Transport in humans

Question 1

Transport of materials in unicellular organisms

Answer 1

• unicellular organisms do not need a transport system for exchange or distribution of materials
• no part of cell is far from environment outside
• exchange of materials carried out easily thru diffusion

Question 2

Transport in multicellular organisms

Answer 2

• diffusion is inadequate of transport
• larger body, reduced SA:V
• cells located deeper in body, away from external environment
• transport system required

Question 3

What does blood contain?

Answer 3

• blood is a fluid tissue

- made up of plasma(55%), wbc, platelets, rbc

Question 4

Plasma

Answer 4

• 90% water, the following are dissolved and transported
• proteins eg. fibrinogen, prothrombin, antibodies
• mineral salts e.g. chlorides, sulfates of calcium, sodium
• food substances e.g. glucose, amino acids, fats
• waste products such as urea, uric acid, creatinine
• hormones e.g. insulin, glycogen

Question 5

Erythrocytes

Answer 5

• 99% cells in blood
• produced in bone marrow (ppl with leukemia need transplant)
• destroyed in spleen
• limited lifespan of 120 days (doesn’t have nucleus)

Question 6

Function of erythrocytes

Answer 6

-transport oxygen to cells in body

Question 7

Features of erythrocytes

Answer 7

• filled with red pigment called haemoglobin (essential for binding oxygen)
• absence of nucleus (more haemoglobin can be packed into cell)
• biconcave shape/enucleated, centre of cell thinner than edges (increase SA:V for efficient uptake of oxygen)
• elastic (enables cells to squeeze thru tiny capillaries)

Question 8

Leukocytes/ WBC

Answer 8

• larger than erythrocytes
• fewer
• produced in bone marrow
• destroyed in spleen

Question 9

Features of leukocytes

Answer 9

• limited lifespan of a few days although they have a nucleus (very highly involved in defense, nullify virus, pathogen, bacteria, toxin)
• colourless (no haemoglobin)
• irregular in shape (contain nucleus)
• mobile (they are able to move, change shape, squeeze thru walls of tiniest blood capillaries

Question 10

Types of leukocytes

Answer 10

• lymphocytes (highly specific)

- phagocytes (not specific)

Question 11

Lymphocytes

Answer 11

• large rounded nucleus
• small amt of non- granular cytoplasm
• produced specific antibodies against microorganisms

Question 12

Phagocytes

Answer 12

• lobed nucleus
• granular cytoplasm
• able to ingest foreign particles (like pacman)
• not specific

Question 13

Blood platelets/ Thrombocytes

Answer 13

• not true cells
• fragments of cytoplasm which are bound by membrane
• important for clotting blood

Question 14

Two things to check before operation

Answer 14

• haemoglobin level

- platelet count (need to heal fast)

Question 15

Antigens and antibodies

Answer 15

• plasma contains natural antibodies which recognize and bind to specific anitgens on the rbc
• rbc have proteins called antigens on their surfaces

Question 16

Blood type A

Answer 16

RBC: antigen A
Plasma: antibody b
Accept: A and O

Question 17

Blood type B

Answer 17

RBC: antigen B
Plasma: antibody a
Accept: B and O

Question 18

Blood type O

Answer 18

RBC: no antigens
Plasma: antibody a and b
Accept: O

Question 19

Blood type AB

Answer 19

RBC: antigens A and B
Plasma: no antibodies
Accept: all

Question 20

What happens if mix eg blood type A and B?

Answer 20

• antibody a in plasma of blood type B binds to antigen A in blood type A
• agglutination/clumping occurs
• antibodies act by binding

Question 21

Blood transfusion

Answer 21

• during blood transfusion, the effect of the recipient’s plasma on donor’s rbc is considered
• blood type O is the universal donor (no antigens so antibodies from recipient’s blood does not react with the rbc)
• blood type AB is the universal acceptor (no antibodies in plasma, no agglutination will occur)

Question 22

Functions of blood

Answer 22

• Transport (carry various substances from one part of body to another)
• Protective function (to protect body against disease-causing organisms)
• blood clotting or coagulation (prevent entry of bacteria into bloodstream or excessive blood loss)

Question 23

Transport function of blood

Answer 23

• blood acts as a transport medium carrying various substances
• digested food
• excretory products
• hormones
• heat
• oxygen

Question 24

Transport of oxygen to blood cells

Answer 24

• blood passes thru lungs, oxygen diffuses from alveoli and into blood
• haemoglobin binds with oxygen to form oxyhaemoglobin
• blood transports oxygen to all tissues in body
• at tissue cells, oxyhaemoglobin releases oxygen

