Integrated endocrine physiology

Question 1

What GLUT transporter exists on the adipose and muscle tissue?

Answer 1

GLUT 4

Question 2

what is synergistic and permissive action of hormones? Example?

Answer 2

synergistic - produce much greater enhanced response than sum of either of hormones alone
e.g. cortisol and GH on met
Permissive - presence of one hormone allows a second hormone to act
e.g. THs on GH activity in growth promotion
prolactin on oxytocin in milk let down

Question 3

what is antagonistic action? Example?

Answer 3

effects of hormones oppose each other

e.g. insulin and glucagon,cortisol,GH,adrenaline

Question 4

what are the 3 points in a person’s life where human growth is at the highest?

Answer 4

foetal development
post-natal
growth spurt at puberty

Question 5

What endocrine hormones can affect growth?

Answer 5

GH

but also thyroid hormones, insulin, glucocorticoids and sex hormones

Question 6

explain some of the direct effects of GH on the liver, muscle, and adipose tissue

Answer 6

liver - increased gluconeogenesis
muscle - increased amino acid uptake, protein synthesis and decreased glucose uptake
adipose tissue - increased lipolysis and decreased glucose uptake

Question 7

Explain how GH indirectly promotes growth

Answer 7

stimulates release of growth factors such as IGF-I and IGF-II (somatomedins) from liver and other cells

IGF-I (increase in hypertrophy and hyperplasia and skeletal growth)

Question 8

what does GH require for it to promote growth?

Answer 8

thyroid hormones

Question 9

What is the effect of GH, thyroid hormones, androgens, oestrogens, and glucocorticoids on linear growth, and bone maturation?

Answer 9

GH - most for linear growth and little on bone maturation
thyroid hormone - mostly linear growth and mostly BM
androgens - little on LG, mostly BM
oestrogens - little on LG, mostly on BM
glucocorticoids - decrease in LG and little inc in bone maturation

overall level of hormones determines total process

Question 10

Why is it a bad idea to give steroids to young children?

Answer 10

as it will decrease linear growth and start bone maturation - they wont grow to full potential

Question 11

what 6 things can cause an increase in GH?

Answer 11

fall in blood glucose - to increase gluconeogenesis 
decrease in FFA
increased aa
stress
sleep
exercise

Question 12

what kind of effect do glucocroticoids and GH have on metabolism? What about at chronic high levels?

Answer 12

synergism on met - mobilise reserves and increase availability of glucose INITIALLY
chronic levels - inhibit GH release (e.g. Cushing’s syndrome - long term use of high doses of steroids)

Question 13

what are 5 possible causes of stunted growth?

Answer 13

pituitary dwarfism (decr GH)
hypothyroidism (insufficient THs for GH)
Cushing’s syndrome (excessive cortisol - inhibits)
CAH (congenital adrenal hyperplasia)
sexual precocity
(both increased androgens result in early rapid bone maturation)

Question 14

what are some symptoms of GHD (growth hormone deficiency) in adults?

Answer 14

psychological changes
malaise, excessive tiredness, anxiety and depression
osetoporosis
poor muscular tone, decrease in lean body mass
impaired hair growht
increase in adipose tissue

Question 15

what are 4 possible causes of accelerated growth?

Answer 15

gigantism (tumour and excess GH)
hyperthyroidism (excess TH to promote GH)
sexual precocity (initial accelerated bone growth)
eunuchoidism - low sex hormone levels = bone extension and delayed BM)

Question 16

what are some symptoms of acromegaly?

Answer 16

excess GH in adult:
coarse facial features
enlarged hands and feet
headaches, visual disturbances
sleep apnoea, tiredness
hypertension, cardiomegaly
glucose intolerance (diabetes)
irregular/loss of periods or impotence (male)