The circulatory system

1B

Reasons why small organisms can rely on diffusion

• Short diffusion distances

• Large Surface area to volume ratio

• Low metabolic demands

Reasons for the need for transport systems in larger organisms

• Cell requirements for respiration and other cell functions

• Waste product removal system

What are the circulation systems in mammals and birds

Systemic circulation and pulmonary circulation

System of nutrient transfer in larger organisms

Mass transport system

Adaptations of erythrocytes

• Biconcave shape for a large surface area: volume ratio for diffusion

• No nucleus to make more room for haemoglobin

• Flexibility and small size to fit through narrow capillaries

Name of white blood cells

Leucocytes

Ways in which CO2 is transported

• Dissolved in the blood plasma

• As carbaminohaemoglobin

• As hydrocarbonate ions in blood plasma

Reaction of CO2 in red blood cell cytoplasm

Reacts with water forming carbonic acid, H2CO3

What enzyme controls the rate of reaction of CO2 with water

Carbonic anhydrase

How is blood pH regulated when H+ ions are formed

Haemoglobin forms haemoglobinic acid to buffer it by removing the acidic ions

How does CO2 concentration and acidic pH lower haemoglobin affinity to oxygen

The formation of H+ and HCO2- ions from carbonic acid means haemoglobin will bind with H+ ions to buffer pH change, forming haemoglobinic acid which has a lower affinity to oxygen

Product formed when H+ ions bind to haemoglobin

Haemoglobinic acid