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physiology exam 2 > cardiovascular system: electrophysiology and ECC > Flashcards

cardiovascular system: electrophysiology and ECC Flashcards

1
Q

what structure most protects the heart

A

pericardium

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2
Q

pericardium is separated in 2 layers: ___ and ___

A

fibrous and serous

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3
Q

serous pericardium consists of

A

parietal and visceral

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4
Q

is supplied by the pericardial cavity, reduces friction within pericardium by lubricating the surface

A

pericardial fluid

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5
Q

visceral layer of the serous pericardium that is the outmost layer

A

epicardium

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6
Q

layers of the heart wall

A

epicardium, myocardium, and endocardium

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7
Q

majority of cells in the myocardium

A

contractile cells

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8
Q

action potential in contractile cells lead to ____ and _____

A

contraction and generation of force or pressure

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9
Q

3 different cell types can function as pacemakers

A

SA node, AV node, purkinje fibers

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10
Q

cardiomyocytes

A

cardiac muscle cells that have one nucleus and are branched cells

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11
Q

what is smaller sarcoplasmic reticulum in skeletal muscle or cardiac muscle

A

cardiac muscle

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12
Q

mitochondria occupies ____ of cell volume

A

1/3, reflects high energy demand

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13
Q

cardiac muscles branching join end to end with neighboring cardiac cells in a _____

A

complex network

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14
Q

helps to electrically connect cardiac muscle cells to one another, causing a wave of conduction former uniform contraction

A

gap junctions

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15
Q

myocardia sarcoplasm is smaller and relies on what

A

extracellular fluid Ca levels for contraction initiation

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16
Q

cell junctions have what 2 components

A

desmosomes and gap junctions

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17
Q

desmosomes ensure what

A

force transfer fromm one cell to next

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18
Q

when an action potential arrives it activates what

A

L-type Ca channels in the T Tubule membrane

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19
Q

provides electrical connection

A

gap junctions

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20
Q

what type of junction is a desmosome

A

Anchoring

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21
Q

the skeleton of the heart is made up of

A

fibrous tissue that forms central support, 4 fibrous rings, 2 fibrous trigons, membranous part of interventricular and interatrial septa

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22
Q

Fibrous skeleton

A

acts as electrical insulator, prevents free flow of electrical impulses between atria and ventricle

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23
Q

an excitable tissue with the ability to generate APs

A

cardiac muscle

24
Q

In cardiac muscle Ca is involved in both

A

autorythmic and contractile AP

25
Q

action potentials produced by ventricular and atrial contractile cells are called

A

“fast response” action potentials.

26
Q

Action potentials observed in the sinoatrial (SA) node and atrioventricular (AV) node are called

A

“slow response” action potentials.

27
Q

phases of cardiac contractile cells

A

0- upstroke or depolarization
1- early rapid depolarization or partial repolarization
2- plateau
3- repolarization
4- resting membrane potential

28
Q

phase 0 is due to what

A

opening of voltage gated Na channels similar to that occurring in nerve and skeletal muscle

29
Q

phase 1 event

A

inactivation of Na channel and transient increase in K permeability

30
Q

Phase 1 cell movement

A

K out

31
Q

phase 2 event

A

activation of slow calcium channels

32
Q

phase 2 cell movement

A

Ca entry

33
Q

phase 3 event

A

inactivation of calcium and increased permeability to K

34
Q

phase 3 cell movement

A

K out

35
Q

phase 4 event

A

normal permeability restored

36
Q

phase 4 cell movement

A

Na-K- ATPase pumps K in and Na out

37
Q

longer myocardial action potential helps to prevent what

A

sustained contraction (tetanus)

38
Q

What phase is associated with the resting potential

A

4

39
Q

the ability of autorhythmic cells to generate spontaneous APs results from their

A

unstable membrane potential, which starts at about -60 mV and goes up toward threshold

40
Q

This unstable membrane potential is called
a

A

pacemaker potential

41
Q

what happens when the membrane potential is at -60mV

A

hyper polarization activated cyclic nucleotide gated channels (HCN channels) open.

42
Q

If channels are permeable to both

A

K and Na

43
Q

What If channels open at negative membrane potentials,

A

Na+ influx exceeds K+ efflux. The net influx of positive charge slowly depolarizes the autorhythmic cell.

44
Q

are auto rhythmic cells membrane potentials stable or unstable

A

unstable

45
Q

what is not an autorythmic cell

A

contractile cell

46
Q

Autorhythmic cells _____ fire action potentials

A

spontaneously

47
Q

depolarizations of the auto rhythmic cells spread rapidly to adjacent contractile cells through

A

gap junctions

48
Q

why can APs not go directly from atrial to ventricular myocardium

A

they encounter fibrous skeleton of the heart at the junction of the atria and ventricles.

49
Q

what does the fibrous skeleton of the heart at the junction of the atria and ventricles do

A

It acts as electrical insulator and prevents the transfer of electrical signals from the atria to the ventricles.

50
Q

functions of AV node

A

delays the transmission of APs and is the only pathway APs generated by SA node can reach contractile fibers

51
Q

purkinje fibers has hoe many BPM

A

20

52
Q

which auto rhythmic cell type has the slowest pacemaker activity

A

purkinje cell

53
Q

ECG represents

A

the summed electrical activity of all cells recorded from the surface of the body

54
Q

The voltage change is much greater when recorded

A

intercellularly

55
Q

which indicated the start of a new AP cycle of the heart

A

P

physiology exam 2 (2 decks)

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