Reproductive physiology

Question 1

what do the testis contain?

Answer 1

• seminiferous tubules: to produce sperm

- Leydig cells: produce testosterone

Question 2

what is the epididymis? what’s stored in them?

Answer 2

• one within each scrotal sac
• sperm stored in them
• at ejaculation, sperm passed through vas deferens
• mixed with fluid from seminal vesicles
• fluid leaves duct and passes into urethra to mix with prostrate secretions

Question 3

what do leydig cells release? what stimulates them?

Answer 3

• testosterone

- LH stimulated

Question 4

what do sertoli cells release? what stimulates them?

Answer 4

• inhibin

- FSH stimulated

Question 5

describe spermatogenesis

Answer 5

- Germ cells (44XY)
mitotic division
- primary spermatocyte (44XY)
1st meiotic division
- secondary spermatocyte (22X, 22Y)
2nd meiotic division
- spermatids (22X, 22Y)
- spermatozoa (22X, 22Y)

Question 6

what does the ovary produce?

Answer 6

• gametes

- steroids (oestrogens and progesterones)

Question 7

what do the fallopian tubes do?

Answer 7

• sustains oocyte

- conceptus

Question 8

what happens in the uterus?

Answer 8

• conceptus implants here

Question 9

what do thecal cells release? What stimulates them?

Answer 9

• oestrogen and androgens

- LH stimulates

Question 10

what do granulosa cells release? what stimulates?

Answer 10

• androgens –> oestradiol
• produce progesterone in second half of cycle
• FSH stimulates

Question 11

what do progestogens and oestrogens do to endometrium?

Answer 11

• progestogens: maintain endometrium

- oestrogens: stimulate proliferation of endometrium

Question 12

what 2 cycles is the menstrual cycle composed of?

Answer 12

• endometrial: menstrual, repair, proliferative, secretory phases
• ovarian: follicular, luteal phases

Question 13

describe the hormonal changes that cause the movement between stages of the cyle

Answer 13

1. FSH and LH stimulate follicular phase
   - results in oestradiol production = endometrial proliferation
2. oestradiol (E2) production continues at greater pace. -ve feedback switches to +ve
   - ovulation occurs
3. corpus luteum produces progesterone and E2
   - endometrium enters secretory phase

Question 14

describe the menstrual phase in the endometrial cycle

Answer 14

• day 1 of cycle
• shed blood and enometrial lining
• remaining basal endometrium is very thin
• lasts around 5 days

Question 15

describe the repair and proliferative phase

Answer 15

• 9 days
• stimulation of endometrial cell proliferation
• inc. in thickness
• number and length of glands
• length of arteries
• stimulated by E2 from follicular phase

Question 16

describe the secretory phase of endometrial cycle

Answer 16

• production of nutrients and other factors
• epithelial glands widen, endometrium thickens, inc. coiling of spiral arteroes
• stimulated by progesterone and E2 from luteal phase

Question 17

describe the follicular phase of ovarian cycle

Answer 17

• around 14 days
• FSH causes growth of ovarian follicle
• FSH and LH causes thecal and granulosa cells to release 17-beta oestradiol
• follicles continue to grow, producing more and more E2
• mid cycle get ovaluation

Question 18

describe the luteal phase of ovarian cycle

Answer 18

corpus luteum produces progesterone and E2

Question 19

what hormone dominates the proliferative or follicular phase?

Answer 19

oestrogen

Question 20

what hormone dominates the secretory or luteal phase?

Answer 20

progesterone

Question 21

how thick is the endometrium?

Answer 21

• 2-4mm

- 7-16mm

Question 22

what happens to basal body temp around ovulation?

Answer 22

inc

Question 23

describe the steps to the menstrual cycle

Answer 23

1. gradual rise of oestradiol by developing follicle
2. follicles grow and -ve feedback on LH and FSH
3. dominant follicle selected and produces lots of E2
4. -ve feedback switch to +ve = LH surge
5. ovulation
6. corpus luteum produces E2 and progesterone –> -ve feedback on LH/FSH
7. no fertilisation = E2 and progesterone fall, endometrium enters secretory phase

Question 24

where does folliculogenesis occur?

Answer 24

inside ovum

Question 25

describe the stages in folliculogenesis

Answer 25

``` - oogonia (44XX) mitotic division - primary oocytes (44XX) 1st meiotic division - secondary oocyte + polar body (22X, 22X) 2nd meiotic division - ovum + polar body (22X, 22X) ```

Question 26

what is the 1st meiotic division linked to?

Answer 26

- LH surge - meiosis 2 follows immediately after this - but pauses in metaphase 2

Question 27

what is the time needed for a primordial follicle to get to a secondary oocyte? how does this work?

Answer 27

- primordial follicle (immature) --> secondary oocyte is more than one month - human ovary contain multiple follicles at ALL stages of development - one dominant Graafian follicle at any one time

Question 28

during meiosis when are the 1st and 2nd divisions paused

Answer 28

- meiosis 1 starts during embryonic development - halts at diplotene stage of prophase 1 (primary follicle) - arrested at puberty - meiosis then resumes and 2nd follicles develop - 2nd follicles undergo 2nd arrest until fertilization

Question 29

how many primordial follicles do ovaries contain?

Answer 29

- around 6m at 20 weeks of development - 1m at delivery of infant - 400 released over lifetime

Question 30

how much sperm does the testes produce?

Answer 30

100m sperm/day from puberty onwards

Question 31

define sexual reproduction

Answer 31

produce genetically different offspring

Question 32

define sexual intercourse

Answer 32

required for: - sexual reproduction - sexual activity - sexual pleasure - human bonding

Question 33

define biological sex

Answer 33

- identifies gender - result of chromosomes - produces different gametes

Question 34

describe 3 different brain pathways involved in sexual reproduction

Answer 34

- meso-limbic DA system: produce genetically different offspring - nigro-striatal tract: control of movements - neuro-endocrine pathways: regulating fertility and parenting

Question 35

what are the penile erection pathways?

Answer 35

- sexy thoughts in brain or tactile stimulus to penis (limbic system) - spinal cord - efferent to penis, afferent back (pudendal nerve)

Question 36

describe the penile erection changes

Answer 36

- inc. PNS to SM of pudendal artery - inc. activity of NOS and so NO release - NO stimulates cGMP --> vasodilation - couteracts SNS-mediated myogenic tone - inc. blood flow in corpus cavernosum

Question 37

state the 6 steps to fertilisation

Answer 37

1. deposition of sperm near cervix 2. passage of sperm through uterus and fallopian tubes 3. sperm moves to fallopian tube ampulla 4. eggs meets sperm, fusion of egg with sperm 5. change in zona pellucida to stop additional sperm fusing 6. initiation of mitotic divisionsin embryo

Question 38

describe the relationship b/ the cervical mucous and sperm

Answer 38

- cervical mucous is hostile to sperm --> forms physical barrier - cervial mucous changes at mid cycle to permit sperm to enter uterus

Question 39

what happens as the sperm moves to fallopian tube ampulla?

Answer 39

- survival of fittest | - capacitation takes place within uterus which matures spermatozoa

Question 40

what happens when the egg meets the sperm?

Answer 40

- acrosome reaction: penetration of zona pellucida - Ca flux - resumption of meiosis, release of 2nd polar body - alignment of maternal and paternal chromosomes to generate zygote

Question 41

what is the cortical reaction?

Answer 41

- hardening of zona pellucida | - exclusion of other sperm