobes of the brain, Circle of Willis Somatotopic organisation of the cerebrum Circulation of cerebrospinal fluid (CSF)
Folded size approximately 9" x 4". Unfolded size approximately 9" x 24".
Spinal Nerves and the Autonomic Nervous System Study GuideThis folding study guide takes our most popular anatomical images and puts them in a durable, portable format-perfect for the on-the-go student. Guide shows numbered anatomical structures and contains answers that can be concealed for easy self-testing and memorisation. Write-on, wipe-off laminated surface. This quick reference covers:
Spinal and cranial nerves Listing and description of important branches emerging from proximal part of spinal nervesSpinal cord segments Descriptions of nerve plexuses Cutaneous distribution of spinal nerves and dermatomes View of spinal cord with spinal nerves & immediate branches Autonomic nervous system, including sympathetic and parasympathetic nervesListing of effector organs with sympathetic and parasympathetic action
Folded size approximately 9" x 4". Unfolded size approximately 9" x 24".
Budget Brain with Arteries ModelAn educational economy model of the brain. Colour markings illustrate arteries (red) and cranial nerves (yellow). Dissects into 8 parts. Life-size, on base. Key card included with 60 labeled structures. Size: 5" x 6" x 6".
Budget Brain ModelA plastic replica of a human brain showing multiple views. Great for hands-on study of brain anatomy. Sits on sturdy base. Includes a key card with 61 structures labeled. Dissects into 3 parts. Size: 5" x 6" x 6-1/2".
Budget Skull with 8-Part Brain ModelDurable plastic life-size skull with removable calvarium and hinged jaw on springs. Translucent 8-part brain fits inside the cranial cavity. Includes key card identifying 75 structures. Size: 5" x 8-1/2" x 6". Weight: 7 lbs.
Diseased Brain in SkullA life-sized brain is shown in its location in the skull. Segmented into a normal half and 3-piece pathology half featuring the following: Alzheimer's, migraine, stroke, seizure related tumor, aneurysm, multiple sclerosis, subdural hematoma, Parkinson's Disease and alcoholism. Patient education card is included. Brain Size: 5" x 6-3/4" x 5".
Classic 5 Part BrainA midsagittally sectioned model of the brain cast from a real human brain. The left half can be divided into the frontal and parietal lobe, temporal and occipital lobes, brain stem, and cerebellum. May be removed from base. Size 5” x 5-1/2” x 7”. 3B Scientific GmbH
Median Section of Head and NeckA finely painted cross-section of the head and neck showing the brain, nose, mouth, larynx and vertebral column of the neck. Bones, brain, larynx, nose, gullet and buccal cavity are numbered according to key included. Made of fiberglass, mounted on base. Size: 10" x 12-3/4" x 2".
Colour Coded Eight Part Brain ModelA life-size model of the human brain and brain stem. The left side is coloured to show the sensory and motor areas. The 12 cranial nerve roots are shown and numbered, together with some of the important arteries. Dissects into 8 parts. Supplied on a base with a key card. Size: 8" x 8" x 7".
Head with Brain ModelA detailed model of the brain in the skull. The complete brain is removable to show dura mater, 12 pairs of cranial nerves and arteries. Life-size. Dissects into 8 parts, on base. Size: 6" x 6" x 9". 3B Scientific GmbH.
Deluxe Brain ModelCast from a human specimen in SOMSO-Plast, this life size brain model dissects into 8 parts: frontal and parietal lobes (2), temporal and occipital lobes (2), medulla (2), and cerebellum (2). Base included. Size: on base 6-1/3" x 6-1/3" x 6-1/2". Somso Modelle.
Human Half HeadA detailed model showing the median and lateral sections. The median section shows the central nervous system and the anatomy of the pharynx and mouth. The lateral view shows superficial verves and vascular distribution along with muscles of the face and neck. Life-size; does not dissect; on base. Size: 9" x 7" x 18". 3B Scientific GmbH.
Deluxe Head with Brain ModelA life-size model of the head and brain showing the 12 pairs of cranial nerves and the basilar artery. The removable brain separates into 8 parts: frontal and parital lobes, temporal and occipital lobes, 2-part medulla, 2-part cerebellum. Size: 8-3/4" x 7" x 8". Somso Modelle.
Transparent Brain ModelThis life-size model separates into 15 parts: left cortex with sinus sagittalis, cervical vertebral column with spinal cord and vertebral artery, right transparent cortex, right half of spheniod bone, removable right and left brain stem, right and left insular cortex, left striate body, right capsularinterna, corpus callosuem, fornix, limbic system and ventricle system, right and left halves of the cerebellum. Mounted on stand. 12" x 7" x 8".
Nervous System ModelA half life-size schematic presentation of the central and peripheral nervous system. One piece on base. Size: 36" x 12" x 2-1/3". Somso Modelle.
Deluxe Brain with ArteriesA life-size brain model cast in SOMSO-Plast. This highly detailed model includes a representation of the arterial network of vessels and dissects into 9 parts: frontal and parietal lobes (2), temporal and occipital lobes (2), medulla (2), cerebellum (2), and basilar artery. Base included. Size: 6-1/4" x 6-1/3" x 6-1/2". Somso Modelle.
Deluxe Brain with ArteriesThis medially divided brain shows the brain arteries and has a removable basilar artery. Both halves of the brain can be dissected into frontal and parietal lobes, temporal and occipital lobe, 2-part brain stem, and 2-part cerebellum. May be removed from the base. Size approximately 6” x 5-1/2” x 6-1/4”. 3B Scientific GmbH.
Two Part Brain ModelCast from a natural specimen, this two-part brain is medially sectioned, Made of SOMSO-plast to endure years of work. Base included. Size: 6" x 6-1/4" x 6-3/4". Somso Modelle.
Antomical Section Model of the Head(Combined with Corresponding MR-Figues)Designed in consultation with Dr. J.W. Rohen, this model shows the anatomical structures of 10 consecutive horizontal sections through the human head, oriented to the plane usual in CT and MR imaging (CA-CP plane) and which have the same section thickness (0.8 cm). The sections were modeled on original preparations and are illustrated from above. Each cross section swivels and is removable. Life-size in special plastic, with explanatory booklet on the base. Size: 11" x 18" x 13". Somso.
Neuroanatomy Head ModelA transparent skull with cervical vertebrae and 8-part brain. Cytoarchitectural areas are indicated on the brain. The cranial nerves and the arterial vessels are also shown. Dissects into a total of 10 parts. Size: 5" x 5" x 6". Somso Modelle.
