Transport in Humans

Question 1

Main component of blood

Answer 1

Red blood cells, white blood cells, Platelets and Plasma

Question 2

Plasma

Answer 2

Carries excretory products such as urea to the excretory organs for removal and carries nutrients such as glucose, proteins and water to other parts of the body

Question 3

Red blood cells

Answer 3

To transport oxygen from the lungs to other parts of the body

Adaptation in Cell Structure and Organisation

Question 4

Types of White blood cells

Answer 4

Phagocytes and Lymphocytes

Question 5

Phagocytes

Answer 5

Phagocytes engulf and destroy pathogens such as bacteria

Question 6

Lymphocytes

Answer 6

Lymphocytes produce antibodies
Antibodies:
- Recognise and destroy pathogens
- They cause pathogens to clump together for easy ingestion for phagocytes
- They neutralise toxins produced by bacteria

Question 7

Platelets

Answer 7

Platelets contain an enzyme that helps convert fibrinogen into insoluble fibrin threads that entangle around the blood cells to form a clot

Importance of platelets:
- Prevent excessive loss of blood
- Prevent the entry of pathogens into the wound

Question 8

Why does tissue rejection occur

Answer 8

The immune system may recognise a donated organ or tissue as a foreign tissue and cause tissue rejection

Question 9

Types of blood groups

Answer 9

A, B, AB and O

Question 10

Antigens and Antibodies

Answer 10

Blood group = Antigen and opposite antibodies
Blood group A = Antigen A and Antibody B

Question 11

Agglutination

Answer 11

Agglutination occurs when a donor’s blood cell have antigens that react with the recipient’s antibodies in the plasma, causing clumping of blood

Question 12

Adaptation of Arteries

Answer 12

1. They have thick muscular and elastic wall to withstand the high blood pressure of blood flowing through them
2. The elasticity helps the artery wall to stretch and recoil

Question 13

Adaptation of Veins

Answer 13

1. Veins have valves to prevent backflow of blood as blood flows more slowly and smoothly than blood in the arteries
2. Veins have thinner walls that arteries

Question 14

Blood capillaries

Answer 14

To facilitate the exchange of substances between red blood and tissue cells in the body

Question 15

Features of blood capillaries to perform its function

Answer 15

1. The walls of capillaries are partially permemable and one cell thick
   - to keep a shorter diffusion distance, allowing for quicker diffusion of substances
2. Capillaries are tiny and numerously branched
   - To increase SATV for exchange of substances
   - Increase the total cross-sectional area of the blood vessels, to lower blood pressure and slow blood flow to give more time for the exchange of substances

Question 16

Tissue fluid

Answer 16

Transports dissolved substances between capillaries and tissue cells

Question 17

Importance of double circulation

Answer 17

1. To enable blood to be pumped around the body at higher speeds, thereby supplying more oxygen to cells
2. To enable blood to be pumped around the body at higher pressure thereby reaching all cells

Question 18

Atrium

Answer 18

The atrium have thin muscular walls
- They force blood to ventricles so they do not need high pressure

*They receive blood from other parts of the body

RA LA
RV LV

Question 19

Ventricles

Answer 19

Ventricles have thick muscular walls
- The LV pumps blood to the rest of the body while the RV pumps blood to the lungs

Question 20

Median septum

Answer 20

The median septum seperates the left and right side of the heart
- to prevent mixing of oxygenated and deoxygenated blood

Question 21

Importance of valves

Answer 21

Valves act as a one way door
- Blood is supposed to move from the atrium to the ventricle
- However when ventricular pressure exceeds the atrial pressure when the ventricles contract, blood tends to move from the ventricle back to the atrium (from an area of greater pressure to lower pressure)
- The valves in the heart are forced closed when the pressure in the ventricles exceen the pressure in the atrium, preventing blood from backflowing from ventricle to the atrium

Question 22

Ventricular systole

Answer 22

It is the contraction of ventricles

Question 23

Path of blood during systole (Left side of heart)

Answer 23

1. Systole is the contraction phase of the cardiac cycle
2. The left atrium contracts to cause pressure to increase above the left ventricle, causing the bicuspid valve opens, allowing blood to flow into the left ventricle.
3. The left ventricle contracts to cause pressure to increase above the aorta, causing the semi-lunar valve to open to allow blood to flow into the aorta and cause the bicuspid valve to close to prevent backflow of blood into the left atrium

Question 24

Ventricular diastole

Answer 24

It is the relaxation of ventricles

Question 25

Coronary arteries

Answer 25

Function:
- Bring nutrients and oxygen to the heart

Question 26

Coronary heart disease

Answer 26

It is caused by excess cholesterol that build up in deposits in between the linings of artery walls, causing blockage and disrupting the flow of blood

Question 27

Causes of coronary heart disease (atherosclerosis)

Answer 27

1. A cholosterol rich diet
2. Emotional stress
3. Smoking