Hypothalamic Pituitary Axis And Growth Hormone

Question 1

What factors influence growth (4)

Answer 1

Genetics, environment, hormones and nutrition

Question 2

What is the most important endocrine regulator of growth

Answer 2

Growth hormone

Question 3

What stimulates the release of growth hormone from the pituitary gland

Answer 3

GHRH - growth hormone releasing hormone

Question 4

What socket of bone does the hypothalamus sit in

Answer 4

Sella turcica

Question 5

From where does the anterior pituitary arise from

Answer 5

Oral ectoderm (primitive gut tissue)

Question 6

Where does the posterior pituitary originate from

Answer 6

Neuroectoderm (primitive brain tissue)

Question 7

What is the connection between the hypothalamus and posterior pituitary called

Answer 7

Infundibulum

Question 8

What hormones are released from the posterior pituitary gland

Answer 8

Oxytocin and antidiuretic hormone

Question 9

What hormones are produced in the posterior pituitary

Answer 9

None - hormones are only stored here

Question 10

Where in the hypothalamus are oxytocin and antidiuretic hormones produced

Answer 10

Supraoptic and paraventricular nuclei

Question 11

Where are hormones stored before they are released to the anterior pituitary gland

Answer 11

Median eminence

Question 12

What does oxytocin do

Answer 12

Releases milk as part of the suckling reflex and caused uterus contractions during birth

Question 13

What does ADH do

Answer 13

Regulate body water volume

Question 14

What are the 6 hormones produced by the hypothalamus which travel to the anterior pituitary

Answer 14

TRH
PIH
CRH
GnRH
GHRH
GHIH

Question 15

What are tropic hormones

Answer 15

Hormone that affect the release of other hormones

Question 16

What hormones are produced by the anterior pituitary gland and what are their functions

Answer 16

TSH - secretion of thyroid hormone from the thyroid gland
ACTH - secretion of cortisol from adrenal cortex
LH - ovulation and secretion of sex hormones
FSH - development of eggs and sperm
PRL - mammary gland development and milk secretion
GH - growth and energy metabolism and stimulates IGFs

Question 17

What hormone causes the anterior pituitary gland to produce and release TSH

Answer 17

Thyrotropin releasing hormone

Question 18

What hormone causes the anterior pituitary gland to produce and release ACTH (adrenocorticotropic hormone)

Answer 18

CRH (corticotropin releasing factor)

Question 19

What hormone causes the anterior pituitary gland to produce and release prolactin (PRL)

Answer 19

Negative control of the prolactin release-inhibiting hormone (PIH)

Question 20

What hormone causes the anterior pituitary gland to produce and release growth hormone

Answer 20

Growth hormone releasing hormone

Growth hormone inhibiting hormone inhibits

Question 21

What hormone causes the anterior pituitary gland to produce and release luteinising hormone and follicle stimulating hormone

Answer 21

Gonadotrophin releasing hormone

Question 22

How are the hypothalamic and anterior pituitary hormones regulated

Answer 22

Negative feedback

Question 23

What is another name for growth hormone inhibiting hormone

Answer 23

Somatostatin

Question 24

Why is growth hormone not orally active like thyroid hormone

Answer 24

It is a protein and so it is degraded in the stomach

Question 25

How does growth hormone give its affect

Answer 25

Either directly or indirectly (through insulin-like growth factors)

Question 26

Which cells release IGFs

Answer 26

Liver and skeletal muscle cells

Question 27

What does growth hormone during childhood

Answer 27

stimulates long bone growth by - stimulating length and width growth before epiphyseal closure - and width after epiphyseal closure - IGF stimulates bone and cartilage growth

Question 28

What do GHs and IGFs do in adults

Answer 28

Help maintain muscle and bone mass Promote healing and tissue repair Modulate metabolism

Question 29

What causes an increase in the production of growth hormone

Answer 29

- deep sleep - stress (trauma/surgery) - exercise - less glucose and fatty acids - fasting

Question 30

What causes a decrease in growth hormone secretion

Answer 30

- somatostatin - rapid eye movement sleep - glucose and fatty acids - obesity

Question 31

How are IGFs involved in the negative feedback loops

Answer 31

mediates long loop - inhibit GHRH from hypothalamus - stimulates somatostatin release from anterior pituitary gland - inhibit GH from anterior pituitary

Question 32

What mediates the short loops of the growth hormone negative feedback

Answer 32

GH via stimulation of somatostatin release

Question 33

What does growth hormone deficiency result in

Answer 33

Pituitary dwarfism (proportionate dwarfism)

Question 34

What is the treatment for pituitary dwarfism

Answer 34

GH therapy - injection of GH produced through recombinant DNA technology

Question 35

What does growth hormone excess in childhood result in

Answer 35

Gigantism

Question 36

What does pituitary dwarfism result in

Answer 36

- slow growth rate (below 3rd percentile) | - delayed/no sexual development

Question 37

What usually causes gigantism

Answer 37

Pituitary adenoma

Question 38

What des growth hormone excess in adults result in

Answer 38

Acromegaly - large extremities

Question 39

How does GH have its direct effect on cells

Answer 39

Binds to tyrosine kinase receptors activating Janus kinases (linked to the receptors) which then phosphorylates the receptors and itself to activate the signalling pathways including IGF production

Question 40

What are the 2 main growth factors and what do they do

Answer 40

IGF2 - involved in fetal growth | IGF1 - major growth hormone in adults

Question 41

What modulates the activity of IGFs

Answer 41

Binding proteins

Question 42

What do IGFs modulate

Answer 42

- hypertrophy - hyperplasia - increase in protein synthesis - increase rate of lipolysis in adipose tissue

Question 43

What other others influence growth

Answer 43

- insulin - thyroid hormones - androgens - estrogens - glucocorticoids

Question 44

How is the release/production of prolactin controlled

Answer 44

Prolactin is produced when there is a lack of prolactin inhibiting hormone (e.g. Dopamine). The production is under inhibitory control