Module 14

Question 1

List the overall functions of both reproductive systems

Answer 1

Pass on genes of the individuals

Maintain the species

Question 2

Describe the fetal development of the reproductive system before differentiation

Answer 2

First 6 weeks, common/indifferent gonads
Two sets of primitive reproductive tracts: Wolffian duct (mesonephric) and Mullerian duct (paramesonephric)
At 6-7 weeks, presence of Y chromosome causes gonads to develop into testes
At 9 weeks, XX chromosomes are activated and ovaries develop

Question 3

Describe male fetus development

Answer 3

7 weeks: testicular cells begin to produce MIH, causing Mullerian duct to regress
9 weeks: testicular cells begin producing testosterone, stimulating Wolffian duct to develop into epididymis, vas deferens, seminal vesicles, and urethra, then external genitalia

Question 4

Describe female fetus development

Answer 4

Development of the reproductive tract and external genitalia requires no hormonal control
Since no MIH, Mullerian duct develops into fallopian tubes, uterus, cervix, and part of vagina
Since no testosterone, Wolffian duct regresses and female external genitalia develop

Question 5

List the functions of the male reproductive system

Answer 5

Produce testosterone
Produce sperm (spermatogenesis)
Deliver sperm to the female vagina

Question 6

List the functions of the female reproductive system

Answer 6

Producing estrogen and progesterone
Produce eggs
Receive sperm
Provide the optimal conditions for the development of the fetus

Question 7

List the parts of the male reproductive system

Answer 7

External genitalia: penis and scrotum
Penis: urethra, glans penis, corpus spongiosum and cavernosum
Scrotum: testes and epididymis
Ductus/vas deferens, seminal vesicles, prostate, bulbourethral gland
Testes: seminiferous tubules, Sertoli cells, Leydig cells

Question 8

Describe the function of the seminiferous tubules

Answer 8

Site of spermatogenesis

Question 9

Describe the function of Sertoli cells

Answer 9

Regulate spermatogenesis, maintain developing sperm cells, produce inhibin, secrete fluid that pushes immature sperm into epididymis, form the BTB
BTB isolates developing sperm cells from blood so immune system won’t attack and destroy them

Question 10

Describe the function of Leydig cells

Answer 10

Produce testosterone

Located in the interstitial space between seminiferous tubules

Question 11

Describe the function of the epididymis

Answer 11

Final maturation area for sperm

Storage site for sperm

Question 12

Describe the function of the vas deferens

Answer 12

Carries sperm from the epididymis to the ejaculatory duct, which drains into the urethra

Question 13

Describe the function of the seminal vesicles

Answer 13

Contribute fluid to semen during ejaculation

The fluid is rich in fructose and enzymes and helps maintain and nourish sperm

Question 14

Describe the function of the prostate gland

Answer 14

Secretes enzymes and fluid that help neutralize the acid environment of the urethra and vagina

Question 15

Describe the function of the bulbourethral gland

Answer 15

Secretes fluid that helps neutralize the pH and lubricate the urethra and vagina to create an optimal environment for the sperm

Question 16

Describe the function of the urethra (in males)

Answer 16

Transports sperm during ejaculation and drains the bladder during urination

Question 17

Describe spermatogenesis

Answer 17

At beginning of puberty, sperm production begins
Germ cells contain 46 chromosomes, located at outer edge of seminiferous tubules, divide by mitosis into spermatogonia and primary spermatocyte
Primary spermatocyte undergoes meiosis into secondary spermatocytes then spermatids (23 chromosomes)
Dividing cells are surrounded by Sertoli cells, make their way into center of tubule
Spermatids develop into sperm cells, released by Sertoli cells into lumen of seminiferous tubules
Takes 64 days
Complete maturation takes 12 more days as sperm moves to epididymis by fluid secreted by Sertoli cells

Question 18

Describe the structure of sperm cells

Answer 18

Head with an acrosome and nucleus
Midpiece with mitochondria
Long tail or flagellum to propel itself once mature

Question 19

Describe the control of testicular function

Answer 19

Functions of testes controlled by FSH and LH
FSH acts on Sertoli cells to promote spermatogenesis while producing inhibin (feeds back to AP to decrease release of LH and FSH)
LH stimulates Leydig cells to produce testosterone (feeds back to both H and AP to decrease LH and FSH)

Question 20

List the functions of testosterone

Answer 20

Development of male reproductive tract and external genitalia in embryo
Growth and development of all male reproductive organs at puberty
Development of male secondary sex characteristics at puberty
Sex drive at puberty
Spermatogenesis
Bone and skeletal muscle growth
Increased aggression

Question 21

Define testosterone (in males)

Answer 21

A steroid hormone produced by Leydig cells in the testes

Question 22

Describe the production of testosterone

Answer 22

A series of complex reactions, begins with cholesterol, forms several intermediates, ends with testosterone
Cholesterol and testosterone are very structurally similar
Progesterone is one of the intermediates

Question 23

Describe testosterone levels in relation to age

Answer 23

Rise during fetal development, and brief rise after birth
Remain low until puberty
Between 9-14, GnRH begins to increase, leads to increase in LH and FSH, causing increase in T
16-18 sexual maturity and peak T levels
Beginning at 40, slow decrease in T levels
At 50, sperm production decreases

Question 24

Define andropause

Answer 24

Period of decreased testosterone production after 40, may occur because Leydig cells no longer fully respond to LH
Accompanied by decreased sexual desire and erectile ability, fatigue and depression, decreased lean body mass, increased obesity, decreased bone density

