NPB Growth Hormone and IGF-1

what makes GH

somatotropes

where is gh made

anterior pituitary

sst from the arc does what to gh production

decrease secretion

ghrh from the arc does what to gh production

increase secretion

when are gh levels highest in the body

at puberty and 12 wks gestation

how does gonadal steroids effect gh release

increase release

how does cortisol effect gh release

decrease release

how does T3 effect gh release

increase release

what does release gh become in the liver

IGF-1

what kind of feedback does gh use

negative feedback

what acts as the signal in negative feedback for gh

igf-1

what does igf-1 stand for

insulin like growth factor 1

T3 has the most significant effect on growth when

postnatal growth and bone maturation

other than gh secretion, what 2 other things does T3 stimulate regarding bone

hypertropic chondrocyte differentiation and bone mineralization

what kinds of effects do sex hormones have on growth

dual effects

what do androgens cause to happen in growth

stimulate gh release, accelerate growth with puberty

what does estrogen cause to happen in growth

closure of the epiphyseal plate and cessation of growth

does cortisol stimulate or inhibit gh secretion

inhibit

what other hormone does cortisol stimulate in the arc to block gh secretion

sst

where does cortisol have a direct inhibitory effect

at the growth plate

what kind of receptor does gh use

cytokine receptor

what kind of signaling does a cytokine receptor use

jak stat signaling

does gh cross into the cell during signaling

no

what does the nuclear response to gh depend on

the type of cell gh lands one

what is the main target of gh

liver

what molecule is the main mediator for gh effects

igf-1

what are some igf-1 dependent growths

increase muscle mass, bone elongation, increase bone mass, increase milk production

what are some igf-1 independent growths

epiphyseal growth, increased bone mass, increased lipolysis, increased amino acid transport

when the body is in fasting or negative energy state, does gh need igf-1 (is it independent or dependent)

it is independent of igf-1

when the body is in fed or positive energy state, does gh need igf-1 (is it independent or dependent)

it is dependent of igf-1, GH is mediated by igf-1

what is the growth plate also called

epiphyseal plate

what does the epiphyseal plate become when closed

epiphyseal line

cells in the resting zone of the epiphyseal plate are called

chondroblasts

what hormone do chondroblasts express

gh

what kind of cells form the proliferating and hypertropic zones of the epiphyseal plate

chondrocytes

what kind of cells dictate bone length

chondroblasts and chondrocytes

what kind of cell dictates bone density

osteoblast

what do chondrocytes become when the bone is no longer growing

osteocytes

how do androgens and estrogens act on the resting zone

they increase gh which increases chondroblast activity, making more igf-1 and cells

how does igf-1 act on the proliferating and hypertropic zone

increase activity

how does T3 act on the hypertropic and ossification zone

increase activity

if the main sex hormone in the body is estrogen, how does this effect the resting zone

decrease activity

how does cortisol effect the resting zone

decrease GHR expression in chondroblasts

how does cortisol effect the proliferating and hypertropic zones

decrease igf-1 expressed in chondrocytes

what are the 4 positive factors to grow and elongate bone

GH, sex hormones, igf-1, and T3

what is the main negative factor to growth and elongation of bone

cortisol

does puberty occur earlier for girls or boys

girls

why does the closing of the epiphyseal plate happen earlier for girls

it is regulated by increased levels of estrogen

what causes gigantism

increased gh before closure of the epiphyseal plate

what causes acromegaly

increased gh after closure of the epiphyseal plate

gigantism and acromegaly are also associated with what

abnormal growth of other organs