Reproductive physiology Flashcards
List the sequence of events during oogenesis, emphasising their timing
1) Meiosis 1 before birth , finished at puberty
2) Meiosis 2 is completed at fertilisation
Name the hormones involved in regulation of the female reproductive cycle and list their actions
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
what are the secondary sexual characteristics in females
4
1) fat deposition in breasts , thighs
2) wide hips , breasts
3) mood swings
4) Uterine muscle effects
so what happens if fertilisation doesn’t take place ( how does the cycle start again )
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
what does oestrogen do ?
- 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
why is there an increase of FSH and then decrease in the cycle at the start of the follicular phase ?
1) FSH increases in repsonse to low oestrogen , but as oestrogen concentration increases FSH is inhibited
Follicular phase day 1 -14
4
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
What happens in the luteal phase
4
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
what does inhibin do ,when is it released ?
Luteul phase released by corpus luteum , it causes inhibition of the follicle stimulating hormone .
No more eggs are needed to mature at this stage
What does progesterone do ?
- Causes INHIBITION of gonadotrophin releasing hormone from hypothalamus
- This in turn leads to decreased amounts of LH , FSH
what does LH do ?
3
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
what is the physiological challenge of the mother
name 4
- 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
Parturition outline ( birth ) (4)
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
what’s the role of oestrogen and progesterone in uterus ?
3
- 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 !
Outline suckling
2
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
outline lactation
(3 hormones )
(4)
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 )
what is the importance of HCG (3)
1) Hormone made by placenta
2) makes sure the corpus luteum doesn’t die
2) this means progesterone , oestrogen are still made before birth
what does oxytocin do ?
3
1) smooth muscle contractor
2) love hormone ( feeling of love)
3) bonding to infant
three stages of labour ?
( outline the oxytocin regulation too)
(3)
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
Components of breast milk
3
1) TRG
2) lactose, vitamins, proteins ,ca2+, phosphate
3) more protein , less fat and lactose
fetal adaptations of circulatory system
4
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
what happens after the baby is born ? to the circulatory system?
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
Neonatal weight gain ?
TRIPLES IN WEIGHT in first year
Temperature regulation
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)
Liver and immune functions
5
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 !
what does gonadotrophin releasing hormone do in males ?
3
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
what is the Function of testosterone ?
1) spermatogenisis
2) makes male phenotype
3) muscle deposition
4) increases BMR
5) Agression
Physiology behind erection ?
2
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
Physiology behind ejaculation
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
what is the semen made of ?
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
