Chapter 7+8

Question 1

Two types of electrical signals in neurons

Answer 1

Graded potentials (short-distance)
Action potentials (short- and long distance)

Question 2

What is resting membrane potential?

Answer 2

Neurons exhibit an electrical voltage difference across the membrane

Question 3

4 types of ion channels

Answer 3

Leakage Channel
Voltage-gated Channel
Ligand-gated Channel
Mechanically gated Channel

Question 4

Explain leak gate channels

Answer 4

Always open and are responsible for the resting membrane potential

Question 5

Explain volatage-gated channels.

Answer 5

They open and close in response to changes in the membrane potential

Question 6

Explain Ligand gated channels

Answer 6

Open and close in response to the binding of a chemical messenger to a specific receptor in plasma membrane

Question 7

What is a graded potential: two states

Answer 7

Small deviations from the resting state.
Hyperpolarized (inside more negative)
Depolarized (inside less negative)

Question 8

Where does graded potential mainly occur?

Answer 8

Occurs mainly in the dendrites of sensory neurons and cell body of a neuron

Question 9

What does the sign of the membrane potential always refer to?

Answer 9

Potential inside the cell relative to the potential outside.

Question 10

Resting membrane potential negative or positive?

Answer 10

Negative

Question 11

What is hyperpolerization ?

Answer 11

membrane potential becomes more negative

Question 12

What is depolarization?

Answer 12

less negative membrane or to a positive potential.

Question 13

What is repolarization?

Answer 13

When the membrane returns to resting membrane potential following a depolarization

Question 14

First phase of action potential? Caused by what?

Answer 14

Depolarization. Caused by rapid inrease in permeability to sodium

Question 15

What is the second phase of an action potential? What increases

Answer 15

Repolarization. Potassium permeability increases.

Question 16

Electrical resting state of -70 is due to what?

Answer 16

Unequal distribution of ions across cell membrane

Relative permeability to Na+ and K+

Question 17

What is the refractory period?

Answer 17

Period of time during which no action potential can be generated( right after)

Question 18

What is the absolute refractory period?

Answer 18

No act. pot. can propagate, Bigger diameter axons mean longer time of this period. Happens during depolarization phase plus most of the re polarization phase.

Question 19

What is the relative refractory period?

Answer 19

Immediately after absolute part, possible for second action potential if stimulus is much stronger. Due to increased permeability of potassium channels.

Question 20

How does propagation of nerve impulses move

Answer 20

From dendrites to axon terminal

Question 21

What is the difference between mylinated axon and unmylinated

Answer 21

Unmyelinated has slow process called continuous conduction, myelinated is fast process called salvatory conduction

Question 22

Steps of continuous conduction

Answer 22

Starts when the threshold is reached (–55mV)
Na+ is moving into cytosol and in the ECF (current)
Local current spreads in all directions, passes the axon hillock and reaches initial segment
Action Potential propagates along the axon

Question 23

Three components of saltatory condution

Answer 23

Impulse leaps from node to node (Ranvier node)
Schwann Cell and Ranvier node allow a faster transmission along the axon
Allows to open a smaller number of channels

Question 24

What effect does axon diameter have on conduction speed?

Answer 24

Smaller diameter= faster conduction

Question 25

Two types of signal transmissions at synapses

Answer 25

Electrical synapse:Action potentials conduct directly between adjacent cells through gap junctions
Faster communication and better synchronization
Chemical synapse
Structured with pre- and post-synaptic neurons

Question 26

Transmission steps

Answer 26

Impulse goes until end bulb
Depolarization opens voltage-gated Ca+ channels
Triggers vesicle movement through the layer (neurotransmitters)
Neurotransmitters diffuse through the cleft
Binding of Neurotransmitters with receptors triggering ion flow across post-synaptic layer
Ion flow triggers the post-synaptic potential
If threshold is reached than back to the step one

Question 27

Removal of neurotransmitter occurs how?

Answer 27

Diffusion (pass through synapse cleft)
Enzymatic degradation (specific enzymes break down neurotransmitters)
Uptake by cells (actively transported back into the neuron)

Question 28

What is spatial and temporal summation

Answer 28

Spatial summation results from several pre-synaptic end bulbs. Generally comes from two or more neurons

Temporal summation results of rapid successions of impulse from one neuron

Question 29

Acetylecholine released by what

Answer 29

PNS and CNS (excitatory and inhibitory effects)

Question 30

Ex of amino acid and released from where

Answer 30

Glutamate, asparate (release by CNS – excitatory effect)

Question 31

Biogenic amines

Answer 31

Catecholamines, serotonin (involve in skeletal muscle tone, lymbic system, sensory aspects

Question 32

atp

Answer 32

When ATP breaks down its residue (ADP, AMP) serves as neurotransmitters in CNS and PNS.

Question 33

Nitric Oxide important why?

Answer 33

Important neurotransmitter through the body (serves for vasodilation, smooth muscle relaxation