N5 -U2 (MO) - KA6 Transport systems in Amimals -Circulatory system.

Question 1

What does blood contain?

Answer 1

Red blood cells, white blood cells and plasma.

Question 2

What is the function of blood?

Answer 2

Nutrients (e.g. glucose and amino acids), oxygen and carbon dioxide are transported around the body in the blood.

Question 3

What is plasma?

Answer 3

Plasma is a watery yellow fluid that contained many dissolved substances such as glucose, amino acids and respiratory gases.

Question 4

Describe the function of red blood cells

Answer 4

RBC’s are very small and very numerous. (5 million in each mm3 of blood) . Red blood cells are very specialised cells that transport oxygen around the body.

Question 5

Describe the ways in which red blood cells are specialised to carry blood (clue - 4 main ways).

Answer 5

1. They contain large quantities of a protein called haemoglobin, which can bind oxygen.
2. RBC’s don’t have a nucleus, so there is more room for haemoglobin.
3. They have a biconcave disc shape, which maximises the surface area of the cell membrane for oxygen to diffuse across.
4. RBC’s are are tiny and flexible so can squeeze through the narrowest of blood capillaries to deliver oxygen.

Question 6

Describe the role of the red pigment haemoglobin in oxygen transport

Answer 6

**Haemoglobin binds with oxygen in body locations where the oxygen concentration is high (in the lungs) and forms oxyhaemoglobin.
****Blood with a high concentration of oxygen is described as oxygenated.
** Haemoglobin + oxygen —-> oxyhaemoglobin
This makes the blood a bright red colour.

Question 7

Haemoglobin + oxygen —-> oxyhaemoglobin

Why is this said to be a reversible reaction?

Answer 7

in locations where the oxygen concentration is low (body tissues) haemoglobin releases oxygen.
then….oxyhaemoglobin goes back to

Oxyhaemoglobin —–> haemoglobin + oxygen

Question 8

What happens to oxygen when it is released from oxyhaemoglobin?

Answer 8

The oxygen then diffuses into respiring cells. Blood that has a low oxygen concentration is a dark red colour and is described as deoxygenated.

Question 9

Describe the role of white blood cells in the body?

Answer 9

White blood cells are part of the immune system and are involved in destroying pathogens (disease-causing micro-organisms bacteria, viruses and fungi).

Question 10

What are the two main types of pathogen killing white blood cells?

Answer 10

Phagocytes and lymphocytes

Question 11

Describe the role of phagocytes

Answer 11

During infection, many phagocytes migrate to the infected area. They then carry out phagocytosis. Dead bacteria and phagocytes often accumulate at the site of infection, forming puss.

Question 12

What is phagocytosis?

Answer 12

In cell biology, phagocytosis (from Ancient Greek (phagein) , meaning ‘to devour’, (kytos) , meaning ‘cell’, and -osis, meaning ‘process’). So it is the process of cell eating. White blood cells act as phagocytes by engulfing pathogens (or other cells or other foreign particles). Once englulfed the phagocyte uses digestive enzymes to destroy for example a bacterium..

Question 13

What does the circulatory system consist of?

Answer 13

Heart, blood vessels, and blood.

Question 14

Can you draw a diagram of the heart?

Answer 14

you need to know heart structure,
it should, show left and right atria, ventricles, location of 4 valves, location of associated blood vessels (aorta, vena cava, pulmonary artery, pulmonary vein and coronary arteries).

Question 15

Why is the left ventricle wall thicker than the right?

Answer 15

It is required to pump blood all around the body, the wall of the right side is less thick since it only pumps blood to the lungs.

Question 16

What is the role of valves 1 and 2 (situated between the atria and the ventricles)?

Answer 16

When they are open they allow blood to pass from the atria into the ventricles. When the ventricles contract, the blood, under pressure, closes valve 1 and 2. This prevents blood flowing back into the atria.

Question 17

What is the role of valves 3 and 4 (situated between the ventricles and the two arteries that leave the heart)?

Answer 17

Once blood has been pumped through valves 3 and 4 they close, preventing backflow of blood from the arteries into the ventricles.

Question 18

Describe the structure and function of Arteries.

Answer 18

An artery is a vessel that carries blood away from the heart.
It has a thick muscular wall that is able to withstand the high pressure of oxygenated blood coming from the heart

Question 19

Describe the structure and function of a vein.

Answer 19

A vein is a vessel that carries blood towards the heart. Although muscular its wall is thinner than an artery since deoxygenat materials between the blood and living tissueed blood flows along a vein at low pressure. Compared with an artery the central cavity (lumen) is wider. This helps to reduce resistance to the flow of blood along the vein. Valves are present in veins to prevent backflow.

Question 20

Describe the structure and function of a capillary

Answer 20

Capillaries present a large surface ares and are in close contact with the living cells in tissues and organs.
All exchanges of materials between blood and living tissues take place efficiently through their thin cell walls (one cell thick).

Question 21

You should be able to describe the flow of blood through the heart. Can you draw a diagram to show this or describe it!

Answer 21

Deoxygenated blood coming from the body flows through the vena cava into the right atrium and down into the right ventricle where it is pumped to the lungs through the pulmonary artery. The blood is oxygenated in the lungs and flows back to the heart in the pulmonary vein, into the left atrium and down into the left ventricle where it is pushed up and out of the aorta to the body

Question 22

Describe the role of the coronary artery

Answer 22

The heart muscle cells are supplied with blood by the coronary arteries. These are the first arteries to branch off from the aorta.

Question 23

What happens if the the coronary artery gets blocked?

Answer 23

Blockage of the coronary arteries can deprive part of the heart muscle of oxygen, causing it to die. This is called a heart attack.