Food and Digestive System Quiz

Food and Digestive System

• Food Needs: Humans require six essential food substances: carbohydrates, proteins, fats, vitamins, minerals, and water.
• Macronutrients: Carbohydrates, proteins, and fats are needed in large amounts and are digested before being absorbed.
• Micronutrients: Vitamins, minerals, and water are needed in small amounts and are absorbed directly without digestion.
• Carbohydrates: These are organic compounds made up of carbon, hydrogen, and oxygen with the formula C6H12O6. Carbohydrates provide 4.1 kcalories per gram.
  • Types of Carbohydrates:
    • Monosaccharides: Simple sugars such as glucose, galactose, and fructose.
    • Disaccharides: Made up of two monosaccharides combined, for example, maltose, lactose, and sucrose.
    • Polysaccharides: Complex carbohydrates formed by multiple monosaccharides linked together.
• Carbohydrate Excess: Excess carbohydrates are converted into glycogen and fat. Glycogen is stored primarily in the liver and muscles, while fat is stored in areas such as the belly, kidneys, and under the skin.
• Carbohydrate Deficiency: A lack of carbohydrates can lead to weakness, thinness, decreased immunity, and reduced energy levels.
• Proteins: These are made up of carbon, hydrogen, oxygen, and nitrogen.
  • Classifications:
    • Animal Protein: Found in sources like meat, eggs, and dairy products.
    • Vegetable Protein: Sources include legumes, nuts, and seeds.
  • Amino Acids: The building blocks of proteins, with each gram providing 4.1 kcalories.
• Protein Functions:
  • Structural Functions: Essential for growth and cell repair.
  • Functional Functions: Proteins are involved in enzyme activity, hormone production, and antibody formation.
• Protein Digestion: Protein is broken down through a series of steps:
  • Pepsin breaks down protein into peptone.
  • Trypsin further breaks down peptone into amino acids.
• Fats: Composed of carbon, hydrogen, and oxygen, fats consist of glycerol and fatty acids. They provide 9.3 kcalories per gram.
  • Sources:
    • Animal Fat: Meat, butter, milk, fish, eggs, fish oil.
    • Vegetable Fat: Coconut, candlenut, nuts, avocado, margarine.
  • Saturated vs. Unsaturated: Differing structures with implications for health.
• Vitamins: Organic compounds that act as coenzymes.
  • Water-Soluble Vitamins: B and C vitamins, excess is excreted.
  • Fat-Soluble Vitamins: Stored in fat, excess can cause problems.
  • Vitamin Deficiency: Insufficient vitamin intake can lead to avitaminosis.
• Minerals: Around 14 essential minerals exist, including calcium, phosphorus, potassium, sodium, iron, iodine, and zinc.
• Mineral Functions: Contribute to cell formation, chemical reactions, transportation (like CO2), and bone formation.
• Water: Comprises about 70% of the human body.
  • Roles: Solvent, temperature regulation, structural support, lubrication, transport, and metabolic processes.
• Digestive Process (Four Steps):
  • Ingestion: Taking in food.
  • Digestion: Breaking down food through mechanical and chemical processes.
  • Absorption: Nutrients are absorbed into the bloodstream.
  • Defecation: Removal of indigestible waste.

Digestive System

• Main Digestive Organs: Mouth, esophagus, stomach, small intestine, colon, rectum, anus.
• Accessory Organs: Tongue, teeth, salivary glands, pancreas, liver, gallbladder.

Mouth Cavity (Cavum Oris)

• Tongue (Lingua): Serves functions such as taste, food stirring, swallowing, cleaning the mouth, and speech.
• Saliva: Produced by salivary glands (2 liters per day).
  • Functions: Helps with swallowing, mixes food, initiates chemical digestion through ptyalin (amylase) enzyme which breaks down starch into disaccharides.
  • Result: Forms a bolus.
• Teeth (Dens): Involved in mechanical digestion.
  • Types of Teeth:
    • Milk Teeth: First set, appear around 6 months old and fall out by age six.
    • Permanent Teeth: Replace milk teeth, starting around age 6 and continuing until age 14.
  • Types Based on Function:
    • Incisors: Scrape food, have a flat surface.
    • Canines: Tear food, pointed shape.
    • Premolars/Molars: Chew food, broad and uneven surface.

