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Diet, Disease, and Digestion
Eva Murdoch, PhDAssistant Professor, Anatomy and PhysiologyDepartment of Natural SciencesJoliet Junior College
Organs of the Digestive System
1. Gastrointestinal tract (GI):
mouth, esophagus, stomach,
small & large intestine
2. Accessory organs: salivary
glands, liver, gall bladder,
pancreas
Functions of the GI tract and Accessory Organs
• GI tract: continuous muscular tube which passes, digests, and absorbs food molecules, and eliminates the indigestible residue
• Accessory organs: release digestive juices into the muscular tubule, and aid in the breakdown of nutrients
Digestive System
• Living organisms must obtain
nutrients from their environment to
sustain life
• The digestive system breaks down
large nutrient molecules to small
nutrient molecules that all body cells
can then use to:
– Synthesize ATP (cell’s energy supply)
– Perform structural maintenance, repair
and support growth
Digesting and Absorbing Nutrients
• Salivary glands, pancreas and liver help with the digestion of large food molecules to small molecules by secreting enzymes
• Digestion Absorption– Carbs monosacchrides blood– Fats fatty acids blood– Proteins amino acids blood
Cell Metabolism
• All chemical reactions that occur in a cell– Synthesis of ATP– Synthesis of new organic molecules, and other cell
functions that require ATP
Nutrient Molecules
1. Carbohydrates / Sugars
− Function: short-term energy supply 4 Cal / 1 gram (calories are a unit of energy)
− Found in: grains (wheat, rice, oats, corn), fruits, veggies
2. Lipids / Fats– Function: energy reserve, padding, insulation 9 Cal / 1 gram– Found in: nuts, red meat, milk, eggs, butter
3. Proteins– Functions: enzymes, hormones, muscle, last resort
for energy 4 Cal / 1 gram– Found in: meat, nuts, beans, dairy, eggs
Diet Pyramid
Disease
• GERD – gastro-esophageal (acid) reflux disease– Cause: stomach acid in the esophagus, due to weak
esophageal sphincter– Pathology: erosion of esophageal tissue pain– Treatment: largely preventable by changes in lifestyle,
medication, surgery
• Stomach ulcer– Cause: inflammation due to H. pylori
infection– Pathology: bleeding in stomach– Treatment: antiacid, antibiotics, anti-
inflammatories
• Stomach cancer– Cause: H. pylori infection, genetics– Pathology: abnormal growth (tumor) in
stomach tissue– Treatment: surgery, chemotherapy
• Colon polyp– Cause: irritable bowl syndrome (IBS)
history– Pathology: abnormal growth, rectal
bleeding– Treatment: surgery
• Colon Cancer (3rd most commonly diagnosed cancer)– Cause: genetic, polyps, diet, smoking, excessive drinking– Pathology: uncontrolled cell growth in colon, rectal
bleeding– Treatment: surgery, chemotherapy, radiation therapy
• Liver cirrhosis – Cause: chronic alcoholism and hepatitis C infection– Pathology: liver cells (hepatocytes) are replaced by
fibroblasts (cells found in tendons, can’t perform liver functions)
– Treatment: liver transplant
• Pancreatic Cancer– Cause: genetics, age, smoking, diet, diabetes– Pathology: mutations in the pancreatic cell and tumor growth– Treatment: surgery, chemotherapy