Lecture 19 - Endocrine Principles Flashcards
What are the different classes of hormones and their features?
L19 S5-7
Polypeptide/protein:
- stored in vesicles and released via exocytosis
- release typically involves cAMP
- usually stored as preprohormones
Steroids:
- usually a cholesterol derivative
- lipid soluble and diffuse across membranes
Amine hormones:
- derived from tyrosine
- usually from the thyroid or adrenal glands
- stored in macromolecules of thryoglobulin in thyroid and vesicles in adrenal medulla
What are the potential locations of hormone receptors?
L19 S9
- in or on cell membrane
- cytoplasm
- nucleus
What is down regulation and what are the potential methods of down regulation (5)?
L19 S10
Decrease in a cells response to a hormone
Methods:
- inactivation of signaling pathway
- sequestration of receptor
- inactivation of receptor
- destruction of receptors
- decreased production of receptor
What is up regulation and what are the potential methods of down regulation?
L19 S11
Increase in a cells response to a hormone.
Methods:
- increase in receptor production
- increase in intracellular signaling molecules
- release of sequestered receptor
- activation of disabled receptor
What are the main types of receptors?
L19 S12
Ion channel-linked receptor:
-primarily used by neurotransmitters
G protein coupled receptor
Intracellular receptor:
- bind lipid soluble hormone
- activated complex binds promotor sequences of DNA
Enzyme-linked receptor:
-single transmembrane domain linking extracellular receptor domain with intracellular enzyme domain
What is the mechanism of the adenyl cyclase second messenger system?
L19 S18
- G protein is activated by GPCR and binds adenylyl cyclase, activating it
- adenylyl cyclase produces cAMP
- cAMP activates protein kinases
- protein kinases effect proteins via phosphorylation
What is the mechanism of the membrane phospholipid second messenger system?
L19 S19-20
- receptor indirectly or directly activates phospholipase C
- phospholipase C cleaves PIP2 into IP3 and DAG
- IP3 induces calcium release from the ER
- DAG activates PKC
What is the mechanism of the calcium/calmodulin second messenger system?
L19 S21
Calcium entry caused by:
- change in membrane potential opening calcium channels
- hormone induced opening calcium channels
When calcium binds 3-4 binding sites on calmodulin, it activates calmodulin causing it to either activate or inactivate protein kinases
What is the mechanism of direct hormone signaling via DNA interaction?
What is the significant differences between this and the methods involving second messengers?
L19 S22
- hormone diffuses across cell membrane and binds receptor
- hormone-bound receptor diffuses into nucleus
- hormone-bound receptor binds DNA
*this process is slower than other methods but can be significantly longer lasting
What are the main cell types of the anterior pituitary and what does each produce? (5)
L19 S24
Somatotropes (acidophils):
-HGF
Corticotropes:
-ACTH
Tyrotropes:
-TSH
Gonadotropes:
-LH and FSH
Lactotropes:
-prolactin
What is the function of the hypothalamus?
L19 S27
Controls anterior pituitary via hypothalamic releasing and inhibitory hormones/factors
Hormones moves to the anterior pituitary via hypothalamichypophseal portal system
How does growth hormone stimulate growth? (4)
L19 S30
- increased deposition of protein by chondrocytic and osteogenic cells
- increased rate of chondrocytic and osteogenic cell reproduction
- conversion of chondrocytes into osteogenic cells
- stimulation of osteoblasts
How does growth hormone affect protein synthesis? (4)
L19 S30
- enhances transport of AAs into cytoplasm
- increase RNA translation
- increases transcription
- decreases protein catabolism
How does growth hormone affect fatty acid metabolism? (2)
L19 S31
- release of fatty acids from adipose tissue
- enhances conversion of fatty acid to acetyl-CoA
How does growth hormone affect glucose utilization?
L19 S31
Decrease glucose utilization:
- decreased uptake by skeletal muscle and fat
- increases glucose production in liver
- increases insulin secretion
