lec 10 neurons

Question 1

What is the path that communications take thru the neuron?

Answer 1

Info received at dendrites –> soma along axon(myelin quickens)–>terminal buttons–>dendrites of other cells at meeting points (synapses)

Question 2

what are the 2 major types of cells that comprise the nervous system?

Answer 2

Neurons, glial cells (glia)

Question 3

what is the function of neurons? are the easily replaceable?

Answer 3

receive, integrate + transmit info

less able than other cells to replace themselves

Question 4

what are the features of a neuron?

Answer 4

stoma with nucleus
dendrites
axon and myelin sheath
terminal branches

Question 5

what is the function of a glial cell? how often are they replacing themselves?

Answer 5

support + nourishment to neurons, remove waste, insulate axons

constantly replacing themselves

Question 6

what do glial cells play a role in?

Answer 6

thinking, learning + memory

Question 7

what are the 5 parts of a neuron?

Answer 7

Cell body
Dendrites
Axon
Myelin Sheath
Terminal branches of axon

Question 8

What is the function of each part of a neuron?

Answer 8

Cell body- support center

Dendrites- receive messages from other cells

Axon-passes info

Myelin Sheath- insulation, protection, speeds transmission

Terminal branches of axon- form junctions with other cells

Question 9

What is the function of the myelin sheath?

Answer 9

-insulation layer for axon
-protects from unwanted messages from other cells
-speeds up transmission

Question 10

What increases during myelination?

Answer 10

-neural efficiency
-judgement
-self control

Question 11

What are the areas where myelin is thin/absent called? What is the purpose?

Answer 11

Nodes of Ranvier, allow ions to diffuse in/out of neuron

Question 12

What happens if the myelin sheath degrades?

Answer 12

-results in multiple sclerosis

-communication to muscles slowed
-eventual loss of muscle control and sometimes sensation

Question 13

how do neurons transmit signals?

Answer 13

electrochemically
-neurons generate electricity from chemical events

Question 14

what are the 2 types of signals a neuron receives?

Answer 14

excitatory(‘the gas’)
inhibitory (‘the brake’)

from many other neurons

Question 15

what is an action potential?

Answer 15

when excitatory signals minus inhibitory signals exceed minimum threshold, neuron fires

Question 16

What causes positive sodium ions to flow into neuron

Answer 16

stimulation (axon firing) causes membrane to open, allowing them to flow in

Question 17

What is resting potential?

Answer 17

the positive/negative state between a neuron outside neuron

neurons ‘at rest’ = negative charge

fluid inside+outside of neuron contain electrically charged ions

Question 18

What is depolarization? What does it influence?

Answer 18

shift from negative to positive voltage in a neuron

influences next section of axon, causing its channels to open

Question 19

What is the refractory period?

Answer 19

sodium channels close, positive potassium ions pumped out of cell

allows cells negative resting potential to be restored

Question 20

what is the all or none response with respect to action potential?

Answer 20

-neuron either fires, or doesn’t
-increasing level of stimulation above threshold will NOT increase intensity of impulse
-intensity of action potential same thruout length of axon

Question 21

How is intensity of a stimulus detected?

Answer 21

strong stimulus causes MORE neurons to fire and fire more OFTEN

Question 22

what is the synapse? where are 3 places connections can occur?

Answer 22

junction b/w terminal button on end of axon from one neuron (pre-synaptic) and either:

1. dendrite of another neuron (post synaptic)
2. membrane of a muscle fiber
3. a gland

Question 23

what is the synaptic cleft?

Answer 23

gap b/w terminal button of pre-synaptic neuron and cell membrane of post synaptic neuron

Question 24

what are neurotransmitters responsible for?

Answer 24

transmitting info from one neuron to another thru synaptic gap

Question 25

where do neurotransmitters bind on post-synaptic cell

Answer 25

after diffusing across synaptic cleft, bind to receptor sites

Question 26

What is important about neurotransmitters binding to receptor sites? What kind of mechanism is it?

Answer 26

each neurotransmitter will bind to specific receptor site

lock and key mechanism

Question 27

what happens to excess neurotransmitters left in synaptic cleft?

Answer 27

either…
1. drift away
2. broken down by enzymes
3. re-absorbed by pre-synaptic neuron, used to produce more later (reuptake)

Question 28

what are neurotransmitters? function?

Answer 28

chemical messengers released by terminal buttons of one neuron so it can communicate with other neurons thru synaptic cleft

each has specific function, sometimes many

Question 29

What does Acetylcholine (ACh) play a role in? What happens if there isn’t enough?

Answer 29

-voluntary muscle activity

inadequate ACh results in type of memory loss seen in Alzheimer’s

Question 30

What is the role of serotonin?

Answer 30

-mood, sleep, temperature

too little: depression

Question 31

how does Mylin speed up the transmission of signals?

Answer 31

sodium channels are only open on Nodes of Ranvier

charge essentially ‘skips’ b/c all sodium channels don’t need to open, only on NOR

Question 32

what are the 2 signals neurotransmitters can give to a receiving cell?

Answer 32

inhibitory or excitatory

Question 33

What is the role of epinephrine?

Answer 33

increases heart rate and blood pressure as part of fight or flight response