The respiratory and circulatory systems Flashcards
How are the lungs adapted to their function?
- Alveoli increase the surface ares to maximise diffusion
- They have moist membranes to allow substances to difuse across them faster
- They have linings only one cell thick
- They have a rich blood supply
- Breathing (ventilation) provides a regular supply of fresh air
How are arteries adaped to their function?
Thick muscular walls to cope with the pressure of oxygenated blood
How are veins adapted to their function?
They have valves to stop backflow of blood, as they have to transport blood against gravity.
They have much thinner walls as the blood is at lower pressure
How are capillaries adapted to their function?
They are extremely thin so as to allow as much oxygen as possible to diffuse from the blood into the cells and CO2 vice versa
In what order does blood flow through the heart.
Deoxygenated blood arrives in the left atrium via the vena cava, enters the right ventricle and is pumped to the lungs through the pulmonary artery. In the lungs, it is oxygenated and any wasge products are removed. Oxygenated blood is collected in the right atrium through the pulmonary vein. When the heart contracts, it is pumped into the left artrium. Here it is pumped a secoond time when the heart next contracts and the blood goes out to the body.
