Neurophys 1-2

Question 1

Examples of cells that can generate an electrical current

Answer 1

Neurons
Muscle cells
Some endocrine cells

Question 2

Electrical signaling features

Answer 2

Signaling occurs within neurons
Ions flow through mem channels
Signal propagates from one part of neuron to another

Question 3

Chemical signaling features

Answer 3

Signals occurs between cells
Occurs at synapse (between pre and post)
Release of neurotransmitter from presyn
Binding of neurotransmitter to postsyn
Transmitter is degraded or recycled

Question 4

Sensory neurons

Answer 4

Detect environmental stim
Cell bodies outside CNS
Relay info to CNS

Question 5

Motor neurons

Answer 5

Relay info to CNS —> effector organs
Muscles & glands
Cell bodies are inside CNS

Question 6

Interneurons

Answer 6

Most numerous type
Facilitate communication between neurons
Found entirely in the CNS

Question 7

Structure of neuron

Answer 7

Dendrites
- receive input from neurons
- convert chemical to electrical
Soma
- site of ATP & transmitter synth
Axon
- transmits electrical sig
- converts electrical sign to chemical sig
- releases transmitter

Question 8

Resting membrane potential

Answer 8

Concentration of ions creates a charge differential across the membrane
- more neg inside cell
- more pos outside cell
Maintained by Na/K pump & K+ leak channels
- value around -70mV

Question 9

Average concentration of Na in/out of cell

Answer 9

In - 15mM
Out - 150mM

Question 10

Average concentration of K+ in/out of cell

Answer 10

In - 150mM
Out - 5mM

Question 11

Average concentration of Cl- in/out of cell

Answer 11

In - 10mM (more neg = hyperpolarization)
Out - 120mM

Question 12

Postsynaptic potential

Answer 12

=small changes in membrane potential due to stimulus
- activation of ligand gated channels
- activation of mechanically gated ion channels

Question 13

Excitatory postsynaptic potential

Answer 13

Depolarizes the membrane
Usually due to Na channel opening

Question 14

Inhibitory postsynaptic potential

Answer 14

Hyperpolarizes membrane
Usually due to Cl- channel opening

Question 15

Actions & charge of released excitatory neurotransmitter

Answer 15

Binds & opens Na channels
Na flows into cell
Depolarization
Excitation
-68mV

Question 16

Action & charge of released inhibitory transmitters

Answer 16

Binds & opens Cl- channels
Cl- flows into cell
Hyperpolarization
Inhibition
-72mV

Question 17

Summation at axon hillock

Answer 17

= specialized part of neuronal cell body
Site of sum of postsynaptic potentials
Determines whether or not neuron will fire action potential

Question 18

• spatial summation -

Answer 18

PSPs closest to the axon hillock have the most impact

Question 19

• temporal summation

Answer 19

PSP that occur at the same time will have the most impact

Question 20

Depolarizing phase of AP

Answer 20

Opening of voltage gated Na channels
Flows out of cell
Depolarization

Question 21

Hyper polarization phase of AP

Answer 21

Slower opening voltage gated K+ channels
K+ flows out of cell
Hyperpolarization
+30mV

Question 22

Myelination

Answer 22

Insulation sheath formed by membrane matieral
- oligodendrocytes - CNS
- Schwann cells - PNS

Question 23

Action of myelination

Answer 23

decreased ion leakage
VGC concentrated in gaps between coating (nodes of raniver)
Electric signal jumps from node to node - saltatory condution

Question 24

Effects of axon diameter

Answer 24

Speed of AP increases w diameter
More important in sensory than motor