cardiovascular - lecture 5 Flashcards

1
Q

(T or F) All deoxygenated blood passes through either the superior or inferior vena cava on its way to right chambers of the heart

A

false
coronary circ pumps directly into right atria

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2
Q

(T or F) The pulmonary artery transports oxygenated blood from the heart.

A

false
in general arteries carry oxygenated blood but exception = pulmonary vessels

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3
Q

(T or F) The Purkinje fibers can fire on their own if an impulse isn’t generated by the sinus node.

A

true
all cells of specialized conduction system have potential to beat on their own
usually dont as sa node fires faster

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4
Q

(T or F) The Purkinje fibers form synapses with the myocardium in the ventricles, allowing the ventricles to fire in synchrony.

A

false
bc purkinje fibers are muscle and do not form synapses
only nerves do that

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5
Q

(T or F) Na+ ions pass through gap junctions of cells where one is active and the other is resting.

A

true
but sodium concentrations arent as high as potassium inside cells
can still pass through gap junctions tho
impact on local circuit current = mostly in interstitial space

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6
Q

describe gap junctions

A

mostly located at ends of myocytes
oriented perpendicular to cell axis
concentrated at ends of cells
less gap junctions on sides of cells

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7
Q

what is electrocardiogram and electrocardiograph

A

gram is reading = recording
graph takes reading = device

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8
Q

what is ecg/ekg

A

recording of electrical activity of heart
extracellular recordings
only appear when potential difference

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9
Q

describe ecg set up

A

LL lead = left ankle
RL lead = right ankle
LA and RA lead = right and left wrist
cheat lead
5 leads
lead selector switch - measures potential diff (voltage)
voltmeter v sensitive
rl = right leg always connected = reference lead, set to 0

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10
Q

what is purpose of gel for ecg

A

lowers resistivity of skin
allows free flowing of ions

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11
Q

describe typical ecg

A

divisions to help read it
around 1 second
standard man = resting bpm 60

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12
Q

describe all waves

A

end and start at baseline

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13
Q

what is complex

A

deflection away from base line

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14
Q

what is potential mv of ecg reading

A

+1 mv total amplitude
vs ~100mv for intracellular recording

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15
Q

what is p wave

A

sinus node here fires, invisible tho
atrial contraction = p wave
halfway = av node starts to activate, not seen tho
ends = atria stop contracting and recovery

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16
Q

what is q wave

A

his bundle invisible
left bundle invisible
septum = visible = q wave = left to right propagation
first neg deflection

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17
Q

what is qrs complex

A

r wave and s wave

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18
Q

what is r wave

A

purkinje fibers - invisible
ventricles - visible = r wave

19
Q

what is s wave

A

late activation

20
Q

what is t wave

A

ventricles repolarize

21
Q

Why are ECG waves sometimes positive and sometimes negative? What controls its shape?

A

cell A depolarized and cell B RESTING = ion flow causes b to depolarize
intracellular = +ve ions move from a to b, - ve ions move from b to a
extracellular = +ve ions move from b to a and -ve ions move from a to b

other ions also flow, like if neg opp dir like chloride
ions can flow in both dir
put electrodes on body and sense current flow on outside

22
Q

Case 1: cell A is depolarized (active). B is hyperpolarized (resting). Propagation is going from left to right.

A

v = + - - = +
positive voltage

23
Q

what is voltage equal to

A

v = pos end minus neg end

24
Q

cell A is hyperpolarized (resting) . B is polarized (active)
Propagation is going from right to left

A

v = - - + = -
neg voltage

25
cell A is hyperpolarized (resting). B is polarized (active). A repolarization (relaxation) wave is going from left to right.
v = - - + = -
26
describe voltage when depolarization
depolar going towards +ve electrode, V is +ve depolar going towards -ve electrode, V is -ve
27
describe voltage during repolarization
repolar going towards +ve electrode, V is -ve repolar going towards -ve electrode, V is +ve
28
describe overview of ecg
atrial excitation = activation of sa node, av node right to left, p wave ventricular excitation = q contraction of septum left to right, r s contraction of ventricles ventricular relaxation = t wave, relaxation wave
29
when do atria relax
during qrs but not seen since ventricles mask
30
describe ap durations
diff on inside muscle vs outside propagates inside out with depolarizing and outside in when repolarizing could see some neg t waves
31
why is t wave positive
bc depolarization wave moves in opp dir as repolarization wave due to diff in ap duration from inside to outside of heart
32
describe bipolar limb leads
triangle arounf heart = all display diff info on ecg triangulating reference leads also attacked lead = wire, but also difference between 2 wires
33
describe kirchhoffs voltage law - triangle
sum of changes in potential encountered in complete loop circuit = 0 so voltage of all leads sum 0
34
describe unipolar ecg leads
using kirchhofs law exploring lead limb unipolar and chest unipolar
35
describe sa node ap graph
pacemaker potential spontaneous diastolic depolar driven by flux of calcium one cell drives other potential diff not as great = slower no resting membrane potential since pacemaker cells no Ina in sinus node cells: Ica generates upstroke
36
describe atria ap graph
v fast upstroke ~ -90 very negative no hint of pacemaking current
37
describe his purkinje system ap graph
pacemaking current no stable resting membrane potential can beat on own sodium channel but has pacemaking activity higher rate of flow = depolarization faster has Ina and a fast upstroke and a fast propagation
38
describe ventricular ap graph
resting potential - stable upstroke plateau, longer than other aps repolarization = 150-300ms much longer than nerve or skeletal aps resting potential more hyperpolarized than in neurons
39
describe ionic channels in cardiac cells
sodium and potassium channels
40
describe ionic basis underlying ventricular ap
change in conductance of channels log scale at rest Pk>>Pca and Pna so Vrest = close to Ek Ina = fast inwards na+ current Itotal + Ik1 + Iks + Ikr +... many = can do many things at same time
41
describe Pk+ PNa+ PCa2+(L)
Pk+ = high then sense voltage and close then opens again = repolarization Pna+ = poor conduction of na then channels open, massive change in conductance then closes Pca2+ = channels open and influx calcium into cell = plateau phase, then closes
42
describe slow aps
sa now av noode physiological delay in av node since slow propagation slow upstroke 1-10 v/sec important for synchrony conduction velocity = 0.01-0.05m/sec
43
describe fast aps
activation for rest of them 100-1000 v/sec conduction velo = 0.5-5m/sec ventricular muscle atrial muscle bundle of his bundle branches purkinje fibers
44
what are most important fort aps/ecg
atrial and ventricular cells mostly but many things happening