chapter 11 human digestive system

Question 1

Why must our food be digested?

Answer 1

our body is made up of cells and each cell has a cell membrane which is partially permeable
-but it only allows small molecules to pass through and fats, starch, proteins and carbs and large and complex molecules which are unable to pass through the cell membrane

they need to be broken down small enough to be able to pass through cell membranes

Question 2

describe the functions of teeth, tongue and salivary glands

Answer 2

teeth: cut and grinds food into smaller pieces increasing the surface area the enzymes can act on
tongue: rolls food into small balls

salivary glands: - wets food to swallow easier
- contains an enzyme called salivary amylase which digests starch into maltose

Question 3

describe the function of the oesophagus

Answer 3

• long muscular tube that pushes food down into the stomach
• the muscles above the ball of food contract, pushing the food down
• the muscles below the food relaxes to widen the tube fore the food to move down

Question 4

what is a stomach and what is its function

Answer 4

a muscular bag that contracts and relaxes to churn food into smaller pieces

secrets gastric juices that contains protease which digests proteins into simpler protein molecules
it also secretes hydrochloric acid which helps the protease to work and kills bacteria in food

Question 5

What is a small intestine and what is its function?

Answer 5

• a long muscular tube
• it contracts and relaxes which mixes bile, pancreatic fluid and intestinal fluid
• absorbs digested food molecules into the bloodstream

Question 6

what are the parts of large intestines and what are its functions?

Answer 6

colon: absorbs water and mineral salts from undigested food
rectum: temporarily stores faeces
anus: egest the faeces

Question 7

Where is bile produced and what does it do?

Answer 7

• made in the liver and stored in the gallbladder
• does not contain any enzymes but breaks down fat into smaller yellow droplets
  >called emulsification
• emulsification increases the surface area of fats for the lipases from intestinal and pancreatic juice to digest the fat quickly

Question 8

what are the enzymes in intestinal juice and pancreatic juice?

Answer 8

pancreatic juice: amylase, protease and lipase

intestinal juice: maltase, protease and lipase

Question 9

describe the digestion of fats

Answer 9

before digestion: fats
enzyme: lipase
after digestion: fatty acids and glycerol

Question 10

describe the digestion of starch

Answer 10

before digestion: starch
enzyme: amylase
after digestion: maltose

enzyme: maltase
after digestion: glucose

Question 11

describe the digestion of simpler protein molecules

Answer 11

before digestion: simpler protein molecules
enzyme: protease
after digestion: amino acids

Question 12

describe absorption in bloodstream

Answer 12

1. only small food molecules pass through the wall of small intestine and blood vessels
2. small food molecules move to the bloodstream
3. these are absorbed by body cells and used for respiration, cell repair and other processes

Question 13

what are enzymes?

Answer 13

they are complex proteins that speed up the rate of chemical reactions