Question 25

Acclimatization

Answer 25

- living in high altitudes, have increased no. of rbc - increases amt of haemoglobin in blood - more oxygen can be transported to body cells for aerobic respiration per unit time

Question 26

Protective function of blood

Answer 26

- blood clotting - phagocytosis - production of antibodies

Question 27

Clotting process

Answer 27

- blood clots when exposed to air - this seals wound prevents entry of bacteria and excessive blood loss - damaged platelets and tissues release the enzyme thrombokinase - converts prothrombin to thrombin - thrombin converts soluble fibrinogen to insoluble fibrin threads that entangles rbc to form blood clot

Question 28

Phagocytosis (pacman)

Answer 28

- process of engulfing and ingesting foreign particles e.g. bacteria by phagocytes (a type of wbc) - phagocytes engulf foreign particles e.g. bacteria - they are ingested and digested in the phagocyte

Question 29

Production of antibodies

Answer 29

- antibodies produced by lymphocytes (specific) - bind to bacteria surface membrane, cos it to rupture and unable to control flow of substances, die - bacterial cells clump together in presence of lymphocytes - toxins produced by bacteria is neutralized by antibodies

Question 30

Organ transplant and tissue rejection

Answer 30

- involves replacing damaged or diseased tissue or organ with healthy ones from same person or donor - recipient may produce antibodies to destroy the transplant - ways to reduce risk of tissue rejection include a tissue match and use of immunosuppressive drugs (forces system to accept and adapt)

Question 31

Transport system in humans

Answer 31

- also known as cardiovascular system as it is made up of heart and blood vessels - also known as circulatory system as it circulates blood arnd body

Question 32

At capillary bed

Answer 32

- arterial blood : oxygen and glucose | - venous blood: CO2, metabolic waste products (excretion is removal of CO2 or urea from body)

Question 33

Arteries

Answer 33

- transport oxygenated blood from heart to other organs - have thick, muscular walls to support blood coming from heart which is higher in pressure (prevent slowdown of bloodflow) - highly elastic (expansion when heart pumps) - muscle contracts and relaxes to cause constriction and dilation of artery respectively - constricts, narrower, less blood flow thru it per unit time - dilate, lumen wider, more blood flow thru it per unit time

Question 34

veins

Answer 34

- relatively thin walls, less elastic tissue - flow of blood is slower and bp lower compared to arteries - have valves to prevent backflow of blood and muscle contraction helps to get blood from extremities - valves are foldings of inner walls of veins

Question 35

Capillaries

Answer 35

- endothelium consists of a single layer of flattened cells, walls are partially permeable - capillary network (branch repeatedly) increase surface area and total cross sectional area for more efficient exchange of substances between blood and cells

Question 36

Tissue fluid

Answer 36

- colourless fluid found in tiny spaces between cells - useful materials e.g. oxygen and glucose move from blood in capillaries into tissue fluid and into cells via diffusion - waste products released by cells move into tissue fluid by diffusion, thru capillary walls, into blood, carried to excretory organs for removal

Question 37

Double circulation

Answer 37

- blood moves thru heart twice as it moves from pulmonary circulation to systemic circulation - blood enter pulmonary circulation at low pressure, sufficient time for blood to be fully oxygenated before returning to heart - blood is pumped into systemic circulation at high pressure, blood quickly distributed to all tissues in body

Question 38

Coronary heart disease

Answer 38

- atherosclerosis is the buildup of fatty substances on inner surfaces of coronary arteries - lumen of arteries narrowed, high pressure when blood tries to flow thru, might rupture, blood vessels damage, blood clot - blood clot formed in artery (thromobosis) - reduced blood flow to heart - heart muscle cells receive reduced oxygen and nutrient supply - region of heart muscle is damaged or dies, may lead to heart attack

Question 39

Causes of coronary heart disease

Answer 39

- high- fat diet rich in cholesterol and saturated animal fats - emotional stress - smoking - sedentary lifestyle (makes fat deposits stay on arterial walls)

Question 40

Preventive measures

Answer 40

- healthy diet (reduce intake of animal fats, replace with polyunsaturated plant fats which do not stick to inner surface of arterial wall, lower cholesterol level. more veg and fruits) - manage stress appropriately - avoid smoking as nicotine and carbon monoxide increase risk of coronary heart disease - exercise regularly (strengthens heart, maintains elasticity of arterial walls)