Human Transport System

Question 1

What are the components of blood?

Answer 1

Red blood cells
White blood cells
Platelets
Plasma

Question 2

What are Red blood cells ?

Answer 2

Biconcave discs containing no nucleus but plenty of protein called haemoglobin.
The majority of the other half of the blood contains red blood cells

Question 3

What are White blood cells?

Answer 3

Large cells containing a big nucleus, different types have slightly different structures and functions.
The remaining fraction of the blood consists of white blood cells

Question 4

What are Platelets?

Answer 4

Fragments of cells

The remaining fraction of the blood contains platelets

Question 5

What is Plasma?

Answer 5

Straw coloured liquid

Over half of the volume of the blood is made up of plasma

Question 6

What do red blood cells do?

Answer 6

Red blood cells are specialized cells which carry oxygen to respiring cells.

Question 7

How are red blood cells adapted to their function?

Answer 7

They are full of haemoglobin, a protein that binds with oxygen to form oxyhaemoglobin.
They have no nucleus which creates more room inside the cell to pack in oxygen molecules
The shape of a red blood cell is described as being ‘biconcave disk’ this shape gives them a large surface area to volume ratio to maximise diffusion of oxygen in and out.

Question 8

What does plasma transport?

Answer 8

Carbon dioxide – dissolved in the plasma as hydrogencarbonate ions and transported from respiring cells to the lungs
Digested food and mineral ions – dissolved particles absorbed from the small intestine and delivered to requiring cells around the body
Urea – Urea is dissolved in the plasma and transported to the kidneys
Hormones – chemical messengers released into the blood from the endocrine organs (glands) and delivered to target tissues/organs of the body
Heat energy – created in respiration, heat energy is transferred to cooler parts of the body or to the skin where heat can be lost

Question 9

Actions of white blood cells

Answer 9

They can destroy pathogens in two ways:

Phagocytosis - the WBC phagocyte eats the pathogen alive by engulfing the pathogen and digesting the organism using digestive enzymes found in the phagocyte.

Anti-body production - antibodies are released and they have a complementary shape to the pathogen, they then bind to the pathogen, rendering it harmless.

Question 10

What does vaccination do?

Answer 10

Vaccination stimulates the production of antibodies against a particular pathogen. Usually a dead or weakened form of the pathogen is used, which is sufficient to stimulate antibody production without the person becoming ill.

Question 11

How does vaccination work?

Answer 11

During activation of the immune response, memory cells are generated. These are a type of antibody-producing white blood cell which will ‘remember’ the pathogen if re-infection occurs. If the same pathogen is detected in the body, the memory cells already have the appropriate antibodies ready to enable a quick, effective immune response.

Question 12

What does a platelet do?

Answer 12

Platelet helps clot the blood.

Question 13

How does a platelet clot the blood?

Answer 13

When there is a wound, the platelet arrive to stop the bleeding. A series of reaction occur within the plasma. Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot.
The clot eventually dries and develops into a scab to protect the wound from bacteria entering

Question 14

What’s the importance of blood clotting?

Answer 14

Blood clotting prevents continued blood loss from wounds.
Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection.
It remains in place until new skin has grown underneath it, sealing the skin again.

Question 15

Oxygenated blood

Answer 15

Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit).

The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body,

Question 16

Deoxygenated blood

Answer 16

Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs (the pulmonary circuit).
The right ventricle is pumping blood at lower pressure to the lungs

Question 17

What is the septum?

Answer 17

A muscle wall that separates the two sides of the heart

Question 18

Where is the blood pumped

Answer 18

Blood is pumped towards the heart in veins and away from the heart in arteries

Question 19

What’s the purpose of valves?

Answer 19

To prevent the back flow of blood

Question 20

The pathway of blood through the heart

Answer 20

• Deoxygenated blood coming from the body flows through the vena cava and into the right atrium
• The atrium contracts and the blood is forced through the tricuspid (atrioventricular) valve into the right ventricle
• The ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery
• The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place
  
  • Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs
• Oxygenated blood returns via the pulmonary vein to the left atrium
• The atrium contracts and forces the blood through the bicuspid (atrioventricular) valve into the left ventricle
• The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta
• Thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body

Question 21

Causes of coronary heart disease

Answer 21

Layers of fatty material (plaque) build up inside the coronary arteries.
These fatty deposits are mainly formed from cholesterol

Question 22

Effect of CHD

Answer 22

If a coronary artery becomes partially or completely blocked by these fatty deposits, it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts.

The flow of blood through the arteries is reduced, resulting in a lack of oxygen for the heart muscle

Question 23

Partial blockage

Answer 23

the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina

Question 24

Complete blockage

Answer 24

means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack

Question 25

Risk factors of coronary heart disease

Answer 25

Obesity
High blood pressure
High cholesterol
Smoking

Question 26

Obesity

Answer 26

Carrying extra weight puts a strain on the heart.

Increased weight can lead to diabetes which further damages your blood vessels

Question 27

High blood pressure

Answer 27

This increases the force of the blood against the artery walls and consequently leads to damage of the vessels

Question 28

High cholesterol

Answer 28

Speeds up the build up of fatty plaques in the arteries leading to blockages

Question 29

Smoking

Answer 29

Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure.

Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells

Question 30

Blood vessels

Answer 30

Artries
Veins
Capillaries

Question 31

Features of an artery

Answer 31

Carry blood at high pressure away from the heart.
Carry oxygenated blood (except the pulmonary artery).
Have thick muscular walls containing elastic fibres.
Have a narrow lumen.
Blood flows through at a fast speed.

Question 32

How is the artery adapted to its function?

Answer 32

Thick muscular walls containing elastic fibres withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through.

A narrow lumen also helps to maintain high pressure

Question 33

Features of the vein

Answer 33

Carry blood at low pressure towards the heart.
Carry deoxygenated blood (other than the pulmonary vein).
Have thin walls.
Have a large lumen.
Contain valves.
Blood flows through at a slow speed.

Question 34

How is the vein adapted to its function?

Answer 34

A large lumen reduces resistance to blood flow under low pressure.

Valves prevent the backflow of blood as it is under low pressure.

Question 35

Features of the Capillaries

Answer 35

Carry blood at low pressure within tissues
Carry both oxygenated and deoxygenated blood
Have walls that are one cell thick
Have ‘leaky’ walls
Speed of blood flow is slow

Question 36

How is the capillary adapted to its function?

Answer 36

Capillaries have walls that are one cell thick (short diffusion distance) so substances can easily diffuse in and out of them.

The ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells.

Question 37

What is the circulatory system?

Answer 37

The circulatory system consists of a closed network of blood vessels connected to the heart.

Question 38

What happens in the circulatory system?

Answer 38

Oxygenated blood is carried away from the heart and towards organs in arteries.
These narrow to arterioles and then capillaries as they pass through the organ.
In the organs, respiring cells use up the oxygen from the blood.
The capillaries widen to venules and finally veins as they move away from the organs.
Veins carry deoxygenated blood back towards the heart.