Normal Growth and Development

Question 1

what releases somatotrophin?

Answer 1

the anterior pituitary

Question 2

what does GH (GROWTH HORMONE) require to stimulate growth?

Answer 2

permissive actions of thyroid hormone and insulin

Question 3

true or false:

GH is a peptide hormone

Answer 3

true

Question 4

how does GH promote growth?

Answer 4

through hypertrophy and hyperplasia

Question 5

what does the liver produce in response to growth hormone?

Answer 5

somatomedian or IGF-1

Question 6

describe the negative feedback loop that IGF-1 is involved in

Answer 6

> inhibits growth hormone releasing hormone
stimulates somatostatin
inhibits growth hormone release from pituitary

Question 7

what does IGF-1 stimulate in the bone?

Answer 7

chondrocyte pre-courser cells (prechondrocytes) in the epiphyseal plate to differentiate into chondrocytes

Question 8

what is the effect of differentiating prechondrocytes on IGF-1?

Answer 8

> increased IGF-1 secretion

>increased IGF-1 responsiveness

Question 9

what acts as an auto/paracrine agent on chondrocytes to cause cell division and cartilage production?

Answer 9

IGF-1

Question 10

why does the epiphyseal plate close during adolescence?

Answer 10

due to the influence of sex steroid hormones

Question 11

what are the diabetogenic effects of growth hormone?

Answer 11

> increased glucogenesis by the liver
reduced ability of insulin to stimulate glucose uptake by muscle and adipose tissue
increases adipocyte sensitivity to lipolytic stimuli

Question 12

what are the anabolic effects of growth hormone?

Answer 12

increases muscle liver and adipose tissue amino acid uptake and protein synthesis

Question 13

what change in GH occurs in delta sleep in children?

Answer 13

there is approximately 20% increase in secretion

Question 14

what stimulate GH release?

Answer 14

> stressful stimuli
> actual/potential decrease in energy supply to cells
> increased amino acids in plasma
> delta sleep
> oestrogens and androgens

Question 15

what inhibits GH hormone release?

Answer 15

> glucose
free fatty acids
REM sleep
cortisol

Question 16

what three factors effect growth?

Answer 16

> hormones
nutrition
genetics

Question 17

true or false:

GH and IGF-1 have a large impact in growth during foetal life

Answer 17

false they have a minor impact

Question 18

at what time do androgens and oestrogens dominate the growth spurt?

Answer 18

puberty

Question 19

what hormone dominates uterine growth?

Answer 19

insulin (with IGF-2)

Question 20

what are the growth effects of thyroid hormone?

Answer 20

> permissive to IGF-1
ossifies cartilage
mature teeth
contours face and proportions body

Question 21

what is cretinism?

Answer 21

hypothyroidism from birth:

> stunted growth

Question 22

why do injury and disease stunt growth?

Answer 22

they lead to increased protein catabolism

Question 23

true or false:

gigantism is due to a pituitary tumour BEFORE epiphyseal plates fuse

Answer 23

true

Question 24

true or false:

acromegaly is due to a pituitary tumour BEFORE epiphyseal plates fuse

Answer 24

false this is after plates have sealed

Question 25

what can cause dwarfism?

Answer 25

> GHRH deficiency
> abnormality in GH secreting cells
> end organ unresponsiveness to GH
> genetic mutations: impairment of cells to produce IGF-1
> precocious puberty
> hypothyroidism

Question 26

why dose precocious puberty cause dwarfism?

Answer 26

there is excess GHRH which stimulates puberty and promotes sex hormone release. this causes long bones to fuse creating stunted growth.