Post on 25-Dec-2015
transcript
GENERAL
1st System to Develop“Tube” Within a TubeContents Remain External Until
Absorbed Through WallsHumans are (Anatomical) OmnivoresConsists of Alimentary Canal/Digestive
Tract and Accessory Organs
DIGESTIVE SYSTEM FUNCTIONS
Ingestion – Food Enters Through Mouth Digestion – Breaking Large Molecules
into Smaller, Absorbable Molecules- Mechanical (Physical)- Chemical (Enzymatic)
Absorption – Passage of Molecules Through GI Tract Wall into Blood or Lymph
Egestion – Elimination of Non-digestible Substances Through Anal End
DIGESTIVE SYSTEM ORGANIZATION
Alimentary Canal (Gastrointestinal or Digestive Tract)- Mouth, Pharynx, Esophagus, Stomach,
Small Intestine, Large Intestine- Lumen is part of External Environment
Accessory Organs- Salivary Glands- Liver- Gall Bladder- Pancreas
ALIMENTARY CANAL HISTOLOGY
Mucosa - Innermost, Surrounds Lumen- Mucous Membrane- Secretes, Absorbs, Protects
Submucosa- Below Mucosa- C.T., Blood Vessels, Lymphatics, Nervous
Tissue
ALIMENTARY CANAL HISTOLOGY continued
Muscularis (Externa)- Smooth Muscle- Inner, Circular, Diameter of Lumen- Outer, Longitudinal, Diameter of Lumen- Propels Substances
Serosa (Visceral Peritoneum)- Outermost- Serous Membrane, Lubricates- Adventitia outside of Ventral Body Cavity
MOVEMENT OF FOOD
Peristalsis - Wave-like Contraction of Circular & Longitudinal Smooth Muscle for Propulsion
ANS
- Stimulated by Parasympathetic
- Inhibited by Sympathetic
ALIMENTARY CANAL ORGANIZATION
MOUTH- Oral (Buccal) Cavity Functions in
Ingestion- Digestion:
*Mechanical (Teeth, Tongue) *Chemical (Saliva Begins
Carbohydrate Digestion)- Cheeks- Hard Palate (Bony)
MOUTH continued
- Soft Palate (Muscular)* Blocks Nasopharynx During Swallowing* Uvula - Dangling end
- Tongue* Frenulum Anchors to Floor of Mouth* Skeletal Muscle Tissue covered with
Mucosa* Papillae with Taste Buds* Lingual Tonsil & Sublingual Gland
MOUTH continued
- Teeth* Vestibule – Space between Teeth & Lips* Two Sets: Deciduous (20) & Permanent
(32)* Four Types:
Incisors – BitingCanines – Tearing & GraspingBicuspids & Molars - Grinding
ALIMENTARY CANAL ORGANIZATION continued
PHARYNX- Connects Oral Cavity, Nasal Cavity,
Larynx & Esophagus- Passageway for Food, Water, Air- Muscular Walls (Swallowing)- 3 Regions: Nasopharynx, Oropharynx,
Laryngopharynx
ALIMENTARY CANAL ORGANIZATION continued
ESOPHAGUS- Collapsible, 10” Tube- Connects Pharynx & Stomach- Lies Posterior to Trachea- Lower Esophageal Sphincter Prevents
Stomach Contents from Entering Esophagus
- Passes Through Neck Thoracic Cavity Esophageal Hiatus Abdominal Cavity
ALIMENTARY CANAL ORGANIZATION continued
STOMACH- J-Shaped Organ, Inferior to Diaphragm- Functions:
*Storage*Digestion (Mechanical & Chemical)*Protein Digestion Begins here*Absorption of Water, Alcohol, Drugs
STOMACH continued
- Enters as Bolus – Mixture of Food & Saliva
- Leaves as Chyme – Milky Mixture of Partially Digested Food & Gastric Juices
STOMACH continued
