human digestive system

Question 1

what are enzymes

Answer 1

-catalysts are chemical substances that speed up chemical reactions without themselves being chemically changed at end of reaction
-speed up rate of chemical reactions without themselves being chemically changed at the end of reaction

Question 2

alimentary canal

Answer 2

-tube that extends from mouth to anus, most of its length coiled in the abdomen
-associated organs:
liver, pancreas, gall bladder

Question 3

digestion
*remember the key words!

Answer 3

process that breaks down large, insoluble, complex substances into simpler, smaller, soluble molecules which are small enough to be absorbed into the body

Question 4

*IMPT
physical digestion
chemical digestion

Answer 4

PHYSICAL SUBSTANCES:
breaking UP of food substances
CHEMICAL SUBSTANCES
breaking DOWN of food substances by digestive enzymes

Question 5

digestion in mouth
-food enter from where?
-what does chewing do?
-what is digested by what (enzyme)

Answer 5

-increase SA:VOL ratio
-food enters the alimentary canal via mouth
-chewing(physical digestion): breaks up food into smaller pieces. this increases SA:VOL ratio of starch digestion by salivary amylase
-salivary glands produces saliva, which helps to moisten food and make it easier to swallow
-salivary amylase digest starch to maltose
-tongue rolls food into bolus

Question 6

oesophagus & peristalsis

Answer 6

narrow, muscular tube connection throat and stomach

peristalsis–>bolus is moved along oesophagus
–> peristalsis are wave-like contractions of muscles to mix and propel contents to alimentary canal

Question 7

digestion in stomach
-gastric juices–> ? & ?
-which enzyme digests ———–
-chyme

Answer 7

–> starch digestion, slows down then start protein
–> walls of stomach lined with gastric glands that produces gastric juices
–> gastric juices–> hydrochloric acid and pepsin
–> pepsin(enzyme) digests protein to polypeptide
–> churning action that mixes food with gastric juice = chyme (SA:Vol ratio increases)

Question 8

digestion in small intestine

Answer 8

–> associated organs :liver and gall bladder

Question 9

Bile
-which organ produces it?
-what is it’s function?

Answer 9

produced from liver
gall bladder stores bile, which is released into small intestine by bile duct
BILE emulsifies lipids by breaking up large acidic fat droplets into tiny fat droplets. this increases SA:VOL ratio to increase rate of lipid digestion by lipase.

Question 10

pancreas
-3 enzymes in the pancreas

Answer 10

-pancreatic amylase digests starch to maltose
-trypsin digests proteins to polypeptides
-pancreatic lipase digests lipids to fatty acids and glycerol

Question 11

small intestine
-3 enzymes
-what is completed in the small intestines

Answer 11

-maltase digests maltose to glucose
-peptidase digests polypeptides to individual units of amino acids
-intestinal lipase digests lipids to fatty acids and glycerol
-digestion is completed

Question 12

large intestine, rectum, anus
-function?

Answer 12

absorbs water and mineral salts from the undigested waste matter and this results in formation of faeces
- egestion = faeces expelled