AP110 Chp 19 Digestive system Flashcards
General structure and Function of the Digestive System
General function:
- Digestion
- Absorption
- Elimination
Divisions:
- Digestive tract
- Accessory organs
Wall of the digestive tract
Mucosa (stratified squamous cells, help protect tissues)
Submucosa (contains blood vessels, some nerves, regulate activity)
Muscularis externa (smooth muscles, alternate to create peristalsis)
Serosa (outermost layer of serous membrane)
Peritoneum
Lines abdominopelvic cavity, covers organs.
Layers of peritoneum:
-Parietal
-Visceral
Organs of the digestive tract
- Mouth (Ingestion, Mastication, Mix with saliva (salivary amylase) to breakdown starch)
- Pharynx (throat, transfer food from mouth to Esophagus)
- Esophagus (transfer food using peristalsis from throat to stomach)
- Stomach (Grind food and mix with digestive juices)
- Small intestine (Main digestive area, where bile, enzymes and gastric juices come together to breakdown food absorb nutrients and expel waste)
- Large intestine (Secrete mucus, reabsorb water, form feces, defecation)
The mouth
Oral cavity, processes food by
- Ingestion
- Mastication
- Mixing with Saliva (Salivary amylase)
- Deglutition (Swallowing)
The teeth
Types of teeth
- Incisors (Central incisors)
- Cuspids (Canine)
- Premolars
- Molars
Sets
- Deciduous (baby teeth)
- Permanent
Parts of a tooth
- Crown (visible portion)
- Root (non visible portion)
- Enamel (Hardest substance in body)
- Pulp (vein and nerve area)
- Gingiva (Gums)
- Alveolar (bone)
Pharynx
Throat Divisions -Nasopharynx -Oropharynx -Laryngopharynx
Esophagus
Muscular tube
No digestion
Passes thru esophageal hiatus of diaphragm to join stomach
The stomach
Structure
-Fundus (superior portion by diaphragm)
-Body (Food storage, secretion of gastric juices)
-Pylorus (region leading to small intestine)
-Sphincters (LES lower esophageal sphincter, allows food from esophagus into stomach)
Pyloric sphincter (allows food from stomach into small intestine)
Rugae (stomach lining rigid to breakdown food)
Function -Store food -Secrete gastric juices Hydrochloric acid to prep food for digestion Pepsin digests proteins Deliver chyme to small intestine.
Small intestine
Divisions
- Duodenum (first part that performs majority of digestion)
- Jejunum (middle portion)
- Ileum (remaining portion)
Functions
- Enzymatic digestion of proteins and carbohydrates
- Absorption of nutrients
- Microvilli (increase surface area for digestion and absorption)
- Delivery of chyme to large intestine (segmentation)
Large intestine
Divisions
- Cecum (first part, small pouch)
- Ileocecal valve (prevents food from backflowing into small intestine)
- Appendix (blind tube containing lymphoid tissue)
- Ascending colon (right side toward liver)
- Transverse colon (across the abdomen)
- Descending colon (left side into pelvis)
- Sigmoid colon (distal colon, bends to S shape into rectum)
- Rectum (temporary storage area)
- Anus (opening to outside of body where feces is expelled)
Function
- Secrete mucus
- Reabsorb water
- Form feces
- Defecation
Accessory organs
Salivary glands open to mouth, all others open to duodenum.
- Liver
- Gallbladder
- Pancreas
Salivary glands
Types
- Parotid glands (inferior and anterior to ear)
- Submandibular glands (near lower jaw)
- Sublingual glands (under the tongue)
Function -Secrete saliva Moisten food Facilitate mastication and deglutition Helps keep teeth and mouth clean
Liver
Structure
- Right, left lobes
- Portal vein
- Hepatic artery
Functions
- Manufactures bile
- Stores glycogen for conversion to glucose
- Modifies fats for cellular use
- Stores vitamins and iron
- Forms blood plasma proteins (albumin, globulins, clotting factors)
- Destroys old RBC’s, creating bilirubin for elimination
- Synthesizes urea from protein metabolism
- Detoxifies harmful substances
Gall bladder
Stores bile
Bile from liver to gall bladder via cystic duct
Bile from bladder to duodenum via cystic duct and common bile duct when needed