Giant Regional Brain ModelColour-coded in 9 vibrant colours to differentiate the front, parietal, occipital and temporal lobes as well as the cerebellum, brain stem, and the motor, somato sensory and limbic cortices. Each of the lobes, limbic cortex, and pre- and postcentral gyri is labeled. Divides into 4 parts. The 120 numbered neurostructures are identified in key card. About twice life size, 8” x 8” x 10”, Denoyer-Geppert Co.
Giant Functional-Center Brain ModelAbout 2 times life size, this model of the brain of a right-handed person uses contrasting colours and labels to identify motor and sensory functional centers. Sensory centers receptive to 20 specific body regions are distinguished, as are the motor centers controlling 19 body regions. More than 120 numbered features with corresponding key card. 4-part brain rests on molded base, size: 8” x 8” x 10”. Denoyer-Geppert Co.
Deluxe 8-Part Brain with Arteries ModelLife size model of the brain incorporates the arterial blood supply complete with termini of the internal carotids, basilar artery, and Circle of Willis. Cranial nerves and a dissectible brain stem are featured as well. Right hemisphere divides in 2 parts, left splits into 4 parts including half of the brain stem and ½ of the cerebellum. Pituitary and basilar artery may be detached. Rests on a molded plastic base. 115 numbered features with key card. Denoyer-Geppert Co. Size: 6” x 5” x 7”.
Friday, November 14, 2008
How your body function [head
- Have you ever wonder how you coordinate your self
Converting Neuromag head coordinates to
Talairach coordinates
K. Uutela
November 19, 2000
1 Introduction
Neuromag software uses head coordinate system that is defined by three anatomical
landmarks: nasion and preauricular points. To compare different brain locations,
Talairach coordinate system, referring to the coordinate system used in
Talairach and Tournoux brain atlas (1), where the anterior and posterior commissures
(AC and PC) and the midline are used to define the coordinates. In both
coordinate systems, x-axis increases from left to right, y-axis from posterior to
anterior, and z-axis from inferior to superior, but the origins differ. The approach
described here, used also in fMRI analysis software such as AFNI (2) also scales
the coordinate system to match the extents of the Talairach standard brain.
This document describes how to convert Neuromag head coordinates to Talairach
coordinates by using the Matlab function coordtrans, included in the MEG
toolbox. To use the function, the locations of the anterior and posterior commissure
and the midline in the head coordinate system and the extents of the brain are
needed.
2 Getting Talairach information using MRILab
To get the Talairach information for the magnetic resonance images (MRIs) of an
individual subject, the MR images should have the head coordinate system defined.
See the MRILab manual for details. Then, rotate the coordinate frame so
that the midline (between two hemispheres) is shown. Find the anterior and posterior
commissure and place points in crossing of the posterior and superior edge
of the anterior commissure and at the inferior edge of the posterior commissure
(Fig. 1). Place a third point more superior in the midline. Get the coordinates of
1
AC
PC
Corpus callosum
Y
Z
Figure 1: The anterior and posterior commissures (AC and PC) and Talairach
axes.
these points either by the coordinate tool or by exporting the placed points in head
coordinates.
To find the extents of the brain (see Fig. 2), first rotate the stach so that the
y axis is aligned with the landmarks of AC and PC. Then select a slice which
includes the rightmost part of the cerebrum, and find the distance between ACPC
line and the closest point in this slice using the coordinate tool. Calculate
similarily the distance from AC-PC line to the leftmost part, from AC to the most
anterior part in the frontal lobe, from PC to the most inferior part in the occipital
lobe, from AC-PC line to the most superior part, and from AC-PC line to the most
inferior part of the cerebrum (typically in the temporal lobes; cerebellum is not
included).
3 Using the coordtrans command
Start Matlab with the command /usr/local/bin/matlab, load the head coordinate
points (in meters) to be converted to matrix R (or create it manually using command
like
R=[0.010 ; 0.020 ; 0.030]’*0.001;
Define the individual landmarks using a command like
subjectNN=
[AC x PC x ML x;AC y PC y ML y; AC z PC Z ML Z],
... [right left front back top bottom]
;
where the values are
2
PC AC
Midline
X Y
Z Z
Figure 2: The extents of the brain.
AC x x-coordinate of AC
PX x x-coordinate of PC
ML x x-coordinate of midline point
AC y y-coordinate of AC
PX y y-coordinate of PC
ML y y-coordinate of midline point
AC z z-coordinate of AC
PX z z-coordinate of PC
ML z z-coordinate of midline point
right AC-right -distance
left AC-left -distance
front AC-front -distance
back PC-back -distance
top AC-top -distance
bottom AC-bottom -distance .
All values should be given in meters.
You get the Talairach coordinates using the command
R t=coordtrans(R,subjectNN,’talairach’);
To obtain the individual coordinates from Talairach coordinates use the command
R head=coordtrans(R t,’talairach’,subjectNN);
3
To convert from coordinates of subject NN to coordinates of subject MM, use
the command line
R mm=coordtrans(R nn,subjectNN,subjectBB); which will transform
the coordinates first to Talairach coordinates and then to the second subject’s coordinates.
The command line parameters are shown with the Matlab help command
help coordtrans
4 Saving the results
You can save the individual talairach parameters by using the Matlab save command:
save subjNN parameters.mat subjectNN
You can save the converted points to an ascii file using the -ascii otion:
save -ascii subjNN talairachpoints.txt R t
5 Using Matlab scripts
To spot errors and to automatize the procedure, it may be useful to create a Matlab
script file which does the whole calculation. Simply creare a text file with a “.m”
ending, such as “batch.m”, and include all the commands that you would give in
the Matlab command line. You can run the batch script using the name of the file,
e.g. bat
Thursday, October 16, 2008
KIDDIES HEALTH ON ASTHMA
Keeping Kids' Asthma in Check
This Fall
From the common cold to mold, the respiratory viruses and allergens regularly swirling around the classrooms can send kids' asthma into a frenzy come fall. The No. 1 reason why students chronically miss school, asthma is also the culprit behind the annual early-autumn spike in hospitalizations and doctors' visits for the nearly 5 million children and teens in the United States with the chronic lung disease.
