Circulatory System - Biology Double Award

Explain the composition of Red Blood Cells:

• RBCs have no nucleus so more haemoglobin can be packed in to the cell.

• Haemoglobin joins with O₂ in the lungs forming oxyhaemoglobin.

• They have a biconcave disk shape to increase the surface area to increase the speed of diffusion of oxygen into the cell

Explain the composition of White Blood Cells:

• WBCs defend the body against pathogens which are organisms capable of causing disease

• Phagocytes - Phagocytosis

• Lymphocytes - Makes antibodies

Describe the composition of Platelets:

• Fragments of cells involved in blood clotting and scab formation

• At a wound site, they get trapped and rupture to release thromboplastin

• Thromboplastin causes the conversion of soluble fibrinogen into insoluble fibrin which forms the clot

Describe the composition of Plasma:

This is the liquid component of blood consisting mainly of water with dissolved substances such as:

Glucose, amnio acids, fatty acids, glycerol, hormones (insulin and ADH)

Waste products such as CO₂ and urea and heat

Outline the functions of Blood:

1. To transport blood cells, platelets, nutrients, heat and waste products throughout the body. To collect and deliver O₂ to the cells of the body

2. The blood also has a role in defense against disease whereby the WBCs destroy pathogenic bacteria and viruses

3. Blood clotting - Platelets contain thromboplastin which triggers the blood clotting mechanism

4. To transport hormones from glands to target organs

See Image For Practice - Answer = Cat

Cat

What is the heart made of?

Cardiac muscle

What is double circulation?

Blood passes through the heart twice on each journey through the body. Once to be pumped to the lungs to collect O2 and again pumped around the body.

What -

1. Separates the heart

2. Pushes oxygenated blood out

3. Pushes deoxygenated blood out

4. Pulls deoxygenated blood in

5. Pulls oxygenated blood in

1. Septum

2. Aorta

3. Pulmonary artery

4. Vena cava

5. Pulmonary vein

List the valves used in -

1. Oxygenated blood

2. Deoxygenated blood

Oxygenated blood -

• Bicuspid valve - Separates the atrium from the ventricle

• Semi-lunar valves - Separates the ventricle from the Aorta

Deoxygenated blood -

• Tricuspid valve - Separates the atrium from the ventricle

• Semi-lunar valves - Separates the ventricle from the Pulmonary artery

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

It is thicker because the left side of the heart pumps blood all around the body whereas the right side only pumps blood to the lungs.

Explain the characteristics of Arteries:

• Very high blood pressure (close to heart)

• No valves

• Circular cross-section

• Thick elastic and muscular tissue - contains muscle to control pressure and elastic tissue for stretch and recoil

• Small lumen size

• Oxygenated except pulmonary

Explain characteristics of Vein:

• Low blood pressure (far from heart)

• Has valves (prevent backflow)

• Oblong cross-section

• Thin elastic and muscular tissue

• Large lumen size to reduce friction

• Deoxygenated (except pulmonary)

Explain characteristics of Capillary:

• Low blood pressure - greater SA of capillary wall and therefore increased friction

• No valves

• Circular cross-section

• No middle layer - inner wall is only a single layer of cells to allow for diffusion

• Tiny lumen size

• Oxygenated and deoxygenated blood

Explain the process of blood clotting:

1. Platelets get trapped in damaged fibres

2. Platelets rupture and released thromboplastin

3. Thromboplastin converts soluble fibrinogen into insoluble fibrin

4. Fibrin forms a mesh which traps RBCs

5. This allows the RBCs to form a clot

6. Scab eventually forms and seals the wound

Explain the effect of exercise on pulse rate:

1. During exercise, heart rate and therefore pulse rate increases

2. During exercise, there is an increase in muscle contraction and this requires energy

3. Energy is released by respiration and respiration uses oxygen and glucose

4. So heart rate increases to pump more blood to the muscles, increasing the amount of oxygen and glucose delivered to the cells for the extra respiration that is occurring

5. The breathing rate also increases to get more O2 into the blood and to remove extra CO2 produced as a result of increased respiration

6. Recovery rate is the time it takes for the pulse or heart rate to return to normal after exercise

Cardiac Output - The amount of blood pumped by the heart per minute

Explain the differences between these two people in the graph:

• The unfit person has a higher resting heart rate

• The rate at which the unfit persons heart rate goes up faster

• It takes longer for the unfit person to recover

• The unfit persons heart rate has a higher max