Circulatory System

Question 1

What is another name for the circulatory system?

Answer 1

The circulatory system is also known as the cardiovascular system

Question 2

What is the main function of the circulatory system?

Answer 2

To transport oxygen, nutrients, hormones, and waste products (like carbon dioxide and urea) throughout the body.

Question 3

What are the three main components of the circulatory system?

Answer 3

1. Heart – pumps blood
2. Blood vessels – arteries, veins, capillaries
3. Blood – carries gases, nutrients, and waste

Question 4

What are the advantages of a double circulatory system?

Answer 4

Oxygenated and deoxygenated blood are kept separate
Maintains higher blood pressure
Efficient delivery of oxygen and nutrients to tissues
Increased metabolic support to active organs

Question 5

What are the two circuits of the double circulatory system?

Answer 5

Pulmonary circuit: Heart → Lungs → Heart
Systemic circuit: Heart → Body → Heart

Question 6

Describe the structure of arteries.

Answer 6

Thick muscular and elastic walls
Small lumen
High-pressure blood flow
Usually carry oxygenated blood away from the heart (except pulmonary artery)

Question 7

Describe the structure of veins.

Answer 7

Thinner walls with less muscle and elastic tissue
Larger lumen
Contain valves to prevent backflow
Carry deoxygenated blood towards the heart (except pulmonary vein)

Question 8

Describe the structure of capillaries.

Answer 8

Extremely thin walls (one cell thick)
Very narrow lumen
Site of exchange of gases, nutrients, and waste between blood and tissues

Question 9

What are the four major components of blood?

Answer 9

1. Plasma – fluid that transports hormones, nutrients, and waste
2. Red blood cells – carry oxygen (contain haemoglobin)
3. White blood cells – fight infection
4. Platelets – help with clotting

Question 10

List common substances found in blood.

Answer 10

Water, red/white blood cells, plasma proteins, antibodies, hormones, glucose, urea, drugs, toxins, pathogens.

Question 11

What is the function of red blood cells (erythrocytes)?

Answer 11

To carry oxygen from the lungs to body tissues using haemoglobin; they lack a nucleus for more space

Question 12

Name five types of white blood cells.

Answer 12

1. Lymphocytes
2. Basophils
3. Eosinophils
4. Monocytes
5. Neutrophils

Question 13

What is the function of platelets?

Answer 13

Platelets help form clots to stop bleeding by clustering at wounds and releasing clotting factors.

Question 14

What is the heart and what is its function?

Answer 14

The heart is a muscular organ that pumps blood throughout the body via rhythmic contractions.

Question 15

How many chambers does the heart have and what are they called?

Answer 15

Four chambers:
2 Atria (left and right) – receive blood
2 Ventricles (left and right) – pump blood out

Question 16

Why is the left ventricle wall thicker than the right?

Answer 16

Because it pumps blood to the entire body at high pressure, whereas the right ventricle only pumps to the lungs

Question 17

What is the function of valves in the heart?

Answer 17

To prevent backflow of blood and ensure one-way flow through the heart chambers

Question 18

Name the four main valves in the heart.

Answer 18

1. Tricuspid valve (right atrium → ventricle)
2. Bicuspid/Mitral valve (left atrium → ventricle)
3. Semilunar valve (pulmonary artery)
4. Semilunar valve (aorta)

Question 19

What are the names of the major blood vessels entering and leaving the heart?

Answer 19

Aorta – oxygenated blood to the body
Pulmonary artery – deoxygenated blood to lungs
Pulmonary vein – oxygenated blood from lungs
Vena cava (superior & inferior) – deoxygenated blood from body to heart

Question 20

What are tendinous cords and what do they do?

Answer 20

They are fibrous cords that prevent valve inversion during ventricular contraction.

Question 21

Describe the cardiac cycle.

Answer 21

Diastole: Relaxation; chambers fill with blood
Systole: Contraction; blood is pumped out of the heart

Question 22

What happens during left atrial systole?

Answer 22

Blood enters the left atrium from the pulmonary vein. Atrial contraction increases pressure, forcing the bicuspid valve open, allowing blood into the left ventricle.

Question 23

What happens during left ventricular systole?

Answer 23

The left ventricle contracts, closing the bicuspid valve and forcing blood into the aorta through the semilunar valve.

Question 24

What is the sinoatrial (SA) node and what does it do?

Answer 24

Known as the pacemaker, it generates electrical impulses that cause the atria to contract, setting the heart rate and rhythm.

Question 25

What is the function of the atrioventricular (AV) node?

Answer 25

It delays the electrical impulse from the SA node, allowing the atria to fully contract before the ventricles

Question 26

What is the Bundle of His and the Purkinje fibres?

Answer 26

Bundle of His: Conducts electrical impulses from AV node to base of ventricles. Purkinje fibres: Spread impulses through ventricular walls, causing contraction.

Question 27

What are baroreceptors and what do they do?

Answer 27

Baroreceptors are stretch receptors that detect blood pressure changes and send signals to the brain to adjust heart rate and vessel diameter

Question 28

What is the name of the vessel that brings oxygenated blood from the lungs to the heart?

Answer 28

Pulmonary vein

Question 29

What is the largest artery in the body and its function?

Answer 29

Aorta – transports oxygenated blood from the left ventricle to the rest of the body

Question 30

What are the superior and inferior vena cava?

Answer 30

Superior vena cava brings deoxygenated blood from the upper body. Inferior vena cava brings deoxygenated blood from the lower body.