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18 Cards in this Set
- Front
- Back
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What is a Neuron |
A neuron is the elementary unit of the nervous system and consists of three parts the dendrite, axon and cell body. 50 000 proteins can be expressed simultaneously within neurons |
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What is an axon? |
Axons conduct electrical signals away from the cell body to another cell and can be very long (up to 2m in humans) |
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What is a dendrite? |
Dendrites receive information from other cells. |
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What is the cell body? |
Cell that contains nucleus and organelles |
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What are the three types of neurons? |
Sensory- sensory receptors to CNS Motor- CNS to muscles/glands Interneurons- neuron to neuron
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What are nerves? |
Nerves are made up of many axons with blood vessels to provide the cells with nutrients
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What is membrane potential and how does it work? |
membrane potential is the unequal distribution of cations and anions across a membrane causing a difference in electrical potential across a membrane |
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What is the resting membrane potential for a resting cell? |
-70mv (more anions inside the cell), more K+ inside the cell and more Na+ outside the cell but proteins stuck within the cells are the negative charge mostly |
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What is an ion channel/pump and what does it do? |
Ion channels are membrane proteins that allow passage of ions through the membrane, no energy is used as the flow is passive and up to 1 000 000 ions per second can flow through . Ion pumps use energy to pump ions against the gradient |
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What causes K and NA channels to open/close up? |
Depolarization/repolarization |
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What is an action potential? |
When there is a change in ionic distribution, a change in membrane potential ensues. Action potentials begin in a spot of the membrane and propagate the signal across the entire membrane. After the action potential passes, the membrane cannot be stimulated anymore for a period of time until Na/K pumps rebalance the ion concentrations across the membrane |
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What is a synapse? |
A synapse is a junction between a nerve terminal and another cell. It contains synaptic vesicles that transport small organic molecules called neurotransmitters. Incoming action potentials open up voltage sensitive Ca2+ channels allowing flow into the cell which allows synaptic vesicles to move into the synaptic cleft. The neurotransmitter then proceeds to diffuse into the innervated cell and bind to receptors and activate a cascade of events. |
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What is a neurotransmitter? |
Small organic molecules that bind to receptors and activate a cascade of events within a cell. Deficiency in dopamine leads to parkinsons. Drugs affect synaptic transmission. Other neurotransmitters incude dopaine, gaba, histamine, serotonin, glycine. Each neuron only releases one neurotransmitter. |
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What is a receptor? |
Integral membrane proteins, there are two types: G-protein coupled receptors and ligand gated receptors |
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What is structure and function of ligand gated ion channels? |
Permeable to specific ions, nicotinic acetylcholine receptors is activated by acetyl choline, Glycine and GABA receptors open Cl- channels |
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What is GPCR and function? |
Changes conformation upon binding to neurotransmitter, change detected by intracellular heteromeric membrane bound protein, released alpha subunit activates another molecule (ion channel or enzyme) |
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Inactivation of neurotransmitter |
Time of action is usually 0.5-1.0 ms Three mechanisms to deactivate: enzyme destroys n.t., diffusion out of cell, reabsorption by the cell |
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Inactivation of Acetylcholine? |
Acetylcholinesterase breaks it down into acetyl and choline if enzyme doesnt work it can lead to death. |
