A&P - Chapter 19 (Part 1) Flashcards
Nerve impulse
A self propagating wave of electrical disturbances that travels along the surface of a neruon’s plasma membrane
What is the direction of a neural impulse?
Towards the axon terminals
What is the charge on the outside of a membrane?
Slightly positive
What is the charge on the inside of a membrane?
Slightly negative
Membrane potential
Is the result of difference in an electrical charge across the membrane
Potential
Ions of opposite charges the have the potential to move toward one another if they get an opportunity to cross the membrane
What is a membrane said to be if it exhibits a membrane potential?
Polarized
Resting membrane potential
When a neuron isnt conducting electrical signals
During what phase is there slightly more positive ions outside the membrane?
In resting position
What do neurons of the plasma membrane contain?
Channels that allow efficient movement of the positive ions across it
What are 2 examples of positive ions that can move across the membrane?
- Na+
- sodium ions - K+
- potassium ions
What are the channels called that move Na and K?
Sodium-potassium pumps
What directions do Na and K move through the channels?
In opposite directions
What does the movement of Na and K do?
It maintains the electrical difference across the plasma membrane
- slightly positive on the outside
Local potentials
A fluctuation in the resting membrane potential in a specific part of the plasma membrane
When do local potentials occur?
In response to a stimulus
- excitation
What does excitation trigger?
The opening of stimulus gated channels in the plasma membrane
What does the opening of the stimulated gates allow?
For more Na+ to enter the neuron
- charge is now more slightly negative on the outside
Depolarization
More Na+ entering the neuron means that the size of the membrane potential is reduced
What initiates an action potential?
Depolarization
Resting potential
The membrane of a resting neuron has a slightly positive charge on the outside and a negative charge on the inside
Action potential
A stimulus triggers the opening of the Na+ channels in the plasma membrane of the neuron (starting at the dendrites) allowing Na+ to rush into the neuron (depolarization
When do action potentials move faster?
When they are myelinated
Nerve impulse
An electrical disturbance of the neurons membrane stimulates Na+ channels in the adjacent section of the membrane to open
What does the nerve impulse travel along?
The entire length of the neurons membrane
Why do signals travel faster in myelinated neurons?
Because the impulse will jump over it making it faster
- saltatory conduction
Do neurons normally touch each other or the effector they act on?
No
What is there between neurons and the effector that prevent them from touching?
Synapse
What 2 things can synapse be?
- Electrical
2. Chemical
Where do electrical synapse occur?
Where cells joined by gap junctions allow an action potential to simply continue along the postsynaptic membrane
Where do chemical synapse occur?
Where presynaptic cells release chemical transmitters across tiny gaps to the post synaptic cells
- possibly inducing an action potential
