Growth Flashcards
What does growth hormone do to protein stores, fat stores and carbohydrate stores
Enhances body protein
Uses Fat stores
Conserves carbohydrates
What does Diabetogenic mean?
It produces persistent elevation in blood glucose
What hormone control growth?
Growth Hormone IGF-1 Thyroid Hormones Insulin Sex Hormones Cortisol (antagonistic)
What controls growth in the foetal period
Nutrition
Insulin
Thyroid hormones
When does growth hormone start to become significant in development
10 monthes
What do babies who are born deficient in GH and IGF-1 look like at birth
normal size
What produces spike in the GH release at puberty
Oestrogen/testosterone
What specific dimensions does GH/IGF-1 increases
Bone length
Height
Weight
Body Mass
What will a baby be like if it is born with a thyroid hormone deficiency
It will not grow well after birth and it will have cognitive problems
What will a baby be like if it is born with a growth hormone deficiency
Not grow well after birth but will be cognitively fine
What part of the infant is TH most responsible for developing
Nervous system
What is congenital hypothyroidism
babies are born of normal size but they do not grow
retain infantile facial features
What other deficiency can cause similar symptoms to congenital hypothyroidism and why
Materal iodine deficiency
Iodine is needed for thyroid production
What effect does thyroid hormone have on growth homrone
A permissive effect
What is Growth Hormone also known as
Somatotropin
What cell types release growth hormone
Somatotrophs
What are the normal levels of circulating growth hormone in adults and children
Children - 1.6-3 ng/ml
Adults 6ng/ml
What controls the release of growth hormone
Growth Hormone releasing hormone
Growth hormone ingibiting hormone
What is GHIH also known as
Somatostatin
Why is GH secretion continued throughout adult life
It is essential for maintenance and repair of tissue
What does GH promote in its target tissues at a cellular level
Hypertrophy of cells
Hyperplasia of cells
What kind of receptor does GH act on
Tyrosine Kinase
What is the indirect effect of growth hormone
Growth of long bones mediated by IGF-1
What is the direct effect of growth hormone
Regulation of metabolim
What is IGF-1 also known as
Somatomedin C
What is the effect of IGF-1
It stimulate the glucose uptake in muscles and bone
Are blood glucose levels affected by the effect of IGF-1
NO - the reduce in blood glucose is counteracted by the effects of GH on the liver (increased glucose synthesis)
What inhibits the release of GH
IGF-1 acts on the hypothalamus and the anterior pituitary to stop GH release
GH also directly inhibits its own release when levels get too high.
What secretes IGF-1
The liver (mostly)
How are GH and IGF-1 transported in the blood
Partly bound to carrier molecules
What % of GH and IGF-1 are carried on blood bound carrier protiens
50%
What is the advantage of GH and IGF-1 being transported on blood bound carrier proteins
it prevents their degradation (extends half life)
It helps smooth out the effects of their erratic release pattern
How does GH regulate metabolism
Increases blood glucose levels (increased gluconeogenesis by liver)
Increase AA uptake by cells
What does GH do to adipocytes
Makes them more sensitive to lipolytic stimuli
At what time of day is the most GH released
During the first 2 hours of sleep (since general energy requirements are low)
How many times more GH is released in sleep than during day in children
20x
What time of day is most IGF-1 released
Its fairly constant throughout the day
Why is IGF-1 released more consistently during the day
It binds more tightly to carrier proteins than GH making it less vulnerable to degradation.
What stimulus increase GHRH release
Increased protein in the blood
Actual or potential energy in energy supply to cell
- exercise/cold
- fasting / hypoglycaemia
- physical stress/illness (might be stunted by cortisol)
Delta sleep
Oestrogen/testosterone
How does Oestrogen or Testosterone increased GH
Stimulate GH release from pituitary directly
Decreases IGF-1 mediated negative feedback
What stimulus increases GHIH secretion
Increased blood glucose
Increased Blood FFA
Ageing
Cortisol
