Chapter 23: Digestive System Flashcards
Peritoneum
parietal and visceral; simple squamous on top of CT basement membrane
Mesenteries
double layered extesnions of the peritoneum; provide routes for blood vessels lympahtic and nerves; hold organs in place; store fat
Greater Omentum
extends from stomach and drapes over small intestines
Retroperitoneal
organs that are outside the peritoneum; some of pancreas; kidney and part of large intestine and bladder; these organs are covered by adventitia
Peritonitis
inflammation of perotinium
Four Layers of the GI Tract
inner is mucosa (epithelium, lamina propria, and muscularis mucosae); next layer is submucosa (blood vessels and glands); next layer muscularis externa (mostly responsible for peristalsis, circular layer and longitudinal layer); outer layer is serosa (CT, epithelium) or adventitia
Splanchnic Circulation
feeds/drains digestive organs
Arterial Supply..
consists of celiac trunk which serves stomach, spleen and pancreas; and superior/inferior mesenteric arteries serve small and large intestine
Hepatic Portal Veins
collect nutrients from digestive organs and shunts them to the liver
Nerve Supply Of GI Tract
enteric (means digestive) nervous system (gut brain) regulates digestive system activity
Myentreric Nerve Plexus
sandwhiched between longitudinal and circular layers of muscularis externa
Submucosal Nerve PLexus
located with submucosa
Short Reflexes
mediated entirely by enteric NS
Long Reflexes
mediated by enteric NS and autonomic division of CNS via sympathetic and parasympathetic neurons
Mouth
mucosa (lining) is stratified squamous epithelium; bounded by lips cheeks and palate; soft palate closes off nasopharynx when swallowing; continous with oropharynx; accessory organs include tongue, salivary glands, and teeth
Tongue
bundles of skeletal muscle; mixes food with saliva to form a bolus (compact mass); initiates swallowing; upper surface covered with papillae; root of tongue has lingual tonsil
Intrinsic Tongue Muscles
change shape of tongue
Extrinsic Tongue Muscles
alter tongue position (front, back, left, right)
Filliform Papillae
most numerous; roughen tongue surface
Fungiform, Vallate and Foliate Papillae
possess taste buds
Lingual Frenulum
anchors tongue; children born with a short frenulum (ankyloglossia) are “tongue tied”
Parotid Salivary Gland
anterior to ear; contains serous cells
Submandibular Salivary Gland
media aspect of mandibular body; contains serous cells
Sublingual Salivary Glands
under tongue; contains primarily mucous cells (produce mucus)
Mumps
infection of parotid glands; normally one but can be both;males who get it have a 25% infertility rate
Saliva
functions to cleanse mouth, dissolve food chemicals, moisten food and begin digestion
Composition of Saliva
97-99.5% water; electrolytes; has salivary amylase (breaks down proteins) and lingual lipase (break down lipids); has mucin and lysozyme (inhibits bacterial growth) , IgA antibodies (stops pathogens from attaching to mucous membranes) and defensins
Salivation primarily controlled rby…
PNS but strong SNS stimulation inhibits salavation
Teeth
lie in sockets (alveoli) and secured by periodontal ligament; 2 sets deciduous (baby or milk teeth) (20 total) and permamnent teeth (32 total)
Pharynx
mucosa is stratified squamous epithelium; bolus enter oropharynx and passes to laryngopharynx; pharyngal contricts muscles to propel bolus into esophagus
Esophagus
collapsed tube posterior to trachea; mucosa is stratified squaous epithelium; submucosa (areolar CT) contains esophageal glands; muscularis externa muscles transition from skeletal to smooth; outermost layer is adventitia (fibrous CT)
Upper Esophageal Sphincter
at junction with pahrynx
Lower Esophageal Sphincter
at junction with stomach
Heartburn
Stomach acid is burning the end of the esophagus
GERD
gastro esophagela reflux disease; chronic heart burn
Hiatal Hernia
part of stomach is pushing into mediastinum area
What are the phases of deglutition?