So, the newly updated asthma guidelines from the National Institute of Health's National Asthma Education and Prevention Program (NAEPP) couldn't come at a better time. Though they're geared toward helping doctors help their patients, the recommendations do contain a key take-home message for anyone with asthma: Proactively stay on top of the condition to keep it under control — not just when problems arise, but every day.
When students' asthma isn't in check, it can affect everything from how well they do in class to how much they're able to participate in sports. That's why it's so crucial to consistently manage kids' asthma to prevent symptoms or keep them from getting worse.
People with asthma have airways that are overly sensitive to certain things (called triggers) that normally don't bother others. So, kids with asthma may have a tough time once school is in full swing and they're regularly coming into contact with common in-school triggers such as:
viral infections (like colds or the flu)
dust mites
chalk dust
animal dander (from the class pet)
mold
exercise, cold air, and pollen (which can become a real problem during phys-ed classes)
Kids may react to these triggers over time, with gradual exposure, or suddenly and without warning. The result is usually an asthma flare-up (or attack) — when the lungs' already-inflamed airways become more swollen and clogged with sticky mucus, and the muscles around the airways tighten, leaving little room for air to flow through. But when asthma is well controlled, flare-ups happen less often and may not be as serious.
What This Means to You
You can tell when asthma isn't under control, says the American Academy of Allergy, Asthma & Immunology (AAAAI), if a child:
has asthma symptoms that are waking the family at night
has a hard time playing sports, exercising, or participating in physical activities like dance
chronically misses school (and you keep missing work)
To manage asthma day-to-day and help prevent major flare-ups before they happen, it's also wise to:
Work with your doctor to create — and help kids follow — a written asthma action (or management) plan.
Talk to the school nurse, coaches, and teachers (especially phys-ed teachers) about your child's asthma, possible in-school triggers, and warning signs of an asthma attack. Give the school a copy of your asthma action plan.
Make sure your child carries all controller medications (to keep the asthma in check) and rescue medications (to relieve symptoms and help treat attacks). And always have on hand all meds and a peak flow meter (an inexpensive, portable device that helps monitor asthma).
Encourage and help your child to steer clear of possible triggers.
Drive home the message that regular and thorough hand washing can help keep a lot of infectious bugs at bay.
Recognize the early warning signs that a flare-up might be coming (though you can't always prevent an attack):
rapid or irregular breathing
coughing
throat clearing
unusual fatigue
trouble sitting or standing still
restless sleep
Make sure to track how your child is doing day to day by keeping a weekly asthma diary that records symptoms, medications, and readings from the peak flow meter. This will help your doctor make any necessary changes to the treatment plan.
This Fall
From the common cold to mold, the respiratory viruses and allergens regularly swirling around the classrooms can send kids' asthma into a frenzy come fall. The No. 1 reason why students chronically miss school, asthma is also the culprit behind the annual early-autumn spike in hospitalizations and doctors' visits for the nearly 5 million children and teens in the United States with the chronic lung disease.
So, the newly updated asthma guidelines from the National Institute of Health's National Asthma Education and Prevention Program (NAEPP) couldn't come at a better time. Though they're geared toward helping doctors help their patients, the recommendations do contain a key take-home message for anyone with asthma: Proactively stay on top of the condition to keep it under control — not just when problems arise, but every day.
When students' asthma isn't in check, it can affect everything from how well they do in class to how much they're able to participate in sports. That's why it's so crucial to consistently manage kids' asthma to prevent symptoms or keep them from getting worse.
People with asthma have airways that are overly sensitive to certain things (called triggers) that normally don't bother others. So, kids with asthma may have a tough time once school is in full swing and they're regularly coming into contact with common in-school triggers such as:
viral infections (like colds or the flu)
dust mites
chalk dust
animal dander (from the class pet)
mold
exercise, cold air, and pollen (which can become a real problem during phys-ed classes)
Kids may react to these triggers over time, with gradual exposure, or suddenly and without warning. The result is usually an asthma flare-up (or attack) — when the lungs' already-inflamed airways become more swollen and clogged with sticky mucus, and the muscles around the airways tighten, leaving little room for air to flow through. But when asthma is well controlled, flare-ups happen less often and may not be as serious.
What This Means to You
You can tell when asthma isn't under control, says the American Academy of Allergy, Asthma & Immunology (AAAAI), if a child:
has asthma symptoms that are waking the family at night
has a hard time playing sports, exercising, or participating in physical activities like dance
chronically misses school (and you keep missing work)
To manage asthma day-to-day and help prevent major flare-ups before they happen, it's also wise to:
Work with your doctor to create — and help kids follow — a written asthma action (or management) plan.
Talk to the school nurse, coaches, and teachers (especially phys-ed teachers) about your child's asthma, possible in-school triggers, and warning signs of an asthma attack. Give the school a copy of your asthma action plan.
Make sure your child carries all controller medications (to keep the asthma in check) and rescue medications (to relieve symptoms and help treat attacks). And always have on hand all meds and a peak flow meter (an inexpensive, portable device that helps monitor asthma).
Encourage and help your child to steer clear of possible triggers.
Drive home the message that regular and thorough hand washing can help keep a lot of infectious bugs at bay.
Recognize the early warning signs that a flare-up might be coming (though you can't always prevent an attack):
rapid or irregular breathing
coughing
throat clearing
unusual fatigue
trouble sitting or standing still
restless sleep
Make sure to track how your child is doing day to day by keeping a weekly asthma diary that records symptoms, medications, and readings from the peak flow meter. This will help your doctor make any necessary changes to the treatment plan.
QUIT SMOKING
DIFFICULT TO QUIT HABBIT?
First, congratulate yourself. Just reading this article is a huge step toward becoming tobacco free. Many people don't quit smoking because they think it's too hard to do. They think they'll quit someday.
It's true, for most people quitting isn't easy. After all, the nicotine in cigarettes is a powerfully addictive drug. But with the right approach, you can overcome the cravings.
The Difficulty in Kicking the Habit
Smokers may have started smoking because their friends did or because it seemed cool. But they keep on smoking because they became addicted to nicotine, one of the chemicals in cigarettes and smokeless tobacco. Nicotine is both a stimulant and a depressant. That means nicotine increases the heart rate at first and makes people feel more alert (like caffeine, another stimulant). Then it causes depression and fatigue. The depression and fatigue — and the drug withdrawal from nicotine — make people crave another cigarette to perk up again. According to many experts, the nicotine in tobacco is as addictive as cocaine or heroin.
