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Neurons
| Question | Answer |
|---|---|
| What does the nucleus contain? | genes and chromosomes |
| What are the five steps of a nerve impulse? | resting potential, depolarization, repolarization, hyper polarization, restoration of resting potential |
| describe Step 1: neuron at rest | cell membrane is polarized, maintained by efflux of 3Na and influx 2K through sodium potassium pump |
| Describe step 2: depolarization | cell membrane receptors are activated by stimuli causing brief flip in polarity. Voltage sensitive Na channels open up causing intracellular flux to develop a positive charge relative to extracellular fluid. |
| Describe step 3: repolarization | Na channels close and K channels open to allow intracellular fluid to develop a more negative charge than extracellular fluid. |
| Describe step 4: hyperpolarization | K influx overshoots causing a brief period where intracellular fluid becomes more negative than it is during resting period. |
| Describe step 5: restoration of resting potential | Sodium-potassium pump turn back on sending out 3 Na for and in 2K |
| Typical rate of action potential | 30/s |
| Why can't action potential flow backwards? | refractory periods (absolute and relative) |
| Saltatory conduction | insulation about axon created by Schwann cells in PNS and Oligodendriogial cells in CNS. Leads to faster transmission |
| Degenerative disease that attacks myelin sheath in CNS (oligodendroglial cells) | Multiple Sclerosis (disrupts flow of neural information) |
| What are some symptoms of MS? | auditory, visual, motor, and cognitive disturbances and fatigue. |
| Neurotransmitter | chemical released from synapse in response to an action potential to transmit signal to a postsynaptic neuron |
| What are the 4 steps of neurotransmission | 1. synthesis 2. Release 3. receptor action 4. inactivation |
| What is the most common type of synapse? | Axodendritic synapse (axon to dendrite) |
| What does an excitatory neurotransmitter do? | depolarizes post-synaptic membrane |
| What does an inhibitory neurotransmitter do? | hyper polarizes the postsynaptic membrane |
| Acetocholine (ACh) | small molecule transmitter used for muscle activation in the PNS and involved in sleep/wake and memory in the CNS. Depletion leads to Alzeimer's disease |
| Epinephrine (EP) | involved in sympathetic nervous system |
| Norepinephrine (NE) | Involved in arousal and attention |
| Dopamine (DA) | involved in movement and pleasure/reward. Depletion associated with Parkinson's Disease. |
| Serotonin (5-HT) | Involved in mood, agression, appetite, arousal, pain and respiration |
Created by:
jocelyncor
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