Exchange and Transport Flashcards
How to measure ease of substance exchange
Surface area to volume ratio
How to work out surface area to volume ratio
Work out surface area
Work out volume
Put into ratio
Simplify
Why multicellular organisms need exchange surfaces
Have smaller surface areas to volume
More difficult to exchange enough substances to supply entire volume with outside surface alone
Factors of rate of diffusion
Distance
Concentration difference
Surface area
Alveoli exchange method
Deoxygenated blood from heart arrived (min O2, max CO2)
Due to high concentration differences, O2 gases diffuses from alveoli to blood and CO2 from blood to alveoli
Adaptations of alveoli
Moist lining for dissolving gases
Good blood supply to maintain concentration differences of gases
Very thin walls
Enormous surface area
Fick’s Law
rate of diffusion is proportional to surface area x concentration difference / thickness of membrane
Red blood cell adaptations and function
Carry oxygen to all cells in the body Biconcave disc structure to increase surface area No nucleus (more oxygen space) Haemoglobin used to carry blood to cells in body (oxyhaemoglobin breaks down and releases oxygen in cells)
Blood contents
Red blood cells
White blood cells
Platelets
Plasma
Phagocytes facts
White blood cells
Change shape to engulf unwelcome microorganisms (phagocytosis)
Lymphocytes facts
White blood cells
Produces antibodies against microorganisms
Can produce antitoxins to neutralise toxins made by microorganisms
White blood cell facts
Has nucleus (unlike red blood cell)
Fights against infections (immune system)
Multiplies rapidly when infection is present
Platelets facts
Small fragments of cells
Bundle up and clot at a wound to prevent microorganisms from entering blood stream
Plasma facts
Pale, straw-coloured liquid Carries lots of things e.g. : red and white blood cells platelets nutrients (glucose and amino acids) carbon dioxide urea hormones proteins antibodies and antitoxins
3 types of blood vessel
Capillaries (exchanges materials at tissues)
Arteries (carries blood away from the heart)
Veins (carried blood towards the heart)
Artery adaptations
Blood is pumped at high pressure so:
Walls are thick
Walls contain layers of muscle to make them strong and elastic fibres so they can stretch and spring back
Capillary adaptations
Exchange of materials at tissues so:
They are narrow so they can squeeze between cells (narrows distance of diffusion)
Permeable walls so diffusion can occur
Walls are one cell thick (less distance of diffusion)
Veins adaptations
Blood is at low pressure so:
Walls don’t have to be as thick as the arteries
Bigger lumen than arrives to help blood low despite lower pressure
Valves to prevent blood from flowing in the wrong direction
Double circulatory system meaning
2 circuits for full circulation Heart pumps deoxygenated blood to lungs Oxygenated blood returns to heart Heart pumps oxygenated blood to rest of body Deoxygenated blood returns to heart
Single circulatory system meaning
Only 1 circuit e.g. fish
Deoxygenated blood travels to heart right round body (but passes gills along the way)
How heart pumps blood
Right atrium receives deoxygenated blood from body (via vena cava)
Right ventricle pumps blood to lungs (via pulmonary artery)
Left atrium receives oxygenated blood from lungs (via pulmonary vein)
Left ventricle pumps blood to rest of body (via aorta)
Heart adaptations
Left ventricle’s wall is thicker than right as needs more muscle to pump blood at greater distance, needing higher pressure
Valves prevent backflow of blood
Septum prevented mixing of deoxygenated and oxygenated blood
Cardiac output formula
cardiac output (cm^3 min^-1) = heart rate (bpm) x stroke volume (cm^3)
Respiration facts
Process of transferring (releasing) energy from the break down of organic compounds (glucose) Exothermic reaction 2 types (aerobic and anaerobic)
