Basic Physiology of the Reproductive System

Question 1

What is the male reproductive system responsible for?

Answer 1

Production (by testes) and transport of sperm

Production of androgens to support secondary sexual characteristics

Question 2

What is the transport channel for sperm?

Answer 2

Ductus/vas deferens

Question 3

What is the function of semen?

Answer 3

Provides nutrients/transportation fluid

Question 4

Where does semen come from?

Answer 4

60% seminal glands
30% prostate
5% bulbourethral glands

Question 5

What structures are the testes made up from?

Answer 5

Lobules containing seminiferous tubules

V. convoluted

Question 6

Where is the site of spermatogenesis?

Answer 6

Seminiferous tubules

Question 7

The seminiferous tubules merge to form which structure?

Answer 7

Epididymis

Question 8

What does a cross section of a ST look like?

Answer 8

Spermatogonium right at basement membrane and divide and move forward until they are mature sperm in the lumen

Question 9

Why is it important that blood doesn’t come into contact with STs?

Answer 9

Sperm haploid and looks different so don’t want immune cells interpreting as non-self and destroying them

Question 10

How many sperm would you get from each spermatogonium?

Answer 10

512

Question 11

How much sperm does the epididymis store?

Answer 11

5ml

Question 12

What are some functions of Sertoli cells?

Answer 12

Form blood-testis barrier
Isolate haploid secondary spermatocytes, spermatids, spermatozoa from the immune system
Physically move sperm towards the lumen (spermiation)
Provide nutrients for sperm
Remove waste from sperm
Remove excess cytoplasm following cell divisions

Question 13

Define spermatogenesis
How long does it take?
Where does it occur?

Answer 13

Process of forming mature sperm
75 days
STs

Question 14

Define spermatocytogenesis

Answer 14

Mitotic divisions of spermatogonia (undifferentiated male germ cells) to produce primary spermatocytes

Question 15

What occurs after spermatocytogenesis?

Answer 15

Two meiotic divisions
Meiosis I - primary spermatocytes double up DNA and there is separation of homologous chromosomes that go to make secondary spermatocytes
Meiosis II - secondary spermatocytes half again (separation of chromatids) to make spermatids

Question 16

Define spermiogenesis?

Answer 16

Maturation of spermatids into mature, motile sperm

Occurs in epididymis

Question 17

How long is the sperm stored in the epididymis until it becomes motile?

Answer 17

15 days

Question 18

Where is the final maturation of the sperm?

Answer 18

In the female genital tract that allows it to penetrate the egg and have increased motility

Question 19

What is the blood supply to the testis like?

Answer 19

Arterial blood enters dense network of capillaries coming from testis/epididymis before reaching spermatic cord - this cools it and helps to maintain a constant testicular temperature

Question 20

At what temperature do sperm optimally develop?

Answer 20

32 degrees

Question 21

What two things contribute to keeping the testis slightly cooler than the body in order to maintain optimal spermatogenesis?

Answer 21

Testis outside body

Counter-current heat exchange

Question 22

What factors can affect spermatogenesis?

Answer 22

Testis temperature, should be 2 degrees below body temp, hyperthermia, mumps, measles etc. can raise it

Endocrine: reduces gonadotrophins/androgens, anabolic steroids –> reduced testosterone

Loss of blood-testis barrier: e.g. by physical damage

Immunological reactions - autoimmune disease

Environment - occupation (e.g. car industry, pesticide exposure), radiation (reduces sperm)

Medication - some antidepressants and anti-HTN

Question 23

What two things are associated with a lower sperm count?

Answer 23

Smoking

Alcohol

Question 24

Where does LH act on?

Answer 24

Leydig cells to produce testosterone

Question 25

Where does testosterone act on?

Answer 25

CNS - aggressive behaviour Ant pituitary Penis (erective, copulatory, ejaculatory effectiveness) Striated muscle Prostate & seminal vescicles Testis Systemically deepens voice, leads to male body hair, increased sebaceous gland activity and protein anabolism

Question 26

What is the structure of the ovaries?

Answer 26

Outer cortex containing follicles | Inner medulla containing BVs

Question 27

How many primordial follicles are there in the ovaries at birth?

Answer 27

2 million

Question 28

What kind of cells line the primary, secondary and tertiary follicles? What do these cells produce?

Answer 28

Granulosa cells | Oestrogen

Question 29

Where does fertilisation most commonly occur?

Answer 29

Ampulla of fallopian tube one day after ovulation

Question 30

Define oogenesis

Answer 30

Production of an ovum

Question 31

Describe the process of oogenesis

Answer 31

Mitotic division of oogonium --> primary oocytes Girls born with primordial follicles containing primary oocytes and surrounding later of follicular cells Primordial follicles turn into primary follicles after puberty (follicular cells --> granulosa cells) A few primary follicles in each menstrual cycle develop into secondary follicles and then tertiary follicles (Graafian follicles) FSH makes a few Graafian follicles grow and produce more oestrogen Neg feedback of oestrogen leads to less FSH --> only one follicle becomes dominant Oestrogen leads to positive feedback eventually --> LH surge which triggers the primary oocyte to complete meiosis I (become secondary oocyte) & released into fallopian tube

Question 32

From infancy to puberty, which stage of meiosis I are primary oocytes stuck in?

Answer 32

Prophase

Question 33

After the primary oocyte is released, what does the follicle turn into?

Answer 33

Corpus luteum

Question 34

What does the CL produce?

Answer 34

Inhibin which prevents pituitary making FSH and oestrogen falls so LH drops

Question 35

Which cells make progesterone?

Answer 35

Lutenised theca cells of CL

Question 36

Until when does the CL make progesterone?

Answer 36

Until placenta has developed

Question 37

If the egg isn't fertilised what happens to the CL?

Answer 37

Stops making hormones after about 10 days | Becomes fibrotic and white (corpus albicans)

Question 38

Low oestrogen exerts what kind of feedback?

Answer 38

Negative

Question 39

High oestrogen exerts what kind of feedback?

Answer 39

Positive --> LH surge at about day 12

Question 40

What does GnRH do?

Answer 40

Released from hypothalamus acts on anterior pituitary to stimulate release of LH and FSH

Question 41

What does LH do?

Answer 41

Maintains dominant follicle, induces maturation and ovulation, stimulate CL function

Question 42

What does FSH do?

Answer 42

Stimulates follicle recruitment and development

Question 43

What does oestradiol do?

Answer 43

Supports female secondary sexual characteristics and reproductive organs Negative & positive feedback control Stimulates proliferation of endometrium

Question 44

What does progesterone do?

Answer 44

Maintains secretory epithelium

Question 45

What is the average age of menopause?

Answer 45

51

Question 46

Where does oestrogen act in the body?

Answer 46

``` CNS Ant. pituitary Hypothalamus Fat distribution Mammary glands Bone maturation and turn over Uterus, cervix, vagina, fallopian tubes ```

Question 47

What does oestrogen do in the fallopian tubes?

Answer 47

Induces proliferation of ciliated cells that brush the egg into the uterus

Question 48

What is a reliable sign of ovulation?

Answer 48

Day 21 progesterone

Question 49

What values of FSH/LH/oestradiol/progesterone do you get in menopause?

Answer 49

High FSH and LH | Low oestradiol and progesterone