Flashcards in Ch 26 Digestion Deck (45)
Functions of the Digestive System
mix/move ingested materials,
add secretions to digest into smaller, usable components,
absorb nutrients into blood/lymph,
What are the categories of organs in digestive system?
Organs in GI Tract,
Accessory digestive organs
What are the organs of GI tract
oral cavity, pharynx, esophagus, stomach, small intestine. large intestine, anal canal
What happens in GI tract organs
ingested food is broken down and absorbed along its length
What are the accessory digestive organs
Salivary glands, liver and pancreas
Teeth and tongue
What are the 4 tunics of the GI tract wall? What are their layers
Mucosa - inner most; has epithelium, lamina propria, muscularis mucosae
Submucosa- consist of submucosa and submucosal nerve plexus
Muscularis- outermost; consist of inner circular layer, myenteric nerve plexus, outer longitudinal layer
Adventitia or Serosa; outermost tunic
Difference between serosa and adventitia
Adventitia; composed of areolar connective tissue, w/dispersed collagen and elastic fibers
Serosa: same tissue; completely covered by serous membrane - visceral peritoneum
How are digestive process regulated by the Enteric Nervous System?
Neurons extend from esophagus to anus
Functions independently of CNS
Innervate = supply an organ with nerves
Innervates smooth muscle and glands of GI tract
Mediates the reflexes for mixing and propulsion of materials thru GI tract
How are digestive process regulated by the Autonomic Nervous System
GI tract wall innervated by PNS and SNS (of CNS)
Parasympathetic innervation: promotes GI activity, relaxes sphincters, stimulates GI motility
Sympathetic innervation: OPPOSE GI activity, contracts GI tract sphincters, inhibits GI motility, Vascoconstricts blood vessels within GI tract wall
How are digestive processes regulated by Nerve Reflexes?
ENS and ANS control GI Tract wall thru nerve reflexes
How are digestive process regulated by Hormonal Control?
Gastrin: released from stomach
Motilin released from small intestine
What is an intraperitoneal organ
organs in abdomen that are completely surrounded by visceral peritoneum; stomach, most of small intestine, parts of large intestine
What are retroperitoneal organs?
organs that lie directly outside of parietal peritoneum; directly against the posterior abdominal wall
Pancreas, esophagus, most of duodenum, parts of large intestine and rectum
What is the peritoneum?
serous membrane of the abdominopelvic cavity
what are the types of pertitoneum associated with the digestive system?
Parietal Peritoneum - line inner surface of abdominal wall
Visceral peritoneum- covers internal organs within the abdominopelvic cavity
Peritoneal cavity - potential space between the parietal and visceral peritoneum; contains serous fluid which lubricates organs reduces friction
What is mesentery?
a double later/fold of peritoneum that attaches organs to body wall
Mesentery: Greater Omentum
connects stomach to posterior abdominal wall; fatty apron; insulates organs and stores fat; covers most of abd organs
Mesentery: Lesser Omentum
connects stomach and duodenum to liver
Mesentery: Falciform ligament
attaches liver to internal surface of anterior abdominal wall
Mesentery: Mesentery proper
attaches small intestine to posterior abdominal wall
attaches large intestine to posterior abdominal wall
What is the difference between long and short reflexes?
Short reflex = local and only involves ENS; coordinate small segments of GI tract to changse in stimuli
Long reflex= CNS; sensory input; sends digestive info to brain; secretory activity; coordinated muscle contractions
How is digestive system controlled thru endocrine system?
- regulation of digestive processes
- Gastrin - increase force of contraction and release of secretion
- Secretin- decrease of secretory activity of stomach
- CCK - Cholecystokinin - causes decrease in stomach motility
-Motilin- controls pattern of smooth muscle contractions in upper GI
What happens in upper GI tract organs?
Initial mechanical and chemical process of ingested material takes place
What is bolus?
saliva mixed with ingested materials to form globular wet mass
What path does the bolus travel
Oral cavity and salivary gland > pharynx > esophagus >stomach
2 regions of oral cavity
Vestibule (buccal): space between gums/lips/cheeks
Oral Cavity proper: boudned laterall by cheeks and anteriorly by lips and teeth
Function of Buccinator muscle
compress cheeks against teeth to hold solids in place during mastication (chewing)
Function of Lips
formed by orbicularis oris muscle