endocrine control of the reproductive system Flashcards
1
Q
what are the 2 main structures responsible for hormonal regulation
A
- hypothalamus
- anterior pituitary gland
2
Q
what is the function of the hypothalamus
A
- controls pituitary hormone release
3
Q
what 2 hormones released by the hypothalamus are related to reproduction
A
- gondaotropin releasing hormone (GnRH)
- prolactin inhibiting hormone (PIH/Dopamine)
4
Q
what are the 3 main functions of the pituitary gland in terms of reproduction
A
- stimulates production of oestrogen, progesterone in females
- controls ovulation and pregnancy
- controls testosterone production and spermatogenesis
5
Q
what are 3 hormones released by the pituitary gland
A
- follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
6
Q
describe the process of the hypothalamic pituitary axis
A
- hypothalamus secretes GnRH
- this stimulates the anterior pituitary gland to release LH/FSH
- this then effects the gonads causing the testis to produce testosterone and the ovaries to produce oestrogen and progestogen
7
Q
what is Kisspeptin
A
a group of hypothalamic peptides that are essential for normal human fertility
e.g Kisspeptin —> GnRH —> LH/FSH —–> Gonads
8
Q
describe how female puberty starts
A
- begins with gradual increase in pulsatile GnRH secretion by hypothalamus
- release of LH/FSH (Kisspeptin)
9
Q
at what age range does female puberty begin
A
11-16
10
Q
the first few cycles of female puberty are anovulatory, what does this mean
A
- not ovulating/releasing an egg
11
Q
what is thelarche
A
beginning of breast development
12
Q
describe starting of puberty in boys
A
from ages of 13, increased production of GnRH
- causing testosterone level changes
13
Q
what is spermatogonia
A
undifferentiated male germ cell
14
Q
what happens to spermatogonia at puberty
A
undergoes mitosis
15
Q
what does it mean when a mammalian embryo, the gonad is bipotential
A
can from ovary or testis
- the undifferentiated gonand consists of precursor cell types that can follow either the female or male pathway
16
Q
what are the 4 phases of the menstural cycle
A
- menstural phase
- follicular phase
- ovulation phase
- luteal phase
17
Q
what are the 3 phases of the ovarian cycle
A
- follicular phase
- ovulation
3, luteal phase
18
Q
what happens during each phase of the ovarian cycle
A
follicular phase= follicule grows
ovulation - follicle released
luteal phase - corpus luteum forms then degenerates
19
Q
at what stage of the ovarial cycle is FSH/LH levels hgihest
A
Just prior to ovulation (day 14)
20
Q
at what stage of the ovarian cycle is progesterone levels highest
A
luteal phase (around 21 days)
21
Q
what arteries supply the vaginal, uterus and ovaries
A
vagina = vaginal artery
uterus = uterine artery
ovary = ovarian artery
22
Q
egg does not become fertilized, the lining of the uterus (endometrium) is shed during menstruation, describe the variation in thickness of endometrium over the menstural cycle
A
- menstural phase / follicular phase = very thin endometrium
- proliferative phase / ovulation = growing endometrium
- secretory pro gestational phase / luteal phase = endometrium thickness at a maximum
23
Q
what is the function of FSH
A
triggers the growth of eggs in the ovaries and gets the eggs ready for ovulation.
24
Q
what is function of LH
A
LH stimulates steroid release from the ovaries, ovulation, and the release of progesterone after ovulation by the corpus luteum
25
what is the function of progesterone and where's it made/released
to prepare the endometrium (lining of your uterus) for a fertilized egg to implant and grow
- corpus luteum in ovary
26
what is function of oestrogen and where is it made
produced in your ovaries and helps your body develop pubic hair, breasts, and a regular menstrual cycle (periods).
-stimulate growth of organs important for reproduction
- stim bone growth
- increase body metabolic rate
- increase fat deposition in subcutaneous tissue
- softening and better vascularisation of skin etc
27
describe why during the ovulation phase there is LH/FSH surge and decline in oestrogen
- after follicle phase/ follicle growth, collagenase (enzyme) digests the follicle wall
- the follicle ruptures = ovulation (egg released)
- as a result, oestrogen levels drop to prevent further ovulation (only one egg at a time)
28
what happens during the luteal phase
- ruptured follicle transforms to corpus luteum through luteinization
- yellow comes from cholesterol (precursor of steroid hormones)
- corpus luteum secretes progesterone, which is dominant hormone of 2nd half of cycle
29
what is the process called of follicle turning into corpus luteum
lutenization
30
what is the 2 roles of progesterone
1. inhibits FSH and LH so no further follicle development in ovulation and current cycle
2. prepares uterus for pregnancy should fertilisation occur
31
what happens to the corpus luteum is theres no fertilization also known as menstural phase
(menstural phase)
1. CL degenerates randomly
2. progesterone levels fall
3. uterus loses endocrine support
4. mensturation
5. FSH and LH work on follicles again
32
what is the role of the corpus luteum if there is fertilization
- maintains uterine lining until placenta takes over as a main producer of progesterone at 3 months
33
what maintains the corpus luteum during fertilisation
hCG from chorium
34
endometrial cycle =
- proliferative phase
- secretory phase
- menstural phase
what happens at each of there
poliferative phase = oestrogen goes down, growth of endometrium etc
secretory phase = rise in progesterone, growth of endometrium, softens connective tissue in prep for implantation
menstural phase = CL degeneration, progesterone and oestrogen drops, bleeding etc
35
what are 3 ways oral contraceptives work
1. utilise natural hormonal cycle to prevent ovulation
2. altering mucus in cervix to prevent sperm movement
3. changing endometrium so implantation is impossible
36
how can progesterone work as contraceptive
progesterone prevents FSH but promotes coined production of thick vervical movement and inhibits endometrial development
37
how can oestrogen work as contraceptive
prevent ovum maturation by inhibiting LH surge
38
negatives of oral contraceptives
- x3 increase in thromboembolism
- cardiovascular disease in smoking women
- increase susceptibility to certain cancer e. breast
39
pros of oral contracepts
- reduce indigents of endometrial and ovarian cancers
- decrease risk of ectopic pregnancy
- reduced heaviness of menstural bleeding
40
what age would menopause hit
40-50
41
what causes menopasue
no more follicle supply
42
how are hormones affected during menopause
- decreased production of oestrogen
- FSH production increases
43
what happens as a result of lack of oestrogen during menopause
physiological changes e.g hot flushes, irritability, fatigue, anxiety
44
what are the sertoli and leydig cells in the male reproductive system
- Sertoli cells are normally located in the male reproductive glands (the testes). They feed sperm cells.