Question 25

List the parts of the female reproductive system

Answer 25

External genitalia: vulva Vulva: clitoris, labia majora, labia minora, vaginal orifice Internally: vagina, cervix, uterus, fallopian tubes, fimbria, ovaries

Question 26

Describe the function of the vagina

Answer 26

Receives the penis and sperm during copulation, allows for discharge of fluid during menstruation, and the birth of the baby

Question 27

Describe the function of the cervix

Answer 27

Secretes mucus that varies during the menstrual cycle - from thin to facilitate sperm entry to thick to prevent sperm entry

Question 28

Describe the function of the uterus

Answer 28

The site of implantation of the fertilized egg, and where the developing embryo is nourished and maintained During menstruation, the uterine lining undergoes several phases under hormonal control

Question 29

Describe the function of the fallopian tubes

Answer 29

The site of fertilization of the egg, contain cilia that pass the egg from the fimbria to the uterus

Question 30

Describe the function of the fimbria

Answer 30

Capture the egg after it is expelled from the ovaries and funnel it into the infundibulum

Question 31

Describe the function of the ovaries

Answer 31

Produce eggs (oogenesis), and produce estrogen and progesterone

Question 32

Define oogenesis

Answer 32

The production of one viable oocyte

Question 33

Describe oogenesis

Answer 33

During development, egg contained in a follicle First stage: begins with production of several million oogonia in embryo Develop into primary follicles, consist of outer granulosa cells and contain the primary oocyte Granulosa cells secrete fluid into interior follicle, forms antrum Primary oocyte and follicle remain this way until puberty At puberty, ovaries activated by GnRH (only several hundred thousand primary oocytes and follicles survived, and menstruation begins) After puberty, primary follicle develops theca cells outside granulosa cells Primary follicle enlarges and develops into mature follicle Oocyte separates from granulosa cells, floats into antrum

Question 34

Describe ovulation

Answer 34

Follicle grows, production of estrogen from ovaries increases dramatically, causes granulosa cells to grow and produce more estrogen Instead of decreasing LH and FSH, increases both LH surge causes granulosa cells to secrete large amounts of fluid into antrum, causing swell, rupture, and expelling egg Egg gathered by fimbria into fallopian tube Mature follicle degenerates into corpus luteum Corpus luteum degenerates into corpus albicans if no fertilization

Question 35

Define estrogen

Answer 35

A group of hormones, including 17B-estradiol, estrone, and estriol Principal estrogen secretes by ovaries in humans is estradiol, which is more potent than estrone or estriol

Question 36

Describe the production of estrogen

Answer 36

Similar to testosterone, continuation of same series of reactions Requires uptake of cholesterol by the ovaries LH stimulates theca cells to convert cholesterol into androstenedione Small amount of androstenedione converted to estradiol by theca cells and released into circulation Majority of astrostenedione secreted into granulosa cells to convert into estradiol due to FSH

Question 37

Describe the production of progesterone

Answer 37

Produced in small quantities by both granulosa cells and theca cells before ovulation LH stimulates both cells to produce progesterone After ovulation of the oocyte, mature follicle degenerates into corpus luteum, which secretes E and large amounts of P to prepare lining of uterus for implantation If no implantation, corpus luteum becomes scar tissue P levels vary during menstrual cycle

Question 38

Describe estrogen levels in relation to age

Answer 38

Low levels of E during childhood until puberty Between 8-13, dramatic rise in E, caused by increased secretion of GnRH from H, increases LH and FSH Pulsate nature of E levels due to very high levels causing positive feedback at AP, producing LH surge to cause ovulation E levels reach peak then begin to decline in adulthood Between 40-50, menstrual cycle becomes irregular, ovulation may not occur during some cycles Cycles stop around 50

Question 39

Define and describe menopause

Answer 39

Period of decreased E production and cessation of menstrual cycles Seems to be caused by decrease in number of primary follicles in the ovaries With fewer follicles, less E produced, little negative feedback, rise in LH and FSH, resulting in ovaries less responsive to high levels of LH and FSH, causing drop in E levels Menopause characterized by hot flashes, irritability and anxiety, fatigue, lack of strength, decreased bone density

Question 40

List the stages of the menstrual cycle

Answer 40

Proliferative phase, days 7-14 Secretory/luteal phase, days 14-28 Menses, days 0-7 Cycle repeats

Question 41

Describe the proliferative phase of the menstrual cycle

Answer 41

Days 7-14 Follicle increases production of E, causing LH surge Follicle ruptures, egg expelled E and P stimulate growth of uterine lining

Question 42

Describe the secretory/luteal phase of the menstrual cycle

Answer 42

Day 14-28 Follicle develops into corpus luteum, increases production of P that prepares uterus for implantation If fertilization and implantation don't occur, corpus luteum becomes corpus albicans and P levels drop

Question 43

Describe menses of the menstrual cycle

Answer 43

Days 0-7 Levels of LH, FSH, E and P are low Lining of uterus cannot be maintained, uterine lining lost

Question 44

Describe the birth control pill

Answer 44

Most widely used contraception in NA, two principal hormones, synthetic E and/or P in different combinations and strengths Contraceptive effects occur by several mechanisms, including decreasing GnRH, LH and FSH levels by introducing E and P that act like natural hormones Synthetic P produces thick cervical mucus to inhibit sperm entering the uterus, and decreases motility of uterus and fallopian tubes