2017 Physiology 1 - Signal Transduction Flashcards

1
Q

Primary NT for sympathetics

A

Epinephrine and Norepinephrin

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2
Q

Primary NT for parasympathetics

A

Acetylcholine (ACh)

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3
Q

G Protein Signaling and Cyclin, steps

A
  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
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4
Q

Examples of secondary messengers

A

cAMP, IP3, DAG

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5
Q

Function of Gs class of G-Protein Receptors

A

Stimulatory towards Adenylate Cyclase which increases cAMP activity which has downstream affects on Protein Kinase A (PKA)

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6
Q

Function of Gi class of G-Protein Receptors

A

Inhibitory towards Adenylate Cyclase which lowers cAMP activity

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7
Q

Function of Gq class receptors?

A

Activate Phospholipase C (PLC)

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8
Q

What is Phospholipase C and what does it do?

A

Membrane bound enzyme that converts phosphatidyl inositol (1,4) bisphosphate (aka. PIP2) into Inositol (1,4,5) triphosphate (aka. IP3) and Diacylglycerol (DAG)

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9
Q

What does IP3 do?

A

formed in plasma membrane by PLC, binds to IP3 receptors on the ER causing release of intracellular Ca++ stores

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10
Q

What does DAG do? Effect on Protein Kinase C (PKC)

A

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.

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11
Q

What is Guanylate Cyclase and what is it’s function?

A

Can be membrane bound or soluble; forms cGMP from GTP when receptor site is activated.

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12
Q

How is NO produced in the cell and what is it’s function?

A

Produced from the aa. Arginine

Activated soluble, cytosolic guanylate cyclase -> thus increasing cGMP.

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13
Q

Special features of NO as secondary messenger?

A

Membrane soluble, which allows it to diffuse to nearby cells.
Of importance between vascular endothelial cells and nearby smooth muscle cells.

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14
Q

Phosphodiesterases function?

A

Breakdown cGMP and terminate it’s action

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15
Q

Types of Cholernergic Receptors?

A

Nicotinic (N1/Nm and N2/Ng)

Muscarinic (M1-M5)

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16
Q

Types of Nicotinic Receptors

A

Skeletal Muscle - N1/Nm

Autonomic Ganglia - N2/Ng

17
Q

Types of Muscarinic Receptors

A

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.

18
Q

Types of Adrenergic Receptors and function of each:

A

Beta - stimulate adenylate cyclase - produces cAMP and Activates PKA. Gs mediated.

Alpha 1 - increase IP3 and DAG. Presumably Gq mediated and involve PLC activation.

Alpha 2 - inhibition of adenylate cyclase. Presumably Gi mediated.