Pathways

Acetylcholine (ACh) function in nitric oxide pathway

ACh binds to muscarinic ACh receptors on endothelial cells.

Step 1 of nitric oxide pathway

ACh binds muscarinic receptors on endothelial cells.

Receptor activation result in nitric oxide pathway

Receptor activation causes production of IP3.

Step 2 of nitric oxide pathway

IP3 is produced in the endothelial cell.

Function of IP3 in nitric oxide pathway

IP3 opens Ca2+ channels on the ER membrane, releasing Ca2+ into the cytoplasm.

Step 3 of nitric oxide pathway

Ca2+ is released into the endothelial cell's cytoplasm.

Role of Ca2+ in nitric oxide pathway

Ca2+ stimulates the enzyme NO synthase.

Step 4 of nitric oxide pathway

Ca2+ activates NO synthase.

Product of NO synthase

NO synthase makes nitric oxide gas (NO) from the amino acid arginine.

Step 5 of nitric oxide pathway

NO synthase makes NO from arginine.

NO action in nitric oxide pathway

NO diffuses out of the endothelial cell into neighboring smooth muscle cells.

Purpose of paracrine signaling with NO

NO only reaches neighbors because it is quickly converted to nitrates and nitrites.

Step 6 of nitric oxide pathway

NO activates guanylyl cyclase in the smooth muscle cell.

Guanylyl cyclase function

Guanylyl cyclase converts GTP into cGMP + PPi.

Step 7 of nitric oxide pathway

Guanylyl cyclase makes cGMP.

Effect of cGMP in nitric oxide pathway

cGMP promotes smooth muscle relaxation, causing the blood vessel to dilate.

Insulin receptor action in insulin pathway

Insulin binds the insulin receptor on the outside of the cell.

Step 1 of insulin pathway

Insulin binds its receptor.

Effect of receptor autophosphorylation in insulin pathway

The receptor's intracellular kinase domains phosphorylate the receptor itself.

Result of receptor phosphorylation in insulin pathway

The phosphorylated receptor binds and phosphorylates signaling proteins.

Vesicle action in glucose uptake branch of insulin pathway

Vesicles carrying GLUT4 move to the plasma membrane and fuse with it.

Function of GLUT4 in insulin pathway

Glucose enters the cell through GLUT4 by facilitated diffusion.

Transcription factor action in insulin pathway

Moves into the nucleus to change gene expression.

Second messengers in insulin pathway

PIP2 is converted to IP3 and DAG, activating a transcription factor.

Insulin kinase cascade after MEK

MAPK.

Insulin kinase cascade after MAPK

Erk.

Insulin pathway transcription factors' role

They turn on transcription of DNA into mRNA, changing gene expression.

First step of phosphoinositide pathway

Angiotensin II binds its receptor on the vascular smooth muscle cell.

G protein action in phosphoinositide pathway

The G protein activates phospholipase C (PLC).

Function of phospholipase C in phosphoinositide pathway

Cuts PIP2 into IP3 and DAG.

Role of IP3 in phosphoinositide pathway

IP3 diffuses to the smooth ER and opens Ca2+ channels.

Result of Ca2+ release in phosphoinositide pathway

Ca2+ floods into the cytoplasm from the ER.

Activation of protein kinase C (PKC) in phosphoinositide pathway

Ca2+ and DAG together activate PKC.

Final effect of PKC activation in phosphoinositide pathway

PKC causes vasoconstriction, raising blood pressure.