the heart and blood vessels

Where are the pacemaker cells found what do they do?

Found: right atrium

Function: set the natural rhythm of contraction of the heart

How does the structure of an artery related to its function?

Structure: narrow lumen, thick layer of muscle and elastic fibres

Function: take oxygenated blood at high pressure away from the heart

How does the structure of a vein relate to its function?

Structure: widest lumen and contains valves

Function: take deoxygenated blood at very low pressure towards the heart

How does the structure of a capillary relate to its function?

Structure: walls one cell thick and permeable

Function: exchanges materials between blood of medium to low pressure and tissues

Explain gaseous exchange.

- oxygen moves into red blood cells by diffusion

- carbon dioxide moves out of blood plasma by diffusion

How have alveoli adapted to their function?

- large surface area

- large concentration gradient

- short diffusion distance

Explain the circulatory system?

- Deoxygenated blood enters the heart via the vena cava, emptying into the right atrium.

- Blood flows down through a set of valves into the right ventricle

- When the ventricles contract, blood travels up through the pulmonary artery to the nearby lungs where gas exchange occurs (and the blood becomes oxygenated)

- Oxygenated blood returns to the heart via the pulmonary vein, emptying into the left atrium

- Blood flows down through a set of valves into the left ventricle

- When the ventricles contract, blood travels up through the aorta, and to the rest of the body

What are artificial pacemakers?

Electrical devices used to correct irregularities in the heart rate