Digestive/Metabolism Flashcards
Digestive tract
Muscular tube (GI tract) passes through pharynx, esophagus, stomach, small and large intestines
Major organs of digestive tract
Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine
Accessory organs of digestive tract
Teeth, tongue, salivary glands, gallbladder, pancreas
6 Functions of digestive tract
ingestion, mechanical processing, digestion, secretion, absorption, excretion
Lining of digestive tract
Safeguards against: Corrosive effects of acids and enzymes, mechanical stresses such as abrasion, bacteria
Peritoneal fluid
Produced by serous membrane lining, provides essential lubrication, separates parietal and visceral surfaces, allows sliding without friction
Ascites
excess peritoneal fluid causing abdominal swelling
Peritonitis
inflammation
Mesenteries
Double sheets of peritoneal membrane, stabilize positions of attached organs, prevent intestines from becoming entangled
Lesser omemtum
stabilizes position of stomach, provides access route for blood vessels and other structures entering or leaving liver
Falciform ligament
Helps stabilize position of liver
Dorsal mesentery
Enlarges to form an enormous pouch, called the greater omemtum
Greater omentum
Extends inferiorly between body wall and anterior surface of small intestine (hangs like an apron)
Mesentery proper
Thick mesenterial sheet, provides stability, permits some independent movement, associated with initial portion of small intestine (duodenum) and pancreas
Mesocolon
Mesentery associated with a portion of the large intestine
Transverse mesocolon
Supports transverse colon
Sigmoid mesocolon
supports sigmoid colon
Digestive epithelium
Oral cavity, pharynx, and esophagus, mechanical stresses, lined by stratified squamous epithelium, stomach, small intestine, and most of large intestine, absorption
Enteroendocrine cells
(GI tract and pancreas) Scattered among columnar cells of digestive epithelium and secrete hormones to coordinate activities of the digestive tract and accessory glands
Lining of Digestive Tract
Folding increases surface area for absorption (longitudinal folds, permanent transverse folds)
Lamina propria
Consists of a layer of areolar tissue that contains blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, scattered areas of lymphatic tissue
Muscularis mucosae
Narrow band of smooth muscle and elastic fibers in lamina propria, smooth muscle cells arranged in two concentric layers
Submucosa
Layer of dense irregular connective tissue, surrounds muscularis mucosae, has large blood vessels and lymphatic vessels, may contain exocrine glands
Functions of the oral cavity
Sensory analysis, mechanical processing, lubrication, limited digestion
Oral mucosa
lining of oral cavity, has stratified squamous epithelium, of cheeks, lips, and inferior surface of tongue, inferior to tongue is thin and vascular enough to rapidly absorb lipid-soluble drugs
Tongue
Manipulates materials inside mouth
Functions of the tongue
Mechanical processing by compression, abrasion, and distortion, manipulation to assist in chewing and to prepare material for swallowing, sensory analysis by touch, temperature, and taste receptors, secretion of mucins and the enzyme lingual lipase
Saliva
Mix of glandular secretions with slightly different properties, function: lubrication, dissolves chemical=stimulate taste buds, begin digestion, prevent acid buildup and control bacterial growth
Salivary glands
Parotid (25%), Sublingual (5%), Submandibular (70%)
Types of teeth
incisors, cuspids (canines), bicuspids (premolars), molars
Deciduous teeth
AKA primary teeth, milk teeth, baby teeth
Secondary Dentition
Also called permanent dentition, replaces decidous teeth
Esophagus
Hollow muscular tube, moves solid food and liquids to the stomach, enters abdominal cavity through esophageal hiatus
Wall of esophagus has 3 layers
Mucosal, Submucosal, Muscularis
Stomach:functions
Storage, mechanical breakdown, disruption of chemical bonds, production of intrinsic factor
Cephalic phase
