6 | Transport in Humans

Question 1

Role of blood?

Answer 1

• Transport substances
• Defence

Question 2

Components of blood?

Answer 2

RBCs
white blood cells
Plasma
Platelets (thrombocytes)

Question 3

Structural adaptation of RBCs?

Answer 3

• Circular and biconcave shape to increase SA2VR for faster diffusion of oxygen
• Contains haemoglobin for oxygen to bind reversibly to oxygen
• Has no nucleus to store more haemoglobin to transport more oxygen

Question 4

The function of RBCs?

Answer 4

Transport oxygen from the lungs to the rest of the body

Question 5

What are the different white blood cells?

Answer 5

See drawing in notes
Phagocytes
Lymphocytes

Question 6

Structural adaptations of phagocytes?

Answer 6

• Lobed nucleus to allow the cell to move towards the bacteria and change shape to engulf it
• Granular cytoplasm

Question 7

Function of phagocytes?

Answer 7

Engulf and ingest foreign particles (e.g. bacteria) through phagocytosis

Question 8

Function of lymphocytes?

Answer 8

Produce antibodies to protect the body from pathogens / agglutinate pathogens from phagocytes to engulf and ingest, and neutralise toxins

Question 9

Structural adaptations of lymphocytes?

Answer 9

• Large, rounded nucleus to produce antibodies
• Small amount of non-granular cytoplasm

Question 10

Function of plasma?

Answer 10

Transport dissolved substances to the rest of the body

Question 11

Structural adaptations of plasma?

Answer 11

• A pale yellowish liquid made up of 90% water, which is the solvent for various substances, and various dissolved substances
• Contains: other flashcard

Question 12

What does plasma contain?

5

Answer 12

(examples)
- Soluble proteins (antibodies, fibrinogen, prothrombin)
- Mineral salts (sodium + potassium)
- Nutrients (glucose, A.A, vitamins)
- Excretory / waste products (urea & CO2)
- Hormones (insulin, glucagon)

Question 13

Function of platelets (thrombocytes)?

Answer 13

Aid in blood clotting

Question 14

Structural adaptations of platelets (thrombocytes)?

Answer 14

• Not true cells
• Nucleus is absent

Question 15

Process of blood clotting?

5

Answer 15

• When blood vessels are damaged, damaged tissues and blood platelets release an enzyme, thrombokinase
• Thrombokinase converts the protein prothrombin in the blood plasma into thrombin in the presence of calcium ions
• Thrombin catalyses the conversion of soluble fibrinogen to insoluble fibrin threads in the presence of vitamin K
• Fibrin threads forms a mesh across the damaged surface and traps RBCs, forming a clot
• The clot prevents further blood loss, and also restricts the entry of pathogens into the blood

Question 16

Advantages of blood clotting

Answer 16

• Prevent excessive blood loss
• Prevent entry of microorganisms

Question 17

Disadvantages of blood clotting?

Answer 17

• Sign of tissue rejection
• Heart attack (coronary thrombosis)

Question 18

What is blood type determined by?

Answer 18

• Type of antigens on the cell surface membranes of RBCs
• Type of antibodies in the blood plasma

Question 19

What causes agglutination or clumping of RBCs

Answer 19

An immune response will occur where antibodies in the blood plasma of the recipient would react with the antigens of RBCs of donor, causing agglutination or clumping of RBCs.
- Clumps may block up small blood vessels and prevent the flow of blood, which is very dangerous.

Question 20

Which blood group is the universal donor?

Answer 20

Blood group O

Question 21

Which blood group is the universal acceptor?

Answer 21

Blood group AB

Question 22

Why is blood group O the universal donor?

Answer 22

There are no antigens on the donor’s RBCs and thus will not react with the recipient’s antibodies thus no agglutination will occur

Question 23

Why is blood group AB the universal acceptor?

Answer 23

There are no antibodies in the plasma of the recipient, thus will not react with the donor’s RBC antigens thus no agglutination will occur.

Question 24

Summary of blood groups

Answer 24

Notes

Question 25

What are the different types of blood vessels?

Answer 25

Artery Vein Capillary

Question 26

Function of artery?

Answer 26

- Transports blood away from the heart - Carries oxygenated blood (except pulmonary arteries)

Question 27

Structure and adaptation of artery

Answer 27

- Thick muscular walls to withstand high blood pressure - Elastic walls to stretch and recoil to maintain the high blood pressure

Question 28

Function of the vein?

Answer 28

- Transports blood towards the heart - Carries deoxygenated blood (except pulmonary veins)

Question 29

Structure and adaptation of vein?

Answer 29

- Thinner, less muscular, less elastic walls as blood pressure is much lower in veins. Blood flows smoothly and slowly - Presence of valves to prevent backflow of blood - Skeletal action (pinching of veins by skeletal muscles helps blood flow)

Question 30

Function of capillaries?

Answer 30

Site of exchange of substances (glucose, oxygen, AA, CO2, urea) between blood and the tissue cells

Question 31

Structure and adaptation of capillary?

Answer 31

- Wall is one cell thick made up of single layer of flattened cells (endothelial cells) to decrease the distance for diffusion and increases the rate of diffusion of substances - Partially permeable to allow only some substances to pass through - Extensive branching to form capillary network -- To increase SA2VR -- To increase rate of diffusion of substances - Slower rate of blood flow to provide time for exchange of substances

Question 32

What occurs in the capillaries?

Answer 32

notes

Question 33

What remains in the blood plasma in capillaries?

Answer 33

Plasma proteins, RBCs, platelets

Question 34

What diffuses out into the tissue fluid from the blood capillary?

Answer 34

Only small molecules like glucose, oxygen, A.A., urea, CO2, water, hormones and white blood cells can diffuse out into the tissue fluid from the blood capillary

Question 35

Blood flow?

Answer 35

Blood flows from the arterial end to the venous end due to higher blood pressure at the arterial end

Question 36

How does oxygen diffuse into tissue cells?

Answer 36

Oxygen diffuses down a concentration gradient from the RBC, into the plasma, across the one cell thick capillary walls, into tissue fluid and then into tissue cells

Question 37

Structure of heart

Answer 37

notes

Question 38

Function of vena cava?

Answer 38

Transport blood rich in CO2 (deoxygenated) from tissue cells in te body back to the heart

Question 39

Function of right atrium?

Answer 39

- Collects blood from the vena cava during r relaxation - Pushes blood into the right ventricle during contraction

Question 40

Function of tricuspid valve?

Answer 40

- Allows blood to flow only in one direction (right atrium --> right ventricle) - Snaps shut when muscles of the ventricle contract