Reproductive physiology

Question 1

List the sequence of events during oogenesis, emphasising their timing

Answer 1

1) Meiosis 1 before birth , finished at puberty

2) Meiosis 2 is completed at fertilisation

Question 2

Name the hormones involved in regulation of the female reproductive cycle and list their actions

Answer 2

LOW OESTROGEN ( negative feedback in the first 10 days )

- Inhibits LH
- Inhibits GnRH
- FSH is released in response to low Oestrogen 

RISING , HIGH OESTROGEN
- FSH FALLS , hence steady drop at the start ,as granulosa cells produce more oestrogen
- Release of LH = SPIKE of LH = ovulation at day 14
The ovulation of the follicle will release what we know as the female egg

Question 3

what are the secondary sexual characteristics in females

4

Answer 3

1) fat deposition in breasts , thighs
2) wide hips , breasts
3) mood swings
4) Uterine muscle effects

Question 4

so what happens if fertilisation doesn’t take place ( how does the cycle start again )

Answer 4

So as the corpus luteum degenerates all these hormones that are that were produced by the corpus luteum
the estrogen, inhibin and progesterone, they will decrease
so when the corpus luteum degenerates:
- Progesterone will Decrease
- progesterone cannot inhibit gonadotropin releasing hormone release
- oestrogen decreases too
- So gonadotropin releasing hormone levels will increase meaning FSH, LH levels can rise and start a new cycle

Imbalance of hormones cant maintain the endometrial lining , Hence it is shed = PERIOD

Question 5

what does oestrogen do ?

Answer 5

• Peripheral effects include stimulating bone and muscle Growth it stimulates endometrial growth
• Maintains female Secondary characteristics and maintains a female the glands the breasts amongst many other things

Question 6

why is there an increase of FSH and then decrease in the cycle at the start of the follicular phase ?

Answer 6

1) FSH increases in repsonse to low oestrogen , but as oestrogen concentration increases FSH is inhibited

Question 7

Follicular phase day 1 -14

4

Answer 7

1)FIRST 10 DAYS: Starts of with low oestrogen , this leads to inhibition of LH (steady level) and stimulation of FSH (increases then drops)
Gonadotrophin releasing hormone is released by hypothalamus
2) As follicles mature due to GnRH and FSH , granulosa cells produce more oestrogen
3) Rising oestrogen causes a decrease in FSH and increase in LH = spike causes ovulation at day 14

Question 8

What happens in the luteal phase

4

Answer 8

1) LH drops, GnRH drops and follicle turns into the corpus luteum
2) Corupus lutuem releases 3 main hormones: progesterone , inhibin and oestrogen

Inhibin : inhibits FSH ( we don’t need a new follicle to mature)
Progesterone : only present in luteul phase , Inhibits GnRH
this in turn inhibits the release of LH, FSH

But the main effect of progesterone is that it will stimulate endometrial growth
the endometrial lining is the lining of the uterus which will shed each month
Or the endometrium is where the egg- Will implant if it’s fertilized by sperm

Question 9

what does inhibin do ,when is it released ?

Answer 9

Luteul phase released by corpus luteum , it causes inhibition of the follicle stimulating hormone .
No more eggs are needed to mature at this stage

Question 10

What does progesterone do ?

Answer 10

• Causes INHIBITION of gonadotrophin releasing hormone from hypothalamus
• This in turn leads to decreased amounts of LH , FSH

Question 11

what does LH do ?

3

Answer 11

1- Weeks one to two of the cycle, luteinising hormone is required to stimulate the ovarian follicles in the ovaries , to make oestrogen
2- Surge at day 14= ovulation
3- LH stimulates the Corpus luteum to make progesterone

Question 12

what is the physiological challenge of the mother

name 4

Answer 12

• morning sickness
• CO and BV increases
• O2 consumption increases and so does CO2
• ventillation increases
• BMR increases
• GFR increase and we have fluid retention
• nutrional demand increases
• 10Kg weight gain

Question 13

Parturition outline ( birth )
(4)

Answer 13

1) Fetal stress releases ACTH from anterior pituitary of mother
2) Cortisol is released :
- progesterone , oestrogen produced by placenta decreases
- Prostaglandin increases ( helps uterine contraction )
3) As baby pushes , nerve fibres stimulated –>oxytocin is produced by the hypothalamus
4) Oxytocin contracts the uterus , stimulates the production of prostaglandins

Question 14

what’s the role of oestrogen and progesterone in uterus ?

