endocrinology 3

Question 1

What are the 2 forms of GH signalling for AP?

Answer 1

TROPHIC OR DIRECT

Question 2

What are the 2 types of growth?

Answer 2

bone growth (height)

soft tissue (weight)

Question 3

Where is the site of bone growth?

Answer 3

epiphyseal plate

Question 4

What type of bone growth is bone lengthening?

Answer 4

endochondral

Question 5

What is endochondral ossification?

Answer 5

cartilage (hyaline) is replaced by bone

chondrocytes lay down cartilage and osteoblast replace this with bone

Question 6

When does the epiphyseal growth plate close?

Answer 6

adolescence

Question 7

What are the 2 types of growth hormone control GH release form AP?

Answer 7

GHRH (release)

GHIH (inhibitory)

Question 8

What factors can influence GF release from hypothalamus?

Answer 8

circadian rhythm

stress

cortisol fasting

Question 9

When growth hormone is release form the AP, where does it target?

Answer 9

liver and other tissues

Question 10

When GF influences the liver and other tissue, what does this lead to the release of?

Answer 10

insulin-like GF

IGF

Question 11

In the last stage in the GF cascade, what does IGF influence?

Answer 11

cartilage growth

increase blood glucose

bone and tissue growth

Question 12

What can be a bad effect of the excessive GH?

Answer 12

increase blood glucose and be pro-diabetic

Question 13

Why is GH atypical for a peptide hormone?

Answer 13

has a plasma binding protein (like steroids)

Question 14

What is the benefit of GH having a plasma binding protein?

Answer 14

extend half life

Question 15

What are the direct effects of GH?

Answer 15

growth and metabolism

Question 16

What are the trophic effects of GH?

Answer 16

Effects on growth and metabolism through stimulation of insulin-like GF-1 (IGF-1)

Question 17

Where is IGF-1 released from?

Answer 17

liver and other cells

Question 18

What is the release pattern of GH?

Answer 18

CYCLIC

i.e. at night, the energy is diverted to growth/development

Question 19

When to conc of GH peak and decline?

Answer 19

peak = early childhood/adolescence

decline = later life

Question 20

What does GH stimulate in bone?

Answer 20

differentiation of precursor cells in bone

pre-chondrocytes to chondrocytes

effectively… GH stimulates cell maturation and IGF-1 production

then IGF-1 stimulates cell division and tissue growth

Question 21

What do chondrocytes produce?

Answer 21

IGF-1

Question 22

What does IGF-1 stimulate in bone?

Answer 22

Question 23

Apart from bone, what is the effect of GH and IGF-1 in muscles and other tissues?

Answer 23

stimulate protein synthesis

Question 24

What receptors does IGF1 act upon, because it is similar to another molecule?

Answer 24

insulin receptors

insulin and IGF can and each others receptors - lots of cross over

Question 25

What do IGFs behave as?

Answer 25

auto/paracrine (local) and a hormone (endocrine)

Question 26

What molecule stimulates chondrocytes to divide and produce cartilage?

Answer 26

IGF-1

Question 27

What are the metabolic effects of GH?

Answer 27

uptake plasma amino acids (for protein synthesis)

breakdown of fat (energy for growth)

spares glucose stores (responsible hormone)

Question 28

What does GH preferentially gain energy from?

Answer 28

fat stores as apposed to glucose stores

this is called a responsile hormone

Question 29

What are the metabolic effects of IGF-1 (and insulin)?

Answer 29

uptake of plasma amino acids (for protein synthesis)

glucose/energy substrate uptake into cells

Question 30

How is glucose stored in cells (for growth)? (promoted by IGF-1)

Answer 30

glycogen

Question 31

What hormones allow tight regulation of energy stores?

Answer 31

GH

IGF-1