Chapter 7- Circultory System

Question 1

What are the functions of the circulatory system?

Answer 1

• transports oxygen and nutrients to cells
• transports carbon dioxide and other wastes away from the cells
• transports hormones to the cells
• maintains the pH of body fluids
• distributes heat and maintains body temperature
• maintains water content and ion concentration in body fluids
• protects against disease-causing micro-organisms
• clots when vessels are damaged

Question 2

What are the components of the circulatory system?

Answer 2

• heart
• blood
• blood vessels

Question 3

What is diastole?

Answer 3

The phase when the heart muscle is relaxed during the cardiac cycle.

Question 4

What is systole?

Answer 4

The phase of the cardiac cycle in which contraction of the atrium and/of ventricles occurs.

Question 5

What is an artery?

Answer 5

A blood vessel that carries blood away from the heart.

Question 6

What is a vein?

Answer 6

A blood vessel that carries blood from body tissue to the heart.

Question 7

What is the double circulation system?

Answer 7

The circulation system in which blood flows from the heart to the lungs and back to the heart (pulmonary circulation), then from the heart to the other body tissues and back to the heart (systemic circulation).

Question 8

What are the features of an artery?

Answer 8

Thick wall, small lumen diameter, no valves and very elastic.

Question 9

What are the feature of a vein?

Answer 9

Thin walls, large lumen diameter, valves prevent back flow, less elastic.

Question 10

Where does blood become deoxygenated?

Answer 10

Near the body cells and organs.

Question 11

Where does blood become oxygenated?

Answer 11

The alveoli of the lungs.

Question 12

Which artery carries deoxygenated blood?

Answer 12

Pulmonary artery.

Question 13

Which vein carries oxygenated blood?

Answer 13

Pulmonary vein.

Question 14

What is blood made of?

Answer 14

55% plasma

45% cells + cell fragments

Question 15

What are the functions of blood?

Answer 15

• delivers oxygen from lungs to cells
• delivers nutrients to cells
• transports hormones from endocrine glands to target tissue
• distributes heat evenly
• carries antibodies and white blood cells which provide protection

Question 16

What is pulmonary circulation?

Answer 16

When blood flows from the heart, to the lungs and back to the heart.

Question 17

What is systemic circulation?

Answer 17

When blood flows from the heart, to the body cells and back to the heart.

Question 18

What percent of oxygen is carried in the plasma?

Answer 18

3%

Question 19

What molecule does oxygen combine with in the blood? What molecule does this create?

Answer 19

Oxygen combines with haemoglobin to create oxyhemoglobin.

Question 20

What are the different ways that carbon dioxide is transported in the blood?

Answer 20

8% dissolved in plasma
22% as carbaminohaemoglobin
70% as bicarbonate ions

Question 21

How does carbon dioxide form bicarbonate ions?

Answer 21

The carbon dioxide reacts with water to form carbonic acid (H2CO3). The carbonic acid then disassociates into hydrogen and carbonate ions.

Question 22

What are red blood cells known as?

Answer 22

Erythrocytes

Question 23

What are white blood cells known as?

Answer 23

Leucocytes

Question 24

What are platelets known as?

Answer 24

Thrombocytes

Question 25

What encloses the heart?

Answer 25

The pericardium

Question 26

How can blood flow to an organ be increased?

Answer 26

• increase in heart rate

- vasodialation

Question 27

What is vasodilation?

Answer 27

The relaxing of the artery wall muscles which increases the diameter of the artery.

Question 28

What is vasoconstriction?

Answer 28

The contraction of the artery wall muscles which decreases the diameter of the artery.

Question 29

How long are the atria in systole for?

Answer 29

0.1 sec

Question 30

How long are the atria in diastole for?

Answer 30

0.7 sec

Question 31

How long are the ventricles in diastole for?

Answer 31

0.5 sec

Question 32

How long are the ventricles in systole for?

Answer 32

0.3 sec

Question 33

Where is blood flow the slowest?

Answer 33

The capillaries

Question 34

What is blood flow in the capillaries the slowest?

Answer 34

As it allows time for diffusion to occur.

Question 35

What is the function of erythrocytes?

Answer 35

Oxygen combines with haemoglobin of the surface so that it can be transported around the body via the blood vessels.

Question 36

What is the function of leucocytes?

Answer 36

Destroys/removes dead cells and invading micro-organisms.

Question 37

What is the function of thrombocytes?

Answer 37

Necessary for blood clotting.

Question 38

What is the function of plasma proteins?

Answer 38

Acts as an immune response.

Question 39

What occurs when simple injury to blood vessels is caused?

Answer 39

1. the walls of the blood vessels constrict which reduces the blood flow
2. the platelets stock to the rough surface caused by the injury
3. other platelets are attracted to the site and a plug is formed
4. the plug helps reduce blood flow
5. platelets release vasoconstrictors

Question 40

What occurs when there is serious injury to blood vessels?

Answer 40

Blot clotting or coagulation

Question 41

What are the steps of coagulation?

Answer 41

1. there are a number of clotting actors present in the plasma
2. a complex series of reactions results in the formation of threads of an insolvable protein called fibrin
3. the fibrin threads form a mesh (clot) that traps blood cells, platelets and plasma
4. The threads stick to the damaged blood vessel to hold the clot in position
5. clot retraction occurs: network or threads contract, become closer, denser and stronger
6. the edges of the damaged blood vessel are pulled together
7. serum is squeezed out and the clot dries to form a scab to prevent entry of infection micro-organisms