unit 3; enzymes and digestion

Question 1

define the digestive system

Answer 1

an exchange surface through which food substances are absorbed

Question 2

the oesophagus

Answer 2

carries food from the mouth to the stomach

Question 3

the stomach

Answer 3

muscular sac with an inner layer that produces enzymes- stores and digests food

Question 4

the ileum

Answer 4

long muscular tube that further digests food further by enzymes it secretes

Question 5

describe the ileums adaptations

Answer 5

inner walls folded into villi, villi contain microvilli on the epithelial cells of each villi- increased sa for absorption

Question 6

the large intestine

Answer 6

absorbs water- mainly from secretions of digestive glands

Question 7

the rectum

Answer 7

faeces stored here before being moved to the anus in egestion

Question 8

the salivary glands

Answer 8

near the mouth- pass secretions via a duct into the mouth, secretions contain amylase which hydrolyses starch into maltose

Question 9

the pancreas

Answer 9

large gland near the stomach, produces secretions called pancreatic juice, containing proteases (proteins), lipase (lipids) and amylase (starch)

Question 10

2 stages of digestion

Answer 10

physical breakdown + chemical digestion

Question 11

carbohydrases

Answer 11

break down carbs ultimately into monosaccharides

Question 12

lipases

Answer 12

break down lipids into fatty acids and glycerol

Question 13

which parts of the body are involved in physical breakdown

Answer 13

the teeth and the stomach (muscles in the stomach wall)

Question 14

where is amylase produced

Answer 14

mouth and pancreas

Question 15

where is maltase produced

Answer 15

in the lining of the ileum

Question 16

where are bile salts produced

Answer 16

liver

Question 17

what do bile salts do

Answer 17

break lipids into micelles- increase sa of lipids

Question 18

what do endopeptidases do

Answer 18

hydrolyses the peptide bond between amino acids- forming a series of peptide molecules

Question 19

what do exopeptidases do

Answer 19

hydrolyse peptide bonds on ends of peptide molecules- forms dipeptides and single amino acids

Question 20

what do dipeptidases do

Answer 20

hydrolyse bonds in dipeptidases- membrane bound

Question 21

what happens to micelles when they reach the ileum

Answer 21

they break down, releasing monoglycerides and fatty acids that can diffuse through the membrane into the epithelial cells

Question 22

what happens after monoglycerides and fatty acids enter epithelial cells

Answer 22

recombine to form triglycerides

Question 23

what is a chylomicron

Answer 23

special particles adapted for transport of lipids- a combination of triglycerides, cholesterol and lipoproteins

Question 24

where are chylomicrons formed

Answer 24

in endoplasmic reticulum + golgi apparatus of epithelial cells

Question 25

where do chylomicrons go

Answer 25

released by exocytosis into lacteals - lymphatic capillary- then enter bloodstream