Download - Figure 27-02a Figure 27-05c Figure 27-05b
Figure 27-02a
Figure 27-05c
Figure 27-05b
Figure 27-09c
The Penis
• Parts of the penis• glans penis = head of the penis• penile shaft = body of the penis• corona glandis = rounded ridge at
back end of the glans penis• penile prepuce (foreskin) = not
present in circumcised men; small glands under the foreskin secrete oil which when mixed with skin cells produces smegma
The Penis
• Retraction of the foreskin to remove smegma with soap and water is important to prevent bacterial infection.
• Penile shaft contains three cylindrical spongy tissue masses, two of which are the corpuscavernosa on the top of the shaft and the third is the corpus spongiosum on the bottom of the shaft(through which the urethra runs).
The Penis• Length of non-erect (flaccid) penis is
usually between 8.5 to 10.5 cm (3.3 to 4.1 inches) with an average of 9.5 cm (3.7 inches)
• The average length of an erect penis is 16 cm (6.3 inches) with a range of 12 cm to 23.5 cm(4.7 to 9.2 inches).
• Average circumference of an erect penis at its thickest point is 13.2 cm (5.2 inches)
• There is no correlation between skeletal system make-up and penis size. A smaller non-erect
penis will enlarge more during erection than a larger non-erect penis.
Figure 27-13
Figure 27-20a
The Clitoris
• The clitoris lies at the junction of the upper of the two labia minora above the urethral opening.
• The average length is about 2.5 cm (1 inch) with an average diameter of ½ inch. There is much individual variation with regard to size and shape.
The Clitoris
• The clitoral shaft (similar to the penile shaft) contains a pair of corpora cavernosa spongytissue cylinders. There is no corpus spongiosum in the clitoris.
• This tissue is the labia minora in females (same embryological origin as the corpus spongiosum in the penis).
• The clitoral glans (head or tip) is covered by the clitoral prepuce (similar to the foreskin of thepenis).
The Clitoris
• The clitoris is rich in deep pressure and temperature receptors with only few touch receptors.
• Plays an important role in sexual arousal. During the plateau phase the deep pressurereceptors are important for detecting stimulation of the retracted clitoris through the clitoral hood and mons.
Figure 27-09c
The Penis
• Parts of the penis• glans penis = head of the penis• penile shaft = body of the penis• corona glandis = rounded ridge at
back end of the glans penis• penile prepuce (foreskin) = not
present in circumcised men; small glands under the foreskin secrete oil which when mixed with skin cells produces smegma
The Penis
• Retraction of the foreskin to remove smegma with soap and water is important to prevent bacterial infection.
• Penile shaft contains three cylindrical spongy tissue masses, two of which are the corpuscavernosa on the top of the shaft and the third is the corpus spongiosum on the bottom of the shaft(through which the urethra runs).
The Penis• Length of non-erect (flaccid) penis is
usually between 8.5 to 10.5 cm (3.3 to 4.1 inches) with an average of 9.5 cm (3.7 inches)
• The average length of an erect penis is 16 cm (6.3 inches) with a range of 12 cm to 23.5 cm(4.7 to 9.2 inches).
• Average circumference of an erect penis at its thickest point is 13.2 cm (5.2 inches)
• There is no correlation between skeletal system make-up and penis size. A smaller non-erect
penis will enlarge more during erection than a larger non-erect penis.
Figure 27-13
Figure 27-20a
The Clitoris
• The clitoris lies at the junction of the upper of the two labia minora above the urethral opening.
• The average length is about 2.5 cm (1 inch) with an average diameter of ½ inch. There is much individual variation with regard to size and shape.
The Clitoris
• The clitoral shaft (similar to the penile shaft) contains a pair of corpora cavernosa spongytissue cylinders. There is no corpus spongiosum in the clitoris.
• This tissue is the labia minora in females (same embryological origin as the corpus spongiosum in the penis).
• The clitoral glans (head or tip) is covered by the clitoral prepuce (similar to the foreskin of thepenis).
The Clitoris
• The clitoris is rich in deep pressure and temperature receptors with only few touch receptors.
• Plays an important role in sexual arousal. During the plateau phase the deep pressurereceptors are important for detecting stimulation of the retracted clitoris through the clitoral hood and mons.
