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20 Cards in this Set
- Front
- Back
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Digestive tract |
Also known as the alimentary tract/canal. The tube begins: Mouth Pharynx Oesophagus Stomach Small intestine Large intestine Anus |
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Digestive tract functions |
Ingestion- when food enters the mouth Mastication- mechanically grinding food with teeth & tongue (physical processing) Digestion- chemical breakdown of food into smaller molecules (chemical processing) Secretion- of acids, buffers, enzymes and water Absorption- movement of nutrients through the lining of the digestive tract & into the bloodstream Excretion- elimination of unusable waste products |
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The mouth and oral cavity |
Entry point for digestive tract and where physical breakdown of food and drink takes place through secretion of saliva which lubricates the food. It contains chemicals (enzymes: amylase) to begin digestion & chemical breakdown of carbohydrates. The tongue shapes the masticate food into a ball called bolus and pushes it towards the pharynx. Accessory organs include: tongue, teeth and salivary glands |
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Oesophagus |
The bolus passes though the pharynx and enters the oesophagus. It transports the bolus to the stomach through a process, peristalsis. The contraction of smooth muscle pushes the bolus down until it reaches the lower oesophageal sphincter. The bolus passes through the sphincter and enters the stomach. |
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Stomach |
Serves as temporary holding area for received food. It secretes gastric acids and enzymes that mix with food. It regulates the rate at which partially digested food (chyme) enters the intestine. Absorbs small amount of water and other substances |
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Gastric juice |
Very acidic- pH 1.5-2. Breakdown of protein by pepsin. Breakdown of connective tissue by HCI. Kills pathogens |
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Small intestine |
Three regions include: Duodenum- beginning Jejunum- middle IIeum- end The walls of small intestine have microvilli, villi and circular folds that provide increased efficiency and absorption. Functions: secretes enzymes to chemically digest chyme. Secretes hormones to stimulate pancreas and gallbladder. 80% absorption of nutrients occur. |
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Large intestine |
Three main regions: Caecum, Colon, Rectum Functions: Water absorption Absorption of vitamins produced by healthy bacteria Compaction of waste products for elimination |
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Accessory organs |
Liver Gallbladder Pancreas |
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Liver |
Detoxifies harmful substances Creates body heat Destroys old blood cells Produces blood plasma proteins, clotting proteins and anticoagulant heparin Manufactures bile for digestion of fats Stores and modified fats, simple sugars, iron and some vitamins Synthesises cholesterol and urea |
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Gall bladder |
Stores bile produced by liver While storing bile it absorbs the water content making it more concentrated If bile becomes too concentrated, bile salts may solidify- forming gallstones |
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Pancreas |
Secrete buffers and digest enzymes Secretions travel through the pancreatic duct to the duodenum Secretion is triggered by release of hormones from the duodenum Buffers are needed to neutralise the acidity of the chyme, saving intestinal walls from damage |
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Disorders of digestive system |
Peptic ulcers- caused by breakdown of mucosal membrane in the oesophagus, stomach and small intestine. Factors contributing: Bacterial infection Smoking Heavy alcohol consumption Use of NSAID medication (aspirin, etc) Caffeine consumption Stress Also: gallstones, diarrhoea, constipation and bloating |
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Composition of ATP |
Adenine- nucleotide found in DNA and RNA Ribose sugar- 5 carbon sugar 3 inorganic phosphate groups |
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Heat |
Form of energy measured by temperature |
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Heat transfer |
Conduction- heat transferred from one objected to another through direct contact Convention- heat transferred from body to moving air Radiation- heat from body passed to surroundings Evaporation- sweating energy to convert liquid to gas, produces cooling effect on body |
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Fat catabolism |
Hydrolysis of triglycerides (lipid) produces glycerol and fatty acids Excessive hydrolysis of lipid may lead to production of ketones resulting in ketoacidosis eg. Diabetes |
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Protein catabolism |
Degraded via hydrolysis in liver to liberate free amino acids When in excess are converted to ammonia and finally urea for excretion in the urine |
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Carbohydrate catabolism |
The breakdown (oxidation) of glucose to form water and ATP through -glycolysis -krebs cycle -electron transport chain -oxidative phosphorylation |
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BMI equation |
BMI= weight (kg) divide by height(2) metre |