But don't be discouraged; millions of Americans have permanently quit smoking. These strategies can help you quit, too:
Put it in writing. People who want to make a change often are more successful when they put it in writing. So write down all the reasons why you want to quit smoking, such as the money you will save or the stamina you'll gain for playing sports. Keep that list where you can see it, and add to it as you think of new reasons.
Get support. People whose friends and family help them quit are much more likely to succeed. If you don't want to tell your parents or family that you smoke, make sure your friends know, and consider confiding in a counselor or other adult you trust. And if you're having a hard time finding people to support you (if, say, all your friends smoke and none of them is interested in quitting), you might consider joining a support group, either in person or online.
Set a quit date. Pick a day that you'll stop smoking. Tell your friends (and your family, if they know you smoke) that you're going to quit smoking on that day. Just think of that day as a dividing line between the smoking you and the new and improved nonsmoker you'll become. Mark it on your calendar.
Throw away your cigarettes — all of your cigarettes. People can't stop smoking with cigarettes still around to tempt them. Even toss out that emergency pack you have stashed in the secret pocket of your backpack. Get rid of your ashtrays and lighters, too.
Wash all your clothes. Get rid of the smell of cigarettes as much as you can by washing all your clothes and having your coats or sweaters dry-cleaned. If you smoked in your car, clean that out, too.
Think about your triggers. You're probably aware of the situations when you tend to smoke, such as after meals, when you're at your best friend's house, while drinking coffee, or as you're driving. These situations are your triggers for smoking — it feels automatic to have a cigarette when you're in them. Once you've figured out your triggers, try these tips:
Avoid these situations. For example, if you smoke when you drive, get a ride to school, walk, or take the bus for a few weeks. If you normally smoke after meals, make it a point to do something else after you eat, like read or call a friend.
Change the place. If you and your friends usually smoke in restaurants or get takeout and eat in the car, suggest that you sit in the no-smoking section the next time you go out to eat.
Substitute something else for cigarettes. It can be hard to get used to not holding something and having something in your mouth. If you have this problem, stock up on carrot sticks, sugar-free gum, mints, toothpicks, or even lollipops.
Expect some physical symptoms. If you smoke regularly, you're probably physically addicted to nicotine and your body may experience some symptoms of withdrawal when you quit. These may include:
headaches or stomachaches
crabbiness, jumpiness, or depression
lack of energy
dry mouth or sore throat
desire to pig out
Luckily, the symptoms of nicotine withdrawal will pass — so be patient. Try not to give in and sneak a smoke because you'll just have to deal with the symptoms longer.
Keep yourself busy. Many people find it's best to quit on a Monday, when they have school or work to keep them busy. The more distracted you are, the less likely you'll be to crave cigarettes. Staying active is also a good way to make sure you keep your weight down and your energy up, even as you're experiencing the symptoms of nicotine withdrawal.
Quit gradually. Some people find that gradually decreasing the number of cigarettes they smoke each day is an effective way to quit. However, this strategy doesn't work for everyone — you may find you have to stop completely at once. This is known as "cold turkey."
Use a nicotine replacement if you need to. If you find that none of these strategies is working, you might talk to your doctor about treatments. Using a nicotine replacement, such as gum, patches, inhalers, or nasal sprays, can be very helpful. Sprays and inhalers are available by prescription only, and it's important to see your doctor before buying the patch and gum over the counter. That way, your doctor can help you find the solution that will work best for you. For example, the patch requires the least effort on your part, but it doesn't offer the almost instantaneous nicotine kick that gum does.
If you slip up, don't give up! Major changes sometimes have false starts. If you're like many people, you may quit successfully for weeks or even months and then suddenly have a craving that's so strong you feel like you have to give in. Or maybe you accidentally find yourself in one of your trigger situations and give in to temptation. If you slip up, it doesn't mean you've failed, it just means you're human. Here are some ways to get back on track:
Think about your slip as one mistake. Take notice of when and why it happened and move on.
Did you become a heavy smoker after one cigarette? We didn't think so — it happened more gradually, over time. Keep in mind that one cigarette didn't make you a smoker to start with, so smoking one cigarette (or even two or three) after you've quit doesn't make you a smoker again.
Remind yourself why you've quit and how well you've done — or have someone in your support group, family, or friends do this for you.
Reward yourself. As you already know, quitting smoking isn't easy. Give yourself a well-deserved reward! Set aside the money you usually spend on cigarettes. When you've stayed tobacco free for a week, 2 weeks, or a month, buy yourself a treat like a new CD, book, movie, or some clothes. And every smoke-free year, celebrate again. You earned it.
First, congratulate yourself. Just reading this article is a huge step toward becoming tobacco free. Many people don't quit smoking because they think it's too hard to do. They think they'll quit someday.
It's true, for most people quitting isn't easy. After all, the nicotine in cigarettes is a powerfully addictive drug. But with the right approach, you can overcome the cravings.
The Difficulty in Kicking the Habit
Smokers may have started smoking because their friends did or because it seemed cool. But they keep on smoking because they became addicted to nicotine, one of the chemicals in cigarettes and smokeless tobacco. Nicotine is both a stimulant and a depressant. That means nicotine increases the heart rate at first and makes people feel more alert (like caffeine, another stimulant). Then it causes depression and fatigue. The depression and fatigue — and the drug withdrawal from nicotine — make people crave another cigarette to perk up again. According to many experts, the nicotine in tobacco is as addictive as cocaine or heroin.
But don't be discouraged; millions of Americans have permanently quit smoking. These strategies can help you quit, too:
Put it in writing. People who want to make a change often are more successful when they put it in writing. So write down all the reasons why you want to quit smoking, such as the money you will save or the stamina you'll gain for playing sports. Keep that list where you can see it, and add to it as you think of new reasons.
Get support. People whose friends and family help them quit are much more likely to succeed. If you don't want to tell your parents or family that you smoke, make sure your friends know, and consider confiding in a counselor or other adult you trust. And if you're having a hard time finding people to support you (if, say, all your friends smoke and none of them is interested in quitting), you might consider joining a support group, either in person or online.
Set a quit date. Pick a day that you'll stop smoking. Tell your friends (and your family, if they know you smoke) that you're going to quit smoking on that day. Just think of that day as a dividing line between the smoking you and the new and improved nonsmoker you'll become. Mark it on your calendar.
