L11 Flashcards
growth hormone is antagonistic to _____ and similar to ______
Antagonistic to insulin;
similar to glucagon
GH released in response
to insulin-induced_______
hypoglycemia
role of estrogen and androgen in bone growth (5)
– Stimulates fracture healing through receptor mediated mechanism
– Modulates release of a specific inhibitor of IL-1active at puberty
– initial growth spurt (hormones stimulate osteoblasts)
– masculinization or feminization (affects shape of bone)
– later, cause epiphyseal plate to close
two functions of thyroid hormones (thyroxine and triiodothyronine)
- stimulate osteoclastic bone resorption
- modulates activity of cells in
response to GH to ensure proper proportions of the skeleton
how do glucocorticoids cause increased osteoclastic bone
resorption
Inhibit calcium absorption from the gut causing increased PTH and therefore increased osteoclastic bone
resorption
Intermittent exposure of parathyroid Hormone (PTH) and PTH-like peptide stimulates _______
osteoblasts –> increased bone formation
another name for IGF-1 is _______
Somatomedin C
Inadequate supply of vitamin D results in _______ and ______
rickets and osteomalacia
what happens to bones in the absence of vitamin D?
In its absence, excess osteoid accumulates –> repression of osteoblastic collagen synthesis.
3 main factors affecting bone growth
genetics, nutrition (vitamin C and D), hormones
why is vitamin D necessary for bones?
Necessary for absorption of calcium from intestines
vitamin C is necessary for bone growth for ______
collagen synthesis by osteoblasts
vitamin C deficiency leads to ____
scurvy
explain osteomalacia
soft bones. osteoid is produced but inadequately mineralized. caused by insufficient dietary calcium or vitamin D
_____ is the children’s form of osteomalacia
rickets
signs of rickets
bowed legs, and deformities of the pelvis, ribs, and skull.
thyroid hormones needed for setting _______ and for ______
setting metabolic rate; differentiation
[growth/thyroid hormone] stimulates secretion of [growth/thyroid hormone]
thyroid hormones stimulate GH secretion
name a condition caused by thyroid hormone deficiency and describe it (causes, effects)
cretinism - primarily caused by iodine deficiency, which is crucial for thyroid hormone development. causes stunted growth, mental retardation, potential deaf-mutism, etc.
true or false: thyroid hormone replacement therapy can allow for catch-up growth
true
what is adrenarche?
period btwn ages 6-8 where androgen secretion increases (androstenedione, DHEA, DHEAS), regulated by ACTH
what’s the order of growth in puberty?
hands/feet –> arms/legs –> trunk
what main hormone is released during puberty and in what manner? release is correlated with ________
GnRH from hypothalamus in a pulsatile manner. release is correlated with critical body composition
how is puberty the great equalizer?
if it starts early –> final percentile is less
if it starts late –> final percentile is more
Kisspeptin neurons may act as central processors for relaying signals from _____ to ______
the periphery to GnRH neurons
Androgens and Estrogens promote
__________, terminating adolescent growth spurt
epiphyseal fusion
estrogens and androgens stimulate ____ secretion
GH
what effect does leptin have on the Kiss1 neuron?
leptin stimulates Kiss1 neurons –> the neurons synapse on terminals of GnRH neurons –> release of GnRH
positive stimulators of GnRH neurons (2)
leptin and sex steroids
at what concentration is estrogen stimulatory for growth? when is it inhibitory?
stimulatory at very low concentrations, inhibitory at high concentrations
childhood obesity is associated with [early/late] signs of puberty in girls
early
what is the critical weight/fat hypothesis
A minimum body weight/fat is needed for menarche
______ is a protein that negatively regulates muscle growth
Myostatin
______ is an age-related condition characterized by the gradual loss of muscle mass, strength, and function
Sarcopenia
true or false: the number of secretions of GH decreases with age
false; number is about the same but the volume of those secretions is lowered
Overexpression of IGF-1 results in (2):
sustained hypertrophy and regeneration in senescent skeletal muscle
transcription factor associated with maintaining muscle satellite cells
pax7
how does injury/exercise affect muscle satellite cells?
pax7 expression decreases –> satellite cell activated –> differentiate into myoblasts/myofibers
how does myostatin kickstart its pathway?
myostatin binds to a receptor which causes smad activation –> smad suppresses muscle proliferation
what does a primary endocrine disorder mean?
dysfunction of peripheral gland
what does a secondary endocrine disorder mean? what are the exceptions to this (2)?
usually pituitary dysfunction projected to peripheral gland
exceptions:
Secondary hyperaldosteronism = response of adrenal cortex to rennin hyperactivity
Secondary hyperparathyroidism = response of PTH to low plasma Ca2+
what does a tertiary endocrine disorder mean?
rarely used term for hypothalamic dysfunction
methods for assessing endocrine function that require antibodies (3)
radioimmunoassay (RIA), immunoradiometric assays (IRMA), and enzyme-linked immunosorbent assays (ELISA)
key component of elisa
enzyme-labeled antibody that can change the substrate color
what is a way of quantifying hormonal activity?
bioassay –> standard curve
explain immunoaffinity chromatography
affinity chromatography that uses antibodies as the stationary phase. The target molecule binds specifically to the antibody, while other molecules in the sample pass through or are washed away.
true or false: one-time blood sample collection is a sufficient procedure for a majority of hormones
true
2 examples of hormones with diurnal variability
cortisol, GH
