B7 - human diet (B7.1), nutrients, digestive system, digestion Flashcards
which organs are part of the alimentary canal
-mouth
-oesophagus
-stomach
-Duodenum
-Ileum
-colon
-rectum
-anus
what is the small intestine made up of
-duodenum
-Ileum
what is the large intestine made up of
-colon
-rectum
-anus
what are the extra organs in the digestive system
-salivary glands
-liver
-gall bladder
-pancreas
all the organs in the digestive system
-mouth
-salivary glands
-oesophagus
-stomach
-liver
-gall bladder
-pancreas
-duodenum
-Ileum
-colon
-rectum
-anus
define digestion
break down of food (in the body- mechanical & chemical)
define mechanical digestion
break down of food into smaller pieces without chemical change to the food molecules
define chemical digestion
break down of large insoluble molecules into small soluble molecules
define ingestion
taking of substances into the body (eating)
define absorption into bloodstream
movement of nutrients from the small intestine into the blood
define assimilation
uptake and use of nutrients by cells
define egestion
removal of undigested food from the body as faeces
order of processes
-ingestion
-mechnical digestion
-chemical digestion
-absorption
-assimilation
-egestion
function of mouth
-food is crushed and grinded by the teeth to increase its surface area.
-food is mixed with saliva for starch digestion
-food is converted into bolus of food
function of salivary glands
-releases saliva into mouth via salivary duct
-Starch is broken down into maltose
-has hydrogen carbonate to keep alkaline pH
define saliva
mixture of water, mucus and amylase
what is maltose
sugar made of 2 glucose molecules
function of oesophagus
-tube which carries bolus by peristalsis to the stomach from mouth
Define bolus
lump of food
define peristalsis
muscular contractions
function of stomach
-stored food here for 1-2 h
-churns food with muscular walls (peristalsis) into liquid
-liquid is called chyme
-the wall releases gastric juice which contains Hydrochloric acid to kill bacteria, pepsin to digest protein and mucus to protect the wall
function of gastric juices
-has HCl: kill bacteria and maintain pH
-has pepsin
-mucus to protect stomach
functions of HCl
-kill bacteria in food to prevent food poisoning
-maintain optimum pH for enzyme pepsin to digest protein
function of pepsin
-is a protease
-digests protein in stomach
function of small intestine: duodenum
-where stomach acid is neutralised by alkaline pancreatic juices and bile which flow to duodenum
function of pancreatic juices
-has sodium hydrogen carbonate (alkaline) to neutralise HCl
-contains lipase for lipids, amylase for starch, trypsin for protein
function of ileum
-digestion is completed here
-produces intestinal juice with protease, amylase, maltase and lipase
-products of digestion- glucose, amino acids, fatty acids and glycerol- are absorbed into millions villi into the bloodstream and lacteal (lymphatic system)
-contain lots of long villi to increase surface area for adsorption
function of pancreas
-a gland which releases pancreatic juices into the duodenum via the pancreatic duct
function of liver
-makes bile
-converts glucose into stored glycogen (assimilation)
-removes excess amino acids by deamination
function of bile
-bile salt
-made in live
-stored in gall bladder
-released into duodenum through bile duct
-emulsifies fats to increase surface area for chemical digestion
-alkaline to neutralise HCl from stomach- pancreatic enzymes optimum pH is 7.5-8
define emulsification
-physical process that breaks down large fat droplets into small fat droplets to provide large surface area for fat digestion by lipase
function of gall bladder
-stores bile
-releases bile via the bile duct
function of colon
-absorbs remaining water and salts from undigested foods
function of rectum
-forms and stores faeces until egestion
what are faeces made up of
-fiber
-bacteria
-dead cells
function of anus
-removes faeces by egastion
-has sphincter muscles to control when egestion happens
where does ingestion happen, how
-mouth (food enters body)
where does mechanical digestion happen, how
-mouth (using teeth)
-stomach (churns food)
-duodenum (bile emulsifies fats)
-liver (has bile)
where does chemical digestion happen, how
-salivary glands (saliva)
-stomach (pepsin)
-duodenum (pancreatic juices)
-ileum (intestinal juices)
-pancreas (pancreatic juices)
where does egestion happen, how
-anus (removal of faeces)
where does absorption happen, how
-duodenum
-ileum (long villi)
-colon (water absorption)
where does assimilation happen, how
-liver (glucose to glycogen)
how are food molecules broken down
-hydrolysis reactions
-enzymes
-both on top of arrow
why is physical digestion needed
-break down large food piece into small pieces using teeth/ peristalsis/ bile
-increase surface area of enzymes to digest
why is chemical digestion needed
-to break down large insoluble molecules into small soluble molecules using enzymes
-so it can be absorbed
example of physical digestion
-teeth chewing
-peristalsis
-bile
how is fat digested
-teeth breaks it down to small pieces
-bile salt emulsifies it
-lipase breaks it down to fatty acids and glycerol
how is protein digested
-teeth breaks it to smaller pieces
-pepsin in stomach
-trypsin in pancreatic juice to amino acids
how is starch digested
-teeth breaks it into smaller pieces
-amylase in saliva
-amylase in pancreatic juice to maltose
-maltase to glucose
-site of action
-substrate and products
-secreted from
-types
amylase
-salivary amylase
-from salivary gland
-in mouth
-pancreatic amylase
-from pancreatic juice
-in duodenum
-starch to maltose
-site of action
-substrate and products
-secreted from
-types
protease
-pepsin
-from stomach wall
-in stomach
-protein to peptides/ amino acids
-trypsin
-from pancreas
-in duodenum
-protein to dipeptides/ amino acids
-peptidase
-from ileum wall
-in ileum
-peptides to amino acids
-site of action
-substrate and products
-secreted from
-types
lipase
-pancreatic lipase
-from pancreas
-in duodenum
-triglycerides to fatty acids and glycerol
what are reducing sugars
maltose
is bile an enzyme, if not what
-no
-emulsifying agent
what do you use to test for starch, reducing sugar, lipids, protein
-iodine reagent
-benedict reagent
-ethanol emulsion
-biuret reagent
what is test for lipids called
emulsion test
colours of starch, reducing sugars, lipids, protein (positive)
-brown - blue-black
-blue- green, yellow, orange, brick red
-colourless- cloudy emulsion
-blue- purple
steps to test for starch
-iodine
-check for colour change
steps to test for reducing sugars
-distilled water if food is dry
-benedicts
-put tube in beaker of water at 80C for 3 mins
-check for colour change
steps to test for lipids
-ethanol
-place bung and shake
-put liquid in distilled water (not food too)
-check for emulsion
steps to test for protein
-distilled water if food is dry
-add biuret
-check for colour change
pH of fatty acids
acidic
