neurotrasnmission and propgation

Question 1

what are the 4 functional regions

Answer 1

1) receptive region (cell body and dendrites)
2) inital segment (axon hillocks)
3) conductive region (axon)
4) secretory region (nerve terminals)

Question 2

what do nerve terminals do?

Answer 2

pack neurotransmitters. calcium will drive and plasma membrane will attach to each other.

Question 3

Why are dendrite branch’s so long

Answer 3

to get the electrical signal from other neurons synaptic terminals

Question 4

where is the region capable of initial axon potential

Answer 4

axon hillocks

Question 5

how are changes in membranes potential produced

Answer 5

1)anything that
alters ion concentrations on the two sides of the membrane, or (2) anything that changes
membrane permeability to any ion.

Question 6

what are graded potentials

Answer 6

Graded potentials-usually incoming signals operating over short distances that have variable (graded) strength

Question 7

what are action potentials

Answer 7

long-distance signals of axons that always have the same strength

Question 8

what’s the difference between depolarization and hyper polarization?

Answer 8

depolarization is MP moving closer to 0 mV, hyperpolarization is becoming more negative.

Question 9

what is -70 mV to -65 mV? -70 mV to -75 mV?

Answer 9

depolarization. hyperpolarization

Question 10

what happens if an axon is long?

Answer 10

it will not travel that far because current flow decreases in magnitude with distance

Question 11

13. What determines the size of a graded potential?

Answer 11

the strength of the stimulus.

Question 12

what is the difference between action potential and gradient potential

Answer 12

-action potential is one direction ​

-gradient potential is bidirection

Question 13

what is the presynaptic neuron

Answer 13

neuron conducting impulses toward synapse (sends information)​

Question 14

what is the Postsynaptic neuron

Answer 14

neuron transmitting electrical signal away from synapse (receives information)

• In PNS may be a neuron, muscle cell, or gland cell​

Question 15

what receptors cause rapid synaptic transmission

Answer 15

channel-linked receptors

Question 16

action potential go from -90mV to +50mv with a 140mV. T or F?

Answer 16

False. total amplitude (change in voltage) of about 100 mV (from -70 mV to +30 mV)

Question 17

what is another name for an action potential

Answer 17

nerve impulse

Question 18

what do stimulus do to the membrane?

Answer 18

change the permeability

Question 19

what is the action potential membrane steps

Answer 19

1. resting state (no ions move through voltage gate channels -70mV)
   2.Depolarization cause by Na flowing into cell
2. repolarization caused by k flowing out of the cell
3. hyperpolarization cause by k+ continually flowing out of the cell

Question 20

what is the threshold for AP? what is the Peak?

Answer 20

-55mV

+30

Question 21

how can you tell the difference between how strong stimulus strength is from a weak one or a strong one?

Answer 21

Strong stimuli generate nerve impulses more often in a given time interval than do
weak stimuli.

Question 22

when is the absolute refractory period?

Answer 22

with opening of na+ channels and ends with na+ channels beginning to reset to original resting state

Question 23

what increases the speed of propgation

Answer 23

mylin sheaths

Question 24

what is a synapse?

Answer 24

syn “to clasp or to join” connection of one neuron to another

Question 25

what is a presynaptic neuron?

Answer 25

neuron conducting impulses toward the synapse

Question 26

what is postsynaptic neuron?

Answer 26

neuron transmitting signal away from synapse

Question 27

What is anterograde transport?

Answer 27

movement of supplies down the axon away from soma (cytoskeleton, membrane parts)

Question 28

What is retrograde transport?

Answer 28

movement up the axon toward the soma (recycled and degraded organelles)

Question 29

what is MS

Answer 29

- persistent inflammatory response in which myelin sheaths gradually destroyed -cycles of relapse and remission: flare-ups and then some healing and myelin regeneration; axons develop more Na+ channels in demyelinated areas -blindness (optic nerve), muscle weakness, clumsiness, urinary incontinence​ -ultimately myelin destruction is permanent and axons “drop out” or degenerate​

Question 30

what are types of therapy for MS

Answer 30

1) reduce inflammatory destruction​ (2) manage symptoms​ (3) promote repair of damaged myelin​

Question 31

how many axon terminals do neurons have

Answer 31

1,000 - 10,000

Question 32

what is the post synaptic cell outside of the CNS

Answer 32

effector cell (muscles cell or gland cell)

Question 33

what is the synapses between an axon and dendrite of another neuron called?

Answer 33

axodendritic synapses

Question 34

what is between axon endings of one neuron and the cell body (soma) of another neuron called?

Answer 34

axosomatic synapses

Question 35

what is electrical synapses?

Answer 35

direct physical contact between cells with a gap junction -uncommon -direct current flow through protein channels -rapid transmission (electrically-coupled)​ neurons can be synchronized​ -primarily embryonic, eye movement, non nervous tissues like cardiac or smooth muscle where contractions can synchronize

Question 36

3 ways to terminate neurotransmitter

Answer 36

-Reuptake by astrocytes or the presynaptic terminal, where the neurotransmitter is stored or destroyed by enzymes (as with the neurotransmitter norepinephrine) * Degradation by enzymes associated with the postsynaptic membrane or present in the synaptic cleft (as with acetylcholine) * Diffusion away from the synapse (nitric oxide)

Question 37

what is chemical synapse

Answer 37

-slow -abundant -effectively convert electrical to chemical to electrical

Question 38

what are the steps for chemical synapse?

Answer 38

1)Action potential arrives at axon terminal 2)Voltage-gated ca2 channels open and ca2 enters the axon terminal. 3)Ca 2 entry causes synaptic vesicles to release neurotransmitter by exocytosis. 4)Neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane 5)Binding of neurotransmitter opens ion channels, resulting in graded potentials. 6) Neurotransmitter effects are terminated by reuptake through transport proteins, enzymatic degradation, or diffusion away from the synapse

Question 39

why is a synaptic transmission unidrectional

Answer 39

it can only be produce down the axon not the dendrites

Question 40

what are the proteins in the gap junction?

Answer 40

connexins

Question 41

Mechanism of Synaptic Communication​ Initiation:​

Answer 41

1. Ca++ gates open in presynaptic terminal​ 2. Neurotransmitter release​ 3. Neurotransmitter binds to postsynaptic receptors​ 4. Ion channels open in postsynaptic membranes

Question 42

summations of postsynaptic neurons

Answer 42

no summation (EPSP's dont add) temporal summation: close in time (EPSP's add together) spatial summations: 2 different stimuli in 2 diff locations add together spatial summation of EPSPs and IPSP's (cancel each other out)

Question 43

What do we mean when we say that an area of a neuron is refractory to further stimulation?

Answer 43

at point in time where the nerve cannot be stimulated repeatedly