Normal Growth

Question 1

another name for somatotropin

Answer 1

growth hormone

Question 2

two hypothalamic neurohormones that regulate growth hormone

Answer 2

GH-inhibiting hormone and GH-releasing hormone

Question 3

after what age does GH become the main factor influencing growth

Answer 3

about 10 months

Question 4

how does hypothyroidism stunt a childs growth

Answer 4

thyroid hormones have a permissive effect on GH

low thyroid levels –> low GH action

Question 5

how does diabetes stunt a childs growth

Answer 5

insulin has a permissive effect on GH and so in diabetes where insulin is low GH is underactive

Question 6

what is GH used for in adults

Answer 6

maintenance and tissue repair

Question 7

what doe GH do to cell size and cell division

Answer 7

stimulation cell growth and cell division

Question 8

the tropic action of GH stimulates what hormone

Answer 8

IGF-1, insulin-like growth

factor, from the liver

Question 9

what is “insulin-like” about IGF-1

Answer 9

it has similar structure to pro-insulin and binds to very similar receptors

Question 10

how does GH and IGF-1 exist in the blood

Answer 10

about half free and the other half bound to carrier proteins

Question 11

effect of IGF-1 on GH

Answer 11

negative feedback on GH through acting on GHRH and GHIH accordingly, as well as on anterior pituitary

Question 12

another name for IGF-1

Answer 12

somatomedin C

Question 13

GH and IGF-1 actions on bone growth

Answer 13

growth hormone makes prechondrocytes in epiphyseal plates differentiate to chondrocytes. in the process they secret IGF-1, the IGF-1 then promotes the chondrocytes to further differentiate and produce cartilage

Question 14

what effect of adolescence causes the epiphyseal plates to close

Answer 14

sex steroid hormones

Question 15

effect of GH on gluconeogenesis

Answer 15

increases it

Question 16

effect of GH on insulin

Answer 16

inhibition

Question 17

how does GH aid lipolysis

Answer 17

by making adipocytes more sensitive to lipolytic stimuli

Question 18

why is GH said to be diabetogenic

Answer 18

because it raises blood glucose through an anti-insulin effect

Question 19

what actions make GH unlike cortisol and like insulin

Answer 19

increasing aa uptake and protein synthesis, essentially being anabolic

Question 20

what anabolic action does growth hormone not do that insulin does

Answer 20

increase glucose uptake

Question 21

what stage of life has the highest rates of GH secretion

Answer 21

teenage years

Question 22

what time of day is most GH released

Answer 22

in first two hours of sleep ( deep delta sleep)

Question 23

why is 24 hour monitoring necessary to get a true picture of GH levels

Answer 23

because it undergoes rapid spontaneous fluctuations so a single sample may be a very poor representation

Question 24

true/false IGF-1 varies with GH levels

Answer 24

false - they remains relatively constant despite spikes suggesting that IGF-1 has some kind of buffering ability

Question 25

oestrogen, testosterone, amino acid increase, stress, delta sleep and decreased energy supply to cells all have what effect on GHRH

Answer 25

stimulate GHRH secretion

Question 26

free fatty acids, REM sleep and cortisol all have what effect on GH secretion

Answer 26

inhibitory. these stimuli increase GHIH

Question 27

hormone periods through gorwth

Answer 27

thyroid a lot in early years Androgens and oestrogens in later GH prominent from infancy till end

Question 28

main hormones of intrauterine growth

Answer 28

Insulin and IGF-II

Question 29

what is cretinism

Answer 29

hypothyroidism from birth causing reduced permissive effects on GH. They have retarded growth and retain infantile facial features

Question 30

nutrition in growth

Answer 30

need adequate vitamins, minerals, calories and protein to support growth

Question 31

what is notable about infantile growth

Answer 31

episodic. huge growth spurts and then nothing.

Question 32

place of sex hormones in puberty

Answer 32

permissive to GH and so stimulate growth but then terminate growth in bones at epiphyseal plates

Question 33

what happens when GH is over secreted before epiphyseal plates fuse

Answer 33

they just grow and grow to be really big. | Pituitary giants

Question 34

what happens when GH is over secreted after the epiphyseal plates fuse

Answer 34

grow in ways other than in long bone, so no height increase. | but hands a feet and other flat short bones grow

Question 35

what is the most common cause of excessive GH secretion

Answer 35

an endcrine tumour of the pituitary gland

Question 36

deficiency of GHRH causes

Answer 36

dwarfism, can be treated with supplement GHRH

Question 37

What is Laron Dwarfism

Answer 37

target tissues are unresponsive to GH. They get increased GH the receptors will not respond and so IGF-1 won't be released to inhibit GH through negative feedback loop

Question 38

What happens in precocious puberty

Answer 38

there is stimulation of GnRH and so sex hormones are secreted early and cause long bones epiphyseal plates to fuse, stunting their growth

Question 39

what differs, physically, between hypothyroid children and GH deficient children

Answer 39

hypothyroid children are short, fat and retain infantile faces, whereas GH deficient children have normal proportions but are just small

Question 40

effect on GH secretion when plasma glucose falls following insulin

Answer 40

GH secretion stimulated via GHRH. | GH then increases gluconeogenesis and makes insulin less effective

Question 41

effect on GH secretion when plasma amino acids rise after digestion

Answer 41

increased aa --> GHRH secretion --> GH secretion --> increased amino acid uptake and protein synthesis