3

Answer 14

• Oestrogen = increases oxytocin receptors
• Oxytocin causes contraction of the uterus
• Progestrone = relaxes the smooth muscle in uterus , so it doesn’t contract before its ready !

Question 15

Outline suckling

2

Answer 15

1) Mechanical stimulation =causes prolactin release , as prolactin inhibitory hormone is stopped.
Prolactin initiates and maintains the milk production

2)Nipple stimulation = increases oxytocin, causing contraction of secretory alveoli

Question 16

outline lactation
(3 hormones )
(4)

Answer 16

1)oestrogen = causes milk duct development
2)Progesterone = causes development of secretory alveoli
3) Human chorionic gonadotropin is a hormone produced primarily by syncytiotrophoblastic cells of the placenta= develop enzymes used for milk
4) prolactin also produces enzymes for milk
5) from 20 weeks on the female can produce milk
( progesterone and oestrogen prevent this until after birth )

Question 17

what is the importance of HCG (3)

Answer 17

1) Hormone made by placenta
2) makes sure the corpus luteum doesn’t die
2) this means progesterone , oestrogen are still made before birth

Question 18

what does oxytocin do ?

3

Answer 18

1) smooth muscle contractor
2) love hormone ( feeling of love)
3) bonding to infant

Question 19

three stages of labour ?
( outline the oxytocin regulation too)
(3)

Answer 19

1) Dilation ( oestrogen increases, will increases oxyctocin receptors )
- oxytocin sensitivity increases so baseline oxytocin causes contraction of uterus
-stretch causes reflex ( hypothalamus–>posterior pituitary –>oxytocin –>more contraction and more stretch
(8-24 hours)
end when we have 10cm cervical dilation
2)Expulsion (30-90min) = bearing down
3)Delivery of placenta = placenta shears off the uterus wall

Question 20

Components of breast milk

3

Answer 20

1) TRG
2) lactose, vitamins, proteins ,ca2+, phosphate
3) more protein , less fat and lactose

Question 21

fetal adaptations of circulatory system

4

Answer 21

1) umbilical vein ( oxygenated blood to heart )
2) Ductus venosus ( by passes liver ) –>IVC ( mixed blood)
3) Fossa Ovalis ( blood from RA-LA)
4) Ductus arteriosus ( blood from pulmonary trunk to aorta)

this is a single circulation

Question 22

what happens after the baby is born ? to the circulatory system?

Answer 22

1) Pressure is now higher on the left side
2) ductus venosus and ductus arteriosus = close up
3) foramen ovale closes up
4) umbilical vein is compressed

from fluid –> air
large amount of work in the 1st breath ! inter pleural pressure = -60 !!
after and hour the pressure reduced

Question 23

Neonatal weight gain ?

Answer 23

TRIPLES IN WEIGHT in first year

Question 24

Temperature regulation

Answer 24

1) SA:V ratio increases heat loss
2) Temperature difference = colder outside
3) Immature mechanisms
4) brown fat ( makes a Lot of heat and no ATP)

Question 25

Liver and immune functions

5

Answer 25

1) often poor in new borns
2) jaundice ( leaves after 1-2 weeks)
3) Glycogen is compromised
4) IgG–>placenta
5) IgA–>colostrum

infants do well in a balanced environment they need some immunocompetence !

Question 26

what does gonadotrophin releasing hormone do in males ?

3

Answer 26

1) releases FSH –>causes stimulation of Sertoli cells –>cause spermatogenisis and makes INHIBIN
2) LH–>activates leading cells to make Testosterone
- testosterone negatively feedbacks to stop production of LH,hypothalamus
- INHIBIN - inhibits FSH

Question 27

what is the Function of testosterone ?

Answer 27

1) spermatogenisis
2) makes male phenotype
3) muscle deposition
4) increases BMR
5) Agression

Question 28

Physiology behind erection ?

2

Answer 28

1) dilation of the penile arterioles as they fill with blood ( paired corpus cavernosa, corpus spongiosum)
2) parasympathetic dilator nerves stimulated and sympathetic nerves are inactive

Question 29

Physiology behind ejaculation

Answer 29

2 phases : emission and expulsion

• emission phase = sympathetic reflex (smooth muscle of epididymis , vas deferens, accessory glands)
• Expulsion phase = reflex contractions of skeletal muscle = base of penis

Question 30

what is the semen made of ?

Answer 30

Composition. Most of the fluid in semen is made up of secretions from male reproductive organs. Semen contains citric acid, free amino acids, fructose, enzymes, phosphorylcholine, prostaglandin, potassium, and zinc