-
Digestive system functions
- Ingestion
- Secretion
- Mixing & Propulsing
- Digestion
- Absorption
- Defecation
-
The introduction of solid and liquid materials into the oral cavity
Ingestion
-
Breakdown of large food items into smaller structures and molecules
Digestion
-
Mechanical Digestion
Physically breaks down ingested materials
-
Chemical Digestion
Breaks down ingested materials into smaller molecules by using enzymes
-
Passage of digestive products through epithelial cells lining the lumen
Absorption
-
Elimination of non-digestive substances (feces)
Defecation
-
Gastrointestinal Tract
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small/Large Intestine
- Lumen is part of external environment
-
Accessory organs of digestive system
- Salivary glands
- Liver
- Gall Bladder
- Pancreas
-
Four layers of GI tract
- (Superficial to deep)
- Serosa
- Muscularis
- Submucosa
- Mucosa
-
GI tract extends from
Lower esophagus to anal canal
-
Inner most mucous membrane that surrounds the lumen
Secretes, absorbs, protects
Mucosa
-
Mucosa contains
- Epithelium (usually simple columnar)
- -Tight junctions (prevent leakage)
- -High mitotic rate
- Lamina Propria Muscularis Mucosa
-
Lamina Propria
- Underlying areolar connective tissue
- Site of most M.A.L.T.
- Contains blood/lymph vessels
- (Mucosa layer)
-
Muscularis Mucosa
- Thin layer of smooth muscleContributes to mucosal folding in stomach & small intestines
- (mucosa layer)
-
The C.T. that binds the mucosa to muscularies
Submucosa
-
Submucosa contains
- Many large blood vessels & lymphatics
- Submucosal plexus
- May contain glands & lymphatic tissue
-
Submucosal Plexus
- Network of neurons
- Controls secretory cells & smooth muscle of mucosal epithelium
-
Muscularis contains
- Skeletal muscle in mouth, pharynx, esophagus, and anal canal.
- Smooth muscle throughout rest of GI tract
- Inner circular fibers
- Outer longitudinal fibers
-
Mixes & propels substances
Controlled by myenteric plexus
Muscularis
-
Inner Circular Fibers
- Closes diameter of lumen
- Creating a sphincter
- Part of Muscularis
-
Outer Longitudinal fibers
Shorten/Widen the diameter of the lumen
-
Responsible for the movement of food through intestines
Peristalsis
-
Peristalsis
- Wave-like contractions of circular and longitudinal smooth muscle
- Creates propulsion of substances
-
Outermost/Superficial layer of GI tract &
Contains a serous membrane that lubricates
Serosa
-
Serosa
- Found in organs within abdominopelvic cavity
- Contains serous membrane, lubricates
- Outermost tunic
-
Adventitia
- Connective tissue only! (no epithelium)
- Outermost tunic(layer) of esophagus
- Similar to serosa
-
Largest serous membrane of simple squamous E.T. & areolar C.T. that lines abdominal cavity
Peritoneum
-
Peritoneum layers and cavities
- Visceral Peritoneum- Covers some organs and forms serosa
- Parietal Peritoneum-Attaches to abdominal wall
- Peritoneal cavity- Contains lubricating peritoneal fluid
-
Organs within the abdomen that are completely surrounded by visceral peritoneum are called
- Intraperitoneal organs:
- Stomach
- Part of deodenum
- Ileum
- Jejunum
- transverse/sigmoid colon
-
Greater omentum
Fatty substance from greater curvature of stomach and covers most abdominal organs
-
Lesser Omentum
From greater curvature to liver
-
Falcifrom Ligament
Peritoneal fold that attaches liver to anterior interior abdominal wall
-
Organs that lay directly against the posterior abdominal wall so only their anterior portions are covered peritoneum