- The Leydig cells, also located in the testes, release testosterone
45
describe the hormonal control of male reproductive system
- hypothalamus releases GnRH
- this stimulates the anterior pituitary gland to release FSH/LH
- FSH triggers Sertoli cells to under go spermatogenesis
- LH triggers leydig cells to release testosterone
46
how does growth hormone affect males
controls metabolic function of testis
47
how does luteinising hormone affect males
stimulates leydig cells to produce testosterone
48
how does follicle stimulating hormone affect males
stimulates Sertoli cells to help with transition of spermatids to stem (spermatogenesis)
48
how does testosterone affect males
secreted by leydig cells, growth and division of germinal cells
49
what is testosterone responsible for
male foetus development
descent of testes
adult male primary and secondary body characteristics
50
how does oestrogen affect males
formed from testosterone by Sertoli cells after FSH stimulation
51
what 2 other androgens are secreted by interstitial cells of leydig besides testosterone
- dihydrotestosterone (DHT)
- androstenedione
52
where does testosterone that isnt converted to androstenedione or DHT gone
excreted in liver bile or urine
53
note there are numerous leydig cells in new born males, none in childhood, then numerous after pubety
also when tumours develop, large amount of testosterone is secreted
54
what event does the parasympathetic and sympathetic pathway cause in the penis
parasympathetic = erection
sympathetic = ejaculation
55
what are the components of seminal vesicle fluid
- fructose
- citric acid
- prostaglandins
- fibrinogen
56
what are the components of prostate gland fluid
- calcium
- citrate ion
- phosphate ion
- clotting enzyme
- slightly alkaline
- profibrinolysin
57
what percentage of semen is made from vas deferens, seminal vesicles and prostate gland fluids?
10% fluid = vas deferens
60% fluid = seminal vesicles
30% fluid from prostate gland
58
what is the pH of semen
pH 7.5
59
what component of the seminal vesicle fluid reacts with the female cervical mucus to make it more receptive for sperm movement
prostaglandins, a group of lipids with hormone-like actions
60
what is capicitation
biochemical process occurring in the female reproductive tract, which enables sperm to fertilize an ovum
61
describe capitation process
1. uterine and Fallopian tubes fluid wash away male inhibitory factors
2. membrane of sperm becomes more permeable to Ca2+ changing the activity of the flagellum
3. Ca2+ causes changes to cellular membrane of the acrosome and allows release of acrosome enzymes (help penetrate egg coat)
62
why do male inhibitory factors need to be washed away by uterine and fallopian fluids
they contain large amounts of cholesterol coating acrosome and preventing release of sperm ezymes
63
64
what is low sperm count also known as
oligozoospermia
65
what are some causes of low sperm count
- hormone imbalance
- diet
- undescended testis
- structural issues
- genital infections
- exposure to chemicals
etc
66
3 causes of spermatogenesis sterility
1. inflammation of testis resulting from mumps
2. embryonic abnormalities
3. excessive temps of testes degenerates spermatogonia
67
what is the role of FSH and LH during the follicular phase
- stimulate oocyte development and follicle growth
68
what is the role of LH during the luteal phase
- stimulates development and maintenance of corpus luteum
69
during the ovulating phase, what secretes oestrogen
the follicle that has been ruptured
70
what 2 hormones does the corpus luteum secrete during the luteal phase and what do either of them do
- oestrogen , thickens endometrium
- progesterone, increases number of blood vessels adds secretory glands in the endometrium
71
ovarian cycle/ mestruration - day 0
follicular phase - day 7
ovulation - day 14
luteal phase - day 21
new follicular phase - day 28/0
72
exogenous testosterone administration can have NEGATIVE effects on male fertility due to its NEGATIVE feedback on production of LH and FSH from the anterior pituitary gland, all of which are needed for SPERMATOGENESUS
73
