transport around the body

Question 1

water dipole nature and properties

Answer 1

• Shared electrons pulled closer to the oxygen atom than the hydrogen atoms;
• (this makes it) dipolar; oxygen (-) hydrogen(+)
• makes it a good solvent for other polar molecules;
• susbtances can be transported more easier when dissolved into water;
• Water is also cohesive (due to polar nature) ;
• this helps water to flow

Question 2

structure and properties of artery

Answer 2

Artery
Thick wall and small lumen
Away from the heart
Oxygenated*
High and in pulses (pulsatile)
Transport of blood to organs
Large amount of elastic tissue allows stretching due to surges in pressure and recoil afterwards; endothelium provides smooth inner surface to reduce resistance

Question 3

structure and properties of capillary

Answer 3

Capillary
Microscopic vessels, wall only once cell thick
Around cells of an organ
Oxygenated* then becomes deoxygenated
Pressure falls through capillary network
Formation of tissue fluid to allow exchange between blood and cells
Small size allows close contact with all cells In the body;
thin, permeable walls allow formation of tissue fluid for exchange

Question 4

structure and properties of vein

Answer 4

Vein
Thin wall; little muscle; larger lumen; valves
Away from an organ towards the heart
Deoxygenated*
Low and non-pulsatile
Transport of blood back to the heart
Large lumen of and thin wall offer least resistance to blood flow as blood is under low pressure; valves prevent backflow of blood

Question 5

less complex (single cell organisms not needing vessels)

Answer 5

Insects not needing blood vessels
• Larger surface area to volume ratio;
• Diffusion efficient;
• (because) cells are very close to blood/heart;
• idea of low metabolism ;
• idea that movement of blood back into the heart is fast enough (to return blood back into the heart) ;

Question 6

blood clotting

Answer 6

Reactions in blood clotting
• Thromboplastin is released (from the damaged blood vessel) ;
• Triggers conversion of prothrombin  thrombin (an enzyme) ;
• Thrombin catalyses reaction of fibrinogen to fibrin;
• Fibrin fibres form a mesh which traps blood platelets and RBCs