digestion Flashcards
u better pass science🫵
why do we need food
-food provides energy for vital activities of the body
-this includes synthesizing new protoplasm, growth, and repair of worn out of body parts
what happens during respiration
nutrients and oxygen undergoes respiration which releases energy, carbon dioxide and water
C6H12O6+O2 —(respiration—> energy)—> 6CO2+6H2O
why must food be broken down into small molecules to be digested
cell membranes are partially permeable, containing small pores. thus, substances that are too large are unable to pass through the intestine walls
what is the definition of digestion of food
digestion is the breaking down of large, complex and insoluble food molecules into small, simple and soluble molecules
why does our body physically digest food
so enzymes can access the food by breaking it down
what happens during chemical digestion
it breaks down food into small molecules through the use of enzymes
it breaks the chemical bonds between the atoms in the food and will result in the simplest smallest form of nutrients for absorption
what are enzymes
they are biological molecules produced by the digestive system
they speed up the breakdown of large molecules into small molecules (cuz without them the chemical reaction would take too long)
what are enzymes made out of
protein
what is starch digested by and what does it become
it is digested by amylase (enzyme) and becomes maltose (another enzyme)
what is maltose digested by and what does it become
maltose is digested by maltase (enzyme) and becomes glucose and yippee it is small enough to enter cells
is fibre a carbohydrate or protein
carbohydrate 🥳 (it cant be digested in humans so it will be passed out in feces)
where is carbohydrates found in and what does it break down into
starchy and sweet foods, and it breaks down into glucose
what enzyme break down protein and what does it become
the enzyme protease breaks protein down into polypeptide
true or false - polypeptide gets broken down by protease and becomes amino acid
true
true or false - protein gets broken down to polypeptide in the stomach only
true - only in the small intestines then polypeptide is broken down into amino acids
what are amino acids used for
to make enzymes like protease, amylase and maltose
what does lipase digest
fats
what does fats get digested into
1 glycerol and 3 fatty acids
what are fatty acids used for
to make cell surface membrane
what are fats used for
it is stored under skin to prevent heat loss and cushion internal organs, and provides long term storage of energy in animals (provides twice as much energy per gram as carbohydrates)
what digestion happens in the mouth
physical digestion:
teeth chew and crush food into smaller pieces
- this increases the surface area to volume ratio of the food. allows enzymes to access the food to increase the rate of chemical digestion
chemical digestion:
saliva contains amylase. starch is broken down into maltose
what does the mouth do (other than physical and chemical digestion)
- saliva helps to lubricate the food, making it easier to swallow
- tongue rolls the food into a ball to swallow
- taste buds on tongue allow us to taste food
what digestion happens in the oesophagus
chemical digestion:
starch from mouth continues to be digested by amylase to maltose while travelling down.
(not physical or chemical but) the food travels to the stomach via gravity as well as muscle contractions (peristalsis —> muscles in oesophagus)
what digestion happens in the stomach
physical digestion:
stomach churns the food into smaller pieces
chemical digestion:
gastric juices containing protease is released. proteins are broken down into polypeptides
why does gastric juices contain hydrochloric acid
to kill microorganisms like bacteria and to create and acidic environment for proteases to work
what digestion happens in the small intestines
physical digestion:
bile is produced by the liver, and is accumulated and secreted by gall bladder
chemical digestion:
it is the main site for chemical digestion. amylase, maltase, proteases and lipases are present. all nutrients are COMPLETELY (polypeptide is digested by protease and becomes amino acids) digested. digested nutrients are then absorbed into the bloodstream here.
what is the function of bile
it emulsifies fat from large fat globules to small fat droplets
how does bile work
because fats do not mix well in water and tend to form large globules or clumps, bile emulsifies the fat by surrounding it, allowing it to mix with water (like alchohol)
how does bile help digestion
emulsification increases surface area to volume ratio of fats, allowing it to be exposed to lipase (NOT CHEMICAL DIGESTION)
true or false: rectum absorbs water and mineral salts from food
false: rectums temporarily stores faeces (undigested food)
large intestines mainly absorbs water and mineral salts from food
