Day 3 Transmembrane Proteins and Regulation of Secretion

Secretion in the digestive system is partially regulated by what?

GPCR

What gradient is important in digestive system secretion?

electrochemical

What is an important gradient in enterocytes?

sodium

Where is chloride secreted from?

base of glands

Where is bicarbonate secreted from?

pancreas and biliary cells

What avenues could a pathogen or substance use to impact secretion?

toxins, competitive binding, bind GCPR

When there is increased secretion in the intestines, how can the animal be affected?

diarrhea, dehydration, electrolyte imbalance

What do salivary glands secrete?

water, electrolytes, enzymes, mucus into acini

Where are electrolyte levels changed?

ducts

What stimulates salivary glands?

PNS

Which species has highly basic saliva with elevated HCO3-?

ruminants

Release of enzymes in the pancreas is regulated by what?

cholecystokinin

Cholecystokinin is the extracellular stimulus for what?

CCKa (a GPCR)

What does the pancreas secrete?

zymogens, active enzymes, bicarbonate

The pancreas is an ____________ gland.

exocrine

What leads to cell signaling cascade producing second messengers?

G protein coupled receptors (GPCR)

What are some second messengers resulting from GPCRs?

IP3, DAG, Ca2+, cAMP

What do second messengers do?

activate other proteins/enzymes like protein kinases that open or activate transport proteins

What are some examples of transport proteins opened by second messengers?

proton pump, ATPase (H+, K+), CFTR

What secretory epithelial cell uses CFTR and other chloride channels for secretion?

crypt enterocytes

Crypt enterocyte secretion is controlled by what?

electrochemical gradient and cAMP

What are the histamine H2 receptor antagonists that can be used to treat gastric ulcers?

famotidine, ranitidine

What is the proton pump inhibitor that can be used to treat gastric ulcers?

omeprazole

What does the parietal cell use as a regulator?

GPCR through histamine, muscarinic, and CCK2/gastrin receptors

What regulates the amount of cAMP?

adenylate cyclase

What starts the process of communication in the cell?

ligand binding

What are examples of ligands that serve as signals to cell surface proteins?

hormones, neurotransmitters, drugs

What are examples of membrane proteins needed for transport?

ion channel, carrier protein, GPCR

What are GPCRs composed of?

single polypeptide chain that passes in and out of membrane 7 times

What do GCPRs bind to?

g-protein

What is a heterotrimeric g-protein?

trimeric protein composed of alpha, beta, and gamma subunits

G-proteins bind GTP and do what?

hydrolyze it to GDP

What underlies the on-off switch of a G-protein?

hydrolysis of GTP to GDP

Which G-protein subunit is bound to GDP?

alpha

The activation of the G-protein takes the form of dissociation of what?

beta/gamma complex from the alpha subunit to allow GDP/GTP exchange

The G-protein is considered _______ when GTP is bound to the alpha subunit.

on

The beta/gamma complex of the g-protein is known to activate what?

K+ channels

The beta/gamma complex of the g-protein is known to inhibit what?

voltage-dependent calcium channels

What is a second messenger?

ion or molecule that carries information within cytoplasm in response to a signal outside the cell (triggered by GPCR receptor activation)