Chapter 20: ReproductionThis is a featured page

Birth animation rotated to make physiological sense



Differences between male and female reproductive systems:
Similarities between male and female reproductive systems
The reproductive systems of the male and female have some basic similarities and some specialized differences. They are the same in that most of the reproductive organs of both sexes develop from similar embryonic tissue, meaning they are homologous. Both systems have gonads that produce tes (sperm or semen and egg or ovum) and sex organs. And both systems experience further development of the reproductive organs, which mature and become functional during puberty as a result of the gonads secreting sex hormones (testosterone and estrogen).
The human male reproductive system
Chapter 20: Reproduction - The PhysiWiki Page
The human male reproductive system
Cross-sectional diagram of the female reproductive organs.
Cross-sectional diagram of the female reproductive organs.
In short, this is a known list of sex organs that evolve from the same tissue in a human life.



The differences between the female and male reproductive systems are based on the functions of each individual's role in the reproduction cycle. A male who is healthy, and sexually mature, continuously produces sperm. A woman's ova (eggs) are completely formed during fetal development. The glans of the penis is homologous to the clitoris. The scrotum is homologous to the labia majora.
At about 5 months gestation, the ovaries contain approximately six to seven million oogonia, which then go through meiosis, and are matured into oocytes.
The ovaries of a newborn baby girl contain about two million oocytes. This number declines to 300,000 to 400,000 by the time puberty is reached. On average, 400 oocytes are ovulated during a woman's reproductive lifetime.
When a young woman reaches puberty around age 12 or 13, an ova (one of the matured oocytes) is discharged from alternating ovaries every 28 days. This continues until the woman reaches menopause, usually around the age of 50 years. Occytes are present at birth, and ages as a woman ages. This may be one reason older women are more likely to have a hard time becoming pregnant or more likely to have children with genetic defects.Female Reproductive System
  • Produces eggs (ova)
  • Secretes sex hormones
  • Receives the male spermatazoa during
  • Protects and nourishes the fertilized egg until it is fully developed
  • Delivers fetus through birth canal
  • Provides nourishment to the baby through milk secreted by mammary glands in the breast

CHROMOSOMES

Chapter 20: Reproduction - The PhysiWiki Page

There are 23 pairs of chromosomes
46 in every cell
22 match identically in male
X--1,098 genes
Y--80 genes and is smaller than X
There are 168 known diseases that are X linked. Most genetic diseases are, of course, not linked to the X-chromosome. For a good resource on genetic diseases check out this wiki site (which was made by a class of 8th graders!).

Somatic cells are diploid, wheras sex cells are haploid. Birds do not have a penis. What determines sexual phenotype? The default for embryonic development is female development.

Testosterone: is secreted by the interstitial Leydig cells under stimulation by LH
LH: receptor proteins are located in the interstitial tissue.
FSH: receptors are located in the Sertoli cellls within the seminiferous tubules.
The Leydig cells of the interstitial compartment of the Sertoli cells of the tubular compartment of the testes secrete autocrine regulatory molecules that allow the two compartments to interact.

Tesosterone- onceinside particular target cells, testosterone is converted by the enzyme, 5a-reductase into the active hormone known as dihydrotestosterone (DHT). DHT is needed for the development and maintenance of the penis, spongy urethra, scrotum and prostate.

Sperm production takes place in the spermiferous tubules. Complete development of sperm is in the epididymus. Seminal vesicles provide a buffer for the acidic environment of the vagina. In the testis, sperm production takes place continuously (about 1,000 oer second). It takes 65 days to mature one sperm. At puberty the quiescent gonocytes give rise to spermatogonia. Sertoli cells constitute a blood/testis barrier. Sperm must pass through cytoplasm of the Sertoli cells before entering the germinal cells.

In treatment of erectile dysfunction (ED), or impotence, Viagra is commonly prescribed. It has a 60-80% success rate. the cGMP acts as a second messenger leading to smooth muscle relaxation and vasodilation, which increased the blood flow to the penis to maintain erection.

Chapter 20: Reproduction - The PhysiWiki Page

Chapter 20: Reproduction - The PhysiWiki Page
Barr body is an inactive X chromosome in female cells. This was used in the 1966 Olympic games to test if female athletes were really female. They found several women with Testicular Feminization Syndrome.
These individuals are geno-typically male (xy) but developed physically as females, due to a defect in the androgen receptor gene. They lack pubic hair and have a vagina but never menstruate and are always sterile.

XXY (also known as Klenfelter’s syndrome): affects 1 or 2 out of every 1000 males. Symptoms vary and many have no detectable signs, but generally sterile.


XO (also known as Turner’s syndrome): 1 in 2000 female babies are born with this monosomy -1 in 1000 women have a XXX trisomy and are phenotypically normal. Failure of feminization at puberty is the main problem and cause for diagnosis.

