Biology🪷

• Major components of our food

  • Carbohydrate
  • Proteins
  • Lipids/fats
• Types of carbohydrates

  • Polysaccharides
  • Monosaccharides
• Types of monosaccharides


  • Glucose
  • Fructose
  • Galactose
• Digestion


  The process of conversion of complex food substances to simple absorbable forms
• Digestive system


  • It is carried out by mechanical and biochemical methods
  • It consists of a tube beginning from mouth and ending at anus
  • It includes associated glands

  
• Alimentary Canal


  • It is also known as the Gastrointestinal Tract

  
• Buccal cavity


  The initial site of digestion where food is broken down
• The stomach is located in the upper left portion of the abdominal cavity
• Parts of the stomach

  • Cardiac portion
  • Body/corpus
  • Fundic region
  • Pyloric portion

  
• The stomach stores food for 4-5 hours
• Mammalian teeth types


  • Thecodont
  • Diphyodont
  • Heterodont
• Thecodont


  Teeth embedded in a socket
• Diphyodont


  Teeth that include milk/deciduous and permanent teeth
• Heterodont


  Teeth that include incisors, canines, premolars, and molars
• Excretion


  The removal of waste
• Excretion


  Removal of harmful metabolic wastes from a cell or an organism
• Main excretory products


  • CO2
  • Water
  • Ammonia
  • Urea
  • Uric acid
  • Creatinine
  • Hippuric acids
  • Excess ions (phosphates, sulphates, Cl--, Na+, K+)
• Nitrogenous waste products


  • Ammonia
  • Urea
  • Uric acid
  • Amino acid
• Nitrogenous wastes production

  1. Deamination of excess amino acids

  2. Breakdown of body’s own proteins and nucleic acids
• The dental formula of adults is 2, 1, 2, 3
• The dental formula for children is 2, 1, 0, 2
• Enamel is the hardest substance in the human body and contains the highest percentage of minerals
• Functions of the stomach

  Food storage<|>Digestion<|>Regulation of delivery
• Hydrochloric acid


  Produces a pH of about 2 and breaks down large bits of food
• Castle’s Intrinsic factor


  Needed to absorb Vitamin B12
• Mucus


  Protects stomach lining from acid
• Body can store carbohydrates and fats for future use but cannot store proteins and amino acids
• The accumulation of –NH2 group in body is toxic
• Components of saliva


  • Electrolytes
  • Mucus
  • Antibacterial compounds
  • Various enzymes
• Human excretory system


  • Pair of kidneys
  • Pair of ureters
  • Single urinary bladder
  • Single urethra

  
• Saliva


  Mainly produced by three pairs of salivary glands

  
• Types of salivary glands

  • Parotids
  • Sub-maxillary
  • Sub-lingual

  
• Nitrogenous wastes


  • Ammonia is most toxic and requires large amount of H2O for elimination
  • Urea is less toxic than NH3 and requires moderate amount of H2O for its removal
  • Uric acid is least toxic and requires very little H2O for its removal
• Ureotelic organisms


  • Mammals
  • Terrestrial amphibians
  • Frog
  • Earthworm
• Uricotelic organisms


  • Reptiles
  • Birds
  • Land snails
  • Insects
• Salivary amylase


  Enzyme that breaks down starch into sugars
• Gastric glands


  Secretes gastric juice with a pH of 1.8
• Cells in gastric glands

  • Chief cells
  • Parietal cells
  • Goblet cells
  • Argentaffin cells
  • Endocrine cells

  
• Chief cells


  Secrete pepsinogen and prorennin
• Parietal cells


  Produce hydrochloric acid and Castle’s intrinsic factor