The digestive system

muscle tissue, nervous tissue, connective tissue and epithelial tissue

cells of an organism require nutrients and for vertebrates digestion of food is the first important step that must occur. some nutrients can dissolve in water and redily enter cells but some are too large and must be broken down into smaller units

the chemical process of breaking down large organic molecules into a size that can pass across plasma membranes and around the body

ingestion, digestion, absorption and egestion

the taking in of nutrients

the breakdown of complex organic molecules into smaller components by mechanical and chemical means

the taking up of digested molecules into the cells of the digestive tract through the cell membrane

the removal of waste food materials (unabsorbed food) from the body

when large pieces of food are broken down into smaller pieces of the same food, chemically the food stays the exact same

chewing, the cutting up of food. peristalsis, the muscular contractions of the stomach and bile which is produced in the liver and emulsifiers lipids, breaking up fatty masses into smaller droplets

to increase surface area of the food so chemical digestion can happen at a faster rate

when enzymes break down complex structures into their simplest forms, they go from polymers to monomers

the tube from the top to the bottom of the digestive system

the mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus

salivary glands, gall bladder, liver and pancreas and others which contribute vital subtstancea to the functions of the system

teeth mechanically break down food, saliva contains amylase which digests starch into maltose, saliva lubricates food which makes it easier to swallow. the epiglottis closes off the trachea so food bolus goes down the oesophagus

undirectional muscular contractions which allow fod to move along the digestive system and break it down further

mechanical digestion occurs as the muscles of the stomach wall relax and contract (peristalsis), the food is now called chyme. gastric juice is secreted from the cells lining the stomach walls.

it is converted into the active enzyme pepsin where it then acts on the peptide bonds between amino acids, breaking down the long protein chains into smaller amino acids

the duodenum, jejunum and ileum

digestion - further and final digestion of all organic molecules including carbohydrates, proteins and lipids. absorption - of digested molecules into the bloodstream

pancreatic enzymes and intestinal enzymes enter the duodenum at the top of the small intestine which contain enzymes

contains a mixture of amylase, trypsin, lipase and bicarbonate. the bicarbonate neutralises the acidity of the digested food which stops the action of pepsin

its produced in the liver and passes down the bile duct and into the duodenum but is stored in the gall bladder if there is no food to digest. its involved in the mechanical digestion of fats by emulsifing them into smaller pieces