Reproductive System II

Question 1

What are the 3 sex steroids/gonadal hormones?

Answer 1

1. Oestrogen
2. Progesteron
3. Testosterone

Question 2

How does anorexia nervosa affect menstruation?

Answer 2

Dec fat —> dec leptin —> dec bind to kisspeptin neurone receptors —> dec activation of kisspeptin neurones —> dec GnRH —> dec LH and FSH —> amenorrhea

Question 3

Which hormones are involved in the menstrual cycle?

Answer 3

Follicular Phase (1-13):
- LH gradual inc
- FSH gradual inc —> dec
- oestrogen inc (mini peak at 4)
- progesterone v low

Ovulation (14):
- LH sudden peak
- FSH peak
- oestrogen gradual peak
- progesterone v low

Luteal Phase (15-28)
- LH low
- FSH low
- oestrogen dec (medium peak at 21)
- progesterone inc —> peak at 21 —> slow dec

Question 4

What is the ovarian cycle?

Answer 4

Follicular Phase (1-13):
- primary follicle —> secondary follicle —> vesicular
follicle

Ovulation (14):
- 2° oocyte released

Luteal Phase (15-28)
- corpus leuteum —> corpus albicans

Question 5

What is the uterine cycle?

Answer 5

Menstrual Phase (1-7):
- endometrium sheds

Proliferative Phase (7-14)
- endometrium grows (oestrogen)

Secretory Phase (15-28)
- endometrium thickens (progesterone)

Question 6

How do you medically confirm ovulation?

Answer 6

1. Serum progesterone
2. Urine PdG (progesterone metabolite)
3. Ultrasound —> see corpus luteum

Question 7

What 2 changes occur to epididymal fluid?

Answer 7

1. Tubular fluid reabsorption
   
   • induced by oestrogen
   • in testicular efferent ducts
   • inc concentration of sperm
2. Nutrients and glycoproteins added
   
   • induced by androgens
   • seminal fluid added
   • by seminal vesicles, prostate, bulbourethral
     glands
   • sperm + seminal fluid —> semen

Question 8

What proportion of sperm reach the ovum?

Answer 8

1/mn
- semen —> 15-120 mn/ml
seminal fluid —> 2-5 ml/ejaculation
∴ 30-600 mn/ejaculation
- 1/100 reach cervix
1/10,000 from cervix to ovum

Question 9

What are the accessory sex glands? (3)

Answer 9

Add seminal fluid to epididymal fluid
1. Seminal vesicles
2. Prostate
3. Bulbourethral glands

Question 10

What is the structure of a sperm?

Answer 10

1. Head - acrosome —> acidic vacuole containing
   hydrolytic enzymes
   - nucleus
2. Mid piece - proximal centriole
   - many mitochondria
3. Tail - circumferential fibers —> outer
   - axial filament —> inner
   - end piece

Question 11

What is sperm capacitation? (3)

Answer 11

Process sperm undergoes to carry out fertilisation:
1. Lose glycoprotein coat
2. Surface membrane changes
3. Develop tail whiplash movements

• in fallopian tube —> ionic + proteolytic environment
• needs —> oestrogen
  —> calcium

Question 12

What is the acrosome reaction? (3)

Answer 12

Process of sperm entering ovum
1. Sperm binds to ZP3 glycoprotein (sperm receptor)
2. Ca2+ influx into sperm - by progesterone
3. Acrosome releases hyaluronidase + proteolytic
enzymes —> breakdown zona pellucida

Question 13

What is the cortical reaction?

Answer 13

Process to prevent other sperm entering fertilised egg
1. Ovum cortical granules release molecules
eg. ZP2, ZP3
2. Zona pellucida degrades —> no more ZP3 for
sperm to bind to

Question 14

What 3 processes occur for fertilisation?

Answer 14

1. Capacitation —> prepare sperm
2. Acrosome reaction —> sperm enters egg
3. Cortical reaction —> other sperm can’t enter

Question 15

How does development of the conceptus occur?

Answer 15

Fertilised egg continues to move down fallopian tube (3-4 days) —> nutrients added by uterine secretions
- may take 9-10 days before implantation

Question 16

What occurs during the 9 days after fertilisation?

Answer 16

Day 1 —> zygote
2 —> 2-cell stage
3 —> 8-cell stage
4 —> morula
5 —> blastocyst and inner cell mass forms
6/7 —> zona pellucida forming
- entered uterus
8/9 —> blastocyst implants

Question 17

What are the 2 phases of implantation?

Answer 17

1. Attachment phase = outer trophoblast cells make
   contact with uterine surface
   
   • LIF = leukaemia inhibitory factor
     —> stimulate adhesion of blastocyst to
     endometrial cells
   • IL11 = interleukin-11
     —> released intp uterine fluid
2. Decidualisation phase = underlying uterine stromal
   tissue change
   —> glandular epithelial secretion
   —> glycogen accumulates in stromal cell cytoplasm
   —> capillaries grow - uses TGF-β
   —> inc vascular permeability
   
   • IL11, histamine, prostaglandins

Question 18

Which 2 chemicals are essential for the attachment phase of implantation?

Answer 18

1. LIF
2. IL11
   - from uterine endometrial cells

Question 19

Which 4 hormones change levels during pregnancy and how?

Answer 19

1. hCG —> peak around week 9 —> dec to 0
   - acts on LH receptors of corpus leuteum
2. oestrogens —> gradual increase
   - mainly oestriol
3. progesterone —> inc —> peak week 36 —> dec to 0
4. human placental lactogen —> gradual inc

Question 20

Where are oestrogen and progesterone produced during pregnancy?

Answer 20

First 40 days —> corpus luteum
- stimulated by trophoblast hCG
After day 40 —> placenta
- uses DHEAS from mother (adrenal)

Question 21

Which 6 hormones increase in levels in a pregnant mother?

Answer 21

1. ACTH
2. Adrenal steroids
3. Prolactin
4. IGF1 —> placental GH-varient
5. Iodothyronines ∵ hCG
6. PTH-related peptides —> provide Ca for baby

Question 22

Which 3 hormones decrease in levels in a pregnant mother?

Answer 22

1. LH
2. FSH
3. Pituitary GH
4. TSH ∵ hCG takes over

Question 23

Which 3 hormones control parturition?

Answer 23

1. Oxytocin —> uterine contraction
2. Oestrogen
3. Cortisol

Question 24

Which hormones lactation?

Answer 24

1. Prolactin —> milk production
2. Oxytocin —> milk ejection