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Digestive System

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icer215's version from 2016-08-29 05:30

Section

Question Answer
IngestionSaliva, 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.)
Bolusball of chewed food as chewing processes
Pharynxthroat, 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
Esophagusmuscular tube that propels bolus to the stomach by peristalsis, which squeeze of smooth muscle (sphincter) that allows things to go through the tube
Stomachfunction in storage and churning food
Storagea muscular bag that can stretch to store food
Churningmixes food for mechanical digestion
Mucus protects acidic environment in stomach from self-destruction
Parietal cellssecrete HCl (low pH, very acidic) that causes the pH to be very acidic
Gastric juiceis made up of HCl, pepsin, and hormones.Secreted by the stomach (parietal and chief cells, and enteroendocrine cells)
Pepsinprotease (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)
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Goblet cellssecrets mucus lining that protects the stomach from very low pH (self-destruction).
Gastrina 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 topby the cardiac (gastro-esophageal) sphincter
Sealed off on the bottomby the pyloric sphincter
Small intestinedigests 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
Villifinger-like protrusions inside small intestine
Microvillisame 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
Duodenumfirst section (the most higher division) of the small intestine. Responsible for food breakdown with enzymes
Jejunummiddle section of the small intestine. Absorption of nutrients
Ileumfinal section of the small intestine. Absorb vitamin B and bile salts (whichever that didn’t get absorbed by jejunum)
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Large intestine includes partsCecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum
Function of water absorptionRemaining water that is not absorbed by small intestine is absorbed
Bacterial floraGas ferment, undigested nutrients. Produce vitamin K crucial for clotting
Structure Large intestineMany lobes along the length due to muscle tone, however no villi or microvilli like small intestine
Carbohydrate digestive enzymesAmylase and Sucrase/lactase/maltase
AmylaseBreaks down polysaccharides (starch) into disaccharides (maltose
Sucrase/lactase/maltaseBreaks down disaccharides into monosaccharides (sucrose, lactose, maltose)
Lipid digestive enzymesLipase
LipaseBreaks down fat into glycerol and fatty acids
Protein digestive enzymesPepsin/protease/trypsin and Chymotrypsin/peptidase
Pepsin/protease/trypsinBreaks 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
Albuminis 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 isan influx of interstitial fluids into the bloodstream.
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Functions of the liver Produce bile. Glucose regulation. Store/produce glycogen. Detoxification. Vitamin and iron storage
GallbladderPear shaped organ. Located behind the liver. Store/concentrate bile. Release into the small intestine when necessary for digestion/absorption of fats.
BileEmulsifying 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 pancreasProduces 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)
RectumLocated at the end of the large intestine (sigmoid colon) and terminates in the anus. Usually between 10 – 12 cm in length
Function of the rectumstorage and elimination of waste, feces. Expansion of the rectal walls ➙ activates stretch receptors ➙ stimulates the urge to defecate. Anal sphincter closes/opens
The Sphincter MuscleCircular muscle. Maintain constriction/relaxation of body passages. Most important structures in human body
Sphincter pyloriin stomach muscle that hold/release food for thorough mixing of food
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Classification of the Sphincter MuscleAnatomical. Facilitate localized and circular sphincter muscle actions
Functional of the Sphincter MuscleNo localized muscle Instead, muscle contraction structure. Extrinsic and intrinsic structure
Voluntary of the Sphincter MuscleBy somatic nerves
Involuntary of the Sphincter MuscleBy autonomic nerves
The excretory systemis controlled by the Hypothalamus and Adrenal cortex
HypothalamusProduces 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 cortexProduce 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 systemthe 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 ControlThe excretory system is controlled by nervous system
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