Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
Transmission of impulse in a neuron:
|
Dendrite--> Cell body---> Axon----> Axon terminal---> NT released into synapse.
|
|
|
What makes up a synapse?
|
Axon terminal of presynaptic neuron and dendrite of postsynaptic neuron.
|
|
|
What are some examples of glial cells?
|
Consist of ~90% of CNS cells. Some examples are: astrocytes, oligodendrocytes, microglia, ependymal cells.
The rest of the CNS cells are neurons (~10%) |
|
|
What is the function of glial cells?
|
Physically and metabolically support neurons.
|
|
|
What are some functions of astrocytes?
|
1. Astrocytes sustain neurons metabolically by providing glucose and removing ammonia.
2. Blood brain barrier--> stimulate formation of tight junctions btw cells. |
|
|
What is the function of oligodendrocytes?
|
Myelinate axons.
|
|
|
What is the function of microglia?
|
Immune function, i.e. act as macrophage.
|
|
|
What is the function of ependymal cells?
|
Regulate the production and flow of CSF.
|
|
|
What is the function of Schwann cells?
|
Myelinate axons.
Note: located in PNS. |
|
|
What is the purpose of Node of Ranvier?
|
Speed up conduction.
|
|
|
What is equilibrium potential?
|
The membrane potential at which the electrical gradient and the [ ] gradient are equal in force but opposite in direction.
|
|
|
What is the Nernst Equation?
|
For figuring out the equilibrium potential.
Eion = 60Log[ion out]/[ion in] |
|
|
How is membrane potential related to degree of permeability?
|
Directly related. The more permeable the ion is, the greater the contribution that ion makes to the membrane potential, i.e. likelihood of the gate to open.
|
|
|
T or F: Once the action potential occurs, it is not proportional to the magnitude of the stimulus.
|
True
|
|
|
Describe the inactivation process.
|
An example is when the gate opens for Na to enter cell, it then quickly becomes inactivated.
Once it's been inactivated, it NO LONGER goes back to the open state, but rather to the closed state. NOTE: there is no activation period for K ion. Rather the channel just opens and is closed rather slowly. |
|
|
What is the benefit of Na channel inactivation?
|
It provides the refractory period of action potential.
|
|
|
What is a refractory period?
|
A period which a second stimulus does not produce a second action potential even though the membrane potential is above the threshold potential.
Makes each AP separate and distinct. Prevents the forwardly propagating signal from returning on itself. NOTE: Again, Na channels are inactivated during this period. This is what makes the second AP imppossible to occur. |
|
|
What is absolute refractory period?
|
When a second AP cannot occur no how strong the stimulus is.
|
|
|
What is relative refractory period?
|
Is the period when some Na channels have returned to the closed state and the membrane is hyperpolarized.
NOTE: In this period, it is POSSIBLE for new stimulus to depolarize the membrane above the threshold potential ONLY if the stimulus is large in magnitude. |
|
|
In a nerve cell, where is the AP initiated?
|
Axon hillock, and it propagates toward the axon terminal.
|
|
|
T or F: Axon membranes can propagate AP in either direction.
|
True
|
|
|
What's special about the Node of Ranvier?
|
It's the site where APs can only occur at where they perform saltatory conduction (jumping from one node to another).
|
