Gastrointestinal System Imari Attaway Olivia Di Capua Riley

Gastrointestinal System Imari Attaway, Olivia Di. Capua Riley Dinneen, Stephanie Tyrrell

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

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

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.

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

Esophagus 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.

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

Parts of Stomach Divided into 4 regions: cardiac fundus body pyloric

Stomach Secretions 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 Source Function Pepsinogen Chief cells of the gastric glands Inactive for of pepsin Pepsin Formed from pepsinogen in the presence of hydrochloric acid A protein-splitting enzyme that digests nearly all types of dietary protein Hydrochloric Acid 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 Mucous Cells Provides a viscous, alkaline protective layer on the inside stomach wall Intrinsic Factor Parietal cells of the gastric glands Aids in vitamin B 12 absorption

Pancreas 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.

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

Liver (physiology) 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.

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

Small intestine (cont. ) 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)

Large intestine Begins in lower right side of abdominal cavity 1. 5 meters long 4 parts: Cecum Colon Rectum Anal cord

Large intestine (cont. ) 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

Diseases and Disorders involved 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

Diseases and Disorders (cont. ) 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

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