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KNH 102 CH3
Nutrition CH3; Digestion, Absorption, and Transport
| Question | Answer |
|---|---|
| What is digestion? | The body's way of breaking down foods into nutrients in preparation for absorption. |
| Summarize some challenges of this process (digestion) | -throat must preform breathing & swallowing -food must pass through diaphragm to reach stomach -everything must constantly move forward -foods must be lubricated with right amt of fluid -digestive enzymes must not digest cells of GI tract -control BM |
| What composes GI tract? | -it is a flexible muscular tube that extends from: mouth, esophagus, stomach, small/large intestine, rectum & anus. |
| What is the lumen? | The inner space in the GI tract. |
| Summarize what happens in the mouth | chewing: breaks down food & mixes w/ salivary glands to be tasted by tongue & swallowed. taste buds: taste sweet, sour, salty, bitter --when food is swallowed, passes thru pharynx (shared by digestive & respiratory sys) |
| What is the pharynx? | a short tube shared by digestive & resp sys's. The passageway from nose/mouth to larynx & esophagus. Directs food from mouth to esophagus. |
| What is the epiglottis? | Epiglottis closes off entrance to the lungs so choking doesn't happen when swallowing. |
| What is the role of the esophagus? | Passes food from the mouth to the stomach. |
| What is a bolus? | A portion of food swallowed at one time. |
| What is a sphincter & why is it important? | a circular muscle that constricts a passage/closes an orifice. When relaxed, allows materials to pass through. When contracted, closes the opening. Four main sphincter muscles: the cardiac sphincter, the pyloric sphincter, and two anal sphincters. |
| What is a chyme & where does it go? | A semiliquid mass transferred by the stomach to the remainder of the GI tract [small/large intestine(colon)/rectum] |
| What are the 3 sections of the small intestine? (in order) | 1. Duodenum 2.Jejunum 3. Ileum (makes up about 10 ft of tubing!) |
| What is the ilocecal valve & its purpose? Where is it located? | -it is a sphincter; opens/closes passage to large intestine. -located @ the beginning of large intestine. |
| What is the appendix? Where is it located? | -It is at the beginning of the large intestine past the ilocecal valve. -Store lymph cells; is a narrow blind sac extending from the beginning of the colon that stores lymph cells. |
| What happens in the large intestine (Colon)? | -Chyme passes through a sphincter(ilocecal valve) to enter, passes appendix, travels up right side to front left & down. -Withdraws water, leaving semisolid waste. |
| What is the rectum? | The muscular terminals part of the intestine, extending from the sigmoid colon to the anus; stores waste. |
| What is the anus? | The terminal outlet of the GI tract; it holds rectum closed & opens to allow elimination. |
| What is peristalsis & why is it important? How is it created? | Wave-like muscular contractions of the GI tract's CIRCULAR & LONGITUDINAL muscles that push its contents along. -when rings TIGHTEN & long relax = tube constricted -when rings RELAX & long tighten = tube is bulged. |
| What can interfere with normal GI contractions? | -stress (IBS), medicines & medical conditions. |
| List actions that occur in the stomach | -Thickest walls/strongest muscles of GI -Circular, longitudinal & diagonal muscles force the chyme down while pyloric sphincter stays closed; churns chyme while gastric juices are released. -When contents are liquefied the pyloric sphincter opens 3x mi |
| What is segmentation? What is its purpose? | -When the circular muscles contract to squeeze their contents; this mixes the chyme & promotes close contact w/ digestive juices & the absorbing cells of the intestinal walls before letting the contents move along. |
| Important sphincters? | -Esophageal sphincter [top] -Lower esophageal/cardiac sphincter -Pyloric sphincter -Ileoceal valve -Rectal muscles |
| Lower esophageal sphincter/cardiac sphincter | @ bottom of esophagus; prevents reflux of stomach contents. |
| Pyloric Sphincter | @ bottom of stomach; holds chyme in stomach long enough to be liquefied. Prevents intestinal contents from backing up into stomach. |
| Ileocecal valve | @ end of small intestine; allow contents of small intestine to empty into large intestine. |
| What organ secretions are required for digestion? | (5 different organs) 1.Salivary glands: exocrine glands 2.Stomach: adds acid, enzymes, fluid 3.Pancreas: exocrine sec. of enzymes + bicarbonate 4.Liver: via gallbladder 5.Small instest |
| What are enzymes & what are their functions? | -A protein that facilitates a chemical rxn. -In digestion they facilitate hydrolysis(addition of H2O) to break molecule into smaller pieces. -"ase" denotes an enzyme |
