Heart

Question 1

Structure heart wall

Answer 1

Epicardium
Myocardium
Endocardium

Question 2

Epicardium

Answer 2

lubricative outer covering

membrane including blood, lymph capillaries and nerve fibres

Question 3

Myocardium

Answer 3

cardiac muscle tissue seperated by connective tissue

provide muscular contractions that eject blood from heart chambers

Question 4

Endocardium

Answer 4

Endothelial tissue
thick layer of elastic/collagenous fibres

protective inner lining of chambers and valves

Question 5

Contraction of the heart depends on

Answer 5

electrical stimulation of the myocardium

Question 6

Sinoatrial node

Answer 6

pacemaker
initiates depolarization

Question 7

Atrioventricular node

Answer 7

passes depolarization to ventricles
brief delay to allow ventricular filling

Question 8

Bundle branches

Answer 8

connect atria to left and right ventricle

Question 9

Purkinje fibres

Answer 9

spread wave of depolarization throughout ventricles

Question 10

Conduction system

Answer 10

Action potentials originate in the sinoatrial (SA) node (the pacemaker) and travel across the wall of the atrium (arrows) from the SA node to the atrioventricular (AV) node

Action potentials pass through the AV node and alongthe atrioventricular (AV) bundle, which extends fromthe AV node, through the fibrous skeleton, into theinterventricular septum.

The AV bundle divides into right and left bundlebranches, and action potentials descend to the apexof each ventricle along the bundle branches.

Action potentials are carried by the Purkinje fibersfrom the bundle branches to the ventricular walls

Question 11

P wave

Answer 11

atrial depolarization

Question 12

QRS complex

Answer 12

ventricular depolarization and atrial repolarization

Question 13

T wave

Answer 13

ventricular repolarization

Question 14

What is an intrinsic pacemaker rate?

Answer 14

~100 bpm

Question 15

Relationship between pressure change and ECG

Answer 15

intraventricular pressure rises as ventricles contract (AV valve closes)
falls as ventricles relax (semilunar valve closes)

Question 16

Atherosclerosis

Answer 16

fatty plaque that narrows coronary arteries
reduces blood flow to myocardium

Question 17

Regular exercise beneifts on heart

Answer 17

cardioprotective
reduces incidence of heart attacks
improves survival from heart attack
reduce amount of myocardial damage from heart attack
improve antioxidant capacity
improve function of ATP-sensitive potassium channel

Question 18

PNS

Answer 18

via vagus nerve
slows HR by inhibit SA and AV node

Question 19

SNS

Answer 19

via cardiac accelerator nerves
increases HR by stimulating SA and AV nodes

Question 20

Cardiac muscle

Answer 20

highly oxidative
dense network of capillaries

Question 21

At rest oxygen extraction

Answer 21

high
65-75%

Question 22

During exercise oxygen extraction

Answer 22

increase +90%
but increased oxygen delivery relies on mainly increase in coronary blood flow

Question 23

Oxygen consumption by the heart

Answer 23

required for contraction
maintain basal metabolism (10-20% total)

Question 24

Chronotropic

Answer 24

heart rate increases

Question 25

Inotropic

Answer 25

contractility increases

Question 26

Metabolic vasodilator

Answer 26

adenosine

B-adrenergic via ANS

Question 27

At rest coronary flow

Answer 27

80% during diastole
vessel compression during systole

Question 28

During exercise coronary flow

Answer 28

40-50% during systole
high potential for ischaemia

Question 29

Where is the heart located?

Answer 29

left of midline
protected by protective sac (pericardium)

Question 30

Cardiac arrest

Answer 30

sudden unexpected loss of contractile function of the heart

Question 31

Evaluation of collapsed athlete

Answer 31

assess for pulse - consciousness
life support measures CPR
AED - electric shock to body = reverse abnormal arrhythmia to pump blood

Question 32

What are electrical impulses conducted between heart muscle cells by

Answer 32

intercalated discs