Throw away your cigarettes — all of your cigarettes. People can't stop smoking with cigarettes still around to tempt them. Even toss out that emergency pack you have stashed in the secret pocket of your backpack. Get rid of your ashtrays and lighters, too.
Wash all your clothes. Get rid of the smell of cigarettes as much as you can by washing all your clothes and having your coats or sweaters dry-cleaned. If you smoked in your car, clean that out, too.
Think about your triggers. You're probably aware of the situations when you tend to smoke, such as after meals, when you're at your best friend's house, while drinking coffee, or as you're driving. These situations are your triggers for smoking — it feels automatic to have a cigarette when you're in them. Once you've figured out your triggers, try these tips:
Avoid these situations. For example, if you smoke when you drive, get a ride to school, walk, or take the bus for a few weeks. If you normally smoke after meals, make it a point to do something else after you eat, like read or call a friend.
Change the place. If you and your friends usually smoke in restaurants or get takeout and eat in the car, suggest that you sit in the no-smoking section the next time you go out to eat.
Substitute something else for cigarettes. It can be hard to get used to not holding something and having something in your mouth. If you have this problem, stock up on carrot sticks, sugar-free gum, mints, toothpicks, or even lollipops.
Expect some physical symptoms. If you smoke regularly, you're probably physically addicted to nicotine and your body may experience some symptoms of withdrawal when you quit. These may include:
headaches or stomachaches
crabbiness, jumpiness, or depression
lack of energy
dry mouth or sore throat
desire to pig out
Luckily, the symptoms of nicotine withdrawal will pass — so be patient. Try not to give in and sneak a smoke because you'll just have to deal with the symptoms longer.
Keep yourself busy. Many people find it's best to quit on a Monday, when they have school or work to keep them busy. The more distracted you are, the less likely you'll be to crave cigarettes. Staying active is also a good way to make sure you keep your weight down and your energy up, even as you're experiencing the symptoms of nicotine withdrawal.
Quit gradually. Some people find that gradually decreasing the number of cigarettes they smoke each day is an effective way to quit. However, this strategy doesn't work for everyone — you may find you have to stop completely at once. This is known as "cold turkey."
Use a nicotine replacement if you need to. If you find that none of these strategies is working, you might talk to your doctor about treatments. Using a nicotine replacement, such as gum, patches, inhalers, or nasal sprays, can be very helpful. Sprays and inhalers are available by prescription only, and it's important to see your doctor before buying the patch and gum over the counter. That way, your doctor can help you find the solution that will work best for you. For example, the patch requires the least effort on your part, but it doesn't offer the almost instantaneous nicotine kick that gum does.
If you slip up, don't give up! Major changes sometimes have false starts. If you're like many people, you may quit successfully for weeks or even months and then suddenly have a craving that's so strong you feel like you have to give in. Or maybe you accidentally find yourself in one of your trigger situations and give in to temptation. If you slip up, it doesn't mean you've failed, it just means you're human. Here are some ways to get back on track:
Think about your slip as one mistake. Take notice of when and why it happened and move on.
Did you become a heavy smoker after one cigarette? We didn't think so — it happened more gradually, over time. Keep in mind that one cigarette didn't make you a smoker to start with, so smoking one cigarette (or even two or three) after you've quit doesn't make you a smoker again.
Remind yourself why you've quit and how well you've done — or have someone in your support group, family, or friends do this for you.
Reward yourself. As you already know, quitting smoking isn't easy. Give yourself a well-deserved reward! Set aside the money you usually spend on cigarettes. When you've stayed tobacco free for a week, 2 weeks, or a month, buy yourself a treat like a new CD, book, movie, or some clothes. And every smoke-free year, celebrate again. You earned it.
know your reproductivestatus
Reproductive System
Animals’ reproductive systems can be divided into the internal reproductive organs and the external genitalia. The gonads are the actual organs that produce the gametes. In the male, testes (singular = testis) produce sperm, and in the female, ovaries make eggs.
In most animals, individuals are either definite males or definite females. However, in some species, individual organisms are both male and female. Hermaphroditism is when one organism has both sexes. Earthworms and garden snails always have both male and female organs, and when, for example, two earthworms mate, they fertilize each other. A special variation on the theme is sequential hermaphroditism, in which an organism changes sex during its life. If an organism is female first and later changes to male, that organism is protogynous, and if the organism is male first and changes to female, it is said to be protandrous. In different species, sequential hermaphroditism can be influenced by the organism’s age or size or by various environmental/climatic factors.
While most higher animals reproduce sexually, there are some species in which the females can, under certain conditions, produce offspring without mating. Parthenogenesis is the ability of an unfertilized egg to develop and hatch. This seems to be especially prevalent among insects. Some of the giant walkingsticks at the Zoo are females who, without mating, lay eggs that hatch into more females generation after generation. Other insects, like some aphids, have complicated life cycles that involve sexually-reproducing generations alternating with parthenogenically produced generations. In honeybees, fertilized eggs turn into females (workers and queens), while unfertilized eggs, which are only produced in the spring, turn into males.
In sexual reproduction, there must be some way of getting the sperm to the egg. Since sperm and eggs are designed to be in a watery environment, aquatic animals can make use of the water in which they live, but terrestrial animals must, in some way, provide the wet environment neeeded for the sperm to swim to the egg. There are, thus, two major mechanisms of fertilization. In external fertilization, used by many aquatic invertebrates, eggs and sperm are simultaneously shed into the water, and the sperm swim through the water to fertilze the egg. In internal fertilization, the eggs are fertilized within the reproductive tract of the female, and then are covered with eggshells and/or remain within the body of the female during their development.
In species with external fertilization, at an appropriate developmental stage, the eggs hatch, and the new young simply swim away. However, females of species with internal fertilization must, at some point, expel the growing young. There are three general ways of doing this:
Oviparous organisms, like chickens and turtles, lay eggs that continue to develop after being laid, and hatch later.
Viviparous organisms, like humans and kangaroos, are live-bearing. The developing young spend proportionately more time within the female’s reproductive tract, portions of which are specially-modified for this purpose. Young are later released to survive on their own.
Ovoviviparous organisms, like guppies, garter snakes, and Madagascar hissing roaches, have eggs (with shells) that hatch as they are laid, making it look like “live birth.”
