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Physiology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

describe the resting membrane potential (using K)

A

so… the RMP is determined when there is an electrical and a chemical gradient. The membrane has channels in it that allow K to leave the cell. However, the K in the cell is accompanied by a negative anion. So when the K leaves, its negative counterpart cannot leave (The K only leaves because there is wayyy more K inside the cell then outside, so it goes down its concentration gradient). So now the K is gone, but the inside becomes more negative, which will attract the K to come back into the cell. This is the electrical gradient pulling it back in. This then leads to the RMP of K to be -94mV

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2
Q

what is the RMP of K

A

-94mV

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3
Q

RMP of Na and a how it works

A

So, the Na has a much higher concentration outside the cell then inside. The Na will enter the cell, causing a more (-) environment outside of the cell, and more (+) inside the cell. The (+) inside of the cell repels further Na from entering, which leaves the RMP of Na to be +61mV.

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4
Q

What has a very large impact on the resting membrane potential?

A

passive diffusion (channels about 90%) and only about 10% from the Na/K ATPase pump.

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5
Q

which ion is the membrane more permeable to (K or Na)

A

K+

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6
Q

Describe the active transport of both K and Na

A

There is much more K inside the cell then outside. The Na is higher on the outside then the inside. So, the pump will send 3Na out of the cell, and bring 2 K into the cell. This uses ATP. The break down of ATP will cause a conformational change that brings the Na out and the K inside.

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7
Q

Where is there more K

A

inside the cell

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8
Q

where is there more Na

A

outside of the cell

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9
Q

where does the K get pumped

A

from out to in (against its concentration gradient)

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10
Q

Where does the Na get pumped

A

from inside to outside

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11
Q

ratio of K in to Na out

A

every 3Na out there is 2 K pumped in

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12
Q

why is the Vm closer to that of K then Na

A

the membrane is far more permeable to K then it is to Na, therefore the the RMP is closer to the -94mV (-70 to -90mV)

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13
Q

the resting membrane potential will be closest to the ion with the ____ permeability

A

greatest

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14
Q

How does the Dr. Death thing work

A

Dr. Death administered KCl to patients who wanted to die. This increased the K concentration outside of the cell. Since there is more K inside the cell then out, it usually wants to leave the cell. However, when K is higher on the outside, there is less of a drive for K to leave. If K does not want to leave, no RMP. No RMP means that there is no excitability for cells, can’t breath or heart stops and that is death.

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15
Q

What are the 5 ion channels at the cleft

A
  1. Voltage gated Ca channels, which cause Ca to rush into the axon, and release the NT ACh.
  2. ACh goes across synaptic cleft, and then binds to nicotinic receptors (causes a conformational change and Na influx)
  3. Then the local depolarization causes voltage gated Na channels to open for more depolarization and AP
  4. At the T-tubule, the DHPR opens and Ca is released.
  5. The Ryanodine receptors (RyR) open on the SR and Ca is released into the cytoplasm.
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16
Q

Botulinum toxin

A

Blocks the ACh release from the nerve terminal. Doesn’t go across and open the Na channels which will open the Na voltage gated channels and cause the AP to release the Ca. NO CONTRACTION

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17
Q

Curare

A

Competes with the ACh (pushes ACh away and prevents binding)

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18
Q

Tetrodotoxin

A

puffer fish, inhibits Ca

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19
Q

Neostigmine

A

AChEsterase inhibitor. ACh has more time in the cleft to be picked up by nicotinic receptors. For a contraction

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20
Q

what does neostigmine help treat

A

myasthenia gravis (this is when your body makes antibodies against ACh receptors, so there aren’t as many receipts to bind the ACh to. there is a normal amount of ACh but not enough receptors. So the neostigmine helps to keep the ACh in the cleft so more can be picked up by the remaining receptors

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21
Q

Hemicholinium

A

blocks the choline re-uptake (need choline to make ACh, so when this is blocked, don’t make as much ACh, which depletes stores, which will mean not enough for sufficient contractions, and therefore tired fatigue much MUCH quicker.

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22
Q

how can you increase the conduction velocity of a nerve firing

A

by increasing the fiber size (increase diameter to decrease resistance)
also by myelinating.

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23
Q

Describe how MS has anything to do with myelin

A

the MS prevents the production of myelin, so the impulses top traveling down the axon.

24
Q

why does propagation of a nerve fiber only happen in one direction?

