Endo 1 Flashcards
Who coined the term homeostasis?
Walter Cannon
Homeostatic control relies on?
Constant monitoring
Responding to changes in blood composition
Negative feedback
Positive feedback
increases the original stimulus to push the variable further
-ovulation, parturition and blood clotting
What are the classes of hormones?
amino acid derivates peptides proteins steroids fatty acid derivatives
Modes of secretion
phasic (surge-like)
episodic (pulsatile)
circadian, cyclic (periodic), cirannual
mixed
Endocrine disease status
over production/hypersecretion
under production/hyposecretion
transport or clearance problems
hormone resistance
Other regulating molecules besides hormones include
pheromones neurotransmitters cellular GF angiogenesis-regulating molecules cytokines
Transmembrane receptors
- hormone binds to ECD of receptor and activates one or more cytoplasmic signaling pathways
- pathways involved phosphorylation and enzyme activation
Intracellular receptors (cytosolic and nuclear)
Hormone binds to the inracellular receptor and HR complex acts as a transcription factor that modifies the expression of specific genes
Transmembrane receptor types include
ion channel receptors
tyrosine kinase receptors
cytokine receptors
G-protein linked receptors
How do ion channels work?
Binding of the ligand to the extracellular portion of receptor causes a structural change to the channel (protein) which results in either the opening or closing of channels which leads to changes in transmembrane transport (mostly ionic transport)
What type of effects do ion channels have on the cell?
non genomic effects (non transcriptional processes)
How do tyrosine kinase receptors work?
Transmembrane receptor with ECD and ICD, the ecd binds the ligand and the icd is the activation domain
Dimerization is necessary step for this to work
Ligand binds causing membranes to be paired
TK domain acquires ability to phosphorylate different substances and this phosphorylation cascade can lead to several different effect
DO cytokine receptors have intrinsic kinase activity?
No
How do cytokine receptors work?
Receptor exists as inactive dimer when not bound to hormone
Binding hormone causes rotation of intracellular domains to align JAK tyrosine kinase bound to each receptor monomer
JAK tyrosine kinase phosphorylates the receptor
