The Digestive System
Alexander Ortega
Keith Olejnik
Purpose
• Digestion
• Mechanical and chemical breakdown of foods
• Supply nutrients to cells
Organs and Glands
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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.