BMS 108 Ch. 20 Reproductive System

Question 0

How many chromosomes does each gamete have? What is a cell with 46 chromosomes called? 23?

Answer 0

23; diploid; haploid

Question 1

What is a gamete?

Answer 1

a sex cell formed in the gonads by meiosis

Question 2

What is a zygote?

Answer 2

a 46 chromosome cell resulting from fusion of sperm and egg during fertilization

Question 3

Each zygote inherits 23 chromosomes from mother and 23 from father. Producing 23 pairs of ___________ chromosomes. 22 of these are ___________ chromosomes and the 23rd pair are __________ chromosomes.

Answer 3

homologous; autosomal; sex

Question 4

What are the sex chromosomes of a female? male?

Answer 4

XX; XY

Question 5

How is chromosomal gender of the zygote determined?

Answer 5

All ova contain X chromosomes, some sperm contain X chromosomes and others contain Y chromosomes. Which type of sperm fertilizes the egg determines the sex of the zygote.

Question 6

What chromosome induces the formation of testes?

Answer 6

Y chromosome

Question 7

What induces the formation of male sex organs?

Answer 7

testosterone from the testes

Question 8

Gametes are produced by what process?

Answer 8

Meiosis

Question 9

There are two phases of meiosis, meiosis I and meiosis II. Where does the reduction in genetic material occur?

Answer 9

meiosis I

Question 10

What are the four phases of meiosis I? Meiosis II?

Answer 10

Prophase, metaphase, anaphase, telephase; same as meiosis I

Question 11

Describe the general interactions between the hypothalamus, anterior pituitary and gonads in the production of gametes.

Answer 11

• Hypothalamus releases GnRH to anterior pituitary
• Anterior pituitary releases LH and FSH which stimulates the production of sperm and eggs and gonadal sex steroids; also maintains the size of gonads
• sex steroids provide negative feedback to the hypothalamus and anterior pituitary
• gonads also secrete the hormone inhibin, which negatively feeds back on FSH secretion

Question 12

What causes puberty?

Answer 12

• FSH and LH secretion is high for first 6 mos. of life, but fall to very low levels until puberty
• At puberty hypothalamus increases GnRH secretion&raquo_space;> increases FSH and LH secretion
• Stimulates sex steroid secretion&raquo_space;> drives changes in secondary sex characteristics and menarche (first menstrual flow)

Question 13

What determines age of puberty in girls?

Answer 13

% body fat and activity level. Girls with low body fat and high activity levels enter puberty at an older age

Question 14

What is an ovarian follicle?

Answer 14

an oocyte + surrounding follicle cells

Question 15

What do follicle cells secrete?

Answer 15

estrogen

Question 16

Describe the production of oocytes.

Answer 16

• At 5 month gestation, ovaries contain 6-7 million oogonia
• Toward the end of gestation, oogonia become primary ooctyes and begin meiosis I, but arrest in prophase (2n)
• There is continual loss of primary oocytes throughout life (2 million left at birth, 400,000 left at puberty)
• 400 oocytes are ovulated during reproductive years, the rest undergo apoptosis (programmed cell death)

Question 17

Describe the process of follicular development.

Answer 17

• Primary follicle contains a primary ooctye & a layer of follicle cells
• In response to FSH, some follicles enter the ovarian cycle and grow
• Some primary follicles continue to develop and become secondary follicles (same as primary follicle but has more follicle cells and antrum)
• Graafian (mature) follicle contains a secondary ooctye (n) and is ready for ovulation

Question 18

What is the menstrual cycle?

Answer 18

a month long cycle of ovarian activity characterized by shedding of endometrial lining of the uterus and bleeding (menstruation)

Question 19

What is the follicular phase?

Answer 19

• Lasts from day 1 to about 13
• Dominated by growth of primary follicles into secondary follicles & production of estradiol
• One survivor becomes a graafian follicle, reaching peak at about day 12

Question 20

What is follicular growth and estrogen secretion dependent on?

