Lecture 17 - The Caridac Cycle

Question 1

The cardiac Cycle

Answer 1

• Contraction of atria
• Followed by contraction of ventricles
• Followed by a rest when neither chamber is contracting

Question 2

contraction

Answer 2

Systole - BP: (120)/80

Question 3

Relaxation

Answer 3

Diastole - BP: 120/(80)

Question 4

Pre Load

Answer 4

Initial stretching of the cardiac myocytes prior to contraction

Question 5

After load

Answer 5

Diastolic Arterial Pressure - the pressure the heart must work against to eject blood during systole

Question 6

Nodes

Answer 6

• SA (Sinoatrial Node): Heart’s natural peacemaker where electrical impulses are generated
• AV (atrioventricular) node

Question 7

Nerves

Answer 7

• bundle of His
• Bundle of branches
• Purkinge fibres

Question 8

Intercalated discs

Answer 8

Gap junctions
- cardiac myocytes connected by intercalated discs to work together as a single function organ

Question 9

Arrhythmia

Answer 9

irregular heart rate or rythm

Question 10

Abnormal SA node firing

Answer 10

Can result in tachycardia and bradycardia

Question 11

Blocks (blockages in the heart)

Answer 11

• Slow down or prevent signal propagation from atria to ventricles
• ventricles can contract independently

Question 12

Arterial Fibrillation (A-Fib)

Answer 12

Quivering or Irregular Heartbeat

Question 13

Ventricular Fibrillation (V-fib)

Answer 13

The most serious cardiac rhythm disturbance
- loss of consciousness or death

Question 14

Neural and Endocrine Signals Control Strength and Rate of Heart Contractions

Answer 14

• Sympathetic innervation (norepinephrine): increases heart rate
• Parasympathetic innervation (acetylcholine): decreases heart rate
• Epinephrine: Increases the strength of each contraction

Question 15

Hypertrophy

Answer 15

Sign of being “overworked”
- the heart muscle will respond just like when you’re weight-lifting

Question 16

LV Chamber - Endurance athletes

Answer 16

Increase as they need to increase cardiac output

Question 17

LV Chamber - Weightlifters

Answer 17

Increased LV wall and septum thickness to accompany for overcome the pressure difference when they hold their breath during lifts

Question 18

Enlargement of the Heart - Bad

Answer 18

Causes include high blood pressure and narrowing of aortic valve the heart must work harder

Question 19

Enlargement of the heart - good

Answer 19

Athlete’s Heart

Question 20

Atherosclerosis

Answer 20

• Narrowinf of arteries due to the calcifies fatty deposits and thickening of the wall
• triggered by damage to the arterial wall
• can lead to heart attack or stroke

Question 21

Atherosclerosis - factors

Answer 21

• Elevates blood lipids
• Hypertension
• inflammatory mediators
• diet
• smoking, physical inactivity, obesity/diabetes
• age, genetics

Question 22

Treating Coronary Artery Blockages

Answer 22

• Angioplasty
• Bypass Surgery (saphenous vein is used)

Question 23

systolic blood pressure

Answer 23

Maximum pressure when the ventricles contract and send blood to the artieries

Question 24

Diastolic blood pressure

Answer 24

Minimum pressure when the heart relaxes between beats (not zero due to elastic recoils of arterial walls)

Question 25

Normal Blood Pressure

Answer 25

Systole: Less than 120 Diastole: Less than 80

Question 26

Elevated Blood Pressure

Answer 26

Systole: 120 - 129 Diastole: Less than 80

Question 27

high blood pressure- hypertension stage 1

Answer 27

Systole: 130 - 139 Diastole: 80 - 90

Question 28

High blood pressure - hypertension stage 2

Answer 28

Systole: 140 or higher Diastole: 90 or higher

Question 29

hypertensive crisis

Answer 29

Systole: Higher than 180 Diastole: Higher than 120

Question 30

Vasoconstriction

Answer 30

- Alpha-receptors are located on arteries - Norepinephrine and epinephrine bind to a2 adrenergic receptors - increases blood pressure - ex. During exercise

Question 31

Vasodilation

Answer 31

- Norepinephrine and epenipherine bind to b2 adrenergic rectors found in arteries of skeletal muscle - this dialates vessels of the skeletal muscles so they can receive increased blood flow - during exercise (more blood, more oxygen, more fuel)

Question 32

Does Blood Pressure Increase during Aerobic Exercise

Answer 32

No - distribution of blood flow doesn’t not increase proportionally (to working muscles) - Dilation: vessels to skeletal muscle and heart increases blood flow to muscles - Constriction: vessels to the gut and kidneys decreases blood flow to these organ

Question 33

Does Blood Pressure increase during resistance exercise?

Answer 33

Yes - Holding your breath: increases intra thoracic pressure during the lift - Temporarily raises blood pressure and slows heart rate