Ch.4: Digestion Flashcards
Organ
structure consisting of cells and tissues that perform a specific function in an organism
organ system
group of organs classified as a unit bc they work together to perform a function
ATP
adenosine triphosphate
Chemical that supplies energy for cellular processes and reactions
Digestion
process by which large ingested molecules are mechanically and chemically broken down to produce smaller molecules that can be absorbed across the wall of the GI tract
Absorption
nutrient molecules are absorbed by the GI tract and enter the bloodstream
Peristalsis
rhythmic waves of contraction/relaxation of muscles to move through GI tract toward the anus
Segmentation
a back and forth action of the small intestine breaks apart contents of small intestine into increasingly smaller pieces and mixes them with digestive juices
Enterohepatic circulation
continual recycling of compounds between the small intestine and the liver
(hepatic=liver)
Layers of the GI tract
Mucosa
Submucosa
SMerosa
Villi Microvilli
Mucosa
internal skin separates food from the interior body
submucosa
loose connective tissue, glands, blood vessels, and nerves.
Blood vessels carry substances & nutrients to and from the GI tract
Serosa
protects the GI tract
Villi
fingerlike protrusions into the small intestine that participate in digestion and absorption of food components
Microvilli
microscopic, hairlike projections of the cell membranes of certain epithelial cells
Roles of the Stomach in Digestion
secretes Gastric Juice Mixes food with enzymes and acid Kills mircoorganisms Secretes Intrinsic Factor (for B12) Releases chyme into the Small Intestine
Liver in Digestion
produces bile to aid fat digestion and absorption
Gallbladder in Digestion
Stores and Concentrates bile and releases it into the Small Intestine
Pancreas in Digestion
Secretes pancreatic juice containing digestive enzymes and biocarbonate into the small intestine
Small Intestine in Digestion
Mixes chyme with bil and pancreatic juices to complete remaining residue to large intestine digestion, absorbs nutrients and other compounds in foods
Large Intestine/Colon in Digestion
Absorbs water and electrolytes (sodium & potassium), Forms and stores Feces, and Expels Feces
Rectum
Holds and expels feces
Sequence of the GI tract (10 steps)
mouth esophagus stomach liver gallbladder pancreas small large rectum anus
Forms of Absorption in the Small Intestine
Passive Diffusion Facilitated Diffusion Active Transport Endocytosis Absorbs 90% water
Pyloric Sphincter
controls the flow of stomach contents into the small intestine
Hepatopancreatic Sphincter
Controls the flow of bile and pancreatic juices from the common bile and pancreatic ducts into the small intestine
Ileocecal Valve
prevents contents of the large intestine from reentering the small intestine
Saliva in Digestion
contain lysozymes that kill bacteria
contain amylase that breaks down starch
What is in gastric juice
HCl
KCl
NaCl
Functions of HCl
Inactivates ingested proteins
Destroys bac and viruses
Dissolves minerals
Converts pepsinogen into pepsin
Pepsin
Breaks down protein
What do parietal cells secrete
HCl and Intrinsic Factor
What do chief cells secrete
gastric lipase
pepsin
Why is the stomach lower in pH than the small intestine
Sodium bicarbonate neutralizes chyme in the stomach
Cholecystokinin
Stimulates the release of pancreatic enzymes and bile
Stimulated by dietary fat in chyme
Secreted from the small intestine
Secretin
Stimulates release of pancreatic bicarbonate
Stimulated by acidic chyme and as digestion progresses
Secreted from the small intestine
Gastrin
Triggers the stomach to release HCl and pepsinogen and stimultes gastric and intestinal motility
Stimulated by food reaching the stomach
Stored in the stomach and duodenum
Structures on the surface area of the small intestine
villi and microvilli
passive diffusion
diffusion without a carrier nor energy
facilitated diffusion
diffusion with a carrier protein
active transport
diffusion with both energy and a carrier protein
Phagosytosis
cells engulf compounds
Pinocytosis
cells engulf liquids
How are Water Soluble nutrients transported
Through the cardiovascular system
How are Fat Soluble Nutrients absorbed
Through lacteals in villi
3 main funct of large intestine
house microbiata
absorb water and electrolytes
form and expel feces
Probiotic v Prebiotic
Probiotic: live microorganisms that colonize the large intestine
Prebiotic: non-digestible food ingredients that promote the growth of beneficial bacteria
Ulcer Prevention
Stop smoking Avoid large doses of aspirin Limit caffeine, alc Limit strong spices Chew food well Lose weight
Heartburn Prevention
Same as Ulcer Prevention
Wait 2 hours before laying own after a meal
Portion meals
Elevate head of the bed
