Ligand gated ion channels and GPCR's

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20 Terms

1
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What is a receptor?
- Causes a response via cellular change
- Main target for a drug
2
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What is another name for ligand gated ion channels?
Intropic receptors
3
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How long does a ligand gated ion channel take to activate?
Milliseconds
4
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What are the key features of a ligand gated ion channel?
- Form a channel between intracellular and extracellular environment of a cell.
- Number of subunits vary between channels
- Either activate signally or change excitability of the cell
5
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What is an example of a ligand gated ion channel?
Nicotinic acetylcholine receptor
6
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How do nicotinic Ach receptors work?
Agonist binds to the receptor causing Na+ ions to move into the cell and become excited, causing depolarisation.
7
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how does the GABAa receptor control Cl- flow?
- Activation of GABA via an agonist
- Receptor activation increases Cl- movement through ion channel
- Cell membrane hyperpolarizes
- Result is decreased excitability
8
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How does the neuromuscular junction work?
Motor nerves from the spinal cord synapse with skeletal muscle fibres, then each branch forms an end plate region on a motor end plate, initiating contraction.
9
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What are some clinical uses of antagonists?
Tracheal intubation, surgical procedures e.g. abdominal surgery, therapeutic hypothermia.
10
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How can antagonists treat therapeutic hypothermia?
Cardiac arrest, reduce body temp to 32-34 degrees, improves neurological recovery, prevents shivering. Can only be done after anaesthetic as effects whole body.
11
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What is another name for a G-protein coupled receptor?
7 transmembrane receptor or metabotropic receptor
12
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How long does a G-protein coupled receptor take to work?
Seconds
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What is a G-protein coupled receptor made up of?
- 7-transmembrane domains
- Extracellular N-terminus
- Intracellular C-terminus
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What are key features of G-protein coupled receptors?
- Largest family of receptors in the body
- Highly druggable, almost half of prescription drugs work on them.
15
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What is the basic mechanism of a G-protein coupled receptor?
1. Agonist binds to 7-TM receptor, initiating signalling
2. Signal stimulates G protein, causing it to move along the membrane
3. Effector is activated or inhibited triggers response
16
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What are the different Ga subtypes?
GaS (stimulate), Gai (inhibit), GaQ, Ga12
17
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What are effectors?
Ion channels ad enzymes
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What are 2nd messengers?
Ions, intracellular
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What are some roles of GPCR?
Vascular tone, airway constriction and relaxation, heart contractility, acid secretion, mood, pathogen defense.
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How does vascular tone relate to GPCR?
- Arteries/arterioles contain smooth muscle
- Constriction reduces diameter whereas relaxation increases diameter of the vessel.
- This impacts blood pressure.
- Tone is controlled by: circulating factors (e.g. adrenaline), symp and parasymp nervous system, paracrine factors.