Answer 20

FSH from the Anterior Pituitary

Question 21

What kind of receptors does FSH and estrogen recruit in graafian follicles?

Answer 21

LH

Question 22

Describe how the events in the follicular phase cause ovulation.

Answer 22

• Rapidly rising estrogen secretion causes the hypothalamus to increase pulses of GnRH, resulting in greater LH secretion
• A positive feedback between estrogen and anterior pituitary develops, resulting in a LH surge that causes ovulation

Question 23

What is the phase that follows the follicular phase?

Answer 23

the luteal phase

Question 24

Describe the luteal phase.

Answer 24

- After ovulation, LH causes the empty follicle to become the corpus luteum, secreting estrogen, progesterone & inhibin - This exerts negative feedback on LH and FSH (inhibin inhibits FSH only) - High estrogen and progesterone also triggers uterine lining buildup - If no fertilization occurs, corpus luteum regresses, causing estrogen and progesterone levels to drop - Causing menstruation and allowing a new cycle of follicle development

Question 25

In addition to the hormonal phases, there are also 3 cocurrent endometrial phases during the mentrual cycle. What are the 3 endometrial phases?

Answer 25

1. Menstrual 2. Proliferation 3. Secretory

Question 26

The male reproductive system makes _____ and secretes ______.

Answer 26

sperm; androgens

Question 27

Where is sperm made?

Answer 27

seminiferous tubules

Question 28

What FSH receptive cells initial spermatogenesis?

Answer 28

Sertoli cells

Question 29

What are the cells that secrete testosterone called? Where are they located?

Answer 29

Leydig cells; in the interstitial tissue in the seminiferous tubules

Question 30

In the male reproductive system, what inhibits GnRH? LH? FSH?

Answer 30

Testosterone; Testosterone; Inhibin

Question 31

Describe hormonal control of the male reproductive system.

Answer 31

- Hypothalamus secrets GnRH >>> Ant. Pit. >>> FSH & LH - FSH stimulates Sertoli cells, starting spermatogenesis and secreting inhibin - Inhibin causes negative feedback on FSH - LH stimulates Leydig cells, causing testosterone to be released - Testosterone inhibits LH in the Ant. Pit.

Question 32

What are the Sertoli cells functions?

Answer 32

1. Blood testes barrier 2. Nurture developing spermatozoa 3. Respond to FSH (ant. pit.) & Testosterone (Leydig) which stimulates spermiogenesis 4. Secrete Inhibin (negative feedback on FSH production)

Question 33

Describe the process of making sperm.

Answer 33

- Spermatogonia (stem cells) replicate via mitosis - Spermatogonia that will continue to develop is a primary spermatocyte - Primary spermatocyte undergoes meosis I and become a haploid secondary spermatocyte - Secondary spermatocyte undergoes meiosis II to make spermatids - Spermatids undergo spermiogenesis to become sperm All this takes place in the seminiferous tubules and involves sertoli (nurse) cells

Question 34

Why does spermatogenesis start with mitosis?

Answer 34

to keep our starter cells

Question 35

What does a spermatid develop during spermiogenesis?

Answer 35

a flagellum and acrosome cap

Question 36

What is an acrosome cap?

Answer 36

A cap of digestive enzymes for burrowing into an oocyte

Question 37

What are the functions of the male accessory sex organs?

Answer 37

sperm motility, seminal fluid secretion, and ejaculation

Question 38

Why aren't spermatozoa motile when entering the epididymus?

Answer 38

due to low pH

Question 39

What do the seminal vesicles add to the seminal fluid?

Answer 39

fructose (nutrients)

Question 40

What does the prostate add to the seminal fluid?

Answer 40

neutralizes pH, adds citric acid (nutrients) and coagulation proteins

Question 41

What do the bulbourethral gland add to the seminal fluid?

Answer 41

lubrication for the urethra and neutralizes pH

Question 42

What part of the ANS controls erection? ejaculation?

Answer 42

parasympathetic; sympathetic