A discussion of the human male and female reproductive systems follows.(clipart edited from Corel Presentations 8)
Male Reproductive System
The male reproductive system is illustrated to the right. Sperm are produced in the testes located in the scrotum. Normal body temperature is too hot thus is lethal to sperm so the testes are outside of the abdominal cavity where the temperature is about 2° C (3.6° F) lower. Note also that a woman’s body temperature is lowest around the time of ovulation to help insure sperm live longer to reach the egg. If a man takes too many long, very hot baths, this can reduce his sperm count. Undescended testes (testes are supposed to descend before birth) will cause sterility because their environment is too warm for sperm viability unless the problem can be surgically corrected.
From there, sperm are transferred to the epididymis, coiled tubules also found within the scrotum, that store sperm and are the site of their final maturation.
In ejaculation, sperm are forced up into the vas deferens (plural = vasa deferentia). From the epididymis, the vas deferens goes up, around the front of, over the top of, and behind the bladder. A vasectomy is a fairly simple, outpatient operation that involves making a small slit in each scrotum, cutting the vasa deferentia near where they begin, and tying off the cut ends to prevent sperm from leaving the scrotum. Because this is a relatively non-invasive procedure (as compared to doing the same to a woman’s oviducts), this is a popular method of permanent birth control once a couple has had all the children they desire. Couples should carefully weigh their options, because this (and the corresponding female procedure) is not designed to be a reversible operation.
The ends of the vasa deferentia, behind and slightly under the bladder, are called the ejaculatory ducts. The seminal vesicles are also located behind the bladder. Their secretions are about 60% of the total volume of the semen (= sperm and associated fluid) and contain mucus, amino acids, fructose as the main energy source for the sperm, and prostaglandins to stimulate female uterine contractions to move the semen up into the uterus. The seminal vesicles empty into the ejaculatory ducts. The ejaculatory ducts then empty into the urethra (which, in males, also empties the urinary bladder).
The initial segment of the urethra is surrounded by the prostate gland (note spelling!). The prostate is the largest of the accessory glands and puts its secretions directly into the urethra. These secretions are alkaline to buffer any residual urine, which tends to be acidic, and the acidity of the woman’s vagina. The prostate needs a lot of zinc to function properly, and insufficient dietary zinc (as well as other causes) can lead to enlargement which potentially can constrict the urethra to the point of interferring with urination. Mild cases of prostate hypertrophy can often be treated by adding supplemental zinc to the man’s diet, but severe cases require surgical removal of portions of the prostate. This surgery, if not done very carefully can lead to problems with urination or sexual performance.
The bulbourethral glands or Cowper’s glands are the third of the accessory structures. These are a small pair of glands along the urethra below the prostate. Their fluid is secreted just before emission of the semen, thus it is thought that this fluid may serve as a lubricant for inserting the penis into the vagina, but because the volume of these secretions is very small, people are not totally sure of this function.
The urethra goes through the penis. In humans, the penis contains three cylinders of spongy, erectile tissue. During arousal, these become filled with blood from the arteries that supply them and the pressure seals off the veins that drain these areas causing an erection, which is necessary for insertion of the penis into the woman’s vagina. In a number of other animals, the penis also has a bone, the baculum, which helps to stiffen it. The head of the penis, the glans penis, is very sensitive to stimulation. In humans, as in other mammals, the glans is covered by the foreskin or prepuce, which may have been removed by circumcision. Medically, circumcision is not a necessity, but rather a cultural “tradition”. Males who have not been circumcised need to keep the area between the glans and the prepuce clean so bacteria and/or yeasts don’t start to grow on accumulated secretions, etc. there. There is some evidence that uncircumcised males who do not keep the glans/prepuce area clean are slightly more prone to penile cancer.
Female Reproductive System
The female reproductive system is illustrated to the right. “Eggs” are produced in the ovaries, but remember from our discussion of meiosis, that these are not true eggs, yet, and will never complete meiosis and become such unless/until first fertilized by a sperm. Within the ovary, a follicle consists of one precursor egg cell surrounded by special cells to nourish and protect it. A human female typically has about 400,000 follicles/potential eggs, all formed before birth. Only several hundred of these “eggs” will actually ever be released during her reproductive years. Normally, in humans, after the onset of puberty, due to the stimulation of follicle-stimulating hormone (FSH) one “egg” per cycle matures and is released from its ovary. Ovulation is the release of a mature “egg” due to the stimulation of leutenizing hormone (LH), which then stimulates the remaining follicle cells to turn into a corpus luteum which then secretes progesterone to prepare the uterus for possible implantation. If an egg is not fertilized and does not implant, the corpus luteum disintegrates and when it stops producing progesterone, the lining of the uterus breaks down and is shed.
Each “egg” is released into the abdominal cavity near the opening of one of the oviducts or Fallopian tubes. Cilia in the oviduct set up currents that draw the egg in. If sperm are present in the oviduct (if the couple has recently had intercourse), the egg will be fertilized near the far end of the Fallopian tube, will quickly finish meiosis, and the embryo will start to divide and grow as it travels to the uterus. The trip down the Fallopian tube takes about a week as the cilia in the tube propel the unfertilized “egg” or the embryo down to the uterus. At this point, if she had intercourse near the time of ovulation, the woman has no idea whether an unfertilized “egg” or a new baby is travelling down that tube. During this time, progesterone secreted by the corpus luteum has been stimulating the endometrium, the lining of the uterus, to thicken in preparation for possible implantation, and when a growing embryo finally reaches the uterus, it will implant in this nutritious environment and begin to secrete its own hormones to maintain the endometrium. If the “egg” was not fertilized, it dies and disintegrates, and as the corpus luteum also disintegrates, its progesterone production falls, and the unneeded, built-up endometrium is shed.
The uterus has thick, muscular walls and is very small. In a nulliparous woman, the uterus is only about 7 cm long by 4 to 5 cm wide, but it can expand to hold a 4 kg baby. The lining of the uterus is called the endometrium, and has a rich capillary supply to bring food to any embryo that might implant there.
The bottom end of the uterus is called the cervix. The cervix secretes mucus, the consistency of which varies with the stages in her menstrual cycle. At ovulation, this cervical mucus is clear, runny, and conducive to sperm. Post-ovulation, the mucus gets thick and pasty to block sperm. Enough of this mucus is produced that it is possible for a woman to touch a finger to the opening of her vagina and obtain some of it. If she does this on a daily basis, she can use the information thus gained, along with daily temperature records, to tell where in her cycle she is. If a woman becomes pregnant, the cervical mucus forms a plug to seal off the uterus and protect the developing baby, and any medical procedure which involves removal of that plug carries the risk of introducing pathogens into the nearly-sterile uterine environment.
