STUDY GUIDE Q - UNIT 4

Question 1

1. What are pumps?

Answer 1

a. Move substances against gradient
b. Require ATP

Question 2

2. What are channels?

Answer 2

a. Move substances down gradient
b. No energy needed

Question 3

3. Types of Channels

Answer 3

a. Leak: always open
b. Chemically gated: open with neurotransmitter
c. Voltage-gated: open with voltage change
d. Modality-gated: open via sensory input

Question 4

4. Voltage-Gated Na⁺ Channel States

Answer 4

a. Resting: inactivation gate open, activation gate closed
b. Activated: both gates open
c. Inactivated: inactivation gate closed

Question 5

5. Neuron Segments & Proteins:

Answer 5

a. Receptive: chemically gated channels
b. Initial: voltage-gated Na⁺/K⁺
c. Conductive: voltage-gated Na⁺/K⁺
d. Transmissive: voltage-gated Ca²⁺, Ca²⁺ pumps

Question 6

6. Describe Resting Membrane Potential (RMP)

Answer 6

a. Typically –70 mV
b. Mostly due to K⁺ exit, maintained by Na⁺/K⁺ pump

Question 7

7. Graded Potentials

Answer 7

a. Occur in dendrites/soma
b. Short-lived, vary in strength
c. Can be depolarizing (EPSP) or hyperpolarizing (IPSP)

Question 8

8. Summation

Answer 8

a. Occurs at axon hillock
b. Temporal: rapid signals from one source
c. Spatial: simultaneous input from many

Question 9

9. Action Potential (AP)

Answer 9

a. All-or-none response at threshold (–55 mV)
b. Depolarization: Na⁺ in
c. Repolarization: K⁺ out
d. Propagation = domino effect along axon

Question 10

10. Refractory Periods

Answer 10

a. Absolute: no AP possible (Na⁺ inactive)
b. Relative: AP possible with strong stimulus

Question 11

11. Conduction Types

Answer 11

a. Continuous: unmyelinated
b. Saltatory: myelinated, jumps between nodes

Question 12

12. Transmissive Segment

Answer 12

a. Ca²⁺ enters synaptic knob → neurotransmitter release
b. Neurotransmitter binds to postsynaptic receptor