Digestive System- Part I Flashcards
Digestive System Organs (6)
1) Oral Cavity
2) Pharynx
3) Esophagus
4) Stomach
5) Small Intestine
6) Large Intestine
Digestive System Accessory Organs (7)
1) Tongue
2) Teeth
3) Salivary Glands
4) Tonsils
5) Liver
6) Gallbladder
7) Pancreas
Digestive System Functions (6)
1) Ingestion
2) Propulsion & Mixing (Mechanical Breakdown)
3) Secretion
4) Digestion
5) Absorption
6) Storage & Elimination (Defecation)
What are the 4 Tunics of the Digestive Tract?
1) Mucosa (inner most)
2) Submucosa
3) Muscularis
4) Serosa or Adventitia (outer most)
Bolus vs. Chyme
Bolus- soft mass of food and liquid that moves from the oral cavity into the esophagus
Chyme- mass of undigested food that moves down the digestive tract from the esophagus
2 Types of Mixing Contractions
1) Mixing Waves- gentle contractions in the stomach that churn food with gastric secretions
2) Segmental contractions- mixing of food with secretions in the small intestine
SEE PG 916 FOR EACH PARTS ROLE IN BREAKDOWN OF FOOD & ABSORPTION OF NUTRIENTS
FIGURE 24.2
3 Major Types of Glands associate w/Digestive Tract
1) Unicellular mucous glands in mucosa
2) Multicellular glands in mucosa & submucosa
3) Multicellular glads outside digestive tract (such as Pancreas)
Mucosa of Digestive Tract (3)
1) Innermost tunic of digestive tract
2) Has 3 layers
3) Contains 2 Types of specialized cells –> Mechanoreceptors involved in peristaltic reflexes & chemoreceptors that detect chemical composition of food
3 Layers of the Mucosa
1) Mucous Epithelium- inner most layer composited of strat squam epithelium
2) Lamina Propria -middle layer of connective tissue
3) Muscularis Mucosae- thin outer layer of smooth muscle
Submucosa of Digestive Tract (4)
1) On top of Mucosa
2) Thick connective tissue
3) Contains nerves, blood vessels, lymphatic vessels & small glands
4) Contains portion of Submucosal Plexus which stimulates secretions throughout digestive tract (except esophagus & stomach)
Muscularis of Digestive Tract (3)
1) 3rd most outer layer
2) Muscular layer containing smooth muscle
3) Contains Myenteric Plexus- controls motility of the intestinal tract using a network if interstitial cells that operate as pacemakers to promote rhythmic contractions
Submucosal Plexus vs. Myesteric Plexus
- Submucosal Plexus- controls secretions from submucosa layer
- Myesteric Plexus- pacemaker found in muscularis layer
Enteric Nervous System (3)
1) Network of neuron cell bodies and axons within the wall of the digestive tract
2) Capable of controlling digestive tract independent of CNS through LOCAL REFLEXES (short, specific regional reflexes)
3) Division of the ANS through the Vagus nerve
Serosa or Adventitia of Digestive Tract
1) Outermost layer
2) Serosa- peritoneal cavity, aka Visceral peritoneum, composed of CT & simp squamous epithelium
3) Aventitia- esophagus & retroperitoneal organs, composed of CT
3 Types of Enteric Neurons (Nervous Regulations of Digestive System)
1) Enteric Sensory Neurons- detect changes in chemical compostition of contents and mechanical changes (such as stretch)
2) Enteric Motor Neurons- stimulate or inhibit smooth muscle contraction
3) Enteric Interneurons- connect enteric sensory & motor neurons
Hirschprung Disease
1) Painful developmental disorder caused by absence of enteric neurons in distal large intestine.
2) Results in poor intestinal morality and severe constipation
3 Major Neurotransmitters that chemically regulated Digestive system
1) Acetylcholine- STIMULATES motility & secretions
2) Norepinephrine- INHIBITS motility & secretions
3) Serotonin- STIMULATES motility –> over 95% of Serotonin in the body is in digestive tract which is why drugs that increase serotonin levels also cause nausea & vomiting
Peritoneum (definition) & it’s 2 layers
- the continuous serous membrane that lines the walls and organs of the abdominal cavity
1) Visceral Peritoneum- portion that covers the organs
2) Parietal Peritoneum- portion that covers the interior surface of the wall abdominal cavity
Peritonitis (2)
1) Life threatening inflammation of the peritonium
2) Caused by chemical irritation (bile from digestive tract) or infection from digestive tract (EX: appendix rupture)
Ascites (2)
1) An accumulation of excess serous fluid in the peritoneal cavity that occurs in peritonities
2) Also occurs during starvation, alcoholism, & liver cancer.
Mesentery (4)
1) Structure within the abdominal cavity that holds all digestive organs in place.
2) Continuous, double layer of epithelial tissue attached along it s full length to the posterior wall
3) Extends from junction between esophagus & stomach to the rectum
4) Has 6 continuous regions