Flashcards
Gastro-inestinal system
Flashcards do conjunto (36)
- 1Describe the structure of the GI tract.
- 2Describe the sub divisions of the GI tract.
- 3Explain the main processes of the GI tract.
- 4Describe the function of the salivary glands.BUCCAL CAVITY
*Lubrication - mucous
*Protection - lysozyme
*Digestion- α-amylase and lipase - 5Describe the function of the stomach.*Mixing
*Protein digestion - hydrochloric acid and pepsin
*Fat emulsification - bile
*Folds of stomach - rugi
*Sphincter control passage of food
*Function specific secretory neurones
ACh (acid)
GRP (gastrin) - 6Explain the structure of the stomach wall.
- 7Explain the function of the small intestine.*Digestion and absorption - carbohydrates, proteins and fats
- 8Explain the structure and function of the small intestine villi.*increase surface area
*absorption
*motility
- 9Explain the structure and function of the Crypts of Lieberkuhn.*Paneth cells - regenerate and provided nutrients to stem cells
*defensins
*protection
*immature cells – HCO3-
*goblet cells - mucous
CONTINUOUS SHEDDING AT SURFACE AT TOP INTO LUMEN. - 10Explain the function of Goblet cells.Produce mucus - on contact with aqueous environment rapidly absorbs water and forms protective layer.
- 11Describe epithelial specialisation in the small intestine.
- 12Explain the function of the large intestine.*water and ion conservation
*bulk movement of faeces
*storage
*lubrication
*defaecation - 13Explain the phases of digestion.
- 14Explain control of feeding.
- 15Explain the three phases of swallowing/deglutition.*Swallowing initiated when pressure receptors in the walls of the pharynx are stimulated.
*These send afferent impulses to the swallowing centre located in the medulla. This sends efferent impulses to the muscles in the pharynx, oesophagus and respiratory muscles.
*The soft palate closes to prevent food entering the nasal cavity. Impulses form the swallowing centre inhibit respiration and close the glottis preventing food from moving into the trachea.
*As the tongue forces the food farther back into the pharynx, the epiglottis is forced down to cover the closed glottis, thus preventing the aspiration of food or liquid.
*Upper 1/3 of the oesophagus is surrounded by skeletal muscle and the lower 2/3 by smooth muscle. Closure of the upper (skeletal muscle) and lower (smooth muscle) sphincters prevent the ingress of air and reflux of acid into the oesophagus when not swallowing.
PERISTALTIC WAVES - 16Describe the properties of the swallowing reflex.*initiated voluntarily
*pharyngeal reflex due to distension
*controlled by brain stem
*proceeds automatically - 17Explain movement and mixing in the stomach.*peristalsis
*movement depends on viscosity
*retropulsion forces solids back
*liquids exit faster than solids - 18What is peristasis? How is it generated?*the involuntary constriction and relaxation of the muscles of the intestine creating wave-like movements which push the contents forward.
*Basic rhythm maintained by pacemaker cells in the longitudinal smooth muscle layer of the stomach wall - 19Explain movement and mixing in the small intestine.Consists of cycles of contraction and relaxation lasting a few seconds and extending over a distance of only few centimetres. This has the effect of producing a continuous division and subdivision of the intestinal contents that move the chyme backwards and forwards in the lumen,
- 20Explain segmentation and mixing in the small intestine.*Force, but not rate, of contraction is influenced by hormones, ENS autonomic nerves (PS stimulation increases and S stimulation decreases the force of contraction). Thus cephalic phase stimuli as well as emotional state can alter intestinal motility.
- 21What is the migration motility complex?The migrating motor complex is pattern of electromechanical activity observed in gastrointestinal smooth muscle . It is thought to serve a "housekeeping" role and sweep residual undigested material through the digestive tube.
*successive waves of contraction emanating from the lower portion of the stomach
each wave takes approximately 2 h to reach the large intestine - 22Explain the motility of the large intestine.*Faeces are stored in haustra
*Faeces are propelled towards the rectum by slow, rhythmic segmentation contractions of the circular smooth muscle
*Transit time for material entering the large intestine is 18-24 h
*Defaecation triggered by presence of faeces in the descending colon/rectum - 23Explain the defecation reflex.
- 24Explain the process of digestion initiated by salivary glands.*Serous cells secrete - α-amylase, breakdown of complex carbohydrates , inactivated by low pH in stomach
*lingual lipase - breakdown of triglycerides, optimal at pH 4-5, activity persists throughout the GI tract
*mucin - IgA and lysozyme (anti-microbial) - 25Explain secretion in the stomach.
- 26Explain gastric acid secretion.Acid secretion ↑ by:
*gastrin
*ANS
*protein
*buffering
*distension
- 27Explain digestion in the stomach.*pepsin - exopeptidase
(Secreted at pesinogen converted to pesin by HCl)
*Acid - endopeptidase - 28Explain pancreatic secretion in the role of digestion. Contents of pancreatic juice and function of each component.*Endocrine, function of the pancreas.
*P. fluid is rich in bicarbonate = buffer
*Bile is stored in the gall bladder.
*SM contracts and injects bile into the lumen via bile duct. Bile is alkaline = neutralisation.
* Bile acids (synthesised from cholesterol) for the digestion and absorption of fats = emulsification of fats
*trypsinogen, chymotrypsinogen, procarboxypeptidases = proteases
*amylase = starch - active
*lipase = fat
*RNAase + DNAase - 29Describe control of pancreatic excretions.*Secretion controlled by local reflexes and the gastrointestinal hormones secretin and cholecystokinin (CCK).
* Zymogen granules function as storage vesicles for the pancreatic enzymes. Released into the lumens of the pancreatic ducts by exocytosis. - 30What are the products of protein digestion.
- 31Explain absorption of the products of protein digestion.
- 32What are the products of carbohydrate digestion.
- 33Explain transport of sugars.
- 34Describe the production of bile salts.
- 35What are the products of fat digestion?Colipase is a co-enzyme required for optimal activity. Secreted by the pancreas as inactive pro-colipase, activated by trypsin. It binds to the bile-salt covered triacylglycerol interface of micelles, allowing access of the PTGL to its substrates at the water--lipid interface.
- 36Explain the absorption of products of fat digestion.
Informações
- Descrição
- Pharmacy (6) Gastrointestinal System) FlashCards sobre Gastro-inestinal system, criado por Yasmin Beer em 02-04-2018.
- Criado por
- Yasmin Beer
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