Exam 4: Nervous System: Impulse Conduction

Question 1

what type of event is conduction

Answer 1

electrochemical

Question 2

formation of a charge differential on membrane

- the induction of an action potential through use of ion gradients

Answer 2

electrical conduction

Question 3

manipulation of ion concentrations

using chemical signals to effect either excitatory or inhibitory potentials in target cells

Answer 3

chemical conduction

Question 4

membrane potential

Answer 4

voltage difference across membrane

• resting membrane potential = -70mV
• salty banana: more Na out, more K in, Cl on outside

Question 5

charge differential on membrane

• formed by selective concentration of positive and negative charges
• resting potential results in net pos charge otside, net neg charge inside

Answer 5

electrical gradient

Question 6

ion concentrations set up by membrane pumps

• sodium is concentrated outside, while K is concentrated inside cell
• strictly concentration

Answer 6

chemical gradient

Question 7

what are the main ions involved in membrane potentials

Answer 7

K and Na

Question 8

voltage gated ion channels

Answer 8

need difference in charge on membrane to open

Question 9

ligand gated ion channel

Answer 9

need something to bind ex: neurotransmitter

Question 10

mechanically gated ion channel

Answer 10

distort the membrane

- poke it, vibrate it

Question 11

ungated ion channel

Answer 11

like aquaporins - control if you put them on membrane

Question 12

action potential

Answer 12

• neuron at resting potential, stimulus is applied, mechanically gated Na channels open, Na rushes into cell
• once threshold reached -55, Na channels open, if not they reset and no action potential
• depolarization causes Na channels to close and K channels to open , K rushes in
• repolarization occurs, charge reset
• hyperpolarization
  K channels close
  reset to resting potential

Question 13

absolute refractory period

Answer 13

in repolarization

cannot send another signal no matter how strong stimulus is

Question 14

relative refractory period

Answer 14

in hyperpolarization

need super strong signal

Question 15

factors that affect excitability

-blocking gated channels or altering gradients

Answer 15

caine drugs
serum Ca2+ levels
shifting of K levels

Question 16

caine drugs effects on excitability

Answer 16

block Na channels preventing depolarization of neuron

- cannot send pain signals hence numb feeling - novacaine, cocaine

Question 17

serum Ca levels effect on excitability

decrease

Answer 17

less channels blocked, neuron may have small Na channels opening, can reach threshold - hyperexcitability

Question 18

serum Ca levels effect on excitability

increase

Answer 18

more channels blocked
cardiac muscle - needs external Ca, when raised will not contract as rapidly
- initially the inc riases heart rate bc depolarizing to get more contraction, but as it goes up you get inverse effect - problems with nerve impulses, cardiac irregularities
- harder to depolarize

Question 19

shifting K levels effect on excitability

Answer 19

releasing K can cause problems, screw up the ion balance making it harder to depolarize the cell
- if acidosis - bring in H but releasing K

Question 20

what dose is fatal for saxitoxin

Answer 20

0.2 mg

Question 21

what dose is fatal for tetrodotoxin

Answer 21

1 mg

Question 22

what does the dosage amount indicate regarding binding affinities?

Answer 22

saxitoxin has a higher affinity for saxitoxin bc it is lower dosage to be fatal

Question 23

presynaptic vs postsynaptic cell

Answer 23

presynaptic cell: sends impulse

postsynaptic cell: target cell, receiving

Question 24

cells separated by synaptic cleft, do not directly touch

requires release of neurotransmitter to the target

Answer 24

chemical synapse

Question 25

cells connected by gap junctions, no neurotransmitter required found in hippocampus, retina, cerebellum (equilibrium) rapid, NOT modulated

Answer 25

electrical synapse

Question 26

synaptic vesicles hold the same amount of neurotransmitter, what is this amount called?

Answer 26

quanta

Question 27

same amount per vesicle, the release is directly proprtional to what?

Answer 27

strength of signal you are sending | - stronger depolarization, the longer it will last

Question 28

in chemical synapses what are all of the receptors?

Answer 28

ligand gated

Question 29

what determines if the effect will be excitatory or inhibitory?

Answer 29

the type of ion channel

Question 30

depolarization of the end terminals opens...

Answer 30

voltage gated Ca channels, lets in Ca to do exocytosis via the SNARE complex

Question 31

opening Na channels results in... | opening K channels or Cl channels results in...

