7. Somatotropic Axis Flashcards
What are the following hormones/target cells for the somatorropic axis in each of the following sections
a) hypothalamic hormone
b) anterior pit hormone
c) endocrine target and the hormone it secretes - 2
d) non-endocrine targets
a) GHIH + GHRH (growth hormone releasing/inhibiting hormone)
b) GH - growth hormone
c) liver which releases IGFs
d) many tissues
Match the following terms with; somatomedins, somatotropin, somatostatin
a) GHRH
b) GH
c) IGFs
a) somatostatin
b) somatotropin
c) somatomedins
ANS the following wrt GH
a) what is its half time? - 2
b) Where is GH secreted from? Be specific - 2
c) what role does it play? - 2
a) 6 to 20 mins
b) from the somatotropic cells in the anterior pituitary
c) muscle and bone growth
What is GH (growth hormone)?
a) carbohydrate
b) protein
c) fat
d) NTX
b
GH appears to peak about 1 hour after the onset of sleep. What does this mean?
This means that a majority of growth occurs while we sleep
Describe the pattern of GH secretion - 3
has several large pulses/peak each day from 10 to 30 mins each day in which the largest occurs 1h after onset of sleep
At what points in life is GH secretion patterns the highest? Why might this be?
- early in life - infant = enormous amount of growth occurs when we are infants
- puberty = this explains that growth spurts that occur at this age
T or F - GH can be transported as a free hormone w/in the BV
T - however most GH are bound to GHBP (growth hormone binding protein) and carried in the BV instead
Why might GH be more likely to be transported via a binding protein compare to just traveling as a free hormone w/in the BV
the GH is less protected when free compared to being bound to a transporter
Describe how the following factors influence the release/inhibition of GH
a) sleep
b) exercise
c) hypoglycemia - DEC glucose in blood
d) hyperglycemia - INC glucose in blood
e) high consumption of proteins
f) glucocorticoids present - cortisol
g) endocrine disruptors
h) release of ghrelin - hunger hormone
a) release
b) release
c) release
d) inhibition
e) release
f) inhibition
g) inhibition
h) release
a) What is the target tissue for GH? - 1
b) What hormone does that target tissue release? - 2
a) the liver
b) IGF -1 and 2 (insulin-like growth factors)
IGF is also known as
a) growth hormone
b) insulin-like growth factors
c) somatomedins
d) somatotropins
e) all of the above
b + c
T or F - IGF-1 can be transported as a free hormone in the BV
F - it is bound to the transporter protein IGF-BP
T or F - GH stimulates the synthesis and release of IGF-2 in the liver only
F - its IGF-1 and it can be synthesized and released in many other tissues as well
GH and IGF-1 appear to exert indep roles from each other despite it being difficult to differentiate the two. What types of actions doe these hormones exert wrt each other. - 2
they exert opposite actions in some tissues (if GH activates a process IGF-q would inhibit that process)
What influence do the following fxns have on the INC/DEC on GH and IGF-1 release
a) break down and release of glucose by liver
b) build up of glucose in the BV
c) sensitivity of of insulin on tissues
d) breaking down adipose tissue
e) protein synthesis by muscles that are taking up AAs
a) GH = INC and IGF-1 = DEC
b) GH = INC and IGF-1 = DEC
c) GH = DEC and IGF-1 = INC
d) GH = INC and IGF-1 = DEC
e) GH = INC and IGF-1 = INC
Draw a flow chart of the metabolic effects of GH including the following terms; liver, adipose tissue, most tissues, IGF-1, Cartilage and bone growth, muscle and other organ growth, lipolysis release of FAs, DEC glucose utilization
What are the 2 periods of rapid growth caused by the GH?
- postnatal - right after birth
- puberty
T or F - the size of a babies head is 1/3 of its body
F - 1/4
What are the 2 main things that GH stimulates the growth of?
- bone and cartilage
- soft tissues
Describe the following types of growth that occurs in the soft tissue
a) hypertrophy
b) hyperplasia
a) INC in cell size
b) INC in number of cells produced
What is the most common form of calcium phosphate that bones contain?a
a) Hydroxyapatite Ca5(PO4)3(OH)
b) Hydroxyapatite Ca10(PO4)6(OH)2
c) calcium phosphate Ca10(PO3)6(OH)
d) Hydroxyapatite Ca10(PO3)6(OH)
b
Describe the two ways that bone is formed
- INC diameter by depositing calcium phosphate on the outer surface of the bone
- INC length by adding calcium phosphate to the ends of the bones
Describe 4 steps involved w/ how bone is grown linearly from the epiphyseal plates using the following terms; chondrocytes, collagen, cartilage, osteoblasts, calcium phosphate
- the epiphyseal plates contain chondrocytes which is where the collagen-producing cells are located
- the collagen-producing cells produce cartilage which calcifies
- the chondrocytes degrade
- The osteoblasts lay calcium phosphate on top of the newly calcified cartilage
