Exam 2 Flashcards
What are afferent neurons?
Neurons that carry signals to the sensory perceptions towards CNS.
What are efferent neurons?
Neurons that carry signals from the CNS to the effector organs.
What’s the function of an afferent neuron?
Brings sensory signals to the brain.
What’s the function of efferent neurons?
Carries motor signals to the muscle, important for muscle movement.
What characteristics of neurons make them faster and slower?
Faster: The axon because it transmits AP and the presence of myelin sheaths around the axon.
Slower: A small axon and lack of myelin.
Why is calcium important for the communication of our nerves?
1.) triggers neurotransmitter release.
2.) the use of synaptic transmission.
3.) memory and brain function.
What is our resting charge?
-70 to -90 mv.
How do we maintain resting charge?
We maintain resting charge by actively transporting Na+ ions and by using the sodium-potassium pump to exchange three Na+ ions for two K+ ions.
What is the difference between leaky channels and Na/K pumps?
Leaky channels: always open, rely on passive diffusion, ions flow down gradients, resting membrane potential.
Na/K pumps: not always open, requires ATP, ions flow against gradient, maintain long term by correcting ion gradient.
What is the difference between an oligodendrocyte and a Schwann cell?
Oligodendrocyte: forms several myelin sheaths.
Schwann cell: forms ONE myelin sheath and myelinated one section of the axon.
What does a oligodendrocyte and Schwann cell have in common?
They both form myelin sheaths, but at different amounts.
What happens during action potential?
1.) starts at resting state with a negative charge.
2.) stimulus causes Na+ channels to open and Na+ rushes inside making the inside positive.
3.) K+ channels open and K+ flows out restoring the negative charge inside (more negative than the resting state).
4.) the Na+/K+ pumps restores the original ion balance which returns the neuron to its resting state.
How can a puffer fish ruin someone’s day?
A puffer fish has a toxin (tetrodotoxin) which blocks Na+ channels and prevents action potentials from occurring. This stops signals from being transmitted, leading to paralysis, loss of muscle movement, breathing changes and sometimes death.
What’s the difference between efflux and influx?
Efflux: movement of ions OUT of the cell.
Influx: movement of ions INTO the cell.
What does a threshold do to an action potential?
When the stimulus reaches the threshold, Na+ channels open, starting action potential.
