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Topics > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Na+

Iout, Iin, Keq

A

Iout: 145
Iin: 10
Keq: 70mV

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2
Q

K+

Iout, Iin, Keq

A

Iout: 4
Iin: 135
Keq: -94mV

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3
Q

Ca2+

Iout, Iin, Keq

A

Iout: 2
Iin: 10^-4
Keq: 132

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4
Q

goldmann field equation

A

each permeable ion attempts to drive Emem toward its own Ex (Nernst potential)
-many ions - total permeable ions dictate membrane potential

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5
Q

resting membrane potential

A

membrane potential is stable at this time

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6
Q

nodal tissue

A

pacemaker cells

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7
Q

how are cardiac cells myogenic

A

the electrical impulse starts in the same muscle causing it to contract

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8
Q

pacemakers

A

SA node, AV node, PBH system

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9
Q

provides electricity that generates heart beat by action potentials

A

pacemakers

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10
Q

what is the sinus rhythm

A

pace from the SA node

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11
Q

characteristics of nodal tissue action potential

A
  • sinusoidal curve (wave like)
  • no true RMP - never stable
  • diastolic depolarization (graded potential)
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12
Q

Funny current

A

activated at a negative voltage!!

cation nonspecific!! - allows Na, Ca, and K to pass through

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13
Q

diastolic depolarization

A

sum of 3 currents that flow through funny channel
-each ion that passes drives the membrane potential to its own Nernst potential
-graded potential - slope shows rate of flux slow
current not strong bc slope is gradual

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14
Q

characteristics of cardiac muscle

A
  • myogenic
  • Ca dependent
  • involuntary, striated
  • no true RMP
  • intercalated discs
  • muscle fibers parallel and in series
  • 30% is mitochondria!! - requires lots of energy
  • T tubule and sarcoplasmic reticulum not as extensive as skeletal
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15
Q

physical places with high density of gap junctions

A

intercalated discs

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16
Q

gap junctions

A
  • proteins imbedded in cell membrane of myocytes
  • allow low resistance of current flow
  • allow cell to cell communication and current flow between ICF
  • protein composition with hydrophillic core - aqueous pore
17
Q

what is the dominant pacemaker in a healthy heart

A

SA node triggers myocyte to have an action potential

18
Q

phase 0 nodal tissue/pacemaker cell action potential

A

depolarization

once threshold is hit, Ca channels open

19
Q

phase 3 nodal tissue action potential

A

repolarization

K channels activated

20
Q

phase 4 nodal tissue action potential

A 
diastolic depolarization (pacemaker potential)
gives heart automaticity 
caused by activation of funny channels
21
Q

myocyte action potential

A

square waves
like a light switch - needs to be hit to turn on and needs to be hit to turn off
MP: -90mV more neg than nodal tissue

22
Q

phase 0 of myocyte-cardiac muscle action potential

A

depolarization
main ion moving is Na

Na fast channels - resistance to Na is low

23
Q

phase 1 myocyte action potential

A

at peak of action potential
opening of K+ slow channels - this new current is why the line slopes down
inactivation of Na+ channels

24
Q

phase 2 myocyte action potential

A

plateau
Ca, K, and Na lead to the plateau - all involved bc they are cancelling eachother out
time in the action potential when nothing is changing - parallel to x-axis
heart muscle does not do tetany

25
Q

phase 3 myocyte action potential

A

membrane potential plumeting toward negative (K+)
fast K+ channels
repolarization does NOT extend beyond x-axis

26
Q

in all muscle types, _____ precedes ______

A

electrical activity precedes mechanical

27
Q

How does the PNS lower heart rate?

A
  • interbeat interval

- inc maximum diastolic potential

28
Q

what happens when the interbeat interval increases?

A

it gets longer between heart beats
takes a longer amount of time to reach threshold
lowers HR

29
Q

how does NE effect the heart

A

increases heart rate

30
Q

NADR

A

lowest point, maximum diastolic depolarization - most negative point

31
Q

cardiac control center

cell bodies here travel to thoracic region when they synapse at ganglion

A

medulla

32
Q

interganglionic commisural fibers

A

nerve fibers connecting superior and inferior ganglion together
all target tissues stimulated at same time, low R junctions

33
Q

what responses do you get when you activate the medulla

A

indiscrete, systemic, not specific - sympathetic
indiscrete bc of the impulse by the interganglionic comisural fibers - conduct electricity get massive ganglion activation

34
Q

arenaline is second contributer to SNS response

A

released fom adrenal medulla

- adrenal gland has tissue that can then secrete epinephrine

35
Q

effective refractory period

A

can’t get another action potential

36
Q

why are there effective refractory periods?

A
  1. all Na channels inactivated
  2. in order to get them ready for another action potential the cell has to be negative
    need phase 0 to get anther action potential
37
Q

what fraction of Na channels are closed at phase 4?

A

100%

Topics (10 decks)

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