Endocrine Signalling 3

Question 1

Whats the difference between autocrine and paracrine

Answer 1

Autocrine is to the same cell type and paracrine - different cell type

Question 2

What is a pheromone

Answer 2

Substance that goes into the environment (smells etc)

Question 3

Are there any human pheromones

Answer 3

No robust evidence but believed to be - androstenone

Question 4

What steroid hormones are produced by the gonads

Answer 4

Oestrogens
Androgens (testosterone, DHT etc)
Progesterone

Question 5

What non-steroid hormones are produced by the gonads

Answer 5

Inhibin A and B
Activin
Follistatin

(Growth factors)

Question 6

What hormone is released by the hypothalamus

Answer 6

GnRH

Question 7

What hormone is produced by the anterior pituitary gland

Answer 7

LH
FSH
Prolactin

Question 8

What hormone is produced by the pineal gland

Answer 8

Melatonin

Question 9

What hormones does the placenta produce

Answer 9

hCG
Placental lactogen

Question 10

How are hormones modulated and why

Answer 10

Via desulphation and glucuronidation - allows them to cross the cell membrane.

Question 11

Give some methods of hormone modulation

Answer 11

Sulphation
Glucuronidation
Sex hormone binding globulin
AFP
Serum albumin
Glycosylation
Active transport
Biotransformation in the liver

Question 12

Explain the hypothalamo-pituitary gonad axis for sex hormones

Answer 12

Hypothalamus releases GnRH to AP

AP releases LSH and FH to gonads

Gonads release testosterone, progesterone and oestrogen to target tissues

Question 13

What is an ultrashort feedback loop

Answer 13

Hormones affect cells which secrete them (autocrine)

Question 14

What is a short feedback loop

Answer 14

Releasing hormones (e.g. GHRH on the hypothalamus)

Question 15

What is a long feedback loop

Answer 15

Feedback via the peripheral blood supply (e.g. - GnRH inhibited by sex hormones)

Question 16

What is photoperiod

Answer 16

The change in environment light cycles

Question 17

What hormone is affected by photoperiod

Answer 17

Melatonin - high at night

Question 18

What are retinal ganglion cells positive for

Answer 18

Melanopsin

Question 19

What does melanopsin do

Answer 19

Melanopsin –> retino-hypothalamic tract –> pineal gland –> manipulates melatonin release

Question 20

When do most hormones peak

Answer 20

Night time

Question 21

Why is photoperiod important in humans regarding sexual activity

Answer 21

The rise in melatonin correlated to a rise in pregnancy - therefore melatonin has link to sexual activity.

Question 22

What are the three stages of sex determination

Answer 22

Genetic sex - determine by sperm if XX or XY present
Gonadal sex - uterus or testes grow etc
Phenotypic sex - looks male/female

Question 23

What is SRY

Answer 23

Sex determining region - found on Y chromosome as testosterone pushes testes growth

Question 24

What are the general stages of sex determination

Answer 24

Bipotential gonad - germ cells migrate to gonadal precursor tissue near kidneys

Primary sexual differentiation - reproductive tissues and brain sex - no surge area in males (labour)

Secondary sexual differentiation - secondary sexual characteristics

Question 25

Why does guevedoces help us understand DHT

Answer 25

Guevedoces is children in the dominican republic which dont grow penises until puberty as have a deficiency in 5-alpha-reductase (testosterone to DHT) Boys appear female but get second surge of testosterone in puberty and grow secondary characteristics.

Question 26

What did the guevedoces help achieve

Answer 26

Finasteride - 5 alpha reductase inhibitors

Question 27

What does anti-mularian hormone and testosterone do to the mesonephric duct and paramesonephric duct during sexual development (MALES)

Answer 27

Mesonephric duct - becomes wolffian duct and epididymis Paramesonephric duct degenerates

Question 28

What does no anti-mularian hormone and no testosterone do to the mesonephric duct and paramesonephric duct during sexual development (FEMALES)

Answer 28

Mesonephric duct degenerates Paramesonephric duct - oviducts, uterus and cervix

Question 29

How do XY chromosomes make a male

Answer 29

TDF/SRY on Y chromosome - testes develop --> seritoli cells secrete AMH --> Degeneration of paramesonephric duct and leydig cells differentation --> leydig cells make testosterone and dihydrotestosterone --> male duct system, penis, scrotum and accessory sex glands

Question 30

How does no Y chromosome make a female

Answer 30

No TDF/SRY --> Ovaries develop and no AMH produced --> paramesonephric duct becomes oviducts, uterus and cervix

Question 31

What is the masculination programming window

Answer 31

Important time which is testosterone dependenent between 10-12 weeks gestation. Important for male gonad development

Question 32

What two conditions are important regarding poor testosterone production

Answer 32

Crpytorchidism Hypospadius

Question 33

What three hormones are needed for production of female oocytes

Answer 33

E2 FSH Inhibin

Question 34

How many oocytes do females have at week 22 gestation compared to birth

Answer 34

7 million --> 2 million

Question 35

When is LH needed

Answer 35

Late stages of oocyte development, takes over from FSH

Question 36

Why might a gene have different hormone response elements WIDER READING - Pg973 of molecular cell biology krieger et al

Answer 36

Allows versatile control over the rate of transcription of a specific gene

Question 37

What did melatonin injecctions show in rats regarding sexual activity WIDER READING - Drago 2000

Answer 37

High injections into the amygdala inhibit sexual performance whilst small doses stimulated sexual activity in rats

Question 38

What does melatonin do to erections WIDER READING - Boxkurt et al 2018

Answer 38

Deficiency can cause erectile dysfunction

Question 39

What is an indicator for the masculinization programming window WIDER READING - Welsh et al 2014

Answer 39

Anogenital distance - can be indicated for azoospermia, hypospadias and cryptorchidism.