(aka swallowing); buccal phase, pharyngeal-esophageal phase (3-5); peristalsis and gastrophageal sphincter opens
Buccal Phase
voluntary; upper esophageal sphincter closed; tongue presses against hard palate and forces bolus back
Pharyngeal Esophageal Phase
tongue blocks mouth and soft palate blocks nasopahrynx; epiglottis blocks trachea; upper esophageal sphincter relaxes and food enters esophagus ADDDDD
Main Regions of Stomach
cardia, fundus, body and pylorus
Cardiac Sphincter
aka lower esophageal; prevents reflux
Pyloric Sphincter
regulates emptying of stomach
Lesser Omentum
extends from lesser curvature to liver
Greater Omentum
extends from greater curvature and drapes over small intestine
Rugae
allow distension of the stomach; longitudinal folds
3 Layers of Stomach Muscularis Externa
outer longitudinal layer; middle circular layer; and inner oblique layer
Mucosa of Stomach
lined with simple columnar epithelium composed of mucous cells
Gastric Pits
lead into gastric glands
Gastric Gland Cells
mucous neck cells; parietal cells; chief cells; enteroendocrine cells
Mucous Neck Cells
produce thin acidic mucus
Parietal Cells
secrete intrinsic factor and HCL; intrinsic factor is vital bc without it you can not absorb B12
Chief Cells
secrete pepsinogen (converted to pepsin in lumen of stomach which breaks down proteins) and lipases (lipid breakdown)
Enteroendocrine Cells
secrete chemical messengers; histamin, serotonin and gastrin
Mucosal Barrier
protects stomach mucosa; thick layer of bicarbonate rich mucous; epithelial cells of mucosa joined by tight junctions; damaged mucousa cells shed and quixkly regenerate (3-6 days)
Gastritis
inflammation of stomach lining
Gastric Ulcer
mucosal barrier in an area has thinned and part of stomach digested; becomes deadly if stomach contents get into abdominal cavity; normally occurs in polorus section; normally caused by helicobacter pylori bacteria
ADD IN GASTRIC PHASES
Liver
largest gland in the body; 4 primary lobes: right , left, caudate and quadate; blood enters liver via haptic artery and hepatic portal vein; composed of hexagonally- lobules
Hepatocytes
produce bile
Bile is NOT…
an enzyme; it is an emusifer (such as fats)
Blood Flow through the Liver
celiac trunk to haptic artery to portal arteriole
mesenteric veins to hepatic portal vein to portal vein
both of these converge to liver sinusoids to central vein to haptic vein to inf vena cava
Flow of Bile
hepatocytes to bile canaliculi to bile duct of triad to R and L hepatic ducts to common haptic duct to bile duct to hepatopancreatic ampulla to duodenum
Composition of Bile
bile salts (emulsify fats adnd conserved/recycled); bile pigment (primary bilirubin); cholesterol; triglycerides; phospholipids; electrolytes
Hepatitis
inflammation of the liver due to toxic effects of alcohol, grugs or viruses; HVA and HVE trasminted enterically (consumed) and self limiting (cures itself); HVB and HVC transmitted blood; linked to chronic hepatitis, cirrhosis and cancer
NAFLD (non-alcoholic fatty liver disease)
usually no symptoms; most common in N america; linked to insulin resistance
cirrhosis
late stage fibrosis of the liver; usually results from chronic hepatitis due to alcoholism, NAFLD or viral hepatitis
Gall Bladder
thin walled muscular sac; stores and concentrates bile; released bile into bile ducts via cytic duct
Gallstones
cholesterol crystalized and creates lil balls; can clog ducts; removed best by ultrasounds
Jaundice
piled up pigments
Pancreas
mostly retroperitoneal; has endocrine and exocrine functions; endocrine portion (islets) produces insulin and glucagon; exocrine portion acinar cells produce enzymes and duct cells produce h2o and HCO3
Composition of Pancreatic Juice
pH ~8; water; electrolytes (primarily HCO3); enzymes (amylase, lipases, nuclease, and proteases)
Enteropeptidase
brush border enzyme; activates tripsinogen and then tripsen activates others
Regualtion of Bile and Pancreatic Secretion
under neural and (primarily) hormonal control (primarily CCK and Secretin)
Small Intestine
3 parts: duodenum, jejunum, and ileum; main site of digestion and absorption; blood supplied primarily by superior mesenteric artery; blood drained by superior mesenteric vein into hepatic portal vein
Villi
finger like projections of mucosa; each villus contains blood capillaries and a lacteal
Microvilli
cytoplasmic extension of muscosa; form the brush border which produces several membrane bound enzymes
Intestinal Crypts
tubular glands; located betwee villi
Enterocytes
primarily absorptive cells interconnected via tight junctions
Goblet Cells
secrete mucus
Enteroendocrine Cells
produce enterogastrones (secretin and CCK)
Pareth Cells
secrete defensins and lysozyme (destroy certain bacteria); found primarily at base of crypts
Stem Cells
divide continuously; found primarily at the base of crypts
Duodenal Glands
located in submucosa of duodenum; secrete alkaline mucus (neutralizes acidic chyme entering duodenum);
Peyers Patches
located at mucosa and submucosa of the ileum; component of MALT
Ileocecal Valve
located at junction of small and large intestine
Segmentation
pattern of motility after a meal; mixes chyme with bile, pancreatic and intestinal juices
Migrating Motor Complex
pattern of motility between meals; initated by motilin (hormone porduced by duodenal mucosa during fasting); peristaltic waves move last remnants of meal and bacteria into large intestine
Large Intestine
extends from ileocecal valve to anus; main function is to absorb water and eliminate indigestible food residues (feces); 3 unique features- teniae coli (band of longitudinal muscle), houstra (lil puckers) and epiploic appendages (bundles of fat)
Cecum
blind sac; first part of lg intestine; below where ilium joings lg intestine and appendix hands off
Appendix
part of MALT
Colon
have the ascending, descending, transerse and sigmoid
Rectum
3 rectal valves (prevents ya from pooping when you fart)
Anal Canal
internal (smooth muscle) and external (skeletal muscle); anal sphincter
Hemorrhoids
collection of blood vessels/excess tisue that extends into canal
Microanatomy of Large Intestine
mucosa is simple columnar epithelium (except anal canal which is stratified squamous); lacks circular folds, villi and microvilli; large number of goblet cells
Gut Bacteria
ferment some indigestible carbohydrates (lactose); synthezise (some) B complex vitamins and vitamin K
Valvasalva Maneuver
basically straining
Diverticulosis
lil pockets in lg intestine; recommend eating more fiber
IBS
irritable bowel syndrome; severe abdominal pain; prompted by stress
Diarrhea
watery stool; notime to absorb excess water
Constipation
absorbing too much water
Digestion
catabolic process- lg molecules hydrolyzed into monomers; requires enzymes; most digestion occurs in the small intestine
Absorption
process of moving monomers from lumen of intestine into the body; must pass through epithelial cells to be absorbed