Answer 31

Na - EPSP stimulates target cell | K/Cl - IPSP

Question 32

ionotropic receptors

Answer 32

binding to receptor directly opens ion channels

Question 33

metabotropic receptors

Answer 33

indirect opening of channels via second messengers, G protein - dissociation of G protein is what causes channel to open

Question 34

4 possible cascades of second messengers

Answer 34

Gs, Gi, Gq, Gt

Question 35

Gs cascade

Answer 35

stimulates adenylyl cyclase inc cAMP EPSP

Question 36

Gi cascade

Answer 36

inhibits adenylyl cyclase dec cAMP IPSP

Question 37

Gq

Answer 37

activates phospholipase C splits PIP2 into IP3 and DAG EPSP

Question 38

Gt

Answer 38

transducin to dec cGMP in retina | inhibits dark current - get bleaching of an image onto the eye

Question 39

how do you make acetylcholine (Ach)

Answer 39

acetyl CoA and choline - can not make sufficient amount of choline so get from diet - make Ach and store in synaptic vesicle

Question 40

when you depolarize cell you release Ach, what happens?

Answer 40

it hits cholinergic receptor - never enters postsynaptic cell - does its work on the surface - once bound, acetylcholinesterase snaps it apart the acetyl group is gone and the choline gets recycled

Question 41

Where is Ach found?

Answer 41

- both pre-ganglionic and post-ganglionic parasympathetic divisions - pre-ganglionic sympathetic only - some CNS - the ONLY neurotransmitter in somatic division!!!! ONLY neurotransmitter to interact with skeletal muscle!!

Question 42

Ach role in the functioning of the CNS?

Answer 42

helps memory processing and formation - hippocampus

Question 43

nicotinic cholinergic receptors

Answer 43

ionotropic EPSP somatic CNS all preganglionic (both symp and parasymp) when neurotransmitter hits it opens Na and depolarizes cell

Question 44

muscarinic cholinergic receptors

Answer 44

``` post ganglionic (parasympathetic) CNS - reward, memory formation metabotropic M1-5 some muscle movement ```

Question 45

which muscarinic cholinergic receptors are excitatory?

Answer 45

M1, M3, M5

Question 46

which muscarinic cholinergic receptors are inhibitory?

Answer 46

M2 and M4

Question 47

M1

Answer 47

EPSP glands - inc secretions - salvation, digestion, sweating, mucous production

Question 48

M2

Answer 48

IPSP cardiac - lowers HR, you are relaxed so do not need a pounding HR

Question 49

M3

Answer 49

EPSP smooth muscle - inc peristalsis - lungs : more contracted in resting state, do not need dilated bronchioles when relaxed

Question 50

M4

Answer 50

IPSP brain - muscle movement - more relaxed muscles

Question 51

M5

Answer 51

EPSP brain - reward center - easier to recall memories, learn

Question 52

Pesticide poisoning: what happens to Ach concentartion in synapse if you are blocking acetylcholinesterase?

Answer 52

will not be able to breakdown Ach so get a build up of Ach, inc binding of Ach to receptors in post synaptic cel, over stimulation!

Question 53

what is a drug that blocks ACH activity at muscarinic receptors?

Answer 53

atropine

Question 54

what are catecholamines derived from | 3 examples of catecholamines

Answer 54

tyrosine | norepinephrine, epinephrine, dopamine

Question 55

when NE removed from adrenergic receptor, what 2 enzymes can break it down?

Answer 55

MAO, COMT | usually recycled or in bloodstream and the liver will break it down liver has MAO and COMT

Question 56

all adrenergic receptors are...

Answer 56

metabotropic

Question 57

Alpha 1 adrenergic receptors

Answer 57

Gq cardiovascular, vasconstriction inc BP - if in fight or flight situation you want BP up

Question 58

Alpha 2 adrenergic receptor

Answer 58

Gi self regulatory lowers NE (negative feedback, modulation), lowers anxiety helps you think of an action instead of becoming frozen in fear

Question 59

all beta receptors are...

Answer 59

stimulatory

Question 60

Beta 1 adrenergic receptors

Answer 60

heart: gives faster, stronger HR kidneys: inc pressure of blood going into kidneys increase BP bc heart is pumping faster

Question 61

Beta 2 adrenergic receptors

Answer 61

opposite effect inc cAMP in beta 2 cell dec Ca in muscle, so not strong contraction - in lungs get bronchodilation and vasodilation - better blood flow for oxygenation, opens air ways

Question 62

Beta 3 adrenergic receptors

Answer 62

adipose fat cells lipolysis release lipids from fat cells to have alternate energy source