- 4 Regions:* Cardia – Connects with Esophagus* Body – Principal, Main Part* Fundus – Superior, Bulge, Food Storage * Pylorus – Terminal Part, Pyloric
Sphincter- 2 Curves:
* Greater Curvature* Lesser Curvature
STOMACH continued
- Wall Modifications:* Rugae –Expandable Folds,
Accommodate More Food* Oblique Muscle in Muscularis* Gastric Glands in Mucosa
Mucus Cells (Protective Coating)Parietal Cells (HCl, pH = 2)Chief Cells (Pepsinogen + HCl
Pepsin (Proteolytic)
ALIMENTARY CANAL ORGANIZATION continued
SMALL INTESTINE- Site of Most Chemical Digestion- Site of 90% of Absorption
* Monosaccharides Blood* Amino Acids Blood* Fatty Acids & Glycerol Lymph
SMALL INTESTINE continued
- 3 Subdivisions:* Duodenum
First 10-12”Ampulla of Vater Receives Secretions from
Liver & Pancreas» Bile through Common Bile Duct» Pancreatic Juice through Pancreatic Duct
* Jejunum –Middle Length* Ileum – Last, Joins with Large Intestine at
Ileocecal Valve
SMALL INTESTINE continued
- Wall Modifications:* All Increase Surface Area for Maximum
Absorption* Plicae Circulares – Transverse Folds of
Mucosa & Submucosa* Villi – Finger-like Projections of Mucosa,
contain Capillaries & Lacteal* Microvilli – Microscopic Folds of Cell
Membrane
ALIMENTARY CANAL ORGANIZATION continued
LARGE INTESTINE- Functions:
* Secretes Mucus* Absorbs Water, Ions, Vitamins (From
Bacterial Metabolism)* Forms & Compacts Feces (Undigested
Food, Bacteria, Water)
LARGE INTESTINE continued
- 3 Divisions:* Cecum
Blind PouchAppendix Attached
* Colon - Divided into Ascending, Transverse, Descending, Sigmoid
* Rectum – Anal Canal Internal Anal Sphincter (Smooth) External Anal Sphincter (Skeletal)
LARGE INTESTINE continued
- Wall Modifications:* Taenia Coli – 3 Bands of Longitudinal
Muscle from Muscularis of Colon* Haustra – Pouches in Wall of Colon* No Villi
ACCESSORY ORGANS
SALIVARY GLANDS- Exocrine Glands- Ducts Carry Secretions (Saliva) into Mouth- Saliva: Amylase, Mucous, Water,
Antibodies, Lysozyme- 3 Pairs:
* Parotid (Most Salivary Amylase)* Submandibular* Sublingual
ACCESSORY ORGANS continued
LIVER
- Largest Gland in Body (Exocrine)
- Produces & Secretes Bile (Fat Emulsifier)
- Nutrient Storage & Conversion
- Synthesizes Blood Proteins
- Detoxification
ACCESSORY ORGANS continued
GALL BLADDER- Muscular Sac- Stores & Concentrates Bile- Receives Bile from Liver via Common
Hepatic Duct Cystic Duct- Releases into Duodenum via Cystic Duct
Common Bile Duct Ampulla of Vater (Sphincter of Oddi)
ACCESSORY ORGANS continued
Bile Release:*Chyme Enters Duodenum*Cholecystokinin (CCK) & Secretin
Secreted by Duodenum, Enters Blood
*Secretin stimulates liver to produce bile
*CCK Stimulates Contractions in Gall Bladder & Relaxation of Sphincter
ACCESSORY ORGANS continued
PANCREAS- Exocrine (& Endocrine) Gland- Secretes Pancreatic Juice (Digestive Enzymes
& Buffers)- Leaves Pancreas Through Pancreatic
Duct(s), Enters Duodenum Through Ampulla of Vater
- Raises pH of Duodenum (pH 8, “Natural Antacid”) via bicarbonate ions