Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
Mucosa |
Contains the epithelial layer and a thin connective tissue layer, and a layer of muscle. |
Think epithelial layer, connective tissue and muscle layer |
|
|
Submucosa |
A connective tissue layer; contains blood vessels, glands and nerves. |
Connective tissue layer, blood vessels, glands and nerves |
|
|
Muscularis |
Responsible for the movement of alimentary canal. Skeletal muscle in mouth and threat, thereafter smooth muscle (circular and longitudinal). Contains myenteric plexus (nerve supply to gut, controlled by ANS) |
Movement for AC, skeletal muscle in mouth/throat, then smooth muscle. Myenteric plexus gut ANS |
|
|
Serosa |
A layer of epithelium and connective tissue responsible for linking the alimentary canal to the peritoneum. |
Layer of epithelium, connective tissue = AC To peritoneum |
|
|
Salivary glands |
Bicarbonates and phosphates which act as buffers. Chlorides which activate amylase. Mucin, which forms mucus when dissolved in water. Lysozyme, which destroys bacteria. |
|
|
|
Zymogenic cells |
Secretes pepsinogen, which is the precursor of the protease, pepsin. |
Peptic cells. Secrete pepsinogen |
|
|
Parietal cells |
Secretes HCL, which converts pepsinogen into pepsin. Secretes intrinsic factor, which is required for the absorption of vitamin B12 |
Secretes HCL- converts pepsinogen to pepsin. Secretes intrinsic factor- absorption of vitamin B12. |
|
|
Mucus cells |
Secrete mucus which prevents the wall of the stomach from being digested. |
Secretes mucus= stomach wall from being digested. |
|
|
Bile |
Emulsifies fat, increasing surface area= pancreatic lipase to break down fat. Also neutralises acidic chyme, helps create optimum pH for enzymes in small intestine. |
Emulsify fat Neutralises acidic chyme, optimum pH |
|
|
Liver |
Produces bile. Stores excess glucose as glycogen. Convert certain AA and lactic acid to glucose. Deamination of excess AA to ammonia then urea. Transamination to convert one AA to another that is needed. Stores some triglycerides, converts fatty acids to acetyl coA, converts excess acetyl coA to ketones |
|
|
|
Pancreas |
2 forms of pancreatic juices. Rich in bicarbonate when acid is detected in the duodenum. Under control of hormone secretin Rich in digestive enzymes when fats are detected in duodenum. Under control of hormone cholecystokinin (CCK).
|
|
|
|
Cephalic phase |
Initiated by sight, smell, taste or thought of food. Salivary glands release saliva. Also leads to the stimulation of parasympathetic impulses via vagus nerve which increased gastric secretions and increased gastric motility. |
|
|
|
Gastric phase |
Initiated by, distension of stretch receptors in stomach. Chemoreceptors which detect an increase in pH due to food entering and buffering some of the stomach acid. Neural and hormonal mechanisms regulate the gastric phase to promote gastric secretion and gastric motility. |
|
|
|
Gastric phase Neural regulation |
Stretch receptors and chemoreceptors become activated when food enters the stomach. This leads to the stimulation of parasympathetic and enteric neuroma (in lining of GI system). These nerve impulses stimulate gastric secretions from cells in gastric glands and cause waves of peristalsis which help gastric emptying. When food enters the duodenum and the pH of the stomach drops the receptors are no longer active. |
|
|
|
Gastric phase-Hormonal Regulation |
Gastric released into bloodstream when: Distension of the stomach. High pH (release of gastrin is inhibited by low pH). Acetylcholine released by parasympathetic neurones. |
|
|
|
Gastrin |
Stimulates the release of gastric juices. Strengthens the contraction of the cardiac sphincter. Increases mobility of the stomach and promotes gastric emptying. |
|
|
|
Intestinal phase |
Initiated by chyme containing fatty acids and glucose entering the duodenum. Regulate (slow down) the release of chyme from the stomach into the duodenum to prevent overloading. Promote continued digestion of food. |
|
|
|
Intestinal phase- Neural regulation |
Presence of food in small intestine initiates a Neural reflex called the enterogastric reflex. Stretch receptors in the duodenum send signals to the medulla oblongata to inhibit parasympathetic stimulation and stimulate sympathetic nerves to the stomach. Slows down gastric mobility and leads to stronger contractions of the pyloric sphincter to slow gastric emptying. |
|
|
|
Intestinal phase- Hormonal regulation-CCK |
CCK released in response to chyme containing undigested material entering the duodenum. CCK causes the release of digestive enzymes and bile into the duodenum by: Stimulating the release of pancreatic juices. Causing contraction of the gall bladder (releasing bile). CCK slows gastric emptying by promoting contraction of the pyloric sphincter. |
|
|
|
Effects of CCK |
Stomach- inhibits gastric secretion and motility. Pancreas- stimulates pancreatic juice secretion. Gallbladder- causes gallbladder to contract. |
|
|
|
Secretin- controls pH |
Secretin is released in the duodenum in response to the drop in pH caused by acidic chyme. Secretin: stimulates the flow of pancreatic juices rich in bicarbonate ions to raise pH. Inhibits the secretion of gastric juices which contains HCL. |
|
|
|
Gastric emptying |
Stimulated by nerve impulses in response to distension of the stomach and the hormone gastrin. Inhibited by distension of the duodenum and presence of acidic chyme because these stimulate enterogastric reflex and the release of CCK which inhibit gastric emptying. The rate at which the stomach empties depends on the amount of chyme the small intestine can process. |
|
|
|
Nervous control of digestion |
Parasympathetic impulses. Increase motility of the small intestine. Stimulate the secretion of pancreatic enzymes. Increase the production of bile. Sympathetic impulses. Have the opposite effects of parasympathetic. Inhibits digestion when body is under stress. |
|
