20.3 endocrine Flashcards
what is the function of negative feedback loops?
prevent over-activity of hormone system
Where can feedback regulation of hormones occur?
- gene transcription
- gene translation
- hormone processing
- hormone release
Stages of development and seasonal changes are able to influence the hormone release?
yes
Where are cell receptors located?
surface of PM, cytoplasm, nucleus
What factors can influence down regulation of receptors?
- inactivate intracellular protein molecules
- sequester receptors
- inactivate receptors
- lysosome destruction of receptor
- reduce production
What can cause up regulation of receptors?
- hormone increases production of the receptor via intracellular signaling
- improve reaction rate, to make receptor more available
What receptor is generally used by neurotransmitters?
- ion-channel-linked
What is a leptin receptor?
JAK-STAT pathway, enzyme linked hormone receptor
Which hormones are intracellular signalers?
- adrenal and steroidal
- thyroid
- retinoid
- vitamin D
What are the different classes of hormones?
- polypeptide and protein
- steroids
- amine
What are unique features of polypeptide hormones?
- stored as prohormones in secretory vesicles until needed
2. releases involves cAMP and exocytosis
What are unique features about steroid hormones?
- cholesterol derivatives
- lipid soluble, diffuse across membranes
- stored as cholesterol esters until needed
What are unique features about amine hormones?
- tyrosine derivative
- form adrenal medullary and thyroid hormone
- form catecholamines in the adrenal medulla
- thyroid hormones form in thyroid glandular cells
What is the role of PLC in signal transduction?
cleaves PiP2 into DAG and IP3 which release calcium and activate PKC
How many Ca ions are required to activate the calcineurin-calmodulin system?
3-4 bind with calmodulin to initiate multiple effects
Which hormones act directly on DNA?
steroid ( do not last long) thyroid (have long lasting effect)
* process is longer than the PM receptor binding
Which of the hormones that act on DNA bind inside the nucleus?
thyroid hormones
Which of the hormones that act on DNA bind in the cytoplasm?
steroid hormones
What cells types are located in the anterior pituitary gland (adenohypophysis)?
- somatotropes
- corticotropes
- thyrotropes
- gonadotropes
- lactotropes
What hormones are released from the adenohypophysis?
- HGF
- adrenocorticothyroid hormone
- thyroid stimulating hormone
- LH and FSH
- prolactin
What hormones are secreted from the magnocellular neurons of the supraoptic nuclei?
ADH
What hormones is secreted from the paraventricular nuclei of the magnocellular neurons from the posterior pituitary?
oxytocin: cause uterus contraction and milk secretion
What major system controls the anterior pituitary gland?
hypothalamus via the hypothalamic releasing and inhibitory hormones
Where are hormones from the hypothalamus ultimately secreted?
into the hypothalamic-hypophyseal portal system
How does growth hormone increase growth?
- increase protein deposition of chondrocytic and osteogenic cells
- increases reproduction of chondrocytic/osteogenic cells
- convert condrocyte into osteocyte
- stimulate osteoblast
How does growth hormone affect the protein synthesis?
- increase amino acid transport to cytoplasm
- increas RNA translation
- increase transcription
- reduce protein catabolism
What is the effect of growth hormone on fatty acids?
- release FA from adipose
2. increase FA conversion to acetyl-CoA
How does growth hormone reduce the glucose utilization?
- reduce glucose uptake in skeletal muscle and fat
- increase liver glucose production
- increase insulin secretion
- growth hormone can stimulate formation of diabetes
What effect does growth hormone have on the liver?
- forms somatomedins
- affect bones growth
- called insulin-like growth factor
What is the most important somatomedin?
somatomedin C or insulin like growth factor-1
What factors will stimulate secretion of growth hormone?
- starvation (protein deficiency)
- hypoglycemia
- Ghrelin
- first 2 hr of deep sleep
