Physiology Lecture 2 Q-Bank (Cellular Signaling)
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What is intercellular communication? Communication between cells. What are the 6 types of intercellular communication? Gap Junction Autocrine signaling Paracrine signaling Nervous signaling Endocrine signaling Neuroendocrine signaling What is Gap Junction? Gap Junction is a trans-membrane channel that allows ions and small molecules to pass freely between cells. What is unique with Gap Junction? What organ uses gap junction? Cells having gap junctions act as 1 unit. Whatever happens to one cell is spread to all cells) Cardiac muscle cell has gap junctions. (It allows electrical signals to spread throughout tissue) What is the subunit of Gap Junction? Connexins What is Autocrine Signaling? Autocrine signaling occurs when a cell releases agent (chemical or hormone) that binds to a receptor on the cell itself.
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Transcript of Physiology Lecture 2 Q-Bank (Cellular Signaling)
What is intercellular communication?
Communication between cells.
What are the 6 types of intercellular communication?
Gap JunctionAutocrine signalingParacrine signalingNervous signalingEndocrine signalingNeuroendocrine signaling
What is Gap Junction?
Gap Junction is a trans-membrane channel that allows ions and small molecules to pass freely between cells.
What is unique with Gap Junction? What organ uses gap junction?
Cells having gap junctions act as 1 unit. Whatever happens to one cell is spread to all cells)
Cardiac muscle cell has gap junctions. (It allows electrical signals to spread throughout tissue)
What is the subunit of Gap Junction?
Connexins
What is Autocrine Signaling?
Autocrine signaling occurs when a cell releases agent (chemical or hormone) that binds to a receptor on the cell itself.
What is Paracrine Signaling?
Paracrine signaling occurs when cell releases agent (chemical or hormone) that binds to a receptor on the nearby cell (very close proximity)
What is Nervous Signaling?
Nervous signaling is a neurotransmitter released by a neuron.
What is Neurotransmitter?
A chemical signal
What is Endocrine Signaling?
Secretion of hormones release by endocrine cells
What is a Hormone?
Any chemical agent release in the blood
What is Neuroendocrine signaling?
Neurotransmitter is released into the bloodstream.
With the exception of Gap Junction, what do all types of intercellular communication have in common?
Chemical signal or stimulus binds to a receptor.
What is a post-synaptic receptor?
A protein that receives a chemical signal.
What is a ligand-gated channel?
A ligand-gated channel is a receptor which opens an ion channel through simple diffusion if a specific ligand binds to it.
What is an enzyme-linked receptor?
An enzyme-linked receptor is a trans-membrane protein with an extracellular receptor that is activated by bounded to a ligand.
What occurs after a ligand binds to an enzyme-linked receptor?
Ligand binding induces intracellular enzymatic activity.
What is a G protein-coupled receptor?
G protein-coupled receptor is a trans-membrane protein with extracellular ligand biding site.
What are the subunits of G protein complex?
G protein has 3 subunits alpha, beta, and gamma.
What molecule is bound to the G protein? Why?
G alpha protein has a GDP molecule bound to it that renders the alpha protein inactive.
Describe G-protein signaling.
Ligand (epinephrine and norepinephrine) binds to G-protein coupled receptor.
GTP swaps for GDP in G alpha protein.
Intracellular G protein complex is activated by GTP.
Alpha subunit dissociates from G protein complex.
Alpha subunit travels inside cell to TARGET CELL (EFFECTOR) - an enzyme
Enzyme converts a substrate to a product called 2nd Messenger.
What are 3 types of effectors (enzymes) for alpha G protein?
Adenylyl Cyclase, Guanylyl Cyclase, and Phospholipase C
What substrate does Adenylyl Cyclase act on? What is form?
Substrate: ATP Product: cAMP
What substrate does Guanylyl Cyclase act on? What is form?
Substrate: GTP Product: cGMP
What substrate does Phospholipase C act on? What is form?
Substrate: cleaves PIP2 Product: DAG and IP3What ligand activates Adenylyle cyclase pathway?
epinephrine and norepinephrine.
What function does IP3 hold once produced?
IP3 diffuses through the cytosol to activate ligand-gated calcium channel on ER (Ca2+ is released)
What are intracellular receptors? What do they bind?
Receptors found in cytosol and nucleus; They bind hydrophobic ligands that traverse phospholipid bilayer.
What is the function of nuclear intracellular receptors?
Receptors that traverse nuclear membrane to influence transcription
What is signal amplication?
Amplification of cellular signaling and response.
Describe how signal amplication works in the cell.
1 ligand binds to a ligand-receptorMany G proteins are activatedEach G protein activate one effector enzymeEach effector enzyme catalyzes formation of many second messengers.
How does the cell terminate cellular signaling (4 ways)?
Removal of ligand from receptorInactivation of receptor by de-phosphorylation (or internalization)Inactivation of enzyme producing second messengerRemoval of second messenger by degradation, sequestration, or exil
What is internalization?
Receptors being oriented inside the cell in order to prevent binding to ligand.
