cardiovascular system: electrophysiology and ECC

Question 1

what structure most protects the heart

Answer 1

pericardium

Question 2

pericardium is separated in 2 layers: ___ and ___

Answer 2

fibrous and serous

Question 3

serous pericardium consists of

Answer 3

parietal and visceral

Question 4

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

Answer 4

pericardial fluid

Question 5

visceral layer of the serous pericardium that is the outmost layer

Answer 5

epicardium

Question 6

layers of the heart wall

Answer 6

epicardium, myocardium, and endocardium

Question 7

majority of cells in the myocardium

Answer 7

contractile cells

Question 8

action potential in contractile cells lead to ____ and _____

Answer 8

contraction and generation of force or pressure

Question 9

3 different cell types can function as pacemakers

Answer 9

SA node, AV node, purkinje fibers

Question 10

cardiomyocytes

Answer 10

cardiac muscle cells that have one nucleus and are branched cells

Question 11

what is smaller sarcoplasmic reticulum in skeletal muscle or cardiac muscle

Answer 11

cardiac muscle

Question 12

mitochondria occupies ____ of cell volume

Answer 12

1/3, reflects high energy demand

Question 13

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

Answer 13

complex network

Question 14

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

Answer 14

gap junctions

Question 15

myocardia sarcoplasm is smaller and relies on what

Answer 15

extracellular fluid Ca levels for contraction initiation

Question 16

cell junctions have what 2 components

Answer 16

desmosomes and gap junctions

Question 17

desmosomes ensure what

Answer 17

force transfer fromm one cell to next

Question 18

when an action potential arrives it activates what

Answer 18

L-type Ca channels in the T Tubule membrane

Question 19

provides electrical connection

Answer 19

gap junctions

Question 20

what type of junction is a desmosome

Answer 20

Anchoring

Question 21

the skeleton of the heart is made up of

Answer 21

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

Question 22

Fibrous skeleton

Answer 22

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

Question 23

an excitable tissue with the ability to generate APs

Answer 23

cardiac muscle

Question 24

In cardiac muscle Ca is involved in both

Answer 24

autorythmic and contractile AP

Question 25

action potentials produced by ventricular and atrial contractile cells are called

Answer 25

“fast response” action potentials.

Question 26

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

Answer 26

“slow response” action potentials.

Question 27

phases of cardiac contractile cells

Answer 27

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

Question 28

phase 0 is due to what

Answer 28

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

Question 29

phase 1 event

Answer 29

inactivation of Na channel and transient increase in K permeability

Question 30

Phase 1 cell movement

Answer 30

K out

Question 31

phase 2 event

Answer 31

activation of slow calcium channels

Question 32

phase 2 cell movement

Answer 32

Ca entry

Question 33

phase 3 event

Answer 33

inactivation of calcium and increased permeability to K

Question 34

phase 3 cell movement

Answer 34

K out

Question 35

phase 4 event

Answer 35

normal permeability restored

Question 36

phase 4 cell movement

Answer 36

Na-K- ATPase pumps K in and Na out

Question 37

longer myocardial action potential helps to prevent what

Answer 37

sustained contraction (tetanus)

Question 38

What phase is associated with the resting potential

Answer 38

4

Question 39

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

Answer 39

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

Question 40

This unstable membrane potential is called a

Answer 40

pacemaker potential

Question 41

what happens when the membrane potential is at -60mV

Answer 41

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

Question 42

If channels are permeable to both

Answer 42

K and Na

Question 43

What If channels open at negative membrane potentials,

Answer 43

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

Question 44

are auto rhythmic cells membrane potentials stable or unstable

Answer 44

unstable

Question 45

what is not an autorythmic cell

Answer 45

contractile cell

Question 46

Autorhythmic cells _____ fire action potentials

Answer 46

spontaneously

Question 47

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

Answer 47

gap junctions

Question 48

why can APs not go directly from atrial to ventricular myocardium

Answer 48

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

Question 49

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

Answer 49

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

Question 50

functions of AV node

Answer 50

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

Question 51

purkinje fibers has hoe many BPM

Answer 51

20

Question 52

which auto rhythmic cell type has the slowest pacemaker activity

Answer 52

purkinje cell

Question 53

ECG represents

Answer 53

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

Question 54

The voltage change is much greater when recorded

Answer 54

intercellularly

Question 55

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

Answer 55

P