Transport in animals 3.1.2

Question 1

Why are specialized transport systems needed?

Answer 1

• The metabolic demands of most multicellular animals are high so diffusion over long distances is not enough.
• The surface area to volume ratio (SA:V) gets smaller as multicellular organisms get bigger so less area to absorb or remove substances.
• Molecules such as hormones or enzymes may need to be transported.
• Waste products need to be removed from cells and transported to excretory organisms.
• Food needs to be transported to all cells for respiration.

Question 2

What features do most circulatory systems have in common?

Answer 2

• They have a liquid transport medium (blood).
• They have vessels that carry the transport medium.
• They have a pumping mechanism to move the fluid around.

Question 3

What is the term for substances that are transported in a mass of fluid with a mechanism for moving the fluid?

Answer 3

Mass transport system.

Question 4

What are the types of circulatory systems?

Answer 4

• Open circulatory systems.
• Single closed circulatory systems.
• Double closed circulatory systems.

Question 5

What is the open body cavity in a open circulatory system called?

Answer 5

The Haemocoel.

Question 6

What animals are open circulatory systems mainly found in?

Answer 6

Invertebrate.

Question 7

What is insect blood called?

Answer 7

Haemolymph.

Question 8

What happens in a single closed circulatory system?

Answer 8

Blood travels through two sets of capillaries before it returns to the first. In the first it exchanges oxygen and carbon dioxide and in the second substances are exchanged between the blood and the cells.

Question 9

What is the disadvantage of single closed circulatory systems?

Answer 9

Blood pressure becomes low after first set of capillaries so returns to the heart quite slowly, which limits the efficiency of any exchange processes so animals that posses this circulatory system tend to be relatively low.

Question 10

What are the two parts of a double circulatory system

Answer 10

• Blood is pumped from the heart to the lungs to pick up oxygen and unload carbon dioxide and then returns to the lungs.
• Oxygenated blood is pumped from the heart to travel all around the body before returning back to the heart.

Question 11

What is the advantage of a double closed circulatory system?

Answer 11

A relatively high blood pressure and fast flow of blood can be maintained allowing for a high activity level as exchange processes can be efficient.

Question 12

What are the different components utilised in blood vessels and what are their uses?

Answer 12

• Elastic fibres, can stretch and recoil providing flexibility.
• Smooth muscle, contracts or relaxes which changes the size of the lumen.
• Collagen, provides structural support to maintain shape and volume of the vessel.

Question 13

What are arterioles?

Answer 13

Arterioles link the arteries and capillaries.

Question 14

What are the properties and uses of arterioles?

Answer 14

Arterioles have more smooth muscle and less elastic than arteries where the smooth muscle can contract or relax to either vasoconstrict or vasodilate.

Question 15

What are the proportions of a aorta, a medium-sized artery and a arteriole?

Answer 15

• Aorta, 2.5cm
• Medium-sized artery, 0.4cm
• Arteriole, 30um