Unit 2: Digestion

mouth

• entry of food

• chemical digestion via salivary amylase

• mechanical digestion via chewing

salivary glands

release enzymes eg salivary amylase

amylase = starch → glucose

oesophagus

• carries food to stomach

• bolus (ball of food) passes via peristalsis

  • wave like muscle movements that push bolus one way using circular and longitudinal muscles

liver

• produces basic bile that neutralises stomach’s acidic chine

gall bladder

• stores bile that neutralises stomach’s acidic chine

stomach

• mechanically churns food

• protein digestion occurs here

• acidic chine emulsifies lipids

pepsin, protease, trypsin = proteins/polypeptides → amino acids

pancreas

• releases digestive enzymes into small intestine

lipase = triglycerides → fatty acids and glycerol

duodenum

sucrase = sucrose → fructose + glucose

Small intestine

• most digestion happens here

• villi (small hair like structures composed of capillaries, lymph vessel, mucosa, submucosa, circular muscles, longitudinal muscles, serosa)

• some enzymes released

maltase = maltese → glucose

lactase = lactose → glucose + galactose

lipase = triglycerides → fatty acids + glycerol

protease, trypsin, pepsin → proteins, polypeptides, → amino acids

phospholipase = phospholipids → fatty acids + phosphate + glycerol

dipeptase = dipeptides → amino acids

protase = peptide → amino acids

DNase, RNase = DNA, RNA → nucleotides

Large intestine

• reabsorption of water

• vitamins/minerals absorbed

• processes undigested food, faeces

• extra carb digestion with bacteria

Hydroxyl group

-OH

Amine group

-NH2

Carboxyl group

-COOH

Methyl group

-CH3

alpha - d - glucose

C6 H12 O6 (OH down)

beta - d - glucose

C6 H12 O6 (OH up)

Ribose

C5 H10 O5

Saturated Fatty Acid

carboxyl + CH’s + methyl

Generalised Amino Acid

carboxyl + H/C + R variable side chain + amine

Triglycerides

glycerol + fatty acid

Fibrous proteins

Proteins made of amino acids, structural

• collagen - structure against tears in teeth, bones, nails, hair, skin

• rhodopsin - pigment rods in eyes

• spider silk - strong sticky fluid

Globular proteins

Proteins made of amino acids, functional

• rubisco - converts inorganic carbon to organic carbon

• immunoglobin - antibodies

• insulin - signal to absorb glucose out of the blood if blood sugar too high