Reproductive endocriology

Question 1

what are the 3 main cases of hormones in the body?

Answer 1

proteins/polypeptides
steroids
derivatives of the amino acid tyrosine

Question 2

what are some examples of protein hormones/polypeptides?

Answer 2

insulin
growth hormone
Thyroid stimulating hormone

Question 3

what are some examples of steroid hormones?

Answer 3

cortisol
oestrogen
progesterone

Question 4

what are some examples of dervivates of the amino acid tyrosine hormones?

Answer 4

thyroxine
adrenaline

Question 5

which kinds of hormones are hydrophilic?

Answer 5

proteins/polypeptides (insulin)
derivatives of the amino acid tyrosine (adrenaline)

Question 6

what kind of hormones are hydrophobic?

Answer 6

steroid hormones (oestrogen)

Question 7

where are steroid hormones derived from?

Answer 7

cholesterol
enzymatic modification of cholesterol

Question 8

what is the structure of polypeptide hormones?

Answer 8

chain of amino acids

Question 9

where are derivatives of tyrosine hormones synthesised?

Answer 9

in the adrenal glands as well as the thyroid

Question 10

where do receptors tend to be located?

Answer 10

present in serum and tissues at low concentrations so must have high affinity

Question 11

where does the synthesis of steroid hormones generally occur?

Answer 11

mitochondria and the SER

Question 12

why are steroid hormones not stored before secretion?

Answer 12

because they are lipid soluble and are therefor permeable to membranes

Question 13

what is the mechanism of action of steroid hormones?

Answer 13

1. steroid hormone enters target cell
2. binds to a receptor present in target cell
3. the hormone-receptor complex enters the nucleus
4. binds to DNA in the nucleus and activates transcription
5. new mRNA is made which moves to the cytoplasm
6. translation produces new proteins

Question 14

what are circulating oestrogen?

Answer 14

a mix of oestrone and oestradiol

Question 15

where is oestrogen synthesised?

Answer 15

directly from the ovary or converted from androstenedione

Question 16

how is oestrogen produced from androstenedione?

Answer 16

estradiol produced by the ovary, deduced by direct synthesis in the developing follicles or through conversion of oestrone
the enzyme aromatase is responsible for this conversion

Question 17

what is oestrogen involved in?

Answer 17

development of female secondary sex characteristics
control of the menstrual cycle
pregnancy
bone strength

Question 18

what are the 3 major endogenous oestrogens?

Answer 18

oestrone
oestradiol
oestriol

Question 19

which type of oestrogen is the most prevalent and potent?

Answer 19

oestrodiol

Question 20

what is the hormone that covers androgen to oestrogen?

Answer 20

aromatase

Question 21

what are some examples of oestrogens?

Answer 21

testosterone, androstenedione and dihydrogen, dihydrotesterone

Question 22

where are androgens synthesised?

Answer 22

testis
ovary
adrenal gland

Question 23

what is the role of androgens?

Answer 23

regulate male primary sec organs and secondary sexual characteristics
important in libido and sexual arousal

Question 24

where are progestins (progestogens) synthesised?

Answer 24

from cholesterol via pregenolone
-produced primarily in the Corpus luteum of ovary, the adrenal glands and in the placenta during pregnancy

Question 25

what are the roles of progestones?

Answer 25

maintaining endometrium to support pregnancy important for mammary gland development in pregnancy

Question 25

where is the hypothalamus located?

Answer 25

located anterior and inferior to the thalamus

Question 26

where is the hypothalamus located?

Answer 26

sits above the pituitary gland and. the pituitary gland is cradled within the cellar of the bone of the skull

Question 27

what are the 2 lobes of the pituitary gland?

Answer 27

arise from distinct parts of the embryonic tissue and there is a posterior and anterior lobe

Question 28

what is the posterior pituitary gland lobe made up of?

Answer 28

neural tissue

Question 29

what is the anterior pituitary gland lobe made up of?

Answer 29

glandular tissue

Question 30

roughly how large is the pituitary gland?

