The Blood System (6.2)

Question 1

What is blood made up of?

Answer 1

Plasma - water, proteins, nutrients
Red blood cells (erythrocytes)
White blood cells (leukocytes)
Platelets

Question 2

What is the function of the blood?

Answer 2

1) Transport
Red blood cells transport oxygen, plasma transports nutrients and heat is transported to the skin where it is lost to the environment.

2) Defense against infectious diseases
White blood cells defend the body against infectious diseases and platelets for blood clotting.

Question 3

What was the understanding of the circulatory system prior to William Harvey’s findings?

Answer 3

• Arteries and veins were separate blood networks
• Heart warmed the blood
• Natural blood was produced by the liver

Question 4

Give William Harvey’s findings

Answer 4

• Arteries and veins were part of a single connected blood network (he did not predict the existence of capillaries however)
• Arteries pumped blood from the heart (to the lungs and body tissues)
• Veins returned blood to the heart (from the lungs and body tissues)

Question 5

What are the three types of blood vessels?

Answer 5

Arteries
Veins
Capillaries

Question 6

What is the function of the arteries? + specialised structure

Answer 6

To carry blood at high pressure from the heart ventricles to the body tissues/lungs. (Note: can be oxygenated or deoxygenated blood)

Thick walls and a narrow lumen because they transport blood at high pressure.

Question 7

What is the function of veins? + specialised structure

Answer 7

To collect deoxygenated blood from body tissues and transport it at a low pressure to the atria of the heart.

Thin walls with wide lumens because they transport blood at low pressure. Veins also have valves to prevent the backward flow of blood.

Question 8

What is the function of capillaries? + specialised structure

Answer 8

The function of the capillaries is to exchange materials between the cells in the tissues and blood travelling at low pressure. They connect the arteries and veins.

Thin walls that are only a single cell thick because they exchange materials between blood and tissue (short diffusion distance). Narrow lumen for larger SA.

Question 9

What type of pump is the heart?

Answer 9

The heart is a double pump. The right side of the heart pumps deoxygenated blood to the lungs (pulmonary circulation) and the left side of the heart pumps oxygenated blood around the body (systemic circulation).

Question 10

What are the chambers in the heart?

Answer 10

There are two atria near the top of the heart (the smaller chambers) that collect blood from the veins.

There are two ventricles near the bottom of the heart (the larger chambers) that pump blood into the arteries at high pressure.

Question 11

What are the valves in the heart?

Answer 11

The atrioventricular values are between the atria and the ventricles. On the left is the bicuspid valve and on the right is the tricuspid valve. (Remember you can spell tri in the word right)

The semilunar valves are between the ventricles and the arteries. On the left is the aortic valve and on the right is the pulmonary valve.

Question 12

What are the arteries in the heart?

Answer 12

The pulmonary artery connects to the right ventricle and sends deoxygenated blood to the lungs.

The aorta connects to the left atrium and sends oxygenated blood around the body.

Question 13

What are the veins in the heart?

Answer 13

Vena cava (inferior - bottom and superior - top) connects to the right atrium and returns deoxygenated, low pressure blood from the body.

The pulmonary vein connects to the left atrium and returns oxygenated blood from the lungs.

Question 14

Why is the left ventricle wall thicker than the right?

Answer 14

The left ventricle has to generate enough pressure to move blood throughout the entire body, whereas the right only has to generate enough pressure to move blood to the lungs.

Question 15

Why are the atria walls thinner than the ventricle walls?

Answer 15

Because blood is pumped out of the ventricles at a greater pressure compared to the atria.

Question 16

What is the purpose of the valves?

Answer 16

To prevent the backflow of blood.

Question 17

Discuss the cardiac cycle

Answer 17

The series of events that take place in the heart over a singular heart beat. There is a period of contraction (systole) and relaxation (distole).

Question 18

What happens in systole and distole?

Answer 18

In systole, the heart muscles contract and blood is squeezed out of the heart into the arteries. This occurs at a high blood pressure.

In distole, the heart muscles relax and blood from the veins fills the atria and ventricles. This occurs at a low blood pressure.

Question 19

What are coronary arteries?

Answer 19

The blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working. They branch off of the aorta.

Question 20

Define coronary occlusion

Answer 20

The partial or complete obstruction of blood flow in a coronary artery.

Question 21

What is the cause, consequences and treatment of coronary occlusion?

Answer 21

Atherosclerosis - the hardening and narrowing of the arteries due to the deposition of cholesterol.

If this occurs in the coronary arteries it is called coronary heart disease. When a coronary artery is completely blocked a heart attack will occur.

Treatment is typically by-pass surgery or creating a stent.

Question 22

Risk factors for coronary heart disease (Hint: Mnemonic)

Answer 22

Age
Genetics
Obesity
Disease
Diet
Exercise
Sex
Smoking

Question 23

What controls the heartbeat?

Answer 23

The pacemaker nerve (SAN) are a cluster of cardiomyocytes in the wall of the right atrium that controls the heart beat.

When the pacemaker nerve sends out a signal, the atria contract. Once the atria contract, the VAN nerves are stimulated and cause the ventricles to contract.

Question 24

What is the accelerator (sympathetic) nerve?

Answer 24

The accelerator nerve carries messages from the brain to the pacemaker to speed up the beating of the heart.

Question 25

What is the decelerator (parasympathetic) nerve?

Answer 25

The decelerator nerve carries messages from the brain to the pacemaker to slow down the beating of the heart.

Question 26

What hormone is released when there is danger?

Answer 26

If there is danger then adrenaline is released from the adrenal gland and carried to the pacemaker via the bloodstream, telling it to speed up the beating of the heart for fight or flight.