Blood

Question 1

What are cells?

Answer 1

Cells are the building blocks from which humans and all other living things are made.

Question 2

What are tissues?

Answer 2

Tissues are a group of similar cells with a particular function.

Question 3

What is an organ?

Answer 3

An organ is a group of different tissues that work together. An organ has a particular function

Question 4

What is an organ system?

Answer 4

An organ system is a group of different organs that work together. Organ systems also have specific functions.

Question 5

What does the process of mitosis produce?

Answer 5

The process of mitosis produces daughter cells. These are genetically identical to one another and to their parent cell. However, most adult cells are differentiated

Question 6

What does blood contain and what are the components functions

Answer 6

• Red blood cells - they contain a red pigment called haemoglobin, but they do not have a nucleus.
• White blood cells - they do have a nucleus, they contain cytoplasm which allows them to access tissues so they can protect the body by attacking and destroying bacteria and viruses.
• Platelets - these are fragments of cells with no nucleus but they do contain proteins.
• Plasma - this is a straw coloured liquid that transports carbon dioxide, soluble food products and urea in solution. Plasma also circulates the heat released by the chemical reactions in body cells, this helps to maintain body temperature.

Question 7

What is the function of red blood cells?

Answer 7

The function of red blood cells is to transport oxygen from the lungs to respiring tissues.

Question 8

In the lungs, what do haemoglobin combine to?

Answer 8

In the lungs where oxygen concentration is high, haemoglobin combines with oxygen to form oxyhaemoglobin. Oxyhaemoglboin breaks down to release oxygen to respiring tissues where the concentration of oxygen is low.

Question 9

What do platelets do?

Answer 9

When platelets are damaged by a cut or torn tissue, they release a starts a chain of chemical reactions in the blood. These reactions end with the soluble plasma protein called fibrinogen changing into insoluble fibrin. Fibrin forms a mesh of fibres across the wound and traps red blood cells, forming a clot. The clot plugs the wound and stops bleeding. It also prevents bacteria and viruses from entering the body.

Question 10

Where is the heart?

Answer 10

The heart lies inside the chest cavity, protected by the rib cage. Much of the wall of the heart is made of cardiac muscle.

Question 11

What does the cardiac muscle do?

Answer 11

The cardiac muscle contracts and relaxes to pump blood through the circulatory system.

Question 12

What is the hearts four chambers?

Answer 12

• Two atria (singular atrium)

- Two ventricles

Question 13

What is the hearts four major blood vessels?

Answer 13

• Pulmonary artery
• Pulmonary vein
• Vena cava
• Aorta

Question 14

Why is the wall of the left ventricle thicker than the right ventricle?

Answer 14

The wall of the left ventricle is thicker than that of the right ventricle because it has to pump blood to all parts of the body. The right ventricle only pumps blood to the lungs, so less effort is required.

Question 15

What does the left atrium and ventricle do?

Answer 15

The left atrium and ventricle pump oxygenated blood from the lungs around the rest of the body.

Question 16

What does the right atrium and ventricle do?

Answer 16

The right atrium and ventricle pump deoxygenated blood to the lungs, where it can be oxygenated.

Question 17

What happens when the muscular walls of the heart relax and contract?

Answer 17

When the muscular walls of the heart relaxes, blood fills in the chambers. When the muscles contract, blood is forced from the chambers.

Question 18

What do the valves do?

Answer 18

The valves control the flow blood through the heart and into the arteries leading from the heart, preventing backflow.

Question 19

What is the circulatory system?

Answer 19

The circulatory system is a network of tube-like vessels called arteries and veins.

Question 20

How does the circulatory system work?

Answer 20

• The heart pumps blood through the arteries to body tissues.
• Blood drains from the tissue through the veins, back to the heart.
• Smaller vessels branch from arteries and veins. The smallest are called capillaries. They link arteries and veins.

Question 21

Why does the blood in the veins flow more slowly than blood in the arteries?

Answer 21

Blood in veins flows more slowly than blood in arteries because it is at lower pressure. The large diameter of a vein enables the blood to flow easily.

Question 22

What is the blood flow in veins help by?

Answer 22

Blood flow through the veins is helped by the contractions of the muscles in the arms and legs through which the veins pass.

Question 23

At what pressure does the heart pump blood into the arteries?

Answer 23

The heart pumps blood into arteries at high pressure, as the blood needs to reach the extremities of the blood.

Question 24

What do elastic fibres in the artery do?

Answer 24

Elastic fibres in the artery wall help maintain the flow of blood away from the heart and prevent backflow, so no valves are needed.

Question 25

What do capillaries form?

Answer 25

Capillaries form dense networks, called capillary beds, in the tissues of the body. They provide a large surface area for the efficient exchange of materials between the blood and tissues.

Question 26

What pressure is blood at, at the artery end of the capillary bed?

Answer 26

The blood is at a higher pressure at the artery end of the capillary bed. This higher pressure forces plasma through the thin capillary walls. The liquid, called tissue fluid, carries nutrients and oxygen to the surrounding cells.