Transport in humans (revised)

Question 1

Main constituents of blood

Answer 1

• Plasma (55%)

- RBC, WBC, platelets (45%)

Question 2

Define plasma

Answer 2

• Pale yellowish liquid
• 90% water
• 10% various dissolved substances
• amt of soluble proteins, mineral salts and glucose relatively constant

Question 3

Dissolved substances in plasma

Answer 3

1. Soluble proteins e.g. fibrinogen, prothrombin, anitbodies
2. Dissolved mineral salts e.g. hydrogencarbonates, chlorides, sulfates
3. Food substances e.g. glucose, aa, fats, vitamins
4. Excretory products e.g. urea, uric acid, creatinine
5. Hormones e.g. insulin

Question 4

Erythrocytes (RBC)

Answer 4

• 500 mil/cm3 of blood
• contains pigment haemoglobin
• circular, flattened biconcave disc
• no nucleus
• elastic

Question 5

Haemoglobin (RBC)

Answer 5

• iron-containing protein
• combines reversibly with O2
• enables RBC to transport O2 frm lungs to all cells in body

Question 6

Shape of RBC

Answer 6

• biconcave, circular, flattened disc
• centre thinner than edge
• increase SA:V
• absorb and release O2 @ faster rate

Question 7

No nucleus (RBC)

Answer 7

• carry more haemoglobin, more O2

Question 8

Elastic (RBC)

Answer 8

• can turn bell-shaped

- squeeze thru blood vessels smaller that its diameter

Question 9

Where are RBC produced and destroyed

Answer 9

• bone marrow
• lifespan: 3-4 months
• wornout, destroyed in spleen
• haemoglobin brought to liver and broken down

Question 10

Leucocytes (WBC)

Answer 10

• larger than RBC, fewer
• WBC:RBC is 1:700
• 5000-10 000 WBC/cm3
• lymphocytes and phagocytes
• vital role in keep body healthy by fighting diseases

Question 11

Characteristics of WBC

Answer 11

• colourless, no haemoglobin
• irregular in shape, has nucleus
• can move, change shape, squeeze thru walls of tiny blood capillaries into spaces among tissue cells

Question 12

Lymphocytes

Answer 12

• large rounded nucleus
• small amt of non-granular cytoplasm
• limited movements
• produce antibodies, protect body from disease-causing microoganisms

Question 13

Production of antibodies (Lymphocytes)

Answer 13

• Pathogens like bacteria, viruses enter bloodstream
• stimulate lymphocytes to produce antibodies (chemical substances)
• attach to bacterial membranes and causing them to rupture (destroy)
• cause bacteria to agglutinate, easier for phagocytes to ingest
• neutralise toxins produced by bacteria

Question 14

Immunisation/vaccination

Answer 14

• stimulates body to produce antibodies against pathogens

- expose to dead/weakened forms of pathogen

Question 15

Phagocytes

Answer 15

• pacman
• ingest foreign particles
• lobed nucleus, granular cytoplasm

Question 16

Phagocytosis

Answer 16

• process of engulfing/ingesting foreign particles by WBC
• flowing over, enclosing them, digest
• some phagocytes die in process

Question 17

Clotting process

Answer 17

• damaged tissues and platelets produce thrombokinase (enzyme)
• thrombokinase neutralizes heparin
• thrombokinase activates prothrombin to become thrombin in presence on Ca+ ions
• Thrombin (enzyme) converts fibrinogen to insoluble fibrin
• insoluble firbin threads entangle and trap blood cells, form clot

Question 18

Heparin

Answer 18

• anti-clotting substance

- neutralised by thrombokinase

Question 19

Importance of clotting

Answer 19

• prevents excessive clotting of blood
• prevents foreign particles from entering bloodstream
• haemophilia: blood-clotting mechanism impaired

Question 20

Functions of blood

Answer 20

• Transport medium
• Protects body against disease-carrying organisms/pathogens
• blood clotting prevents excessive loss of blood and entry of pathogens into bloodstream

Question 21

How do human beings adapt at living at high altitudes (Acclimatisation)

Answer 21

• air pressure, conc of O2 in atmosphere lower
• cannot obtain sufficient O2 to maintain metabolic rate
• body produce more RBC to compensate for lower conc of O2

Question 22

Immune system

Answer 22

• includes WBC and their products

- causes immune response to foreign particles

Question 23

Agglutination

Answer 23

• surface of RBC contain antigens
• blood plasma contains natural antibodies
• antibodies doesn’t react to antigens on own RBC, might react with other RBC
• clumping of RBC

Question 24

Tissue rejection

Answer 24

• transplantation of organs

- recipient’s lymphocytes produce antibodies to destroy transplanted organ

Question 25

Prevention of tissue rejection

Answer 25

• Tissue match (genetically close as possible)
• e.g. family members
• use of immunosuppressive drugs, inhibit responses of recipient’s immune system
• -ve: lower resistance towards infection, take for rest of life