Circulatory Systems

Question 0

What do very small organisms use?

Answer 0

They rely on diffusion, as substances only have to travel very small distances into the organism. However, anything bigger than an earthworm uses a mass flow system.

Question 1

What are circulatory systems for?

Answer 1

To transport substances around the body within your blood. Eg. Oxygen, hormones, waste, glucose

Question 2

What do mass flow system include?

Answer 2

• A fluid (blood)
• pump (heart)
• tubes (vessels)

Question 3

What does an open circulatory system consist of?

Answer 3

A heart pumping blood around a cavity ( no tubes). Found in some insects and other invertabrates.

Question 4

What does a closed circulatory system consist of?

Answer 4

The blood is always in vessels, with valves ensuring that blood only flows in only one direction. Eg. Heart-arteries-arterioles-capillaries-venules-veins-back to heart

Question 5

A single circulatory system

Answer 5

• found in fish and amphibians
• the heart pumps deoxygenated blood to the gills, where gas exchange happens.
• then the blood leaves the gills and flows round the rest of the body before returning to the heart

Question 6

Double circulatory systems

Answer 6

• found in birds and mammals
• right ventricle pumps blood to the lungs where it becomes oxygenated
• then returns to the left ventricle where it is pumped to the rest of the body
• blood flows through the heart twice, which maintains a higher blood pressure making the system faster
• this allows a higher metabolic rate so they can be more active

Question 7

Cardiovascular disease

Answer 7

• disease of the heart and circulation
• main forms are coronary heart disease and strokes
• main cause of death in the uk affecting 1/4 men and 1/5 women
• responsible for over 200,000 deaths a year

Question 8

Properties of veins

Answer 8

• blood is at low pressure
• usually deoxygenated (except in pulmonary veins)
• many valves to prevent back flow
• thin walls made of mainly collagen since the blood pressure is low
• function is to carry blood from tissues to the heart
• large lumen to reduce resistance to flow

Question 9

Properties of capillaries

Answer 9

• blood pressure falls
• blood changes from oxygenated to oxygenated (except in lungs)
• very small lumen, so blood must distort to pass through
• no valves
• very thin permeable walls (one cell thick) to allow exchange of materials
• function is to allow exchange of materials

Question 10

Properties of arteries

Answer 10

• blood at high pressure
• blood usually oxygenated (except in pulmonary artery
• small lumen
• no valves (except in heart)
• thick walls with elastic layers to resist high pressure and muscle layers to aid pumping
• function is to carry blood from the heart to the tissues