Infertility Rates and Woman’s Age in American Women
• Age Infertility Rate• 21-24 4.1%• 25 to 29 5.5%• 30 to 34 9.4%• 35 to 39 19.7%• Due to increase in chromosomal
abnormalities due to eggs arrested in Prophase I of Meiosis I
Menopause
• In vertebrates, only human females (African Elephants, Pilot Whales & Chimpanzees) live a significant portion of their lives postreproductively
• Average age of Menopause in U.S. = 52 years old • Normal age range for menopause is 45 to 55• Nulliparous women tend to have an earlier
menopause than women who were pregnant• Use of the pill tends to delay menopause
Stages of Menopause
• 1. Perimenopause begins several years before menopause, when the ovaries gradually produce less estrogen. Perimenopause lasts up until menopause, the point when the ovaries stop releasing eggs. In the last one to two years of perimenopause, the decrease in estrogen accelerates. At this stage, many women experience menopause symptoms.
• 2. Menopause is the point when a woman has her last menstrual period. At this stage, the ovaries have stopped releasing eggs and producing most of their estrogen. Menopause is diagnosed when a woman has gone without a period for 12 consecutive months.
• 3. Postmenopause is the time after menopause. During this stage, menopausal symptoms, such as hot flashes ease for most women. However, health risks related to the loss of estrogen increase as the woman ages.
Symptoms of Peri/Menopause
• Irregular Menstrual Periods• Hot Flashes• Night Sweats• Disturbed Sleep Patterns• Vaginal Dryness• Shrinkage of Genital Tissue• Dry Skin• Frequent Minor Vaginal Infections
Menopause Characteristics
• Menopausal Symptoms• Decrease in estrogen from ovaries• Significant decrease in progesterone once
she stops ovulating• During perimenopause = anovular cycles
with menstruation but no ovulation• Increased blood levels of LH and FSH due
to loss of negative feedback (4 – 10 X)
Premature Menopause
• Premature menopause can be the result of genetics, autoimmune disorders or medical procedures. Occurs in about 1 in 100 women.
• Premature Ovarian Failures - Normally, the ovaries produce both estrogen and progesterone. Changes in the levels of these two hormones occur when the ovaries, for unknown reasons, prematurely stop producing eggs. When this happens before the age of 40, it is considered to be premature ovarian failure. Unlike premature menopause, premature ovarian failure is not always permanent.
• “Induced" Menopause - occurs when the ovaries are surgically removed for medical reasons, such as uterine cancer or endometriosis. Induced menopause can also result from damage to the ovaries caused by radiation or chemotherapy.
Complications due to Menopause
• The loss of estrogen associated with menopause has been linked to a number of health problems that become more common as women age.
• After menopause, women are more likely to suffer from:• Osteoporosis (brittle-bone disease). • Heart Disease• Poor bladder and bowel function. • Poor brain function (increased risk of Alzheimer's disease). • Poor skin elasticity (increased wrinkling). • Poor muscle power and tone. • Some deterioration in vision, such as from cataracts (clouding of
the lens of the eye) and macular degeneration (breakdown of the tiny spot in the center of the retina that is the center of vision).
• There are a number of treatments to consider that can reduce the risks associated with menopause.
Pregnancy and Menopause
• Woman’s fertility more dependent on how close she is to menopause than her age
• Most infertility due to loss of pre-embryos or implanted embryos
• After 40 = more affected by ovarian function and failure to ovulate
• After age 42 = less than 10% chance of pregnancy• Decline in egg quality precedes the decline in egg
quantity
Evolution of Menopause
• Why did Menopause evolve in Humans?• Limits ovulation of abnormal oocytes• Younger mothers tolerate pregnancy, birth and
childcare stresses better• Higher risk of death in older mother and thus risk
her older children• Kin selection = “grandmother hypothesis” =
menopausal women can help in childcare and her daughter could have more children = increases grandmother’s evolutionary success
Andropause = “male menopause”
• Nothing like menopause; many men father children into their nineties• Due to decrease in androgen (testosterone) production as a man ages =
about 1% per year after age 40 • Due to decrease in ability of testes to respond to LH and FSH• Decreases in:• Ability to achieve and maintain erections• Facial hair growth; voice pitch may rise• Shrinkage of penis and scrotum• Muscle mass• Bone density = increased risk of osteoporosis• Sex drive (libido)
May lead to depression and irritability due above symptoms.