Pharynx and Esophagus:

• Pharynx: Junction between the esophagus and trachea.
• Esophagus:
  • A muscular tube connecting the mouth to the stomach (25 cm long).
  • Epiglottis: A flap that prevents food from entering the windpipe.
  • Peristalsis: Wave-like muscular contractions propelling food down the esophagus.

Stomach (Ventriculus)

• Description: J-shaped organ located beneath the diaphragm.
  • Muscles: Contains circular and longitudinal muscle layers that cause mixing and churning of food.
  • Chyme: Partially digested food.
  • Regions: Cardiac, fundus, pylorus.
• Gastric Secretion: Produced by the stomach lining:
  • Water, mucus
  • Renin (chymosin) enzyme: Important for digesting milk proteins in young ruminants.
  • Pepsinogen: Inactive enzyme converted into pepsin by HCl.
  • Hydrochloric Acid (HCl):
    • Stimulates the production of intestinal juices.
    • Activates pepsinogen.
    • Breaks down protein into peptone.
    • Kills microbes.
• Sphincters:
  • Lower Esophageal Sphincter/Cardiac Sphincter: Controls the flow of food from the esophagus into the stomach.
  • Pyloric Sphincter: Regulates food movement from the stomach into the small intestine.

Small Intestine (Intestinum Tenue)

• Sections: Duodenum, jejunum, ileum.
• Duodenum:
  • About 30 cm long.
  • Ester of Pancreatic Gland and Bile Duct: Where pancreatic and bile juices enter.
  • Intestinal Juices: Produced by the duodenum wall:
    • Disaccharidase enzyme (for breaking down maltose, lactose, and sucrose).
    • Erepsinogen (inactive enzyme) -> converted into erepsin -> digests peptides into amino acids.
    • Lipase -> breaks down fats into fatty acids and glycerol.
    • Enterokinase -> activates erepsinogen and trypsinogen.
• Pancreatic Gland: Produces pancreatic juices:
  • Pancreatic Amylase: Breaks down disaccharides.
  • Trypsinogen: Inactive enzyme converted into trypsin -> breaks down peptides into amino acids.
  • Pancreatic Lipase (Steapsin) -> breaks down fats into fatty acids and glycerol.
• Gallbladder (Vesica Felea):
  • Stores bile produced by the liver.
  • Emulsification: Bile helps break down fats.
• Jejunum:
  • Around 7 meters long.
  • Site of final digestion.
• Ileum:
  • Approximately 1 meter long.
  • Absorption: Nutrients in the simplest form are absorbed.
  • Villi: Finger-like projections that increase surface area for absorption within the ileum.
  • Capillary Blood Vessels: Absorb glucose, amino acids, vitamins, and minerals.
  • Lymph Vessel: Transports fatty acids and glycerol.
• Nutrient Transport: From villi, nutrients move through blood capillaries to the body's cells.
• Cell Respiration: Cells utilize oxygen from hemoglobin and produce energy, CO2, and H2O.

Large Intestine (Colon/Intestinum Crassum)

• Sections: Cecum, appendix, ascending colon, transverse colon, descending colon, rectum, anus.
• Function: Absorption of water from digestive waste.
• Digestion: Indigestible matter moves into the colon and is further broken down, forming feces.
• Feces: Stored in the large intestine (12-24 hours).
• Escherichia Coli: Bacteria in the colon that aid in digestion, produce vitamin K (blood clotting), and contribute to a symbiotic relationship:
• Rectum: Smooth and striated muscle, stores feces until elimination.
• Anus: Opening for feces.
• Appendix: A thin, four-inch tube located at the junction of the small and large intestines.

Digestive System Disorders and Diseases

• Parotitis: Inflammation of the parotid gland, often viral or bacterial.
• Ulcers: Stomach pain, reduced food intake, excess HCl.
• Colic: Intestinal pain, often due to viral or bacterial infection.
• Appendicitis: Infection of the appendix.
• Diarrhea: Watery feces, caused by infections, rapid passage through the colon, or decreased water absorption.
• Constipation: Difficult defecation, caused by slow passage of feces in the colon and excess water absorption.
• Xerostomia: Dry mouth, often due to impaired saliva production.
• Bacterial Infections:
  • Salmonella typhii
  • Staphylococcus
  • Clostridium botulinum
  • Entamoeba histolytica
  • Vibrio cholera