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