LESSON 3

• Digestion and Nutrition


  Humans and other animals obtain oxygen for cellular respiration through breathing. The oxygen you breathe is used to break down the nutrients you consume through food in order to make ATP, while carbon dioxide and water are generated as waste products.
• Ways animals get and eat food

  • Different ways
  • Differences in their diets
• Types of animal diets

  • Herbivores (plants and algae)
  • Carnivores (other animals)
  • Omnivores (plants and animals)
• Feeding Mechanisms


  • Suspension feeders (filter small organisms or food particles from water)
  • Substrate feeders (eat their way through food source)
  • Fluid feeders (get food from blood or sap of hosts)
  • Bulk feeders (eat large pieces of food)
• Food Processing


  1. Ingestion (taking in food through mouth)

  2. Digestion (breaking down food into smaller components)

  3. Absorption (carbohydrates, fats, proteins, and nucleic acids digested into building blocks)

  4. Elimination (undigested materials excreted)

  
• Ingestion


  The process of taking in food through the mouth. In vertebrates, the teeth, saliva, and tongue play important roles in mastication (preparing the food into bolus). While the food is being mechanically broken down, the enzymes (salivary Amylase) in saliva begin to chemically process the food as well.

  
• Digestion


  Animals use enzymes to break down food material. Digestion occurs in compartments surrounded by body cells but not within the body cells; hence, avoiding self-digestion.
• Digestion in single-celled organisms

  • Protists and sponges digest food inside food vacuoles which fuse with lysosomes containing hydrolytic enzymes
  • Cnidarians and flatworms use a gastrovascular cavity with only the mouth as an opening

  
• Alimentary canal


  A type of digestive tract with two openings, allowing digestion to proceed in one direction and specialization in different parts of the tract
• Structures after esophagus


  • Crop (to make food softer and store it)
  • Gizzard (store food and mechanically break it down)
  • Stomach
• Human Digestive System


  1. Oral cavity (mechanical digestion with teeth, saliva, tongue)

  2. Pharynx (food moves to esophagus, epiglottis covers larynx)

  3. Esophagus (peristalsis moves food to stomach)

  4. Stomach (stores food, secretes gastric juice)

  5. Small intestine (nutrients absorbed, bile and pancreatic juice added)

  6. Liver (processes nutrient-rich blood, regulates cholesterol)

  7. Large intestine (reabsorbs water, stores feces)

  
• Appendicitis happens when the inside of your appendix is blocked, often due to infections in the digestive tract
• Large intestine


  Main function is water reabsorption, also has bacterial inhabitants. Rectum stores feces, anal sphincters control defecation.
• Colorectal cancer is a common type of cancer that affects the colon or rectum, risk increases with age and common symptoms include diarrhea, constipation, and blood in the stool
• Colon


  The feces are mainly made up of undigested bacteria, fiber, and other wastes
• Large Intestine


  • Also has bacterial inhabitants
• Defecation


  1. Rectum stores feces

  2. Muscles of the colon contract to create urge to defecate

  3. Two sphincters in the rectum control the opening of the anus
• Anal sphincters


  • There is an inner (internal) and outer (external) sphincter at the end of the anal canal
  • The inner sphincter is ring-like in shape and made up of smooth muscles, it makes sure the rectum does not open when sleeping
• Colorectal cancer


  • A type of cancer that affects the colon (large intestine) or rectum
  • One of the most common types of cancer worldwide
  • Can cause severe harm and death
• Colorectal cancer


  • The risk increases with age, most cases affect people over 50 years old
  • Common symptoms include diarrhea, constipation, blood in the stool, abdominal pain, unexplained weight loss, fatigue, and low iron levels
• Macronutrients


  • Important molecules whose components will be used to synthesize new molecules needed by the body
  • Carbohydrates supply the energy needed for all cellular processes
• Micronutrients


  Vitamins and minerals in small quantities are important for our metabolic needs
• Basic needs from food

  • Sources of raw materials
  • Energy
  • Vitamins and minerals
• Vitamin C


  • An antioxidant that protects your body's cells against free radical exposure
  • Helps your body produce collagen, improves iron absorption, and helps your immune system function properly
• Vitamin C


  • Adult women need 75 mg, adult men need 90 mg
  • Found in citrus fruits, kiwis, peppers, strawberries, broccoli
  • Cooking can reduce vitamin C content
• Thiamine (B1)


  • Helps your body use carbohydrates as energy
  • Plays a critical role in nerve function, as well as skin, hair, and muscle health
• Thiamine (B1)


  • Adult women need 1.1 mg, adult men need 1.2 mg
  • Found in whole grains, meat, fish, legumes, seeds, nuts, and fortified foods
• Riboflavin (B2)


  • Helps convert food into energy and is important in the growth and function of your body's cells
  • Plays a key role in metabolism of fats, drugs, and steroids
• Riboflavin (B2)


  • Adult women need 1.1 mg, adult men need 1.3 mg
  • Found in animal products, green vegetables, and fortified foods
• Niacin (B3)


  Helps convert food into energy and is important in the development and function of your body's cells
• Niacin (B3)


  • Adult women need 14 mg, adult men need 16 mg
  • Found in poultry, beef, pork, fish, nuts, legumes, grains, and fortified foods
• Pantothenic Acid (B5)


  Helps convert food into energy and helps your body produce and break down fats
• Pantothenic Acid (B5)


  • Adults typically need 5 mg per day
  • Found in beef, poultry, seafood, mushrooms, avocados, potatoes, broccoli, whole grains, peanuts, chickpeas, and sunflower seeds
• Pyridoxine (B6)


  • Used in over 100 different enzyme reactions involved in aiding your body's metabolism
  • Plays a key role in brain development during pregnancy
• Pyridoxine (B6)


  • Adults typically need 1.3 mg
  • Found in fish, organ meat, potatoes, other starchy vegetables, and non-citrus fruits
• Biotin (B7)


  • Helps your body turn carbohydrates, fats, and proteins into energy
  • Synthesizes glucose and is essential for healthy bones and hair
• Biotin (B7)


  • Adults typically need 30 mcg
  • Found in whole grains, fish, egg yolks, seeds, nuts, spinach, broccoli, and sweet potatoes
• Folate (B9)


  Plays an important role in cell division and the creation of DNA and other genetic materials
• Folate (B9)


  • Adults typically need 400 mcg per day
  • Found in asparagus, brussels sprouts, dark green leafy vegetables, fruits, and fortified foods
• Cobalamin (B12)


  Plays an essential role in making DNA, aids in making red blood cells, and protects nerve cells