Digestive system
Mechanical and chemical breakdown of food into smaller components that allow it to be absorbed into the blood stream.
GI Tract:
Mouth
Salivary glands
Pharynx and Esophagus
Stomach
Pancreas
Liver
Small intestine
Large intestine

Two types of digestion: 1. Chemical 2. Mechanical
Mechanical=Chewing and swallowing
Chemical=Salivary Glands

Located under tongue and near lower jaw
Once mouth is chewing salvia gets released from glands and begins breaking down food.
Moistens food
Enzymes
Amylase : A digestive enzyme in the saliva that breaks down carbohydrates .

Connects nasal and oral cavities with the larynx and esophagus.
Aides in swallowing.
3 structures:
1. Nasopharynx
2. Oropharynx
3. Larynopharynx

25 centimeter long passageway for food. Pharynx --> stomach.
Along the esophagus are mucus glands which moisten passageway. (food goes smoothly)
Lower esophageal sphincter: area above where esophagus meets stomach. Contains smooth muscle fibers which can contract to close the entrance of the stomach and prevent food from going back into esophagus.

A j-shaped pouch-like organ
Hangs inferior to the diaphragm in upper left portion of abdominal cavity.
capacity=1liter+
Receives food from esophagus>mixes with gastric juice>initiates digestion>carries on absorption>moves into small intestine

Divided into 4 regions: cardiac fundus body pyloric

Mucous membrane of stomach is thick, studded with many small openings called gastric pits that are at the ends of tubular gastric glands.
Gastric glands generally have 3 types of secretory cells:
Mucous Cells- in the necks of the glands near the openings of the gastric pits
Chief Cells- in the deeper part of the glands, secrete digestive enzymes
Parietal Cells- in the deeper part of the glands, cellsrelease hydrochloric acid.
Together they form Gastric Juice.

Components of gastric juice:
Component
Pepsinogen
Pepsin
Hydrochloric Acid
Source
Chief cells of the gastric glands
Function
Inactive for of pepsin
Formed from pepsinogen in the presence of hydrochloric acid
A protein-splitting enzyme that digests nearly all types of dietary protein
Parietal cells of the gastric glands Provides the acid eniviornment needed for the conversion of pepsinogen into pepsin and for the action of pepsin
Mucus
Intrinsic Factor
Mucous Cells Provides a viscous, alkaline protective layer on the inside stomach wall
Parietal cells of the gastric glands Aids in vitamin B12 absorption

Extends horizontally across the posterior abdominal wall in the Cshaped curve of the duodenum
Pancreatic Actinar-cells that produce pancreatic juice, make up the bulk of the pancreas.
Smaller tubes unite to form larger ones, Panceratic duct, extending the length of the pancreas.
Hepatopancreatic spincher- controls movement of pancreatic juices into the duodenum(the first segment of the small intestine).
Makes insulin, secreting it directly into the bloodstream.
Insulin is the chief hormone for metabolizing sugar.

Reddish-Brown color-well supplied by blood vessels.
Covered by fibrous capsule and connective tissue

Breaks down food
Stores important substances
Contains Macrophages
Help lipid metabolism (food-->fats):
Converts portions of carbs and protein molecules into fat molecules oxidizes fatty acids
Synthesizes lipoproteins.
Helps protein metabolism (food -->protein): synthesizing plasma proteins and converting certain amino acids to other amino acids.

Tubular organ
Runs between stomach and large intestine
Fills most of abdominal cavity
Made up of 3 parts:
Duodenum-25cm
Jejunum-2/5 of peritoneal cavity
Ileum-remainder of peritoneal cavity

Wall of the small intestine:
Lined with villi (part of mucus membrane)-increase surface area and aid in mixing and absorption
Intestinal gland-located between villi
Secretions and Absorptions:
Mucus secreting goblet cells
Digestive enzymes (peptidases, sucrase, maltase, and lactase)
Movement:
Segmentation (major mixing)
Peristalsis (when irritated)

Begins in lower right side of abdominal cavity
1.5 meters long
4 parts:
Cecum
Colon
Rectum
Anal cord

Large intestine wall: similar to other walls in alimentary canal unique layer of longitudinal, banded muscle fibers
Functions: secretes mucus absorbs water and electrolytes forms and stores feces
Movement: similar to small intestine mass movements 2-3 times a day defecation reflex: stimulates waste elimination

Crohns disease (aka iletis or enteritis) what is it- inflammation of any area of the digestive tract. Most commonly affects the lower part of the small intestine causes- pain, empties intestines resulting in diarrhea most common age is 20-30
Jewish have increased risk-Blacks have decreased
Symptoms-pain, diarrhea
Diagnosis-thorough physical exam and a series of tests
Treatment- drugs, nutrition supplements and/or surgery

Appendicitis what it is- an irritation, inflammation, and infection of the appendix. occurs when inside becomes filled with mucus, stool, or parasites
(causes swelling) causes- pain, no purpose but if goes untreated it can burst and lead to infection symptoms- stomach ache on right side diagnosis-blood and urine test most occur between ages 10 and 30 treatment: removal

lactose intolerance what it isthe body’s inability to break down lactose
(sugar found in milk) causes pain, digestive diseases, injury to small intestine symptoms-pain 30min-2hrs after eating, diarrhea, bloating, gas diagnoses- lactose intolerance test treatment- diet, oral pill