Lecture 4: How does the cardiovascular system work?

Question 1

What are the 2 circulations of the Cardiovascular system?

Answer 1

Systemic and pulmonary circulations

Question 2

Which organ does the pulmonary circulation supply?

Answer 2

Lungs

Question 3

Which organs does the systemic circulation supply?

Answer 3

All the organs, tissues and cells of the body.

Question 4

What is the mediastinum?

Answer 4

The midline space between the two lungs.

Question 5

Describe the heart’s location in the body. (3)

Answer 5

• Slightly left of the midline
• Deep to the body of the sternum
• Deep to the medial ends of costal cartilages 2 and 6.

Question 6

What is the pericardium?

Answer 6

A 3 layered bag located in the mediastinum that protects the heart.

Question 7

What are the three layers of the pericardium? (Outer to inner)

Answer 7

• Fibrous pericardium
• Parietal serous pericardium
• Visceral serous pericardium

Question 8

What are the positive functions of the fibrous pericardium? (2)

Answer 8

• Prevents overfilling of the heart.

- Prevents cardiac injury (For example from penetrating knife injuries.)

Question 9

What is haemopericardium?

Answer 9

When the pericardium fills with blood.

Question 10

What is cardiac tamponade?

Answer 10

When pressure of fluid surrounding the heart prevents it’s contraction.

Question 11

What is a negative feature of the fibrous pericardium?

Answer 11

If haemopericardium occurs, it causes cardiac tamponade.

Question 12

What are cardiac myocytes?

Answer 12

Spirals of cardiac tissue.

Question 13

Name and describe the three layers of tissue that make up the heart.

Answer 13

• Epicardium (Visceral serous pericardium)
• Myocardium (Makes up most of the heart wall, made up of cardiac myocytes).
• Endocardium (internal lining, continuous with the endothelium of connecting blood vessels)

Question 14

Name the three clinically important surfaces of the heart.

Answer 14

• Anterior (sternocostal) surface
• Base (posterior surface)
• Inferior (Diaphragmatic surface)

Question 15

Describe the process that pumps blood from the heart.

Answer 15

Cardiac myocytes contract (Think “wringing out”) in a coordinated fashion.

Question 16

What is the septum?

Answer 16

The internal wall of the heart that separates it into a left and right section.

Question 17

Describe the function of the right side of the heart.

Answer 17

Pumps deoxygenated blood from the systemic circulation into the pulmonary circulation.

Question 18

Describe the function of the left side of the heart.

Answer 18

Pumps oxygenated blood from the pulmonary circulation into the systemic circulation.

Question 19

Describe the blood flow through the heart naming the vessels and structures is passes through. (Start with vena cava) (8)

Answer 19

• Vena cava
• Right atrium
• Right ventricle
• Pulmonary trunk and pulmonary arteries
• Lungs
• Pulmonary veins
• Left atrium
• Left ventricle

Question 20

Name the valve between the Right atrium and ventricle.

Answer 20

Tricuspid valve

Question 21

Name the valve between the right ventricle and the pulmonary trunk.

Answer 21

Pulmonary valve

Question 22

Name the valve between the left atrium and ventricle.

Answer 22

Bicuspid (Mitral) valve

Question 23

Name the valve between the left ventricle and the aorta.

Answer 23

Aortic valve

Question 24

What is the function of the heart valves?

Answer 24

They ensure unidirectional flow of blood.

Question 25

Where does conduction in the heart start, and where is this position anatomically?

Answer 25

At the Sinoatrial Node (SAN), located on the superior wall of the right atrium.

Question 26

What is the interatrial septum?

Answer 26

The wall that separates the left and right atria.

Question 27

Describe the route of impulses from the atria to the ventricles.

Answer 27

- Sinoatrial node - Atrioventricular node - Atrioventricular bundle

Question 28

What is the function of the cardiac skeleton?

Answer 28

It restricts the spread of the cardiac impulses by acting as an insulator.

Question 29

Describe the parts of the cardiac skeleton. (7)

Answer 29

- Fibrous ring of pulmonary valve. - Fibrous ring of aortic valve - Crux of the heart (Junction of all 4 chambers) - Fibrous ring of tricuspid valve - Fibrous ring of mitral valve - Fibrous parts of interatrial septum - Fibrous parts of interventricular septum

Question 30

What is fibrillation?

Answer 30

An uncoordinated contraction of the cardiac myocytes that results in ineffective pumping of blood.

Question 31

What is the cardiac plexus?

Answer 31

The mixture of nerves that supply the heart.

Question 32

Describe the action of the sympathetic nerves on the heart. (2)

Answer 32

- Increase heart rate | - Increase force of contraction

Question 33

Describe the action of the parasympathetic nerves on the heart. (1)

Answer 33

Decrease heart rate