The Heart

Question 1

What is the function of the cardiovascular system?

Answer 1

Pumps blood around the body which:

• delivers substances essential to cells for body homeostasis.
• Removes waste products from cells to designated areas.
• Functions as part of the immune system.

Question 2

What type of system is the cardiovascular system?

Answer 2

Closed system.

Question 3

In what cavity is the heart located?

Answer 3

Thoracic cavity.

Question 4

What does the pulmonary circulation include?

Answer 4

Blood travels from the heart to the lungs and is oxygenated, then travels back to the heart to be pumped to the head to provide oxygen to the brain. Then deoxygenated blood travels back to the heart to be pumped to the lungs to be oxygenated again.

Question 5

What does the systemic circulation include?

Answer 5

Oxygenated blood from the lungs travels to the heart to be pumped to the rest of the body where it offloads the oxygen.

Question 6

Describe the order that blood travels through the heart:

Answer 6

• Blood flows into the heart through the superior/inferior vena cava and into the right atrium.
• The blood then flows from the right atrium into the right ventricle through the tricuspid valve.
• Blood then travel from the right ventricle to the pulmonary artery through the pulmonary valve, where it is then pumped to the lungs.
• From the lungs, oxygenated blood enters through the pulmonary veins into the left atrium.
• Blood travels from the left atrium into the left ventricle through the mitral valve.
• Blood then moves from the left ventricle to the aorta through the aortic valve.
• From the aorta, oxygenated blood travels to the rest of the body.

Question 7

What are the layers of the Heart Wall?

Answer 7

• Pericardium
• Myocardium
• Endocardium

Question 8

Describe the pericardium:

Answer 8

Outermost layer
Double walled sac enclosing the heart
2 layers = fibrous pericardium and serous pericardium
Serous pericardium is divided into parietal and visceral.
Pericardial cavity filled with pericardial fluid

Question 9

Describe the myocardium:

Answer 9

Middle muscle layer

Specialised heart muscle - striated and branching, ends join to contract as a unit.

Question 10

Describe the endocardium:

Answer 10

Smooth innermost lining
Attached to the myocardium
Lines the heart chambers and valves
Enables friction free flow

Question 11

Describe the atria:

Answer 11

Receive blood
Thin walled
Blood moves into ventricles

Question 12

Describe the ventricles:

Answer 12

Discharge blood
Thick walled
Left side has more muscle as blood travels to the whole body

Question 13

Left Side Heart Valves:

Answer 13

Mitral (bicuspid) valve between left atrium and left ventricle.
Aortic valve between the left ventricle and aorta.

Question 14

Right Side Heart Valves:

Answer 14

Tricuspid valve between the right atrium and right ventricle.
Pulmonary valve between the right ventricle and pulmonary artery.

Question 15

Describe coronary blood flow:

Answer 15

Coronary arteries from the aorta carry oxygenated blood and deoxygenated blood is returned via coronary sinus to the right atrium

Question 16

Describe the sequence of cardiac conduction:

Answer 16

The action potentials generated by the SAN spread through the atria walls causing the atrium to contract and blood to be pushed through the tricuspid and mitral valve into the ventricles. This causes a slight delay before the action potentials are passed to the AVN which is carried down the bundle of His (septum) and through the Purkinje fibres, causing the ventricles to contract and blood to be pushed through the pulmonary and aortic valve.

Question 17

What letters represent an electrocardiogram?

Answer 17

P, Q, R, S and T.

Question 18

What does the P wave represent in an electrocardiogram?

Answer 18

Atrial Systole (contraction) = depolarisation as it passes across the atria from the SAN.

Question 19

What does the QRS complex represent in an electrocardiogram?

Answer 19

Ventricular Systole (contraction) = depolarisation passing through the bundle of His and Purkinje fibres from the AVN.

Question 20

What does the T wave represent in an electrocardiogram?

Answer 20

Ventricular Diastole (relaxation) = repolarisation of ventricles

Question 21

What is heart rate?

Answer 21

The number of heart beats per minute (bpm).

Question 22

What structure sets the heart rate?

Answer 22

Sino Atrial Node

Question 23

What does a pulse tell us about heart rate?

Answer 23

Strength of the contraction and regularity.

Question 24

What is the formula for cardiac output?

Answer 24

Cardiac Output = Stroke Volume x Heart Rate

Question 25

What is Stroke Volume?

Answer 25

Amount of blood ejected from each ventricle (70mls = average adult)