Endo 3 Flashcards
The bulk of the products created by the paraventricular nucleus is?
GHRH
SRIF-inhibiting factor
GH/GHIH go to pituitary gland and act on somatotrope and release their products which go into circulation to have their effect where
Bone/muscle
Liver
-produces IGF-1 when stimulated by GH
-IGF-1 produces negative feedback effects of GH production- responsible for the decline in circulating GH
GH uses which type of receptor?
Cytokine receptor
IGF-1 uses which type of receptor/
Tyrosine kinase receptor
GHRH and SRIF use which type of receptor
G-protein linked receptors
IGF-1
systemic and autocrine effects
low neonatally, high at puberty, lower later in life
needed for skeletal and extra-skeletal development, adipocyte differentiation
IGF-2
prominent during embryonic/fetal growth, with insulin
GH secretion patterns
- rate of secretion of GH decreases after adolescence
- Levels fluctuate with the time of day (22hr-0200hr)
- Secretion regulated by GHRH and GHIH
- In older animal GH and IGF remain essential regulators of tissue renewal and metabolism
How is the majority of GH found?
Bound to binding protein GHBP
some can be trasported as a free hormone
How is IGF-1 found
almost entirely bound to transport proteins
-some IGF-1 transport/binding proteins have an endocrine function
Factors affecting GH secretion include
sleep- increase exercise- increase hypoglycemia-increase hyperglycemia- decrease high dietary protein- increase steroids-increase glucocorticoids- decrease endocrine disruptors -decrease ghrelin -increase
What is the function of GH and IGF-2 in the fetus/neonate
act together on the growth plate of long bones in young animals
GH promotes growth of cartilage while IGF-2 promotes the ossification (calcification) of cartilage cells
Function of GH and IGF-1 on: Hepatic glucose release Plasma glucose concentration Sensitivity of tissue to insulin Lipolysis in adipocytes
GH: In, In, Dec, In
IGF-1: Dec, Dec, In, Dec
GH is a _________ factor that opposed the actions of insulin and IGF-1 on ____ and ____ homeostasis
diabetogenic
carbs and lipid
Other physiological roles of GH
Contributes to the maintenance and function of pancreatic islets
Stimulates the immune system
Anti-aging effects
Stimulates the growth and regeneration of internal organs except for the brain
Normal reproduction
In which country are hormonal growth promoters banned?
European union
What are the problems associated with GH use
- increased stress of animal associated with high milk production and increased risk of mastitis
- adverse effects on reproduction: cystic ovaries, uterine disorders, decreased gestation length
Dwarfism
- deficiency of anterior pituitary hormones during childhood
- specifically due to deficiency of GH
- parts of body develop in proportion to eachother
Pygmy
african pygmy -normal levels of GH -hereditary inability to form somatomedin Laron-type dwarfism -decreased responsiveness to GH and IGF
Gigantism
cells of pituitary become active due to following reasons and produce excess GH
-hyperplasia
-tumor
If over production occurs before epiphyses of long bones fused with shafts then bone will continue to grwo
-hyperglycemia - 10% have diabetes mellitus
Acromeagaly
tumor occuring after epiphysis has fused
soft tissue can grow and bone grows in thickness
results in enlarged hands and feet, membranous bones in cranium
enlarged organs: tongue, liver, kidney