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40 Cards in this Set
- Front
- Back
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What is the function of the upper GI tract? |
Release the constituents of chemically complex foods by DIGESTION to be absorbed from the ALIMENTARY TRACT |
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What are the constituents released by the upper GI tract? |
Amino acids Mineral salts Fat Vitamins |
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What do specialised glands/accessory organs in the upper GI tract do?
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Release digestive enzymes
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Explain mechanical digestion |
When food is broken down into smaller pieces |
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What happens to carbohydrates during chemical digestion? |
Carbohydrates > Disaccharides > Monosaccharides |
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What happens to Proteins during chemical digestion? |
Proteins > Peptides > Amino Acids |
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What happens to Lipids during chemical digestion? |
Lipids > Diglycerides > Monoglycerides & Fatty Acids |
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Name the 3 phases of digestion |
Cephalic Gastric Intestinal
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What is the response the cerebral cortex in the cephalic stage? |
INCREASES saliva, salivary amylase, lysozyme and immunoglobulin production |
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What happens in the Gastric phase of digestion? |
Enhance secretion Food moves to the stomach Food is digested into CHYME (liquid) by PEPSIN and mechanical digestion |
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What happens in the Intestinal phase of digestion? |
Feedback forward to promote digestion, secretion, motility & absorption of nutrients |
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What are the 6 basic processes of digestion? |
Ingestion Secretion Mixing & propulsion Mechanical & Chemical digestion Absorption Defecation |
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Explain secretion |
The release by cells w/in the cells of the GI tract of WATER, ACID, BUFFERS & ENZYMES in the lumen of the tract |
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Explain mixing and propulsion |
It results from the alternating CONTRACTION & RELAXATION of the smooth muscles in the walls of the tract |
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Explain Chemical digestion |
A serious of catabolic (hydrolysis) reactions that break down food molecules into smaller molecules used by body cells |
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Explain absorption |
The passage of end products of digestion from the GI tract into blood/lymph for the distribution of cells |
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Explain defecation |
Emptying of the rectum |
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What are the mechanisms of the gastric phase? |
NEURAL: reflexes due to stimulation of STRETCH receptors as stomach fills & CHEMOreceptors as pH increases HORMONAL: stimulation of GASTRIN release by G cells by parasympathetic activity LOCAL: release of HISTAMINE |
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What is Peristalsis? |
The CONTRACTION & RELAXATION of the muscle layers which occur in waves and push the contents of the tract onwards. |
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Describe the main functions of the Stomach |
Acid (HCl) kills bacteria Produces Chyme Liquefaction of fats Secretion of Gastric juices Secretion of mucus |
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What are Rugae? |
Folds of mucosa and submucosa |
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Why does the stomach secrete mucus? |
To protect epithelial cells from enzymes & acid |
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Why does the stomach secrete pepsinogen? |
So it gets converted into PEPSIN when mixed w/ HCl for protein digestion |
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What type of gland is the pancreas? |
BOTH an endocrine and exocrine gland |
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Where is the pancreas situated? |
In the EPIGASTRIC & the LEFT HYPOCHONDRIAC regions of the abdominal cavity
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What happens during protein digestion? |
1) Pancreatic amylase converts polysaccharides (starches) > disaccharides 2) Trypsinogen > Trypsin 3) Bicarbonate ions help neutralise the acidity of Chyme |
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What increase the surface area of the small intestine? |
Villus Folds Microvilli |
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What sections are the large intestine divided into? |
Ascending Transverse Descending Sigmoid Colon Rectum |
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Which hormone causes the pancreas to produce pancreatic enzymes for digestion? |
Cholecystokinin (CCK) |
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What is the response to the hormone secretin? |
The pancreas produces buffers and bicarbonates that neutralise the acidity of chyme |
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What is motility? |
Spontaneous mass movement |
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What is the Valsava maneuver? |
The INVOLUNTARY MOVEMENT of the bowel wall & the relaxation of external sphincters are assisted by diaphragm thoracic and abdominal muscle contraction |
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What are the main components of colonic secretion? |
Water Mucus Potassium Bicarbonate |
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What is secreted by Goblet cells? |
Alkaline mucus which lubricates intestinal walls & protects mucosa from acidic bacterial action |
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What is the Caecum? |
The 1st part of the l.intestine. Forms a dilated pouch into which opens the ileum, colon, vermiform appendix |
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What is the ascending colon? |
Portion of the l.intestine between the caecum & hepatic flexure |
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What is the transverse colon? |
Runs across the upper part of the abdomen, from the right > left colic/splenic flexure |
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Where is the descending colon? |
Left side of the abdomen from the spleen > iliac crest |
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What is the sigmoid colon? |
S-shaped part of the colon, in the pelvis, extending from the pelvic brim > 3rd segment of the sacrum |
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What is the rectum? |
Distal portion of the colon, beginning anterior to the 3rd sacral vertebra as a continuation of the sigmoid & ending at the anal canal |
