Digestive system Flashcards
Mucosa
Inner most layer of the gut. Contains villi and goblet cells which secrete mucin to produce a mucus layer.
Submucosa
Dense connective tissue that supports the mucosa.
Serosa
Outer most layer of the gut. it is smooth and secretes lubricant to reduce friction.
Gut Epithelium
One cell thick and lines the intestine.
Ileum
Absorbs the useful molecules from the hydrolysed food. The villi have a large surface area to volume ration, small diffusion pathway to the blood supply and a large network of capillaries to maximise absorption. The nutrients then get processed by the liver. This is transported by the hepatic portal vein.
Oesophagus
Connect the mouth (from the pharynx) to the stomach. the food forms balls called bolus and and the muscular tube pushes the bolus down by a process called peristalsis.
Pancreas
Produces pancreatic juices which are then secreted by exocrine cells in the duodenum. The pancreatic juices contain lipase, pancreatic amylase, dipeptidase and trypsinogen (pro-enzyme of trypsin). Produces sodium bicarbonate which neutralises the stomach acid.
Liver
Produces bile which is then stored in the gall bladder and secreted in the duodenum to emulsify fats and help neutralise the stomach acid. the bile duct transports the bile. It processes nutrients absorbed by the ileum.
Primary structure of protein
A sequence of coded amino acids joined by peptide bonds. Forms a polypeptide through a condensation reaction which then forms different shapes.
Secondary structure of protein
The polypeptide forms a 3D structure of alpha helix or beta pleated sheets which hydrogen bonds or amino acid residue holding it in place.
Tertiary structure of protein
The 3D structure is folded and has different bonds between each amino acid (hydrogen, ionic, disulphide and covalent). If disturbed the protein could denature so no longer function. This structure determines the structure of the protein.
Quaternary structure of proteins
The forming of more than 1 polypeptide. The way they combine shows there structure. It has the same bonds as tertiary structure.
Biochemical test for protein
Add biuret reagent (alkaline) made up of sodium hydroxide and copper sulphate (cu 2 ions). If a protein is present the ions form complexes with peptides. This changes the solution from blue to purple. Low sensitivity and specificity.
Amino acid structure
Amine NH2
Centre carbon + Hydrogen above
Variable group (centre below)
Carboxylic COOH
Protein hydrolysis
Mouth- mechanical digestion (teeth chew, salivary to lubricate and form bolus)
Stomach- Pepsinogen (pro enzyme of pepsin) breaks down protein to smaller polypeptides. Endo/exopeptidase hydrolyse to dipeptides.
Small intestine - hydrolyse dipeptides to amino acids by dipeptidase.