Gastric secretion begins when you see, smell taste, or think of food, this phase usually lasts only minutes
Gastric phase
Begins with arrival of food in the stomach, alkaline tide
Intestinal phase
Begins when chyme (undigested) enters SI, function-ensure efficiency of secretion, digestion, and absorption
Small intestine
Plays key role in digestion and absorption of nutrients, 90% of nutrient absorption occurs here
Duodenum
The segment of small intestine closest to stomach, mixing bowl that receives chyme from stomach and digestive secretions from pancreas and liver
Functions of the duodenum
To receive chyme from stomach, to neutralize acids before they can damage the absorptive surfaces of the small intestine
Jejunam
middle segment of small intestine, location of most chemical digestion and nutrient absorption, has few plicae circulares, small villi
IIleum
Final segment of small intestine, ends at ileocecal valve
Enteropeptidase
brush border enzyme, activates pancreatic proenzyme trypsinogen
Enteroendocrine cells
Produce intestinal hormones such as gastrin, cholecystokinin, secretin
Duodenal glands
AKA submucosal glands/Brunner’s glands, produce copious quantities of mucus
Gastrin
Secreted by G cells in duodenum, promotes increased stomach motility, stimulates acids and enzyme production
Secretin
Is released when chyme arrives in duodenum, increases secretion of bile and buffers by liver and pancreas
Gastric Inhibitory Peptide (GIP)
Is secreted when fats and carbohydrates enter small intestine
Cholecystokinin (CCK)
Secreted in duodenum, when chyme contains lipids and partially digested proteins, accelerates pancreatic production/secretion of digestive enzymes
Intestinal absorption
Takes about five hours for materials to pass from duodenum to end of ileum, movements of mucosa increase absorptive effectiveness
Large intestine functions
Reabsorption of water, compaction of intestinal contents into feces, absorption of important vitamins produced by bacteria, storage of fecal material prior to defecation
Parts of the large intestine
Cecum, Colon, rectum
Appendix
Slender, hollow appendage about 9 cm long, dominated by lymphoid nodules, is attached to posteromedial surface of cecum
Four regions of the colon
Ascending colon, transverse colon, descending colon, sigmoid colon
Rectum
Forms last 15 cm of digestive tract, expandable organ for temporary storage of feces, movement of fecal material into this triggers urge to defecate
Anus
Has keratinized epidermis like skin
Internal anal sphincter
Circular muscle layer of muscularis externa, has smooth muscle cells, not under voluntary control
External anal sphincter
Encircles distal portion of anal canal, a ring of skeletal muscle fibers, under voluntary control
Absorption in the large intestine
Reabsorption of water, reabsorption of bile salts, absorption of vitamins produced by bacteria, absorption of organic wastes
3 vitamins produced in large intestine
Vitamin K, Biotin, Vitamin B5
Bacteria break down peptides and feces and generate:
Ammonia, Indole and skatole (nitrogen compounds responsible for odor of feces), hydrogen sulfide
Digestive enzymes-salivary glands
amylase, result-polysacchs
Digestive enzymes-stomach
pepsin, result-proteins
Digestive enzymes-pancreas
lipase, trypsin, chymotrypsin, nucleotidase, result-lipids, proteins, proteins, DNA/RNA
Digestive enzyme-brush-border
Peptidases, nucleases, lactase, maltase, sucrase, result-protein, dinucleotides, lactose, maltose, sucrose
Functions of liver
Metabolic regulation-hepatic portal system: all blood leaving GI tract enters liver, extracts nutrients/toxins, storage: excess vitamins and minerals, metabolism: carbs, lipids, AAs, Bile production
Functions of bile
Bile salts break droplets apart (emulsification), increases surface area exposed to enzymatic attack
Celiac disease
immune reaction to eating gluten
Diverticulitis
inflammation of diverticula (bulging pouches)
Ulcerative colitis
inflammatory bowel disease, affects one area
Crohn’s disease
inflammatory bowel disease, affects multiple areas
