Digestion 112 Final Wilson Flashcards
ingestion,
taking food into the mouth (eating)
mechanical digestion
consists of movements of the GI tract that aid in chemical digestion
chemical digestion,
series of catabolic (hydrolysis) reactions that break down large carbohydrate, lipid, and protein food molecules into smaller molecules that are usable by body cells
propulsion,
result from the alternating contraction and relaxation of the smooth muscle
secretion,
the release, by cells within the walls of the GI tract and accessory organs, of water, acid, buffers, and enzymes into the lumen of the tract
defecation,
emptying of the rectum, eliminating indigestible substances from the GI
peritoneum,
membranes of the digestive system
mesentery,
double layer of membrane; back to back
omentum,
tethers stomach to other digestive organs
adventitia,
ordinary fibrous CT that is found in esophagus and retroperitoneal organs
amylase,
begins starch digestion at pH 6.5 or 7.0 found in mouth
lipase,
- Secreted by glands in tongue
* Begins breakdown of triglycerides into fatty acids and glycerol
protease,
digestive enzyme that breaks down protein
nucleases,
breaks down nucleic acids
deglutition,
the bolus is swallowed
peristalsis,
propels chyme onward through the intestinal tract
bolus
Mass of food prepared by the mouth for swallowing
chime,
creamy paste that food is converted into
rugae,
Folds that flatten when filled with bolus
emesis,
reflexive emptying of stomach thru the esophagus and pharynx (vomiting)
plicae circularis,
Permanent ½ inch tall folds that contain part of submucosal layer
villi,
1 mm tall on surface of plicae circolarus that contains vascular capillaries and lacteals (lymphatic capillaries)
microvilli,
Tiny projections on the surface of each cell of villus
hepatocytes
liver cells
bile,
greenish-yellow or brownish fluid produced in and secreted by the liver, stored in the gallbladder, and released into the small intestine
bile canaliculi,
Tiny canals
hepatic portal vein,
carries nutrient rich venous blood, from the small intestine, to the liver
pancreatic acini,
produces the enzyme-rich component of pancreatic juice
segmentation,
the major movement of the small intestine; a localized contraction in areas containing food
teniae coli,
Smooth muscle (3 cords)
haustra,
pocket-like sacs in large intestine
haustral churning,
relaxed pouches are filled from below by muscular contractions (elevator)
gastroilial reflex,
when stomach is full, gastrin hormone relaxes ileocecal sphincter so small intestine will empty and make room
gastrocolic reflex,
when stomach fills, a strong peristaltic wave moves contents of transverse colon into rectum
feces,
dead epithelial cells, undigested food such as cellulose, bacteria (live & dead)
defecation
The elimination of feces from the rectum
Mumps,
Myxovirus that attackes the parotid gland
hiatal hernia,
stomach pierces the diaphragm at hiatus
gastroesophageal reflux disease (GERD),
stomach acids enter esophagus & cause heartburn
appendicitis,
inflammation of the appendix
diarrhea,
not enough water absorbed from chyme
constipation,
too much water absorbed from chyme
dental caries,
tooth decay
diverticulitis,
inflammation of the diverticula
hepatitis
inflammation of the liver
What are the functional segments of the GI tract?
- mouth
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
What are the accessory structures of the GI tract?
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
What are the features and role of the mouth?
features:
• Lips (labia) and cheeks—–contains buccinator muscle that keeps food between upper & lower teeth;
• Vestibule—area between cheeks and teeth;
• Oral cavity proper—the roof = hard, soft palate and uvula (floor = the tongue )
Role: bite, chew, swallow, limited lipid & carb digestion
What are the features and role of the pharynx?
Features:
• Funnel-shaped tube extending from internal nares to the esophagus (posteriorly) and larynx (anteriorly)
Roles: transport
What are the features and role of the esophagus?
Features:
• Collapsed muscular tube
Role: Secrete mucus and transport food to stomach
What are the features and role of the stomach?
Features:
• J-shaped enlargement of the GI tract that begins at the bottom of the esophagus and ends at the pyloric sphincter
Role: mixing and holding area for food; begins the digestion of proteins, and continues the digestion of triglycerides, converting a bolus to a liquid called chyme. It can also absorb some substances.
