Digestive System
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2016-08-29 05:30
Section
| Question | Answer |
|---|---|
| Ingestion | Saliva, Pharynx, Esophagus |
| Saliva | is used as lubrication and is a source of enzymes. Dissolves food. Contains mucin, a protein that lubricates the bolus. Contains antibodies and lysozyme that kill pathogens (any virus etc.) |
| Bolus | ball of chewed food as chewing processes |
| Pharynx | throat, a muscular tube that is located between mouth and esophagus in functioning of swallowing by squeezing and routing food to the esophagus (pathway to nasal cavity and airway is closed off) |
| Epiglottal | action occurs when swallowing – flap of cartilage that closes off of airway |
| Esophagus | muscular tube that propels bolus to the stomach by peristalsis, which squeeze of smooth muscle (sphincter) that allows things to go through the tube |
| Stomach | function in storage and churning food |
| Storage | a muscular bag that can stretch to store food |
| Churning | mixes food for mechanical digestion |
| Mucus | protects acidic environment in stomach from self-destruction |
| Parietal cells | secrete HCl (low pH, very acidic) that causes the pH to be very acidic |
| Gastric juice | is made up of HCl, pepsin, and hormones.Secreted by the stomach (parietal and chief cells, and enteroendocrine cells) |
| Pepsin | protease (enzyme) that works best in acidic environment, digests proteins which are secreted in an inactive form (called proteases at this time) and get activated as entering into acidic environment (called pepsin now, low pH) |
| Question | Answer |
|---|---|
| Goblet cells | secrets mucus lining that protects the stomach from very low pH (self-destruction). |
| Gastrin | a hormone secreted by the wall of the stomach and cleaves large proteins into smaller size |
| Inner membrane | is folded densely, accommodating for stretchy property |
| Sealed off on the top | by the cardiac (gastro-esophageal) sphincter |
| Sealed off on the bottom | by the pyloric sphincter |
| Small intestine | digests and absorbs food molecules and water. Large surface area from folds, villi and microvilli is essential for absorption. Digested food get absorbed into circulation. makes their own enzymes like protease and amylase, pancreas is the major source for enzymes |
| Villi | finger-like protrusions inside small intestine |
| Microvilli | same as villi but on the surface of a single absorptive cell |
| Acidic stomach acid | (HCl) gets neutralized by bicarbonate ions produced by pancreas |
| Active transport | is required to absorb against concentration gradient |
| Passive/ facilitated diffusion | occurs to absorb down the concentration gradient |
| Duodenum | first section (the most higher division) of the small intestine. Responsible for food breakdown with enzymes |
| Jejunum | middle section of the small intestine. Absorption of nutrients |
| Ileum | final section of the small intestine. Absorb vitamin B and bile salts (whichever that didn’t get absorbed by jejunum) |
| Question | Answer |
|---|---|
| Large intestine includes parts | Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum |
| Function of water absorption | Remaining water that is not absorbed by small intestine is absorbed |
| Bacterial flora | Gas ferment, undigested nutrients. Produce vitamin K crucial for clotting |
| Structure Large intestine | Many lobes along the length due to muscle tone, however no villi or microvilli like small intestine |
| Carbohydrate digestive enzymes | Amylase and Sucrase/lactase/maltase |
| Amylase | Breaks down polysaccharides (starch) into disaccharides (maltose |
| Sucrase/lactase/maltase | Breaks down disaccharides into monosaccharides (sucrose, lactose, maltose) |
| Lipid digestive enzymes | Lipase |
| Lipase | Breaks down fat into glycerol and fatty acids |
| Protein digestive enzymes | Pepsin/protease/trypsin and Chymotrypsin/peptidase |
| Pepsin/protease/trypsin | Breaks down protein into amino acids |
| Liver | is triangular shaped organ. Extends across the abdominal cavity. Located on the right side of the stomach, superior (above) to the small intestine, and inferior (below) to the diaphragm. Thus close relationship with digestive system |
| Albumin | is a protein made by the liver. It makes up about 60% of the total protein in the blood and plays many roles. It keeps fluid from leaking out of blood vessels; nourishes tissues; and transports hormones, vitamins, drugs, and ions like calcium throughout the body. |
| The effect of a sharpe rise in the level of serum albumin is | an influx of interstitial fluids into the bloodstream. |
| Question | Answer |
|---|---|
| Functions of the liver | Produce bile. Glucose regulation. Store/produce glycogen. Detoxification. Vitamin and iron storage |
| Gallbladder | Pear shaped organ. Located behind the liver. Store/concentrate bile. Release into the small intestine when necessary for digestion/absorption of fats. |
| Bile | Emulsifying agent that digest lipids (fats). Digest large fat droplets into smaller pieces, increasing the surface area for fat to be digested by lipase |
| The liver | produces bile and the gallbladder stores it |
| Pancreas | is located behind the stomach with pancreatic duct |
| The pancreas produces digestive enzymes, including: | Amylase-digests starch (polysaccharide). Proteases-digests proteins. Lipase-digests lipids .Ribonuclease-digests nucleic acids |
| The pancreas | Produces bicarbonate, which neutralizes the hydrochloric acid (HCl) from the stomach (very acidic pH). Transports enzymes to the small intestine. a large gland; it secretes enzymes into the small intestine through pancreatic duct (exocrine function) |
| Rectum | Located at the end of the large intestine (sigmoid colon) and terminates in the anus. Usually between 10 – 12 cm in length |
| Function of the rectum | storage and elimination of waste, feces. Expansion of the rectal walls ➙ activates stretch receptors ➙ stimulates the urge to defecate. Anal sphincter closes/opens |
| The Sphincter Muscle | Circular muscle. Maintain constriction/relaxation of body passages. Most important structures in human body |
| Sphincter pylori | in stomach muscle that hold/release food for thorough mixing of food |
| Question | Answer |
|---|---|
| Classification of the Sphincter Muscle | Anatomical. Facilitate localized and circular sphincter muscle actions |
| Functional of the Sphincter Muscle | No localized muscle Instead, muscle contraction structure. Extrinsic and intrinsic structure |
| Voluntary of the Sphincter Muscle | By somatic nerves |
| Involuntary of the Sphincter Muscle | By autonomic nerves |
| The excretory system | is controlled by the Hypothalamus and Adrenal cortex |
| Hypothalamus | Produces antidiuretic hormone (ADH) and released by the posterior pituitary. ADH causes more water to be absorbed through aquaporin by the kidneys before excreted when water level in the body is low |
| Adrenal cortex | Produce aldosterone, which increase the level of sodium and potassium ions in the blood, causing more water to be resorbed to retain water in the body |
| The sympathetic nervous system | the part of the autonomic nervous system (ANS), stimulates the fiber of the hypo gastric nerve, suppressing contraction of the smooth muscle of the bladder, which stimulates the bladder to fill |
| The parasympathetic nervous system | the other part of the autonomic nervous system (ANS), stimulates the fibers in the pelvic nerve, contracting them, which stimulates the bladder to empty |
| Nervous Control | The excretory system is controlled by nervous system |
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