Sec 2 human digestive system Flashcards
state the 4 processes
ingestion, digestion, absorption, assimilation
what is digestion
it is the process where large insoluble food particles are broken down into small soluble molecules that can be absorbed into the blood
how long is the human digestive system
9 metres
what is physical process of digestion
food broken up smaller pieces grinding chewing no new product
what is chemical process of digestion
food broken down small molecules through biological molecules enzymes new product
how does carbohydrases help
speed up
breakdown of carbohydrates (starch)
simple sugars
how does proteases help
speed up
breakdown of proteins
amino acids
polypeptides
how does lipase help
speed up
breakdown of fats (lipids)
fatty acids
glycerol
what is enzymes
biological molecules / catalysts made up of protein speed up rate of reaction remains unchanged end of reaction
where does the substrate meet with enzyme
active site
what are the 2 factors that the enzyme can change
weak bonds
not staying there permanently
induced fit
enzyme changes shape to bind substrate perfectly
how many active site for one substrate
specific active site for ONE type of substrate
what are the 2 ideal conditions for enzymes
PH
temperature
what happens when environment changes for enzyme
enzyme becomes DENATURED
distorted shape
what are the 3 main nutrients
CPF
state enzyme reaction for carbohydrates
starch (amylase) maltose (maltase) glucose
enzyme reaction for proteins
protein (protease) polypeptides (protease) amino acids
enzyme reaction for fats
fats / lipids (lipase) fatty acids + glycerol
what is physical digestion by mouth
strong teeth, jaw muscles
break up food
smaller pieces
what is chemical digestion by mouth
saliva contain salivary amylase
partial digestion of starch
what are the other functions of the mouth
saliva softens and lubricates food
easier swallowing
what is the function of oesophagus
muscular tube
transports food to stomach through peristalsis
alternate waves of relaxation and contraction of its muscular walls
what is food present in oesophagus called
bolus
what is the physical digestion of stomach
stomach churns
food
smaller pieces
increase surface area to volume ratio
mix with gastric juices
describe the stomach
J-shaped
sac-like muscular organ
upper part of abdomen
what does gastric juice in stomach contain
water
hydrochloric acid
proteases
how does hydrochloric acid help in digestion
kill bacteria
provide acidic environment for proteases to work efficiently
how does proteases help in digestion
proteases break down and digest proteins into polypeptides and further into amino acids
how does the stomach prevent its wall from breaking down
lines itself with mucus
prevent acid from breaking it down
how long does food remain in stomach
2 to 6 hours
what is partly digested food called
chyme
what does the pancreas do
pumps out juice which neutralises stomach acid
what does liver do
produce bile
what does bile do
break up fat droplets into smaller fat droplets
emulsification
what does gall bladder do
store bile
what is short form for gastric juices
PALP IMPL
what is the pH levels
7 2 8
what is small intestine for
main site of digestion
numerous enzymes released
breaks down food further
absorb nutrients into bloodstream
how does villi help
lined with millions of microscopic projections (villi)
increase surface to volume ratio
easier to absorb nutrients
what is function of large intestine
absorb water from undigested food
what is function of rectum
indegestible food and waste form faeces
what is function of anus
faeces is released through this opening