| Purposes of saliva? What does it contain? | -from salivary glands -contains H2O, salts, mucus, enzymes -Initiates digestion of carbohydrates, protects teeth & lining of mouth/esophagus/stomach |
| What is in gastric juice? | Water, enzymes, hydrochloric acid (protein digestion) |
| Why does the stomach have strong acidity? What pH is maintained? | -Prevents bacterial growth & kills most bacteria that enter w/ food. -below 2 on the pH scale [gastric juice] |
| How does body protect stomach? | The cells of the stomach wall secrete mucus. |
| [In the stomach] What happens to salivary enzymes? other enzymes? | Sal. enzymes do not work in acid this strong [pH: 2], they become other proteins to be digested. -Stomach enzymes work best in strong acid. |
| As food leaves stomach what happens to pH? How is this done? | Pancreatic juice neutralizes the acidic chyme arriving in the small intestine from the stomach; from then on, chyme is neutral or slightly alkaline pH. |
| After food leaves stomach what other enzymes are provided? What are their sources? | -Pancreas gives pancreatic juice contains enzymes -Cells of intestinal wall also produce digestive enzymes on their surfaces |
| What is bile? What is its source & purpose? | -Bile is an EMULSIFIER; brings fats into suspension in H2O so that enzymes can break them down into components. -Liver produces bile - stored in gallbladder |
| What happens to fiber? What is its function? | Some fibers are not absorbed; continue through tract carrying minerals, bile acids, additives & contaminants out of the body. Also retains H2O, accounting for consistency of stools. |
| What happens in the colon? | Intestinal bacteria ferment some fibers, producing water, gas & small fragments of fat |
| What is absorption? | -The retrieval of carbohydrates, protein, fats, vitamins & minerals from digesting food. |
| How do the nutrients get across the intestinal wall/describe anatomy of intestinal wall | -Hundreds of folds in intestinal wall, contoured into thousands of finger-like projections. These are villi. -A single villus is composed of hundreds of cells - each covered in microscopic hairs [MICROVILLI] |
| Crypts | Crevices btwn villi lie in the crypts: tubular glands that secrete intestinal juices into the small intestine. |
| Goblet cells | -secrete mucous -glandular simple columnar epithelial cells whose sole function is to secrete mucin, which dissolves in water to form mucus. They use both apocrine and merocrine methods for secretion. |
| What nutrients are absorbed into the capillaries of the blood stream where they are sent? | -water soluble nutrients & smaller products of fat digestion & guided to liver -larger fats & fat-soluble vitamins insoluble in H2O cluster to form CHYLOMICRONS. |
| What nutrients are absorbed into the lymph system? Where are they sent? | -large fats & fat soluble vitamins -once inside vascular system, nutrients travel freely to any destination. |
| What is the purpose of the vascular system? | - closed system of vessels through which blood flows continuously, with the heart as the pump. as blood moves thru system it picks up & delivers materials as needed |
| What happens to blood leaving the digestive system? | Blood leaving goes thru the hepatic portal vein- which directs blood to the liver - branches into capillaries then collects into the hepatic vein- returns blood to the heart. |
| What organ first receives nutrients absorbed from the GI tract? | The liver first receives the nutrients |
| What are some of the roles of the liver? | -bodys major metabolic organ, defends body by detoxifying substances, preparing waste products for excretion |
| What is the purpose of he lymphatic system? How does it ultimately enter the blood stream? | -1-way route for fluid from tissue spaces to enter blood. Lymph circulates between cells & collects into tiny vessels. -Fluid moves thru body as muscles contract/create pressure; lymph ends in thoracic duct behind heart which opens to subclavian vein |
| What factors can affect normal GI functions? | -bacterial/hormonal regulation/peristalsis and sphincter action poorly coordinated/ diseases/ lack of nourishment/young age/ aging/illness/nutrition |
| GI tract health depends on.. | -adequate nutrition |
| What is homeostasis? How does body maintain/regulate it? | -the maintenance of constant internal conditions by the body's control systems. -hormonal (endocrine) & nervous system |
| what are hormones? | -chemical messengers secreted by a variety of glands in response to altered conditions of the body - travels to specific areas where it elicits a specific response to maintain homeostasis. |
| What are the roles of secretin? | stimulates the pancreas to release bicarbonate rich juices that neutralize the chyme. |
| What is the role of CCK? | Cholecystokinin hormone -when fat is present in the intestine, CCK is the messenger that tells gallbladder to squirt bile to emulsify fat. |
Created by:
bgodbey
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