Topic 1A - THE CIRULATORY SYSTEM Flashcards
The structure of water
- Dipolar molecule
- slightly negative oxygen
- slightly positive hydrogen
- negatively charged oxygen atoms attract the positively charged
hydrogens of other water molecules - hydrogen bonding
How is water a good transport substance?
- Its a solvent = some substances dissolve in it
- Water is a solvent and liquid = easily transport all sorts of material
- dipole nature = makes water cohesive
- water molecules are cohesive = they tend to stick together so it
helps water flow
Why do multi cellular organisms need mass transport systems?
- diffusion across the outer membrane would be too slow
- due to the large distance the substances would have to travel
How does a mass transport system help multi cellular organisms?
- used to carry raw materials from specialised oragns to the rest of the body cells
- remove metabolic waste
The heart
Why does the left ventricle have thicker walls than the right?
Left ventricle has to be thick to pump blood around the whole body whereas right ventricle only has to pump blood to the lungs
The heart
what is the role of the AV valves?
- link atria to ventricles
- stop blood flowing back into the atria when the ventricle contracts
The heart
What is the role of the SV valves?
- link ventricles to the pulmonary artery + aorta
- stop blood flowing back into the heart when the ventricles contract
The heart
What is the role of valves?
Blood vessels
What is the structure + function of an artery?
- Arteries carry blood away from the heart to the rest of the body
- Thick walled + muscular
- Elastic tissue in the walls to cope with the high pressure
- Endothelium lining folded to allow the artery to expand
- small lumen
Blood vessels
Why do arteries have thick muscular walls?
- maintain blood pressure
- control blood flow
Blood vessels
why do arteries have small lumen?
Blood travels at a higher pressure so the small lumen can withstand the high pressure and maintain it
Blood vessels
What is the structure and function of a vein?
- Take blood back to the heart
- Little elastic fibres or muscles tissues as blood travels under low pressure
- Contain valves to stop back flow of blood
- Large lumen
Blood vessels
Why do veins have a large lumen?
- Blood travels at a lower pressure
Blood vessels
What is the structure + function capillary?
- Site where metabolic exchange occurs
- one cell thick
- networks of capillary in tissues allow for large surface area
Blood vessels
Why are capillaries one cell thick?
To allow for quick diffusion and short diffusion distance
