Hormones

Question 1

What are hormones?

Answer 1

chemical messengers that are secreted by endocrine glands in the bloodstream and that can produce specific responses when reaching a target organ

Question 2

What type of hormones are there based on chemical structure?

Answer 2

1. peptide/protein
2. steroids
3. amino acid derivative/amine

Question 3

What are the characteristics of peptide/protein hormones?

Answer 3

• synthesised as pro hormones
• secondary messengers
• mostly water soluble
• fast changes in protein activity
• LH, FSH, GH, insulin etc.

Question 4

What are the characteristics of steroid hormones?

Answer 4

• synthesised from cholesterol
• lipid soluble
• primary messengers
• slower onset, longer duration
• Cortisol, estrogen, testosterone, etc.

Question 5

What are the characteristics of amino acid derivative/amine hormones?

Answer 5

• synthesised from amino acid tyrosone or tryptophan
• mix of water and lipid soluble
• mix primary and secondary messengers
• adrenaline functions like peptides, thyroid hormones function like steroids.
• catecholamines(adrenaline and noradrenaline), thyroxine etc.

Question 6

What is the difference between primary and secondary messengers?

Answer 6

primary messengers go all the way to the nucleus to activate protein synthesis by itself
secondary messengers activate a cascade in the cytoplasm to activate protein synthesis, it does not go into the cell itself

Question 7

What are the types of hormones based on functional effects?

Answer 7

1. autocrine (targets itself)
2. signalling across gap junctions
3. paracrine (targets nearby cells)
4. endocrine (targets distant cells through the blood streams)

Question 8

What is the pathway and production of TH t3 and t4?

Answer 8

1. hypothalamus gets stimulated by decreased TH, cold weather, hypoglycemia etc.
2. Releases TRH in the hypothalamo-hypophyseal portal system
3. Anterior pituitary releases TSH
4. TSH stimulates thyroid gland to release TH in blood
5. TH acts on cell and inhibits hypothalamus

Question 9

Does testosterone work in a paracrine or endocrine manner?

Answer 9

BOTH! paracrine > leydig cells to stimulate spermatogenesis and endocrine to stimulate muscle growth

Question 10

What is the pathway and production of GH?

Answer 10

1. hypothalamus gets stimulated to release GHRH by age, time of day, stress and exercise etc.
2. Releases GHRH in hypothalamo-hypophyseal portal system
3. Anterior pituitary releases GH
4. GH stimulates hepatocytes to relase IGF’s in the blood
5. Both GH and IGF’s stimulate target cell effectors and inhibit hypothalamus

Question 11

What is the target of testosterone?

Answer 11

• liver tissue > increase glycogenolysis
• lungs
• heart
• bone (stimulate osteoblast activity and chondrocyte maturation)
• skeletal muscle
• sertoli cells

Question 12

what is hyperthyroidism?

Answer 12

the thyroid glands make too much TH, causing weight loss, hand tremors, and irregular heartbeat

Question 13

What effects does IGF1 have?

Answer 13

• increase AA uptake and protein synthesis in muscles
• increase osteoblast and osteoclast activity, collagen type I and proteoglycans
• stimulates proliferation/differentiation of chrondroblasts (interstitial growth) in cartilage

Question 14

What effects does GH have?

Answer 14

• increases gluconeogenesis and IGF1 production in liver
• stimulates lipolysis in adipose
• stimulates increased amino acid uptake in muscle

Question 15

What is adrenarche?

Answer 15

activation of adrenal glands

Question 16

what is pubarche

Answer 16

appearance of pubic arche

Question 17

what is menarche

Answer 17

first menstrual bleeding

Question 18

what is thelarche

Answer 18

appearance of breast tissue

Question 19

from the anterior pituitary gland, what hormone is released to stimulate leydig cells to make testosterone

Answer 19

LH

Question 20

from the anterior pituitary glandm what hormone is released to stimulate sertoli cells to up spermatogenesis?

Answer 20

FSH

Question 21

What starts puberty?

Answer 21

growth peptide, nitric oxide etc. in the hypothalamus stimulates the GnRH pulse generator, meaning the pulse for GnRH gets higher and puberty is set in motions.

Question 22

What are factors that stimulate the GnRH neuron?

Answer 22

• Kisspeptin
• neurokinin B
• GABA
• MKRN3
• neuroexcitatory amino acids

Question 23

what is juvenile pause?

Answer 23

months and years after birth: decrease in activity of the hypothalamic- pituitary gonadal axis.

Question 24

What are the 3 phases in the menstrual cycle?

Answer 24

1. menses
2. proliferative phase (estradiol and LH peaks)
3. secretory phase (progesteron peaks)

Question 25

What is the follicular phase?

Answer 25

Eggs begin to develop and one matures completely. after menstruation until 14 days

Question 26

What happens in the luteal phase?

Answer 26

Corpus luteum is formed happens after 14 days untill menstruation

Question 27

What is the process of the growth hormone(process to production)

Answer 27

• hypothalamus get stimulated to release GHRH by time of day, age, stress and exercise, nutrient levels in the blood
• release GHRH in hypothalamus-hypophyseal portal system
• anterior pituitary releases GH
• GH stimulates hepatocytes to release IGF’s in liver into the blood
• both GH and IGF’s stimulate target cell effectors and inhibit the first step again

Question 28

What hormones/molecules can growth be affected by?

Answer 28

• glucocorticoid, inhibitory effect on the growth plate
• insulin, deficiency blocks growth, hyperinsulimia stimulates excessive growth