The vagina is a relatively-thin-walled chamber. It servs as a repository for sperm (it is where the penis is inserted), and also serves as the birth canal. Note that, unlike the male, the female has separate opening for the urinary tract and reproductive system. These openings are covered externally by two sets of skin folds. The thinner, inner folds are the labia minora and the thicker, outer ones are the labia majora. The labia minora contain erectile tissue like that in the penis, thus change shape when the woman is sexually aroused. The opening around the genital area is called the vestibule. There is a membrane called the hymen that partially covers the opening of the vagina. This is torn by the woman’s first sexual intercourse (or sometimes other causes like injury or some kinds of vigorous physical activity). In women, the openings of the vagina and urethra are susceptible to bacterial infections if fecal bacteria are wiped towards them. Thus, while parents who are toilet-training a toddler usually wipe her from back to front, thus “imprinting” that sensation as feeling “right” to her, it is important, rather, that that little girls be taught to wipe themselves from the front to the back to help prevent vaginal and bladder infections. Older girls and women who were taught the wrong way need to make a conscious effort to change their habits.
At the anterior end of the labia, under the pubic bone, is the clitoris, the female equivalent of the penis. This small structure contains erectile tissue and many nerve endings in a sensitive glans within a prepuce which totally encloses the glans. This is the most sensitive point for female sexual stimulation, so senstiive that vigorous, direct stimulation does not feel good. It is better for the man to gently stimulate near the clitoris rather than right on it. Some cultures do a procedure, similar to circumcision, as a puberty rite in teenage girls in which the prepuce is cut, exposing the extremely-sensitive clitoris. There are some interesting speculations on the cultural significance of this because the sensitivity of the exposed clitoris would probably make having sexual intercourse a much less pleasant experience for these women.
Animals’ reproductive systems can be divided into the internal reproductive organs and the external genitalia. The gonads are the actual organs that produce the gametes. In the male, testes (singular = testis) produce sperm, and in the female, ovaries make eggs.
In most animals, individuals are either definite males or definite females. However, in some species, individual organisms are both male and female. Hermaphroditism is when one organism has both sexes. Earthworms and garden snails always have both male and female organs, and when, for example, two earthworms mate, they fertilize each other. A special variation on the theme is sequential hermaphroditism, in which an organism changes sex during its life. If an organism is female first and later changes to male, that organism is protogynous, and if the organism is male first and changes to female, it is said to be protandrous. In different species, sequential hermaphroditism can be influenced by the organism’s age or size or by various environmental/climatic factors.
While most higher animals reproduce sexually, there are some species in which the females can, under certain conditions, produce offspring without mating. Parthenogenesis is the ability of an unfertilized egg to develop and hatch. This seems to be especially prevalent among insects. Some of the giant walkingsticks at the Zoo are females who, without mating, lay eggs that hatch into more females generation after generation. Other insects, like some aphids, have complicated life cycles that involve sexually-reproducing generations alternating with parthenogenically produced generations. In honeybees, fertilized eggs turn into females (workers and queens), while unfertilized eggs, which are only produced in the spring, turn into males.
In sexual reproduction, there must be some way of getting the sperm to the egg. Since sperm and eggs are designed to be in a watery environment, aquatic animals can make use of the water in which they live, but terrestrial animals must, in some way, provide the wet environment neeeded for the sperm to swim to the egg. There are, thus, two major mechanisms of fertilization. In external fertilization, used by many aquatic invertebrates, eggs and sperm are simultaneously shed into the water, and the sperm swim through the water to fertilze the egg. In internal fertilization, the eggs are fertilized within the reproductive tract of the female, and then are covered with eggshells and/or remain within the body of the female during their development.
In species with external fertilization, at an appropriate developmental stage, the eggs hatch, and the new young simply swim away. However, females of species with internal fertilization must, at some point, expel the growing young. There are three general ways of doing this:
Oviparous organisms, like chickens and turtles, lay eggs that continue to develop after being laid, and hatch later.
Viviparous organisms, like humans and kangaroos, are live-bearing. The developing young spend proportionately more time within the female’s reproductive tract, portions of which are specially-modified for this purpose. Young are later released to survive on their own.
Ovoviviparous organisms, like guppies, garter snakes, and Madagascar hissing roaches, have eggs (with shells) that hatch as they are laid, making it look like “live birth.”
A discussion of the human male and female reproductive systems follows.(clipart edited from Corel Presentations 8)
Male Reproductive System
The male reproductive system is illustrated to the right. Sperm are produced in the testes located in the scrotum. Normal body temperature is too hot thus is lethal to sperm so the testes are outside of the abdominal cavity where the temperature is about 2° C (3.6° F) lower. Note also that a woman’s body temperature is lowest around the time of ovulation to help insure sperm live longer to reach the egg. If a man takes too many long, very hot baths, this can reduce his sperm count. Undescended testes (testes are supposed to descend before birth) will cause sterility because their environment is too warm for sperm viability unless the problem can be surgically corrected.
From there, sperm are transferred to the epididymis, coiled tubules also found within the scrotum, that store sperm and are the site of their final maturation.
In ejaculation, sperm are forced up into the vas deferens (plural = vasa deferentia). From the epididymis, the vas deferens goes up, around the front of, over the top of, and behind the bladder. A vasectomy is a fairly simple, outpatient operation that involves making a small slit in each scrotum, cutting the vasa deferentia near where they begin, and tying off the cut ends to prevent sperm from leaving the scrotum. Because this is a relatively non-invasive procedure (as compared to doing the same to a woman’s oviducts), this is a popular method of permanent birth control once a couple has had all the children they desire. Couples should carefully weigh their options, because this (and the corresponding female procedure) is not designed to be a reversible operation.
The ends of the vasa deferentia, behind and slightly under the bladder, are called the ejaculatory ducts. The seminal vesicles are also located behind the bladder. Their secretions are about 60% of the total volume of the semen (= sperm and associated fluid) and contain mucus, amino acids, fructose as the main energy source for the sperm, and prostaglandins to stimulate female uterine contractions to move the semen up into the uterus. The seminal vesicles empty into the ejaculatory ducts. The ejaculatory ducts then empty into the urethra (which, in males, also empties the urinary bladder).
