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Published byAudra Thompson Modified over 9 years ago
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cavity not involved in digesting food passageway leads to stomach connection between nasal & oral cavities to larynx & esophagus
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1. nasopharynx- connects w/ nasal cavity 2. oropharynx- passageway food moving down & air moving into trachea 3. laryngopharynx- passageway to esophagus
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1 st stage: › voluntary › food chewed- mixed w/ saliva › rolled into mass by tongue- BOLUS- forced into pharynx
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food is prevented entrance to nasal cavity epiglottis slaps shut over larynx to keep food from going down trachea tongue seals off oral cavity different muscle actions open esophagus & forces food down it
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epiglottis trachea
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breathing momentarily inhibited peristalsis transports food down into & through esophagus choking occurs when food lodges in larynx Heimleich maneuver can dislodge food
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straight tube ~ 25 cm long food passageway from pharynx to stomach goes thru opening in diaphragm contains mucous glands w/ secretions that moisten & lubricate inner lining
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wavelike motion propels food down tubular structures contraction of muscle occur above food & relaxation below it
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hiatal hernia acid reflux Barrett’s esophagus
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Caution!
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j-shaped, pouched organ ~ 1 L capacity fxns: receives food from esophagus, mixes food w/ gastric juices, begins protein digestion, limited absorption, moves food into small intestines
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1. cardiac- 2. fundus- temp storage area 3. body- main part 4. pylorus- approaches small intestines
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inner lining contains gastric glands w/ 3 types secretory cells: A. mucous cells- secrete mucus w/ other secretions keeping stomach from digesting itself B. chief cells- secrete digestive enzymes- pepsinogen C. parietal cells- release HCl & intrinsic factors all these form GASTRIC JUICE (2-3 L/day)
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inner lining= RUGAE- disappears when stomach is distended ulcer is open sore in the lining of stomach may be caused by presence of H pylori bacteria
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pepsinogen is released & when hits HCl forms PEPSIN which digests almost ALL types of protein intrinsic factors aid in vitamin B 12 absorption in small intestines mostly digestion occurs in stomach, but some absorption of water, salts, and drugs does occur
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mechanical & chemical digestion begin here resulting in a semi-paste called CHYME rate at which this enters sm intestine depends of type of food liquids pass thru quickly fatty foods 3-6 hours proteins & carbs pass thru more quickly
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medulla oblongata- vomiting center body prepares for the process by closing off nasal cavity, trachea, contraction of diaphragm, contraction of abdominal muscles, etc
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dual fxn- endocrine gland & digestive gland closely associated w/ small intestine in the curve of duodenum fxn: release pancreatic juice juice contains enzymes that digest carbs, fats, nucleic acids, proteins
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PANCREATITIS- condition where there is a blockage in release of juice essentially pancreas digests itself
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largest internal organ in body inferior to diaphragm on right side of body (under ribs) 4 lobed organ (2) connected to sm intestines by ducts main fxn: manufacture bile salts
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imp role in carb metabolism › regulates glucose in bld imp in lipid metabolism- converting subst into fats (bile salts) imp in protein metabolism
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produce plasma proteins destroy bacteria/old rbc & wbc
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produce enzymes that break down poisons that are harmful to body stores certain vitamins/minerals needed by body also stores poisons that can’t be broken down & excreted activates vitamin D
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cirrhosis hepatitis cancer
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surrounds gallbladder- small, green sac embedded in liver stores & concentrates bile
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gallstones gallbladder attacks
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major digestive organ ~ 21 feet long 3 subdivisions: A. duodenum- ~10” long (25cm) diameter: ~ 2” (5cm) C-shaped around the pancreas B. jejunum- ~ 8’ long greater diameter thicker walls, more vascularized
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C. ileum- ~ 12’ long hard to distinguish between jejunum & ileum
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mesentery- thin membrane that suspends the portions of the intestines from walls contains blood vessels, nerves, lymphatic vessels
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only processes small amount of food at a time so pyloric sphincter muscle considered gatekeeper produces enzymes to digest food (w/ help of pancreatic enzymes & bile)
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enzymes secreted by mucosal cells break down proteins, carbs, fats wall of intestine has many tiny projections called villi microvilli project off the villi the epithelial lining is replaced every 3 to 6 days food absorption occurs thru these structures
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carries on mixing movements & peristalsis chyme moves slowly; 3-10 hours if wall becomes distended/irritated, a peristaltic rush pushes contents to large intestine so quickly that water, nutrients, & electrolytes aren’t absorbed - diarrhea
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~ 5’ length greater diameter than small int fxns: 1. dry out indigestible food residue by absorbing water 2. eliminate residues from body as feces
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little or no digestive fxns no secretions except mucus by goblet cells in wall › protects inner wall › binds fecal matter normally absorbs water & electrolytes many bacteria, intestinal flora, inhabit organ (100 trillion) help break down substances that aren’t by our digestive system
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4 principle regions: 1. cecum- beginning; dilated pouchlike contains appendix (appendicitis) 2. colon- subdivided into 4 parts: a. ascending colon- right side b. transverse colon- across c. descending colon- left side d. sigmoid colon- s-shaped 3. rectum 4. anal canal
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mixing & peristalsis occurs but slower 2-3 mass movements happen per day forces feces into lower 2 regions until eliminated if feces stay in too long leads to constipation
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