Lecture 15

Question 1

Cardiac Cycle step 1

Answer 1

Contraction of atria
(AKA atrial systole)

Question 2

Cardiac Cycle step 2

Answer 2

contraction of
ventricles (ventricular
systole)

Question 3

Cardiac Cycle step 3

Answer 3

rest (diastole) when neither chamber is contracting

Question 4

contraction name

Answer 4

systole (BP: 120)

Question 5

relaxation name

Answer 5

diastole (BP: 80)

Question 6

doctors are more interested in….

Answer 6

diastole because its the force by which the heart has to work against to eject blood against the contraction (diastole is period when heart fills back up with blood)

Question 7

AFTERLOAD

Answer 7

diastolic arterial pressure, how hard heart has to work to overcome systolic pressure

Question 8

strength and rate of heart contractions controlled by

Answer 8

Neural and Endocrine signals

Question 9

sympathetic innervation (norepinephrine) causes

Answer 9

increased HR eg these signals released when doing excersize

Question 10

parasympathetic innervation (acetylcholine) causes

Answer 10

decreased HR eg. these signals are released when sitting in a lecture

Question 11

epinephrine causes

Answer 11

increased strength of heart contractions / how much blood is being ejected with each contraction

Question 12

from rest to excersize:

Answer 12

HR can increase to nearly 200 bpm
cardiac output increases from 5 L/min to 25 L/min
(elite athletes: 40 L/min)

Question 13

Max HR formula

Answer 13

220 - age

Question 14

Electrical signal is propagated by: (3)

Answer 14

Nodes, Nerves, Intercalated disks (gap junctions)

Question 15

Nodes

Answer 15

SA (sinoatrial) nodes, AV (atrioventricular) nodes

Question 16

SA nodes are:

Answer 16

Heart’s natural pacemaker, electrical impulses generated here.

Question 17

electrical impulse tells:

Answer 17

Heart to beat

Question 18

Nerves

Answer 18

Bundle of His, Bundle branches, purkinge fibers
(All have lots of gap junctions)

Question 19

Intercalated disks (gap junctions)

Answer 19

send signals between parts of heart, eg SA node sends signal to left atrium

Question 20

Cardiac muscle consists of

Answer 20

individual cardiomyocytes connected by intercalated discs (GAP JUNCTIONS!) to work together as a single functional organ

Question 21

miscommunication usually results in

Answer 21

some kind of arrhythmia

Question 22

miscommunication is

Answer 22

something wrong with the sequential sequencing of the heart

Question 23

Abnormal sinoatrial node firing results in

Answer 23

tachycardia (fast), bradycardia (slow)

Question 24

Blocks can:

Answer 24

slow down or prevent signal propagation from atria to ventricles

Question 25

blockages (eg at AV node)

Answer 25

can vary in terms of degree of the blockage

Question 26

Ventricles can:

Answer 26

contract independently (bundle of His, 40 bpm)

Question 27

Fibrillations

Answer 27

more serious, occur when cells depolarize independently

Question 28

Atrial Fibrillations (A-Fib)

Answer 28

a quivering or irregular heartbeat (arrhythmia)

Question 29

Ventricular fibrillation (V-fib)

Answer 29

the most serious cardiac rhythm disturbance. Must try and reset electrical signal

Question 30

Atherosclerosis is

Answer 30

Narrowing of arteries due to calcified fatty deposits (plaque) and thickening of the wall

Question 31

Atherosclerosis is triggered by

Answer 31

damage to arterial wall (inflammation)

Question 32

Atherosclerosis can lead to

Answer 32

- heart attack or stroke - When this occurs in the arteries of heart muscle, it is called coronary artery disease

Question 33

Factors contributing to Coronary Artery Disease:

Answer 33

Elevated blood lipids, hypertension, inflammatory mediators (C-reactive protein), Diet (sodium, potassium, saturated/trans fats, cholesterol), Smoking, physical inactivity, obesity/diabetes, Age, genetics

Question 34

Treating Coronary Artery Blockages

Answer 34

Angioplasty, Bypass Surgery

Question 35

Angioplasty

Answer 35

a catheter and balloon are threaded into the coronary artery to the point of blockage. Plaque is pushed to the outside of the artery walls and held there by stent.

Question 36

Bypass Surgery

Answer 36

Vein taken from arm or leg; one end attached above the blockage and the other below

Question 37

Hypertrophy

Answer 37

a sign of being “overworked”. The heart muscle will respond and hypertrophy just like your skeletal muscle would respond to weight-lifting

Question 38

Endurance athletes

Answer 38

mostly an increase in LV chamber (need to increase cardiac output)

Question 39

Weightlifters

Answer 39

mostly increased LV wall and septum thickness (need to overcome increased afterload – the amount of pressure needed to eject blood during ventricular contraction)

Question 40

Enlargement of the Heart pros

Answer 40

Athlete's heart – an appropriate adaptation! Occurs in both endurance athletes and weightlifters! ☺

Question 41

Enlargement of the Heart cons

Answer 41

Causes include high blood pressure and narrowing of aortic valve ... the heart must work harder to overcome these

Question 42

Hypertension # stage 1

Answer 42

130-139/80-89

Question 43

Hypertension # stage 2

Answer 43

140+/90+

Question 44

Hypertensive crisis #

Answer 44

higher than 180/higher than 120

Question 45

Vasoconstriction (artery hole gets smaller)

Answer 45

* Alpha-receptors are located on arteries. * Norepinephrine and epinephrine bind to 2 adrenergic receptors * This causes arteries to constrict (vasoconstriction) * This increases blood pressure * E.g. during exercise

Question 46

Vasodilation (artery hole opened wider)

Answer 46

* Blood vessels in skeletal muscles lack alpha-receptors * Norepinephrine and epinephrine bind to b2 adrenergic receptors found in arteries of skeletal muscle * This dilates vessels of the skeletal muscles (vasodilation) so they can receive increased blood flow * E.g. also during exercise!

Question 47

how much does Cardiac output increase during excersize

Answer 47

5x, 8x in elite athletes

Question 48

why does BP not increase much during exercise

Answer 48

Distribution of blood does not increase proportionally. blood flow is diverted to where it is needed during exercise! The working muscles! Dilation of vessels to skeletal muscle and heart increases blood flow to muscles (β2 receptors and local metabolites). Constriction of vessels to the gut and kidneys decreases blood flow to these organs (B2 receptors). Dilating vessels in the muscle decreases resistance and we have a lot of muscle mass!

Question 49

Resistance exercise (e.g. weightlifting) can cause

Answer 49

dramatic increases in blood pressure - up to 345/245 mmHg. Holding your breath – increases intrathoracic pressure during the lift – called the “Valsalva maneuver” Temporarily raises blood pressure and slows heart rate!