An Overview of Reproductive physiology:
Human reproduction involves the fundamental processes of gametogenesis, fertilization, pregnancy, and parturition. Reproductive ability is acquired during puberty, during which the reproductive organs mature, gametogenesis begins, and secondary sex characteristics develop. Males are able to reproduce continuously through adulthood, but in females reproductive capacity is cyclic and is lost at menopause.
The male and female reproductive systems include the gonads (testes in males and ovaries in females), which carry out gametogenesis and secrete sex hormones (androgens in males and estrogens and progesterone in females), and accessory reproductive organs, which include organs of the reproductive tract and various glands that secrete fluids into the tract. (taken from Principles of Human Physiology)

VASECTOMY
A vasectomy is a surgical procedure performed on men to prevent unwanted pregnancies. The vasectomy can be performed by a urologist and some family practitioners. A vasectomy interferes with sperm transport but does not interfere with the secretions of androgens from Leydig cells in the interstitial tissue. During the procedure the Dr. will use a local anesthesia to numb up the scrotum. A small incision is made in the scrotal sac. The vas deferens or ductus deferens are pulled through the incision and a small section is taken out of both. The incision is sewn up. Recovery is 3-7 days. The man is to follow up with semen analysis until the count is zero. A reversal is possible, but there is a chance that he will produce anti-sperm antibodies.

vasectomy

Female Reproductive Cycle
The ovary isn't connected directly to the fallopian tube. Ovaries are the primary sex organs. Other organs involved are the clitoris, vagina, urethra, cervix, labia minora, labia majora. The ovaries are well protected within the pelvis.
In the ovaries oocytes are produced, it is also the site of fertilization.

Women conceiving over the age of 50, have a 10% chance of giving birth to a child with Down's Syndrome. If multiple eggs are fertilized, Fraternal twins is the result. Mittleshmertz is ovulatory pain i.e. knowing when one ovulates.

Once an egg is fertilized in travels down the fallopian tube to the uterus where implantation occurs. The uterus is a sterile environment. The endometrial layer has to thicken for implantation to occur.

Having infertility problems? Eat more ice cream!


Questions

1. Which male organ is homologous to a woman's ovary?
a. glans of penis
b. bulbourethral glands
c. testes
d. scrotum

2. Which of these structures release testosterone into the male reproductive system?
a. Cells of Leydig
b. Androgenous cells
c. Orchitic cells
d. Sertoli (nurse) cells

3. All of the following are female secondary sex characteristics except...
a. Clitoris
b. Ovaries
c. Breasts
d. Feminine Shape

4. The release of a mature oocyte in the female reproductive system is also known as __________.
a. Menarche
b. Ovulation
c. Puberty
d. Amenorrhea

5. How long does it take for a sperm to mature?
a. 30 days
b. 45 days
c. 65 days
d. 2 weeks

6. What is a homologous tissue?
a. a tissue that has the same genes.
b. a tissue that has the same tissues but develop into different functions.
c. no such thing.
d. produces sperm.

7. A person with the genotype XO has
a. ovaries.
b. testes.
c. both ovaries and testes.
d. neither ovaries nor testes.

8. What determines the sex phenotype in humans?
a. somatic cells
b. adult stem cells
c. gonadotropin
d. chromosomes

9. Fertilization normally occurs in...?
a. the ovaries
b. the uterine tubes
c. the uterus
d. the vagina

10. Uterine contractions are stimulated by?
a. oxytocin
b. prostaglandins
c. prolactin
d. both a and b
e. both b and c

11. When does ovulation occur?
a. when progesterone levels goes up and peaks
b. when progesterone levels goes down.
c. when estrogen levels goes down.
d. when estrogen levels goes up and peaks

12. Joe has a bulge in the groin area that seems to get worse when he lifts things. This most likely is
a. epididymitis
b. testicular cancer
c. varicocele
d. hydrocele
e. inguinal hernia

13. Sally has noticed that her cervical mucus has changed and now resembles egg whites- from this Sally could assume
a. her period will begin soon
b. nothing, this is a normal occurrence
c. she has a yeast infection
d. she is ovulating

14. Debbie recently went to the OBGYN and was diagnosed with PCOS (polycystic ovary syndrome) because of this she has
a. nothing, its normal in women
b. antisperm antibodies
c. an overproduction of LH
d. leaking of milk from her mammary glands
e. problems becoming pregnant

15. An embryo with the genotype XX develops female accessory sex organs because of?
a. androgens
b. estrogens
c. lack of androgens
d. lack of estrogens

16. The contents of the birth control pill
a. inhibit secretion of gonadotrophins
b. exert negative feedback on the hypothalamus
c.prevent ovulation
d. maintain the endometrium
e. all of these



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