Double closed circulatory system

What is the first circuit?

Pulmonary circulation, blood goes to lungs for gas exchange between air and blood

What is the 2nd circuit?

Systemic circulation, blood pumped to body tissues for exchange of material between blood and cells

How did the heart evolve?

To pump both circuits simulataneously so blood passes thru heart twice for 1 complete circuit of the body

What are the advantages? (1)

Fast flow maintained

What are the advantages? (2)

Heart increases so blood pressure in systemic circulation after blood has been thru capillaries of lungs

What are the advantages? (3)

Maintains higher blood pressure for systemic circulation but lower for pulmonary circulation

What are the advantages? (4)

Provides sufficient materials to cells to maintain life in homeothermic organisms, which can be highly active

What are the advantages? (4)

Keeps oxygenated and deoxygenated blood separate

How are alveoli adapted for gas exchange? (things that I tend to forget)

Surfactant reduces cohesive action between water molecules and prevents alveoli from collapsing, elastic fibres stretch and recoil and increase surface area so there is more space for molecules to pass and high diffusion rate, thin walls as alveoli are made of squamous epithelium which are flattened cells which means short diffusion pathway

How are alveoli adapted for gas exchange? (things that I tend to forget) (2)

Well ventilated so oxygen is constantly replenished and CO2 constantly removed which maintains conc gradient and keeps O2 higher in alveolar air than blood and CO2 lower in alveolar air, warm temperature for high rate of diffusion