3 - Neuro 1

Question 1

What are neurons

Answer 1

specialized cells for communication via synaptic transmission

Question 2

What is the receptive zone

Answer 2

recieves signals

dendrites, nucleus, cell body

Question 3

What is the transmission zone

Answer 3

passes on signals to other cells

axons, terminal bouton, axon terminal

Question 4

What are dendrites

Answer 4

reach to other neurons for signals to be relayed

Question 5

What is the cell body

Answer 5

maintains structure
contains genetic info
provides energy for neuron

Question 6

What is saltatory conduction

Answer 6

AP can be wholly restored, doesn’t lose info to communicate

Question 7

What are glial cells, what are the types

Answer 7

throughout the NS
- structural support
- nourishment
- insulation for neuron

oligodendrocytes (CNS)
schwann cells (PNS)

Question 8

What are the types of channels for potasisum

Answer 8

voltage-gated
leak

Question 9

What are the channels for sodium

Answer 9

ligand-gated
voltage-gated

Question 10

What cells are in the extracellular fluid

Answer 10

Cl-
Na+

Question 11

What cells are in the intracellular fluid

Answer 11

K+
A- (large proteins)

Question 12

Describe the sequences to an action potential

Answer 12

Reaching threshold: temporal and spatial summation (-70 –> -50) – potassium leak channels open
- change in membrane potential from -50 to +40

Depolarization:
- voltage gated potassium channels (K+ begins to leave the cell)
- reaches voltage peak of +40

Repolarization:
- sodium channels begin to close, no more Na+ can enter the cell
- K+ still open and ions leave cell (brings back to resting membrane potential)

Voltage gated K+ channels fully closed and K+ stops leaving the cell
- K+ stops leaving the cell and voltage gated Na+ channels reset

Hyperpolarization: Because many K+ ions leaked out of the cell

Question 13

Describe the sodium-potassium pump

Answer 13

Pumps out 3 Na+
Pumps in 2 K+

uses a lot of energy
(small role in AP)

maintains ion balance of neuron

Question 14

How are messages encoded in AP

Answer 14

by frequency and pattern of AP
- weak signal: few AP
- strong signal: many AP

signals are identical in strength and duration

Question 15

What is the refractory period

Answer 15

determines upper limit of AP frequency/maximal possible firing rate

Question 16

What is the absolute refractory period

Answer 16

second AP cannot be fired in this interval, no matter how large the stimulus

Question 17

What is the relative refractory period

Answer 17

during hyperpolarization of an AP

a greater than normal stimulus is required to generate another AP

Question 18

Describe the pathway of neurotransmitters from the presynaptic neuron to the postsynaptic neuron

Answer 18

1. neurotransmitter vesicle
2. fuses to the presynaptic neuron terminal
3. released into the synapse cleft
4. Binds to receptors on the receptive zone of the postsynaptic neuron

Question 19

What is an ESPS

Answer 19

excites post-synaptic neuron towards AP threshold

depolarization –> more positive

Na+ channels open

more likely for AP to occur

Temporal summation: high frequency stimulation by one presynaptic neuron

Spatial summation: simultaneous stimulation by several presynaptic neurons

Question 20

What is an IPSP

Answer 20

inhibits post synaptic potential

AP less likely to be fired

Cl- channels open

Question 21

TF EPSP and IPSP occur at the same time

Answer 21

True: whichever wins = AP or no AP

Question 22

Describe the process of brain development

Answer 22

neurogenesis –> migration –> differentiation –> maturation

1. 18 days (neural plate formation)
2. neural groove
3. 21 days (closing to form neural tube)
4. 28 days (neural tube - top part is brain, bottom part is spinal cord)

Question 23

TF brain grows inside out

Answer 23

true: deepest layers formed before the outermost layers

Question 24

Describe the neuron formation in the neural tube

Answer 24

day 28: ventricular zone lined with founder cells close together

day 42: cell division/symmetrical

day 125: asymmetrical & neurons and radial glial cells migrate outward from the ventricular zone

Question 25

Describe neural migration

Answer 25

day 42-6 weeks

1. founder cells on ventricular zone
2. radial glial cells at outermost surface of the brain (extending from ventricular zone)
3. migrating neuron bound to radial glial cell
4. migrated neuron (born later than glial cells and travel a longer distance)

Question 26

What are radial glial cells

Answer 26

fibers that extend outwards

provide scaffolding at the outer layer of the cortex
- neurons use radial cells to migrate from ventricular zone to surface of the cortex

Question 27

What role do genetics play in brain development

Answer 27

Genetics: neuronal differntiation is partially determined by the location in the ventricular zone where founder cell orginatied

After reaching final destination, neuron differentiates and takes on specific function, determined by genetics

Question 28

What role does the environment play in brain development

Answer 28

adds flexibility to genetics (not completely pre-wired)

Question 29

How does the environemnt affect neuronal differentiation

Answer 29

1. surrounding cells (connections with other neurons)
2. external environment (child with cataract –> neurons do something else)

Question 30

TF neuronal connections are pruned after infancy

Answer 30

True: demonstrates the plasticity of the brain

after ~10 months starts to go down, way down at 10 years