- Retroperitoneal Organs:
- Kidneys, Ureters, pancreas, part of duodenum & colon
-
Organs within the pelvic cavity and peritoneum on superior surface
- Subperitoneal Organs:
- Urinary bladder & uterus
-
Formed by lips, cheeks, palate, tongue
Oral cavity
-
Tongue
- Skeletal muscle covered by mucosa
- Papillae & taste buds on upper surfaces and sides
- Contains ingual tonsils
-
The tongue is attached by
Lingual frenulum
-
Function of Oral cavity
- Indegestion
- Digestion (mechanical & chemical)
-
Blocks nasopharynx during swallowing
Soft palate/ Uvula (dangling end of soft palate)
-
4 types of teeth
- Incisors - Biting
- Canines- Tearing & grasping
- Premolars & Molars - Grinding
-
Deciduous teeth
- In infants
- about 20 teeth
- AKA milk teeth
-
Permanent Teeth
- Replace deciduous teeth after 6-30 months
- 32 teeth
-
Salivary Glands (Exocrine)
- Ducts that carry secretion (saliva) into oral cavity
- Moistens, cleans, lubricates, digests and protects
- 3 pairs: Parotid, submandibular, sublingual
-
Saliva
- Mucous cells secret mucin
- Serous cells secrete mixture: Water, ions, amylase, antibodies, lysozyme
-
3 pairs of salivary glands
- Parotid ( most salivary amylase )
- Sublingual
- Submandibular
-
Largest salivary glands
Parotid galnds
-
Produce the most saliva (60-70%)
Submandibular Glands
-
Connects oral cavity, nasal cavity, larynx & esophagus
Pharynx
-
Pharynx
- Passageway for food, water and air
- Contain muscular walls for swallowing
- Broken into 3 regions: Nasopharynx, Oropharynx and Laryngopharynx
-
Collapsed, tubular passageway for food
Esophagus
-
Esophagus
- Extends from laryngopharynx to stomach
- Last location of stratified squamous ET in mucosa (until rectum)
- Mixture of skeletal and smooth muscle in muscularis
- Adventitia NO SEROSA
-
Another word for swallowing
Deglutition
-
During swallowing
- Soft palate moves upward closing nasopharynx
- Larynx lifts, epiglottis closes larynx opening
- Bolus moves into esophagus
- Peristalsis of esophagus
- Relaxation of esophageal sphincter
- Bolus enters stomach
-
Mixing chamber/Holding reservoir
Muscular, j-shaped enlargement
Stomach
-
Stomach
- Site of mechanical & chemical digestion
- Digestion of proteins and lipids begins
- Semisolid bolus is converted into liquid chyme
-
4 regions of the stomach
- Cardia - Connects with esophagus
- Body - Principal, main part
- Fundus - Superior bulge, food storage
- Pylorus - terminal part, pyloric sphincter
-
Contains oblique muscles in muscularis
Stomach
-
Stomach wall
- Rugae/Gastric folds (Expandable folds to accommodate more food)
- Oblique wall
- Gastric glands in mucosa
-
4 gastric secretions
- Mucus cells (protective coasting)
- Parietal cells - secret Hydrochloric acid
- Chief cells -
- Enteroendocrine cells - secrete gastrin (a hormone that stimulates secretory activities
-
Upper right quadrant, inferior to the diaphragm
Liver
-
Liver
- Stores vitamins of old RBCs
- Detoxification
- Metabolism of carbs proteins and lipids
- 4 lobes - right, left, caudate, quadrate
- 2 ligaments- Falciform & round ligament
- Synthesizes & secretes bile - emulsifies fats & aids in absorption of lipids by small intestine
-
Porta Hepatis
Where portal vein, hepatic artery and hepatic duct leave the LIVER
-
Receives bile from liver via common hepatic duct -> cystic duct
Gallbladder
-
Gallbaldder
- Muscular, sac like organ on inferior liver surface
- Concentrates and stores bile
- Releases bile into duodenum via cystic duct -> common bile duct -> duodenal papillae
|
|
