MCAT BIO CH. 8 PART 1 Flashcards
What is action potential?
Localized area of depolarization of the plasma membrane that travels along an axon
What is synaptic transmission?
Signal exiting the end of an axon at a synapse, transformed into a chemical signal with the release of neurotransmitter into the synaptic cleft
What is the soma?
Central cell body of the neuron
What does the soma contain?
The nucleus and biosynthetic activity takes place
What is the structure axons and dendrites?
Slender projections from the neuron; only one axon and multiple dendrites
What are bipolar neurons? What about multipolar neurons?
- Neurons with only one axon 2. Multipolar
What are synaptic knobs?
A button-like swelling on an axon where it has a synapse (connection) with another neuron
What is the synaptic cleft?
Small gap that chemical messengers travel across after being released from synaptic knob
What is the difference between a neuron and a nerve?
Neuron is a single cell; nerve is a large bundle of many different axons from different neurons
What are the two primary membrane proteins are required to establish the resting membrane potential?
- Na+/K+ ATPase
2. Leak K channels
How does the Na+/K+ ATPase work in regards to its ion pumping?
Pumps three Na out, two K in with hydrolysis of 1 ATP molecule
What type of transport s Na+/K+ ATPase?
Primary active transport
Are there only K+ leak channels?
No; very few sodium leak channels
Because the cells are negative on the inside and positive on the outside, they are described as _____?
Polarized
Action potential, based on the cell being always polarized, is a….?
Disturbance to the membrane potential, a wave of depolarization of the plasma membrane traveling along an axon
After depolarization, what returns the membrane potential normal?
Repolarization
Why is action potential considered electrochemical?
Because its no just movement of electrical impulse (electrons) but also ions
What are key proteins in the propagation of action potentials?
Voltage-gated sodium channels
What happens in response to a change in the membrane potential?
Ion channels open to allow sodium to flow down their gradient into the cell and depolarization
When are the voltage-gated sodium channels opened based on depolarization?
At threshold potential, approx -50 mV
When do the ion sodium channels become inactive? (To what voltage?) based on depolarization?
-35 mV
How does the neighboring neurons also go through depolarization?
Some sodium ions flow down the interior of the axon and depolarize the next section of the membrane
What happens in the beginning of repolarization?
- Na channel inactive
2. K+ channels open but more slowly and for longer
Does the K+ channels cause the mV to return to - 70mV?
No, it overshoots and reaches - 90 mV before the channels close