1.1 Heart and Circulation

Question 1

Open Circulatory System

Answer 1

1. Heart pumps blood into cavities surrounding organs.
2. Substances diffuse between blood and cells.
3. Blood circulates in large open spaces.

Question 2

What is the purpose of having a heart and circulation?

Answer 2

Move substances around the body by diffusion. Oxygen, Carbon Dioxide and digestive products.

Question 3

What is diffusion?

Answer 3

Diffusion is the movement of molecules or ions from a region of high concentration to a region of low concentration.

Question 4

What are multi cellular organisms too large for?

Answer 4

Multi-cellular organisms are too large for diffusion.

Question 5

What do multi-cellular organisms use instead of diffusion?

Answer 5

A heart to pump, known as the circulatory system which helps pump blood around the body therefore carrying substances around the body.

Question 6

Closed Circulatory System (4)

Answer 6

1. Blood is enclosed within tubes.
2. Generates high blood pressure as the blood is forced along narrow channels.
3. Blood travels faster.
4. Blood system moves more efficient at delivering substances around the body.

Question 7

How does blood move through the body?

Answer 7

Leaves heart under pressure.

Flows along arteries to arterioles to capillaries.

Question 8

What are the key features of capillaries? (3)

Answer 8

1. Large number of capillaries.
2. Contact with most cells.
3. Substances exchanged between blood + cells.

Question 9

What is the importance of valves?

Answer 9

Allows blood to flow in one direction.

Question 10

How does blood return back to the heart?

Answer 10

Blood returns to the heart by venules then veins.

Question 11

Single Circulatory System: How does a fish’s circulatory system work?

Answer 11

1. Closed circulation
   - Heart pumps deoxygenated blood to the gills.
   - Gaseous exchange (Diffusion of carbon dioxide from blood into the water) + (diffusion of oxygen from water to blood).
   - Blood leaving the gills flows around the rest of the body and returns to the heart.

Question 12

Double Circulatory System: How does a mammals circulatory system work?

Answer 12

1. Right ventricle pumps deoxygenated blood to the lungs where it receives oxygen.
2. Oxygenated blood returns to the heart to be pumped the second time by the left ventricle to the rest of the body.
   - Heart took twice to complete circuit around the body.

Question 13

Why do mammals have a high metabolic rate?

Answer 13

High metabolic rate because oxygen and food substances required for metabolic processes are delivered rapidly to cells.