Normal Growth

Question 1

Where is GH released?

Answer 1

Anterior pituitary gland

Question 2

What is another name for GH?

Answer 2

Somatotrophin

Question 3

What is unusual about GH as a peptide hormone?

Answer 3

Around 50% bound to carrier proteins

Question 4

What does GH require to stimulate growth?

Answer 4

Insulin and thyroid hormones

Question 5

When does GH become important for growth?

Answer 5

After the first 8-10 months of life

Question 6

How is the growth effect achieved by GH?

Answer 6

Hyperplasia and hypertrophy

Question 7

How is the growth effect of GH achieved?

Answer 7

Through the intermediate IGF-1

Question 8

On what tissue will IGF have a hypoglycaemic effect?

Answer 8

Muscle (liver and adipose have few IGF receptors)

Question 9

Where is IGF-1 secreted from?

Answer 9

Liver and other cells in response to GH

Question 10

How does IGF-1 exert a negative feedback effect on GH?

Answer 10

Stimulate somatostatin

Inhibit GHRH

Question 11

What are the direct effects of GH?

Answer 11

Increase gluconeogenesis by the liver
Reduces the ability of insulin to stimulate glucose uptake by muscle and adipose tissue
Makes adipocytes more sensitive to lipolytic stimuli

Question 12

How is release of GH controlled?

Answer 12

The hypothalamus through GHRH and GHIH

Question 13

When is GH at its highest concentration during children’s sleep?

Answer 13

Deep delta sleep

Question 14

What can stimulate release of GHRH? (5)

Answer 14

Actual or potential decrease in energy supply to cells
Increased amounts of amino acids in the plasma
Stressful stimuli
Delta sleep
Oestrogen and androgens

Question 15

What stimuli can increase GHIH release? (4)

Answer 15

Glucose
FFA
REM sleep
Cortisol

Question 16

What three factors influence growth?

Answer 16

Genes
Nutrition
Hormones

Question 17

What hormones influence intrauterine growth?

Answer 17

Insulin and IGF-II

Question 18

How do thyroid hormones influence growth?

Answer 18

Help ossification of cartilage, teeth maturation, contours of body and proportions and NS development.
Have a permissive effect on GH.

Question 19

What is the usual cause of hypersecretion of GH?

Answer 19

Endocrine tumours

Question 20

What can hypersecretion of GH lead to?

Answer 20

Gigantism (before epiphyseal plates close)

Acromegaly

Question 21

What are some of the causes of reduced height? (6)

Answer 21

Deficiency in GHRH
Abnormal GH secreting cells
End organ unresponsive to GH
Genetic mutations
Precocious puberty
Hypothyroidism in children