Chapter 23 Digestive System Flashcards
Alimentary canal
- GI tract
- Digest and absorb food
- Mouth, esophagus, stomach, small intestine, large intestine
Ingestion
-The intake of food into the mouth
Propulsion
-Movement of particles through the alimentary canal, through peristalsis
Mechanical digestion
-Chewing and mixing food for chemical digestion and segmentation, rhythmic local constrictions in the stomach
Chemical digestion
-Catabolation of particles into chemical building blocks; accomplished by enzymes
Absorption
-Passage of products from the GI lumen to the blood and lymph, though active and passive transport
Defecation
-Elimination of indigestible products
Peristalsis
-Adjacent segments of alimentary tract organs alternately contract and relax, which moves food along the tract distally
Segmentation
-Nonadjacent segments of alimentary tract organs alternately contract and relax, moving the food forward then backward. Food mixing and slow food propulsion occurs.
Short reflex
-Local control of enteric plexus (gut brain)
Long reflex
-Uses the CNS and autonomic nerves
Peritoneum
-Serous membrane of the abdominal cavity
Visceral peritoneum
-On external surface of most digestive organs
Parietal peritoneum
-Lines the body wall
Peritoneal cavity
- Between the two peritoneums
- Fluid lubricates mobile organs
Mesentary
-Double layer of peritoneum
Retroperitoneal
-Lie posterior to the peritoneum
Intraperitonial
-Surrounded by the peritoneum
Splanchnic circulation
-Arteries that branch off the dorsal aorta and are part of the Hepatic Portal System
Mucus
- Protects digestive organs from enzymes
- Eases food passage
Lamina propia
- Loose areolar connective tissue
- Capillaries for nourishment and absorption
- Lymphoid follicles (part of MALT)
Muscularis mucosa
-Smooth muscle that produces local movements of mucosa
Adventitia
-Replaces the serosa in the esophagus
Sphincter
-Cylindrical muscle that maintains constriction of a passage
Enteric neurons
-Regulate digestive activity within the gut; it is local rather than systemic
Mouth
-Oral (buccal) cavity
Buccal cavity
-Bounded by lips, cheeks, palate, and tongue
Orbicularis oris
-Muscle of the lips
Buccinators muscle
-Muscle of the cheeks
Vestibule
-Recess internal to lips and cheeks, external to teeth and gums
Oral cavity proper
-Lies within the teeth and gums
Labial frenulum
-Median attachment of each lip to the gum
Hard palate
-Palatine bones and palatine processes of the maxillae
Soft palate
-Fold formed mostly of skeletal muscle
Filiform papillae
-Whitish, give the tongue roughness and provide friction
Fungiform papillae
-Reddish, scattered over the tongue, house taste buds
Vallate papillae
-V-shaped row in back of tongue, house taste buds
Foliate papillae
-On the lateral aspects of the posterior tongue, house taste buds used in infancy and early childhood
Terminal sulcus
-Marks the division between the body and root
Body of the tongue
-Anterior 2/3 residing in the oral cavity
Root of the tongue
-Posterior third residing in the oropharynx
Extrinsic salivary glands
-Parotid, submandibular, and sublingual
Intrinsic salivary glands
-Scattered in the oral mucosa
Saliva
- Cleanses the mouth
- Moistens and dissolves food chemicals
- Aids in bolus formation
- Contains enzymes that begin the breakdown of starch
- Immune function
Deciduous teeth
-milk, 20
Permanent teeth
-32
Incisors
-Chisel shape for cutting
Canines
-Fanglike for tearing or piercing
Premolars
-Bicuspids
Molars
-For grinding and crushing
Enamel
- Hardest substance in the body
- External surface of the tooth
Dentin
-Beneath the enamel
Crown
-Visible portion of tooth
Gum
-Pink tissue that holds teeth
Dental caries
- Cavities
- Decay by bacterial action
Periodontal disease
- Plaque buildup causing infection in surrounding tissues
- Destroys periodontal ligament
Gingivitis
-Inflammation of the gums
Pharynx
- Oropharynx and laryngopharynx
- Allow passage of food, fluids, and air
Mastication
-Chewing, physical manipulation
Deglutition
-Swallowing
Chyme
-Creamy paste created by the physical breakdown of food
Mucous neck cells
-Acidic mucous
Parietal cells
-HCl and intrinsic factor (for B12 absorption in SI)
Chief cells
-Pepsin (protein digestion)
Enteroendocrine cells
-Hormones to regulate digestion
Duodenum
- Initial part of the small intestine
- Curves around the head of the pancreas
Ileum
-Joins the large intestine at the ileocecal valve
Jejunum
-Extends from duodenum to the ileum
Villi
-Folds that increase surface area
Microvilli
- Increase surface area
- Give the impression of a brush border
Lacteals
-Drain fatty lymph from digestive tract organs and convey it to blood
Mucosa structure
- Between villi: intestinal crypts (crypts of Lieberkuhn) secrete intestinal juice
- Paneth cells
- Goblet cells
Crypts of Lieberkuhn
-Secrete intestinal juice
Paneth cells
-Secrete lysozyme
Goblet cells
-Secrete mucus
Peyer’s patches
-Lymphoid follicles
Brunner’s glands
-Alkaline bicarbonate to neutralize HCl in chyme
Bile salts
- Cholic acid and chenodeoxycholic acid emulsify fats
- Recycled rather than secreted by the enterohepatic circulation
Bile
-Yellow-green alkaline solution that emulsifies fat
Pancreatic juice
- Water, enzymes, and electrolytes (primarily bicarbonate)
- Helps neutralize chyme
Pancreatic enzymes
- Amylase, lipase, nuclease
- May be active, but require ions or bile for optimal activity
Secretin
- Regulated by HCl in the lumen
- Target: duct cells to release pancreatic juice, which is bicarbonate rich
Cholecystokinin
- Regulated by presence of protein and fat
- Target: acini, to release enzyme rich pancreatic juice
Teniae coli
-Three bands of smooth muscle
Haustra
-Pocket-like sacs created by muscle bands
Epiploic appendages
-Fat filled pouches of the visceral peritoneum
Cecum
-First part of intestine
Appendix
-Masses of lymphoid tissue (part of MALT)
Colon
- Ascending and descending colon are retroperitoneal
- Transverse colon and sigmoid colon are anchored via mesocolons
Rectum
-Three rectal valves stop feces from being passed with gas
Anal canal
-The last segment of the large intestine
Internal anal sphincter
-Smooth muscle
External anal sphincter
-Skeletal muscle
Defecation
-Elimination of waste is initiated by the parasympathetic nervous system
Hydrolysis
-The enzymatic breakdown of food molecules, as there is the addition of water in breaking the molecular bonds
Vitamins
- fat soluble vitamins
- water soluble vitamins
Fat soluble vitamins
- A, D, E, K
- Incorporated into micelles and move by passive diffusion
Water soluble vitamins
- Enter by diffusion
- B12 bound to intrinsic factor which is taken up by endocytosis
Electrolyte
-Sodium pumped across, most others by simple diffusion