Answer 30

generally the size of a pea

Question 31

what are the main roles of the hypothalamus?

Answer 31

-links the nervous system to the endocrine system -located below the thalamus -part of the limbic system -controls body temp. hunger, thirst, sleep etc

Question 32

what is the main roles of the pituitary gland?

Answer 32

-endocrine gland -suspended from the underside of the brain by the pituitary stalk -has an anterior and a posterior portion

Question 33

what connects the hypothalamus to the pituitary gland?

Answer 33

a stem called the infundibulum sometimes called the pituitary stalk

Question 34

what is the unique vasculature between the hypothalamus and pituitary?

Answer 34

hypothalamo-hypophysial portal system which allows connection between them

Question 35

what hormones are released by the posterior pituitary?

Answer 35

ADH oxytocin

Question 36

what hormones are released by the anterior pituitary?

Answer 36

FSH/LH growth hormone thyroid stimulating hormone adrenocorticotrophic hormone prolactin

Question 37

what does oxytocin do?

Answer 37

promotes uterine contractions during labour milk ejection during lacation

Question 38

what does FSH/LH do?

Answer 38

regulation of gamete production and reproductive hormones

Question 39

what does growth hormone do?

Answer 39

stimulates cell proliferation and regulates growth

Question 40

what does thyroid stimulating hormone do?

Answer 40

stimulates synthesis and release of thyroid hormones

Question 41

what does adrenocorticotrophic hormone do?

Answer 41

stimulates cortisol secretion from the adrenal gland

Question 42

what does prolactin do?

Answer 42

stimulates milk production during lactation

Question 43

what is the hypothalamic-pituitary axis?

Answer 43

command centre of the endocrine system coordinates messages of the endocrine and nervous system together stimulus is received by NS will pass through the hypothalamic pituitary complex to be translated into hormones that elicit a response

Question 44

what regulates reproduction?

Answer 44

hypothalamic-pituitary-honadal axis

Question 45

how does the hypothalamic-pituitary-honadal axis work?

Answer 45

-hypothalamus secretes gonadotrophin (GnRH) which stimulates anterior pituitary to release FSH and LH -thr ovary or testis (and placenta) respond to the levels of gonadotrophin and secrete steroid sex hormones

Question 46

where is GnRH secreted from?

Answer 46

neurosecretory cells within the hypothalamus

Question 46

what Is GnRH?

Answer 46

a 10 amino acid peptide with a short half life

Question 47

what is the hypothalamic control of GnRH?

Answer 47

It is secreted into the portal vessel secreted in a pulsatile manner activates its receptor (GnRHR) within the anterior pituitary which stimulates the release of gonadotrophin

Question 48

what level of hormonal control of reproduction do we consider the pituitary gland?

Answer 48

2nd level

Question 49

what does the anterior pituitary gland do?

Answer 49

secrete peptide hormones -FSH -LH -acts on the ovary and testis

Question 50

what does the posterior pituitary gland do?

Answer 50

secretes oxytocin -involved In childbirth and lactation

Question 51

what is the role of FSH in males?

Answer 51

-stimulates primary spermatocytes to undergo meiosis -enhances production of androgen binding protein in Sertoli cells of the testis

Question 52

what does FSH do in females?

Answer 52

-initiates recruitment and supports growth of ovarian follicles (granulose cells)

Question 53

what does LH do in males?

Answer 53

-acts on the leydig cells of the testis to regulate production of testosterone

Question 54

what does LH do in females?

Answer 54

-supports ovarian theca cells -LH surge triggers ovulation -trigger for ovulation

Question 55

what effect does LH have on theca cells?

Answer 55

produce androgens which get passed to the granulose cells t produce oestrogens

Question 56

what effect does rising oestrogen or testosterone have?

Answer 56

negative feedback on the hypothalamus and inhibits the release go GnRH and FSH, LH

Question 57

when do we get positive feedback for FSH and LH?

Answer 57

to allow ovulation breast feeding

Question 58

which pituitary hormone stimulates Sertoli cells in the testis?

Answer 58

FSH