Open and Closed Circulatory Systems

Question 1

What are the main roles of circulatory systems?

Answer 1

Provide an efficient and constant supply of nutrients, and a method of removing waste products.

Question 2

What are the core elements of a circulatory system?

Answer 2

A heart as a driving mechanism, a system of vessels, and a fluid transport medium.

Question 3

Describe the main components of an open circulatory system.

Answer 3

One or more hearts, and open ended vessels that are not sealed.

Question 4

Describe how the heart in an open circulatory system circulates ‘blood’ around the body.

Answer 4

When the heart contracts, it pumps the haemolymph into the smaller vessels, and then into cavities called sinuses, where the fluid baths the organs and tissues. When the heart expands, it causes haemolymph to move to the open end of the tubular heart, or may enter through holes called ostia.

Question 5

What is haemolymph and what is it made of?

Answer 5

Haemolymph is the transport fluid of open circulatory systems. It contains blood and tissue fluid.

Question 6

How are nutrients and wastes exchnaged between haemolymph and the cells?

Answer 6

Exchange of nutrients and wastes occur directly between the haemolymph and the cells.

Question 7

In what types of animals are open circulatory systems found?

Answer 7

Open circulatory systems are found in invertebrates such as insects, spiders, crabs,

Question 8

Describe the flow of the haemolymph in the body.

Answer 8

The movement of the organism assists the haemolymph in bathing all organs and tissues. The fluid is pumped slowly at low pressure.

Question 9

In what types of animals are closed circulatory systems found?

Answer 9

In vertebrates, including mammals, fish, frogs, birds, reptiles.

Question 10

Identify the features of a closed circulatory system.

Answer 10

A heart, and a completely sealed vessel system containing blood.

Question 11

What is the main transport system in mammals known as?

Answer 11

The cardiovascular system

Question 12

Which animals have 2/3/4 chambered hearts?

Answer 12

Fish - two chambered
Frogs - Three
Birds, Reptiles, Mammals - Four

Question 13

Identify the different types of vessels that blood flows through.

Answer 13

Veins - carry blood towards heart
Arteries - blood away from heart
Capillaries - links between arteries and veins
Arterioles - branch of artery leads to capillary
Venules - branch of veins

Question 14

Describe how nutrients and wastes are exchanged between blood vessels and cells.

Answer 14

While the blood remains in the capillaries, the required substances move into the fluid surrounding cells, called interstitial fluid, or tissue fluid. From here they move again into their required location (blood or cell).

Question 15

Identify how blood is pumped around the body.

Answer 15

In a closed circulatory system, blood is pumped at high pressure, ensuring efficient transport, and suits large animals such as vertebrates.

Question 16

What is the main advantage of a four-chambered heart?

Answer 16

It is the most efficient pumping mechanism, as it keeps oxygenated and deoxygenated blood separate.

Question 17

What is the main role of the lymphatic system?

Answer 17

To prevent the build up of interstitial fluid in tissues.

Question 18

What is lymph and what is it composed of?

Answer 18

Lymph is the transport medium of the lympahtic system, and is composed of tissue fluid, white blood cells, and the end products of lipid digestion.

Question 19

Describe the flow of lymph in the lymph vessels.

Answer 19

Lymph vessels only flow from tissues to the heart. This movement is assisted by muscles contractions, and valves that prevent the lymph from flowing backwards.

Question 20

Where do the main lymphatic channels join the veins?

Answer 20

The two main lymphatic channels join the veins at the shoulder region, allowing lymph to rejoin the blood.

Question 21

Identify some other roles of the lymphatic system.

Answer 21

It helps maintain blood volume and pressure, and has a role in the defence of the body.