2.6c absorption of materials

Question 1

What do the rings of cartilage do in the trachea?

Answer 1

they hold the airways open at all times

Question 2

What is gas exchange in the lungs?

Answer 2

the diffusion of oxygen from an area of high concentration in the lungs to an area of low concentration in the red blood cells and the diffusion of carbon dioxide from an area of high concentration in the blood to an area of low concentration in the lungs.

Question 3

Describe the features of the alveoli

Answer 3

• large surface area (millions of alveoli)-rapid diffusion of gases
• thin walls(one cell thick) - rapid diffusion of gases
• good blood supply (network of millions of capillaries) - products of diffusion are carried away quickly
• they are moist (thin layer of water) - allows the oxygen to dissolve

Question 4

Where does gas exchange take place?

Answer 4

the alveoli

Question 5

Describe the flow of air in the lungs

Answer 5

• trachea
• bronchus
• bronchiole
• alveoli

Question 6

Describe the function of cilia

Answer 6

hair-like cells that have upwards in a wave like motion to move trapped germs and dirt away from the lungs.

Question 7

describe how the lungs are protected

Answer 7

the airways are lined by cells that produce mucus that traps microorganisms, dust and dirt.
cilia move the trapped dirt, dust and microorganisms away from the lungs.

Question 8

what is the role of capillaries in the villi?

Answer 8

to absorb the products of carbohydrate digestion (glucose) and protein digestion (amino acids)

Question 9

what is the role of the lacteal in the villi?

Answer 9

to absorb the products of fat digestion (fatty acids and glycerol)

Question 10

describe the features that allow villi to to carry out absorption efficiently

Answer 10

• millions of villi - large surface area for rapid diffusion of food molecules into the villi
• good blood supply - transport the food molecules rapidly around the body.
• thin lining-the walls of the villi are only one cell thick-allows rapid diffusion

Question 11

what is peristalsis?

Answer 11

• the movement of food through the digestive system
• occurs along the length of the alimentary canal and not just the oesophagus
• the muscles behind the food contract and the muscles in front of the food relax

Question 12

What is the job of the small intestine?

Answer 12

to absorb the food molecules into the blood stream

Question 13

what is digestion?

Answer 13

the breakdown of large, insoluble food molecules into small, soluble food molecules by enzymes.

Question 14

why do we need digestion?

Answer 14

because only small, soluble food molecules can dissolve and diffuse through the wall of the small intestine and enter the blood