Neurophysiology

Question 1

Capacitance

Answer 1

of ions needed to change membrane voltage

Question 2

Conductance

Answer 2

• ease of moving ions across membrane (how fast they can flow)
• representation of how many open channels there are on the cell (low conductance=less open channels)

Question 3

Voltage (potential)

Answer 3

energy to move ions across cell membrane

Question 4

Excitaton

Answer 4

-makes cell more positive=DEPOLARIZATION
think about de-polarizing or making the north pole less cold (polar-like) you would be increasing the temp. or making it more POSITIVE

Question 5

Inhibition

Answer 5

-makes cell more negative=HYPERPOLARIZATION

Question 6

Na/K Pump

Answer 6

• pumps Na out and K in
• against concentration gradient
• uses energy from ATP
• *Normally inside=low conc. Na and high conc. K

Question 7

Uniport carrier

Answer 7

transports only one kind of substrate

Question 8

Cotransporters (2 types)

Answer 8

• symport carriers

- antiport carriers

Question 9

Symport carrier

Answer 9

move two or more substrates in the SAME direction across membrane

Question 10

Antiport carrier

Answer 10

move substrates in opposite directions across membrane (one in, one out)

Question 11

Primary active transport

Answer 11

• energy dependent (ATP)
• Na/K ATPase (antiport)
• Ca ATPase (uniport)

Question 12

Secondary active transport

Answer 12

-uses energy(gradient) from primary active transport

Ex: sodium binds creating a spot for glucose to bind, when glucose binds, carrier changes formation

Question 13

Gated channels (3 kinds)

Answer 13

• voltage=APs ad synaptic release
• ligand=chemical neurotransmitter
• mechanical deformation=hair cells in inner ear
• **gated channels are normally closed

Question 14

Ionotropic recepters-ligand gated channels

Answer 14

Excitatory=ACh and glutamate-selective for Na and K ions

Inhibitory=GABA and glycine-selective for Cl ions

Question 15

Graded potential

Answer 15

slow, analog, usually produced at synapses

• the more channels that are open, the greater the size of the potential
• decline exponentially as they travel along nerve fiber
• good at coding signal (b/c they can change size and frequency) but not good at transmitting over long distances (voltage gets smaller-# of Na ions decreases)

Question 16

Action potential

Answer 16

fast, fixed size, digital signals, is regenerative

• *don’t change size based on size (amplitude) based on the strength of the stimulus, instead it changes its frequency
• produced if graded potentials are still at threshold when they reach the trigger zone (size of GP determines frequency of AP)

Question 17

Trigger zone

Answer 17

location on neuron (between cell body and axon) where there is a high density of Na channels
-if GP is still at threshold when it gets to this location it will produce an AP (Larger GP creates greater frequency of APs-more APs which releases more neurotransmitter)

Question 18

Depolarization

Answer 18

• make cell membrane potential more positive-bring in positive (Na) ions
• as you depolarize more and more, the probability that Na channels are open increases

Question 19

Hyperpolarization

Answer 19

-make cell membrane potential more negative-bring negative ions in or let positive ions out

Question 20

Rising phase of AP

Answer 20

-Na rapidly enters cell to depolarize it=Na channels opening

Question 21

Falling phase of AP

Answer 21

• K moves out of cell to hyperpolarize it

- Na channels closing, K channels slowly opening

Question 22

Peak of AP

Answer 22

• Na channels start to close while K channels start to open

- cell is close to the sodium equilibrium potential

Question 23

How is acetylcholine transported from the presynaptic membrane to the postsynaptic membrane?

Answer 23

ACh diffuses across the synaptic cleft and binds to the ligand-gated channels on the postsynaptic neuron

Question 24

What does the absolute refractory period cause

Answer 24

Action potential propagation to occur in one direction

Question 25

What effect does acetylcholine have on the postsynaptic neuron

Answer 25

Ligand-gated sodium channels open and sodium flows in

Question 26

What happens when an action potential arrives at the presynaptic terminal

Answer 26

Voltage-gated calcium channels open, causing calcium ions to flow into the cell

Question 27

White matter of spinal cord contains

Answer 27

Ascending and descending tracts

Question 28

The S4 transmembrane segment determines what property of the voltage gated sodium channel

Answer 28

Voltage sensitivity

Question 29

Ionotropic vs metabotropic

Answer 29

fiifijodsf

Question 30

What channel event determines the absolute refractory period

Answer 30

Inactivation of the sodium channels

-have to wait for inactivation gate to be back in place before another AP can be generated

Question 31

Botulinum toxin blocks proper synaptic signaling at the neuromuscular junction by doing what

Answer 31

Blocking vesicle fusion and transmitter release at the synapse

Question 32

Myasthenia gravis

Answer 32

autoimmune disease

Question 33

Slow pain fibers produce these two synaptic responses in the spinal cord

Answer 33

Excite ascending pain pathways and suppress inhibitory interneurons

Question 34

Myelin

Answer 34

lowers capacitance of membrane so it takes less Na to produce same depolarization (easier to depolarize)
-if there was a missing myelin sheath segment, the Na would leak out of the axon and slow conduction-AP may not even be able to make it to next node
EX: multiple sclerosis=loss of myelin=slowed conduction

Question 35

Hypokalemia

Answer 35

• low blood potassium

- neuron is less likely to fire b/c it is hyperpolarized since K flows out of cell to compensate for low K outside cell

Question 36

Synaptic vesicle

Answer 36

package holding neurotransmitter

Question 37

SNARE proteins

Answer 37

attach vesicle to presynaptic membrane

Question 38

Botulinum toxins

Answer 38

interfere with SNARE proteins and prevent ACh vesicle fusion

Question 39

Tetanus toxins

Answer 39

disrupts SNARE proteins to prevent fusion of glycine vesicles
-muscles contract too much

Question 40

Synaptotagmin

Answer 40

binds to calcium and stimulates vesicle function

-changes conformation when it binds to Ca

Question 41

Neurotransmitter deactivation

Answer 41

Can be:

1) returned to axon terminal for reuse or transported into glial cells
2) enzymes inactivate neurotransmitters
3) neurotransmitters diffuse out of synaptic cleft