A

the refractory periods prevent the AP from traveling in reverse down an axon.

25
Q

What is ACh made of, and what catalysis this reaction

A

ACh is made from acetyl CoA and choline, catalyses by choline acetyltransferase

26
Q

EPSP vs IPSP

A

the EPSP causes depolarization, by opening the Na and K channels. Depolarization brings it closer to the threshold for an AP. IPSP hyperpolarizes it, bringing it away from threshold, like opening of Cl channels.

27
Q

Examples of EPSP and IPSP

A

the EPSP are norepinephrine, ACh, epi, dopamine, serotonin, glutamate.

IPSP’s are GABA and glycine.

28
Q

what causes relaxation of a skeletal muscle contraction

A

the re-uptake of Ca from interacellular back into the SR via SERCA.

29
Q

What causes tetanus

A

increased intracellular Ca

30
Q

passive tension

A

the tension of the muscle when it is stretched

31
Q

total tension

A

tension under the muscle when it is contracted (at different lengths)

32
Q

active tension

A

difference between total and passive tension

33
Q

where is tension maximum

A

when there are maximum overlaps between the actin and myosin

34
Q

tension and cross bridge

A

overstretched, not enough cross bridge, not as much tension, same applies to too short, too much overlap and bands hit into each other.

35
Q

when after load increases (the load against which the muscle must contract), the velocity of shortening ____

A

decreases.

36
Q

as you increase the load, you ____ the velocity

A

decrease

37
Q

fast twitch vs slow twitch fibers

A

the fast twitch are anaerobic (Type II). These have a high glycolytic enzyme amount, and few mitochondria’s, and decreased capillary density and a decrease myoglobin. These are for the smaller movements of things like the eye, because they have rapid movement

slow twitch are aerobic, (Type I), so they have a lot of myoglobin, mitochondria and a high capillary density, but a low glycolytic enzyme count. They are responsible for the increased court movements like postural movements.

38
Q

Motor unit

A

all muscle fibers innervated by a single nerve

39
Q

small motor units

A

fast things, like precise movements like the eye. very precise

40
Q

large motor units

A

slower, course movements, like the quad.

41
Q

how do we get tetanus

A

strength of contraction increases because there is an increase in the firing rate, not the size of the stimulus.

42
Q

Treppe

A

this is the phenomenon that when you increase the amount of Ca in the intracellular, by not picking it all the way up after the first stimulus, there is more Ca available to bind to sites, which leads to a stronger contraction. Not picked up in time, not that it can’t be picked up

43
Q

hypertrophy vs hyperplasia vs atrophy

A

hypertrophy is when you get an increase in the size of the fiber, more sarcomeres arranged in parallel. Lifting weights
Hyperplasia is when you increase the number of muscle fibers, which s cray hard
Atrophy at first is a decrease in size, then a decrease in the number of fibers (from disuse)

44
Q

what does hyperplasia and hypertrophy do to Vmax and force production

A

they increase force production but nothing happens to Vmax.

45
Q

lengthening and Vmax and force production

A

force production remains the same, but the velocity increases.

46
Q

what is special about actin in terms of movements

A

they can cause cell locomotion by breaking a piece off and shifting it to the end of the actin molecule

47
Q

why is titin important

A

it allows the molecules to bounce back after being stretched. holds the shape of the sarcomere.

48
Q

lidocaine

A

blocks the Na channels and therefore blocks an AP

49
Q

the heads and tails of a membrane

A

tails are hydrophobic, and made of fatty acids. Heads are POLAR

50
Q

how do lipid and water soluble things get through the membrane

A

the lipid soluble can pass right through because they dissolve. The water soluble need channels, pores, etc.

51
Q

benefit of an unsaturated hydrocarbon

A

the unsaturated hydrocarbon has a kink in it, which leaves more space between heads and flows things to diffuse in more easily

52
Q

the thicker the membrane, and ____ the diffusion

A

harder

53
Q

Hypertonic solution

A

the hypertonic solution means there is more solute outside of the cell. So, water will leave the cell and travels out, causing the cell to shrink.

54
Q

what three things increase permeability

A

decreasing the membrane thickness
decrease the size (radius) of the solute
increasing the oil/water perm coefficient

55
Q

osmolarity and osmotic pressure of water

A

osmolarity is 282mOsm/L and the osmotic pressure is 5400mmHg.

Physiology (7 decks)

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