The initial segment of the urethra is surrounded by the prostate gland (note spelling!). The prostate is the largest of the accessory glands and puts its secretions directly into the urethra. These secretions are alkaline to buffer any residual urine, which tends to be acidic, and the acidity of the woman’s vagina. The prostate needs a lot of zinc to function properly, and insufficient dietary zinc (as well as other causes) can lead to enlargement which potentially can constrict the urethra to the point of interferring with urination. Mild cases of prostate hypertrophy can often be treated by adding supplemental zinc to the man’s diet, but severe cases require surgical removal of portions of the prostate. This surgery, if not done very carefully can lead to problems with urination or sexual performance.
The bulbourethral glands or Cowper’s glands are the third of the accessory structures. These are a small pair of glands along the urethra below the prostate. Their fluid is secreted just before emission of the semen, thus it is thought that this fluid may serve as a lubricant for inserting the penis into the vagina, but because the volume of these secretions is very small, people are not totally sure of this function.
The urethra goes through the penis. In humans, the penis contains three cylinders of spongy, erectile tissue. During arousal, these become filled with blood from the arteries that supply them and the pressure seals off the veins that drain these areas causing an erection, which is necessary for insertion of the penis into the woman’s vagina. In a number of other animals, the penis also has a bone, the baculum, which helps to stiffen it. The head of the penis, the glans penis, is very sensitive to stimulation. In humans, as in other mammals, the glans is covered by the foreskin or prepuce, which may have been removed by circumcision. Medically, circumcision is not a necessity, but rather a cultural “tradition”. Males who have not been circumcised need to keep the area between the glans and the prepuce clean so bacteria and/or yeasts don’t start to grow on accumulated secretions, etc. there. There is some evidence that uncircumcised males who do not keep the glans/prepuce area clean are slightly more prone to penile cancer.
Female Reproductive System
The female reproductive system is illustrated to the right. “Eggs” are produced in the ovaries, but remember from our discussion of meiosis, that these are not true eggs, yet, and will never complete meiosis and become such unless/until first fertilized by a sperm. Within the ovary, a follicle consists of one precursor egg cell surrounded by special cells to nourish and protect it. A human female typically has about 400,000 follicles/potential eggs, all formed before birth. Only several hundred of these “eggs” will actually ever be released during her reproductive years. Normally, in humans, after the onset of puberty, due to the stimulation of follicle-stimulating hormone (FSH) one “egg” per cycle matures and is released from its ovary. Ovulation is the release of a mature “egg” due to the stimulation of leutenizing hormone (LH), which then stimulates the remaining follicle cells to turn into a corpus luteum which then secretes progesterone to prepare the uterus for possible implantation. If an egg is not fertilized and does not implant, the corpus luteum disintegrates and when it stops producing progesterone, the lining of the uterus breaks down and is shed.
Each “egg” is released into the abdominal cavity near the opening of one of the oviducts or Fallopian tubes. Cilia in the oviduct set up currents that draw the egg in. If sperm are present in the oviduct (if the couple has recently had intercourse), the egg will be fertilized near the far end of the Fallopian tube, will quickly finish meiosis, and the embryo will start to divide and grow as it travels to the uterus. The trip down the Fallopian tube takes about a week as the cilia in the tube propel the unfertilized “egg” or the embryo down to the uterus. At this point, if she had intercourse near the time of ovulation, the woman has no idea whether an unfertilized “egg” or a new baby is travelling down that tube. During this time, progesterone secreted by the corpus luteum has been stimulating the endometrium, the lining of the uterus, to thicken in preparation for possible implantation, and when a growing embryo finally reaches the uterus, it will implant in this nutritious environment and begin to secrete its own hormones to maintain the endometrium. If the “egg” was not fertilized, it dies and disintegrates, and as the corpus luteum also disintegrates, its progesterone production falls, and the unneeded, built-up endometrium is shed.
The uterus has thick, muscular walls and is very small. In a nulliparous woman, the uterus is only about 7 cm long by 4 to 5 cm wide, but it can expand to hold a 4 kg baby. The lining of the uterus is called the endometrium, and has a rich capillary supply to bring food to any embryo that might implant there.
The bottom end of the uterus is called the cervix. The cervix secretes mucus, the consistency of which varies with the stages in her menstrual cycle. At ovulation, this cervical mucus is clear, runny, and conducive to sperm. Post-ovulation, the mucus gets thick and pasty to block sperm. Enough of this mucus is produced that it is possible for a woman to touch a finger to the opening of her vagina and obtain some of it. If she does this on a daily basis, she can use the information thus gained, along with daily temperature records, to tell where in her cycle she is. If a woman becomes pregnant, the cervical mucus forms a plug to seal off the uterus and protect the developing baby, and any medical procedure which involves removal of that plug carries the risk of introducing pathogens into the nearly-sterile uterine environment.
The vagina is a relatively-thin-walled chamber. It servs as a repository for sperm (it is where the penis is inserted), and also serves as the birth canal. Note that, unlike the male, the female has separate opening for the urinary tract and reproductive system. These openings are covered externally by two sets of skin folds. The thinner, inner folds are the labia minora and the thicker, outer ones are the labia majora. The labia minora contain erectile tissue like that in the penis, thus change shape when the woman is sexually aroused. The opening around the genital area is called the vestibule. There is a membrane called the hymen that partially covers the opening of the vagina. This is torn by the woman’s first sexual intercourse (or sometimes other causes like injury or some kinds of vigorous physical activity). In women, the openings of the vagina and urethra are susceptible to bacterial infections if fecal bacteria are wiped towards them. Thus, while parents who are toilet-training a toddler usually wipe her from back to front, thus “imprinting” that sensation as feeling “right” to her, it is important, rather, that that little girls be taught to wipe themselves from the front to the back to help prevent vaginal and bladder infections. Older girls and women who were taught the wrong way need to make a conscious effort to change their habits.
At the anterior end of the labia, under the pubic bone, is the clitoris, the female equivalent of the penis. This small structure contains erectile tissue and many nerve endings in a sensitive glans within a prepuce which totally encloses the glans. This is the most sensitive point for female sexual stimulation, so senstiive that vigorous, direct stimulation does not feel good. It is better for the man to gently stimulate near the clitoris rather than right on it. Some cultures do a procedure, similar to circumcision, as a puberty rite in teenage girls in which the prepuce is cut, exposing the extremely-sensitive clitoris. There are some interesting speculations on the cultural significance of this because the sensitivity of the exposed clitoris would probably make having sexual intercourse a much less pleasant experience for these women.
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