Week 5 - Heart

Question 1

Define cardiac output

Answer 1

Volume of blood ejected from the heart per minute

Question 2

Cardiac Output calculation

Answer 2

Stroke Volume x Heart Rate

Average 70ml x 70bpm = ~4.9Lt

Question 3

Stroke volume equation

Answer 3

End Diastolic Volume - End Systolic Volume

On average 130 - 60 = 70ml

Question 4

Define diastole and EDV

Answer 4

Relaxation of the heart, ventricular filling.

End diastolic volume is ~130ml

Question 5

Define systole and ESV

Answer 5

Contraction of the heart

End systolic volume is ~60ml

Question 6

What does RBC transport around the body?

Answer 6

Lungs - O2, CO2
Liver - Bilirubin, Lactate
Kidneys - Urea
Other - Hormones, fatty acids, electrolytes, antibodies, WBCs, Cytokines

Question 7

Two branches of left main coronary artery

Answer 7

Left circumflex artery, left anterior descending artery

Question 8

Right and left atrial appendage

Answer 8

LAA and RAA serve as a reservoir for blood during cardiac cycle. Helps manage volume and pressure.

LAA is a common site for the formation of blood clots in patients with atrial fibrillation (Afib), a type of irregular heartbeat.

Question 9

What substance is needed before a muscle contracts?

Answer 9

Calcium

Question 10

First beat of the heart

Answer 10

S1 - mitrul and tricuspid valve closure for ventricular systole

S2 - semilunar valves closure

Question 11

Two categories of arrhythmia

Answer 11

Bradyarrhythmia and tachyarrhythmia

Question 12

Atrial fibrillation (AFib)

Answer 12

An irregular and often rapid heart rate

Question 13

Atrial flutter (AFL)

Answer 13

The atria beat regularly but too fast, which results in atrial muscle contractions that are faster and out of sync with lower chambers or ventricles, of the heart.

Question 14

Supraventricular tachcardia (SVT)

Answer 14

Rapid heartbeat caused by faulty electrical signals in the upper parts of heart.

Question 15

Ventricular tachycardia

Answer 15

Abnormal electrical impulse that begins in the ventricles and causes irregular fast heartbeat

Question 16

Ventricular fibrillation

Answer 16

Occurs when rapid and erratic electrical impulses cause the ventricles to quiver instead of pump blood properly.

Question 17

Long QT syndrome (LQT)

Answer 17

Causes uncoordinated heartbeats which can lead to sudden, uncontrollable and dangerous arrythmias.

Question 18

Bradycardia

Answer 18

Heart beats too slow

Question 19

Ectopic beats

Answer 19

Extra heart beats that can arise from atria or ventricles.

Question 20

Example of a reversible condition that might alter cardiac rhythm?

Answer 20

Emotions, exercise

Question 21

Example of an irreversible condition that might alter cardiac rhythm?

Answer 21

Myocardial infarction (MI) or heart attack

This happens when there is a blockage in the coronary arteries that supply the heart.

Question 22

Biological process of parasympathetic nervous system and heart rhythm

Answer 22

Acetylcholine (ACh) is released from Vagus Nerve affecting the SA and AV nodes.

ACh bind to muscarinic receptors on the cardiac pacemaker cells and conducting tissue.

Increase permeability to potassium ions (K+) and decrease in permeability of calcium ions (Ca2+). K+ leave cell, Ca2+ are blocked to enter.

Hyperpolarization occurs due to increased K+ leaving cell (makes cell more negatively charged). Decreased Ca2+ reduces rate of depolarization. Together they slow down the pace at which the SA node generates electrical impulses, thereby reducing the heart rate.

Parasympathetic also slows conduction through the AV node allowing for longer ventricular filling.

Question 23

Biological process of sympathetic nervous system and heart rhythm

Answer 23

Norepinephrine released by heart nerve fibres and epinephrine released by the adrenal medulla. Both catecholamines bind to Beta-agonist (B1) adrenergic receptors on cardiac cells.

This activates to G proteins which leads to activation of adenylate cyclase.

Adenalate cyclase catalyzes the conversion of ATP to cyclic AMP (cAMP), which acts as a second messenger within cells.

cAMP activates protein kinase A (PKA), which phosphorylates various proteins within the cell.

PKA phosphorylates calcium channels keeping them open.

PKA also enhances calcium release from sarcoplasmic reticulum, and accelerates reuptake of calcium into sarcoplasmic reticulum to get ready for next contraction.

This enhances the depolarization process which increases heart rate.

Question 24

Three factors that impact stroke volume

Answer 24

1. Preload
2. Contraction
3. Afterload

Question 25

Explain Preload

Answer 25

*Venous return
*hearts ability to stretch and fill
*Frank-Starling Mechanism = more you stretch heart, greater the contraction = more blood ejected

Question 26

Explain substance that can increase or decrease contraction and its agonists and antagonists

Answer 26

Ca2+

Antagonists increase Ca2+ = noradrenaline, thyroid hormone

Agonists decrease Ca2+ = Ca2+ blockers, electrolyte imbalances

Question 27

Explain afterload

Answer 27

Resistance the blood experiences as it leaves the ventricle

Plaques can decrease diameter of artery and increase resistance.

Question 28

Blood pressure calculation

Answer 28

CO x Systemic Vascular Resistance