What are the features and role of the small intestine?
Features:
• The small intestine extends from the pyloric sphincter to the ileocecal sphincter.
• The small intestine is divided into the duodenum, jejunum, and ileum.
Role: The major events of digestion and absorption occur in the small intestine
What are the features and role of the large intestine?
Features:
• extends from the ileocecal sphincter to the anus.
• Its subdivisions include the cecum, appendix, colon, rectum, and anal canal.
• Teniae Coli
• Haustra
• Epiploic appendages: small fat-filled pouches of visceral peritoneum
Role:
– Metabolize some host-derived molecules (heparine, mucin, hyaluronic acid)
– Ferment indigestible carbohydrates
– Release irritating acids and a mixture of gases
– Makes Vitamin K and B
What are the features and role of the teeth?
Features: • Crown • Neck • Roots • Pulp cavity • Enamel • Dentin • Cementum Role: adapted for mechanical digestion
What are the features and role of the tongue?
Features:
• Muscle of tongue is attached to hyoid, mandible, hard palate and styloid process
• Papillae (protects taste buds)
Role: pushes food to back of oral cavity
What are the features and role of the salivary glands?
Features: • 99.5% water and .5% solutes • Under parasympathetic NS Role: • Lubricates & dissolves food • Starts chemical digestion of carbohydrates • Keeps mucous membranes of mouth moist
What are the features and role of the liver?
Features:
• Heaviest gland
• Second largest organ (after skin)
• Divisible into left and right lobes, separated by falciform ligament
• Associated with right lobe are the caudate and quadrate lobes
Role:
• Carbohydrate, lipid, and protein metabolism
• Removal of drugs and hormones from the blood
• Excretion of bilirubin
• Synthesis of bile salts (made by liver cells)
• Storage of vitamins and minerals
• Phagocytosis
• Activation of vitamin D
What are the features and role of the gallbladder?
Features:
• sac located in a depression on the posterior surface of the liver.
Role: storage of bile
What are the features and role of the pancreas?
Features:
• 5” long by 1” thick
• Head close to curve in C-shaped duodenum
• Main duct for pancreatic juices joins common bile duct from liver
• Sphincter of Oddi on major duodenal papilla
Role: produce pancreatic juice (acini cells); islets of Langerhans produce hormones.
What are the main sphincters that separate different areas of digestive system?
- Esophageal sphincter:
- Cardiac sphincter: between stomach and esophagus
- Pyloric sphincter: between stomach and duodenum
- Ileocecal sphincter: between ilium and cecum
- Sphincter of Oddi: between duodenum and hpatopancreatic ampulla
- Internal anal sphincter: at anus: most inner
- External anal sphincter: at anus; lying outside internal sphincter
how the histological features of the lining of the digestive tract changes (what are main epithelial types in different areas),
• Stratified squamous in mouth, esophagus, and anus; rest is simple columnar
Four layers of digestive system wall,
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
role of saliva (what enzymes?),
lubricates and dissolves food and starts the chemical digestion of carbohydrates. –keeps the mucous membranes of the mouth and throat moist.(salivary amylase and lingual lipase)
four types of stomach cells and their secretions,
- Mucus neck cells: secrete acidic mucus
- Chief cells: secrete pepsinogen
- Parietal cells: secrete HCl and intrinsic factor
- Enteroendocrine cells; secrete several paracrines and hormones (includes G cell)
Four cells in small intestine & their roles,
- Enteroendocrine cells: secrete several paracrines and hormones (includes G cell)
- T cells: represent important immunological defensive component
- Paneth cells: secrete antibacterial enzymes
- Intestinal crypt cells: secrete intestinal juices
role of bicarbonate in small intestine,
to neutralize acidic contents coming into it from the stomach
role of cholecystokinin & gastrin,
- Cholecystokinin: controls the quantity of pancreatic juice and bile
- stimulates the secretion of hydrochloric acid, increase motility, and stomach emptying
role of bacteria flora in large intestine
• Bacteria ferment
– undigested carbohydrates into carbon dioxide & methane gas
– undigested proteins into simpler substances (indoles)—-odor
– turn bilirubin into simpler substances that produce color
• Bacteria produce vitamin K and B in colon
