The Digestive System

Alexander OrtegaKeith Olejnik

Purpose

• Digestion• Mechanical and chemical breakdown of foods• Supply nutrients to cells

Organs and Glands

• Salivary glands• Liver• Gallbladder• Pancreas• Mouth• Pharynx• Esophagus• Stomach• Small/large intestine

Pathway: The Mouth

• Food Begins digestion in the mouth• The mouth mechanically reduces food size

through Saliva and teeth • The mouth the lips, cheeks, tongue, and the

oral cavity

Pathway: Pharynx

• The pharynx do not digest food but are important to transportation

• The pharynx includes 3 parts• Nasopharynx: provides passagway for breathing• Oropharynx: Passageway for food to travel downward from

the mouth

• Laryngopharynx: Passageway to esophagus

Pathway: Esophagus

• The esophagus does not digest food • 25 CM long • Begins at the base of the pharynx to the

traveling to the stomach• Just above the stomach the lower esophageal

sphincter forms which is a layer of thick smooth muscle preventing regurgitation to the esophagus

Pathway: Stomach

• Capacity of about 1 liter• Mixes food with gastric juice to initiate protein

digestion• 4 regions: Cardiac, fundic, body, and pyloric regions• Gastric pits line the stomach walls• Releasing many helpful digestive materials • Pepsin is the most important as it begins digestion of

nearly all dietary protein into polypeptide• Gastric juice is regulated based on sight, smell, and

taste of food entering the body

Stomach pt. 2

• Gastric enzymes break down proteins• The stomach wall can only absorb a small amount

of water, salt, alcohol, and some lipid soluble drugs• Mixing of fluids cause creation of chyme which is a

semifluid paste of food particles and gastric juice• Rate of digestion depends on fluidity of chyme• Such as fat foods may stay from 3-6 hours while

protein high foods move quickly and carbohydrates will move through the quickest

Pancreas

• Exocrine digestive fluid secretion called pancreatic juice

• The juice digests carbohydrates, fats, nucleic acid, and proteins

• The carbohydrate digesting enzyme is pancreatic amylase

• The protein digesting enzyme is pancreatic lipase

Liver

• Helps maintain normal blood glucose also regulates carbohydrate metabolism

• Converts portions of carbohydrate and protein molecules into fat for energy and storage in the adipose tissue

Gallbladder

• Stores bile between meals• Bile: yellowish green liquid includes water, bile

salts, bile pigments, cholesterol, and electrolytes

Releases bile into the small intestine to continue digestion

Pathway: Small intestine

• The small intestine is a tubular organ which receives secretions from secretions from pancreas and liver, also transports material to the large intestine

• Varies in size from 4.6 M to 9.8 M• The small intestine consists of three parts• Duodenum, Jejunum, ileum• The small intestine secretes mucous throughout

breaking down food even further• Villi absorb many materials and nutrients from food

traveling through

Pathway: Large intestine

• The large intestine is the last part of the digestive system

• The large intestine takes about 16 hours to finish the digestion of the food

• It removes water and any remaining absorbable nutrients from the food before sending the indigestible matter to the rectum

• The large intestine differs from the small intestine in being much wider

• Little to no digestive function

Nutrition

• Nutrition is the study of nutrients and how the body utilizes them

• Carbohydrates, lipids, and proteins are macronutrients which are required in large amounts

• Vitamins and nutrients are micronutrients which can be extracted to energy but are not a direct supply

• Carbohydrates are the primary fuel source of the body

• Protein supplies essential amino acids

Diseases and Disorders

• Achalasia: esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES) It is characterized by incomplete LES relaxation

• Symptoms: Difficulty swallowing, regurgitation, and sometimes chest pain

• The most common form is primary achalasia, which has no known underlying cause

• Cure: Drugs that reduce LES pressure are useful. These include calcium channel blockers such as nifedipine, Heller myotomy helps 90% of achalasia patients.

Diseases and Disorders

• Dyspepsia: also known as indigestion• It is a medical condition characterized by

chronic or recurrent pain in the upper abdomen, upper abdominal fullness and feeling full earlier than expected when eating

• Symptoms: The characteristic symptoms of dyspepsia are upper abdominal pain, bloating, fullness and tenderness

• Cure: natural herbs

Diseases and Disorders• Dysentery: an inflammatory disorder of the intestine• Symptom: Severe diarrhea containing blood and mucus in the

feces with fever, abdominal pain• caused by any kind of infection.• Cure: Dysentery is initially managed by maintaining fluid intake

using oral rehydration therapy. antibiotics, such as ciprofloxacin or TMP-SMX (Bactrim). However, many strains of dysentery shigella are becoming resistant to common antibiotics

• The seed, leaves, and bark of the kapok tree have been used in traditional medicine by indigenous peoples of the rain forest regions in the Americas, West-Central Africa, and South East Asia to treat this disease.