DHN 101 CHAPTER 4

GI tract

a holllow, muscular tube that textends approx. 15 feet in length

enterocytes

absorptive cells that is the outer layer of the villus

bioavailability

amount of a particular nutrient that can be effectively digested, absorbed and used by the body

inflammatory bowel disease

autoimmune disorder that is chronic inflammation of the GI tract two types include crohn's disease and ulcerative colitis

roles of digestion

breakdown food into smaller components, absorb nutrients, eliminate solid waste products

chemical digestion

breakdown of large nutrient molecules in food into smaller components, primarily by the action of stomach acid and various enzymes

gastroesophageal reflux

characterized by a dull or burning sensation in the back of the throat or upper chest caused by the passage of acidic content from the stomach into the esophagus

irritable bowel syndrome

characterized byintestinal cramps and abnormal bowel function, usualyl diarrhea, constipation, or alternating episodes

ilocecal sphincter

circular muscle at the end of the ileum that control the rate of emptying undigested material into the large intestine

small intestine

coiled, hollow tube that extends from the stomach to the large intestine; largest component of the GI tract

anosmia

complete inability to detect odors due to obstruction of passageways, brain tumors, dental disease, and irritation of inner lining of the nose bc of cold/allergies

aguesia

complete loss of sense of taste

hypoguesia

condition characterized by diminished ability to taste

bile

contains cholesterol, minerals, bile salts, bilirubin

ulcerative colitis

development of ulcers in the mucosa of the colon and rectum; can spread in a continuous pattern from the rectum to the colon, but not elsewhere in GI tract

gut microbia

ecosystem of bacteria, fungi, and viruses that colonizes the intestinal tract at birth and maintains a symbiotic relationship w the human host

facilitated diffusion

enterocytes absorb some nutrients through this, carries nutrient in transport protein within the membrane of the enterocyte, requires no energy

lysozyme

enzyme in saliva that can destroy some bacteria in food or in the mouth

lingual lipase

enzyme that breaks down fat; typically inactive until it reaches the stomach

salivary amylase

enzyme that initiates chemical digestion in the mouth by beginning the breakdown of starch

pepsinogen

example of a zymogen, inactive form of an enzyme that is store in cells until it is needed for digestion

epiglottis

flap of rough tissue preventing food from entering the larynx and the trachea

bile

greenish yellow fluid that is needed for fat digestion and absorption

gastrin

hormone stimulating stomach motility and gastric gland secretions

mucosa

innermost layer of the GI tract where fluids flow

muscular layer

layer of GI tract w circular and longitudinal muscles

probiotics

live, beneficial bacteria that have been shown to promote human health; lactobacillus and bfidobacterium most often

active transport

low concentration to high concentration, require both transport protein and energy

fermented foods

made through controlled activity of live microbes to change their chemical composition

bolus

mass of food that has been chewed and mixed w saliva and mucus

primary components of GI tract

mouth, esophagus, small intestine, large intestine, rectum, anus

simple diffusion

occurs when the concentration of a particular nutrient is higher in the lumen of small intestine than an enterocyte does not require energy

large intestine

organ that has mucus secreting goblet cells and fecal matter is pushed through the colon by way of muscular contractions until it reaches the end of the sigmoid colon

liver

organ that processes and stores many nutrients as well as synthesizes cholesterol and makes bile

pancreas

organ that produces and secretes many of the enzymes that break down carbs, proteins and fat also secretes bicarbonate ions to neutralize chyme

mechanical digestion

physical breakdown of food as it passes through the GI tract

dysbiosis

potentially harmful and fungal populations override the effects of the beneficial population - due to diet changes, antibiotic use, environmental toxins, and various diseases

small intestine

primary site of chemical and mechanical digestion of nutrients

digestion

process of breaking down large food molecules into nutrients that the body can use

absorption

process of nutrient uptake from the GI tract for transport through the circulatory or lymphatic system

vomiting

process that prevents potentially harmful foods and beverages from entering the small intestine; way of expelling noxious substances

enzyme

protein that allows chemical reactions to occur at a rapid rate

lower portion of stomach

purpose is to mix food with gastric juice

intrinsic factor

secreted by parietal cells, it is a substance needed to absorb vitamin B - 12

pharynx

section of ailmentary canal that connects the nasal cavity w the top of the esophagus

small intestine

sections include the duodenum, jejunum, and ileum

endocytosis

segment of cell membrane surrounds and swallows large substances

chyme

semiliquid mass that forms when food mixed w gastric juice

gastric ulcer

sore that occurs in the lining of the stomach or upper intestine; hcl cmes in contact and digests the lining of the mucosa of the organ

upper esophageal sphincter

sphincter allowing mass of food to enter the esophagus

lower esophageal sphincter

sphincter preventing the backflow of acidic stomach contents into the esophagus

peristalsis

stimulated by swallowing, this includes waves of muscular contractions that help move material through the intestine

cholecystokinin

stimulates gallbladder to contract and release bile into the duodenum facilitates digestion and absorption

secretin

stimulates the pancreas and liver to release a bicarbonate rich solution

olfactory bulbs

structures in the brain that are essential for being able to sense odors

prebiotics

substances that are nondigestable by humans but support and promote the growth of beneficial bacteria in the large intestine

six basic tastes

sweet, salty, sour, bitter, piquancy (spicy), and umami (savory)

accessory organs

teeth, tongue, salivary glands, liver, gallbladder, and pancreas

intestinal sphincters

thickened regions of circular muscle that function like valves to control the flow of contents at various points in the GI tract when it relaxes the passageway opens contraction restricts the flow

villi

tiny, fingerlike projections that covers the mucosa of the small intestine

crohn's disease

type of IBD where certain immune system cells invade the intestinal lining and cause patches of inflammation and tissue damage resulting in accesses, blockages, and fistulas

mastication

type of mechanical digestion that prepares solid foods for swallowing and chemical digestion makes food easier to swallow and increases its surface area, which enables digestive enzyme to have greater access to nutrient

bilirubin

waste products that result from the breakdown of hemoglobin

osmosis

water moving across membranes

gastric juice

watery solutions of stomach secretions that include mucus, HCl, intrinsic factor, and digestive enzymes