UNIT 3 (topic 3) digestion and absorption

Question 1

how are the villus adapted for its function

Answer 1

• good blood supply (efficiently carries away products)
• thin outer layer (short diffusion pathway)
• epithelial cells have microvilli (increases SA)
• muscular walls that contract (maintain concentration pathway)

Question 2

what is the function of the mouth

Answer 2

mechanically breaks down food through chewing

Question 3

what is the function of the salivary glands

Answer 3

produce secretion that contains the enzyme amylase - hydrolyses starch to maltose

Question 4

what is the function of the oesophagus

Answer 4

muscular contractions squeeze the food down from the mouth to the stomach (peristalsis)

Question 5

what is the function of the stomach

Answer 5

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

Question 6

what is the function of the liver

Answer 6

produces bile salts - emulsifies lipids and allows enzymes to act quickly on hydrolysing lipids

Question 7

what is the function of the gall bladder

Answer 7

stores bile

Question 8

what is the function of the pancreas

Answer 8

glands that secrete pancreatic juices containing protease, lipase and amylase

Question 9

what is the function of the small intestine

Answer 9

long muscular tube, enzymes produced by walls of the ileum - walls fold into villi and microvilli

Question 10

what is the function of the large intestine

Answer 10

absorbs water from the waste

Question 11

what is the function of the rectum

Answer 11

stores faeces before it is egested out through the anus

Question 12

what is the function of the anus

Answer 12

egestion of waste from the body

Question 13

what are the ways in which food is physically digested

Answer 13

• food is mechanically broken down by structures like teeth and stomach walls
• gives a large SA for chemical digestion

Question 14

what are the ways in which food is chemically digested

Answer 14

large, insoluble molecules hydrolysed into smaller, soluble ones by enzymes

Question 15

which enzymes are used for carbohydrate digestion, where are they found and what do they break the molecule down to

Answer 15

• salivary amylase - made in the salivary glands - maltose
• pancreatic amylase - made in the pancreas and found in the small intestines - maltose
• maltase - made in the walls of the ileum - a-glucose
• sucrase - found in the small intestines - glucose and fructose
• lactase - found in the small intestine - glucose and galactose

Question 16

what enzymes are used to digest proteins and where are they found

Answer 16

endopeptidase - stomach
exopeptidase - stomach
dipeptidase - stomach

Question 17

what is the function of the endopeptidase

Answer 17

hydrolyses peptide bonds in the centre of the chain

Question 18

what is the function of the exopeptidase

Answer 18

hydrolyses peptide bonds between terminal amino acids

Question 19

what is the function of the dipeptidase

Answer 19

hydrolyses dipeptides into amino acids

Question 20

what enzyme is used for lipid digestion, where it is found and the products

Answer 20

pancreatic lipase - found in the small intestines - produces monoglycerides and fatty acids

Question 21

describe the stages of lipid digestion

Answer 21

• form large droplets (globules) in the digestive tract as triglycerides are not water soluble
• converted into smaller droplets (micelles) using bile emulsifying
• pancreatic lipase converts triglyceride into monoglycerides and fatty acids
• use facilitated diffusion to get into the epithelial cell as now polar
• SER synthesises the triglycerides
• packaged by Golgi body into a vesicle (chylomicrons)