Flashcards in 2017 Physiology 1 - Signal Transduction Deck (18):
Primary NT for sympathetics
Epinephrine and Norepinephrin
Primary NT for parasympathetics
G Protein Signaling and Cyclin, steps
1. Signal molecule binds to G-protein
2. Receptor/protein complex allows GTP to displace GDP from alpha-subunit
3. Binding of GTP causes dissociation into free alpha and beta+gamma subunits
4. Alpha subunit interacts to cause secondary messengers
5. Alpha unit has intrinsic GTPase activity to turn GTP into GDP
6. Cycle repeats
Examples of secondary messengers
cAMP, IP3, DAG
Function of Gs class of G-Protein Receptors
Stimulatory towards Adenylate Cyclase which increases cAMP activity which has downstream affects on Protein Kinase A (PKA)
Function of Gi class of G-Protein Receptors
Inhibitory towards Adenylate Cyclase which lowers cAMP activity
Function of Gq class receptors?
Activate Phospholipase C (PLC)
What is Phospholipase C and what does it do?
Membrane bound enzyme that converts phosphatidyl inositol (1,4) bisphosphate (aka. PIP2) into Inositol (1,4,5) triphosphate (aka. IP3) and Diacylglycerol (DAG)
What does IP3 do?
formed in plasma membrane by PLC, binds to IP3 receptors on the ER causing release of intracellular Ca++ stores
What does DAG do? Effect on Protein Kinase C (PKC)
Made by PLC, remains membrane bound.
Protein Kinase C (PKC) translocates from cytosol to membrane and is activated by DAG.
Activated PKC then phosphorylates other proteins to alter function.
What is Guanylate Cyclase and what is it's function?
Can be membrane bound or soluble; forms cGMP from GTP when receptor site is activated.
How is NO produced in the cell and what is it's function?
Produced from the aa. Arginine
Activated soluble, cytosolic guanylate cyclase -> thus increasing cGMP.
Special features of NO as secondary messenger?
Membrane soluble, which allows it to diffuse to nearby cells.
Of importance between vascular endothelial cells and nearby smooth muscle cells.
Breakdown cGMP and terminate it's action
Types of Cholernergic Receptors?
Nicotinic (N1/Nm and N2/Ng)
Types of Nicotinic Receptors
Skeletal Muscle - N1/Nm
Autonomic Ganglia - N2/Ng
Types of Muscarinic Receptors
M1,M3,M5 - activate PLC via Gq receptors. PLC leads to increase in intracellular Ca++ (via IP3)
M2,M4 - inhibit adenylate cycle via Gi receptors.