Biology ✔️

• The digestion system


  Animals convert macromolecules into smaller component for cellular function
• • During digestion food particles are broken down through physical means chewing and chemical means through enzyme
• Ingestion

  • Taking food into mouth
• Digestion

  • Breaking down complex organic molecule to smaller component by enzyme & chemical process begins in the oral cavity extends to stomach and intestine
• Absorption

  • Is the transport of digestive nutrient from small intestine to the cell of the body through finger like projection called Villi
• Egestion

  • Is the removal of waste from the body in form of faces
• Excretion

  • The removal of waste
• Bolus 


  Grak ward for ball like things
• Peristalsis

  • Wave like smooth muscle that contract and found in esophagus
  • Used to push down food
• • Most digestion takes place in small intestine
  • Bile produced by Liver
  • Enzyme produced by pancreas and small intestine
• -> the smaller molecule are absorbed into blood stream through epithelial cells lining on the wall of small intestine
• • The waste material travels to large intestine where water is reabsorbed & the drier waste is compacted into faces and stored in rectum until discharged through anus
• The oral cavity

  1. Food broken down into smaller particle by mastication (chewing)
  2. Salivary produced by Salivary gland containing Salivary amylase to break starch
  3. Salivia dissolves food & make it possibe to taste
  4. Salivia lubricate food so it can be swallowed
  5. Taste bud is found in tongue and cheeks wc helps to taste flavour
• The teeth

  1. Incisor: are 8 chisel shaped teeth - used for cutting - found at front
• 2. Canine

  • Are sharp shaped
  • Used for tearing
• 3. Premolar

  • Are broad and flat
  • Used for grinding
• 4. Molar

  • More broader than premolar & have cusp that are even more flat
  • For crushing and grinding
• Wisdom teeth

  • Are the set of lost teeth we have until we reach 16 to 21 years
• Enamel

  • Covered by teeth and the hardest substance in the human body
• External structure of teeth

  • Crown:- the visible part of teeth

  - the top portion of teeth

  • Neck:- lies below crown
  • Root:- lies inside the gum and hold the teeth in position

  ○ Gem called gingiva are tissue that attaches the neck of teeth & cement (in amharic ded)
• Internal structure

  • Enamel:- made up of CaPo4 and hard rocky materials that protects teeth from damage
  • Dentine:- a layer underlying the enamel

  - a hard tissue that contain microscopic tube

  - when damage it cause pain
• Pulp cavity:- the inner soft structure that contains blood vessles and nerves