Human digestive system

• What is the primary reason food must be digested?

  Food is too big to be absorbed
• What must polymers be converted into during digestion?

  Monomers
• What are the main functions of the gut?

  • Ingestion: Taking in food
  • Digestion: Breaking down food
  • Absorption: Passing molecules into blood
  • Egestion: Eliminating waste
• What process propels food along the gut?

  Peristalsis
• What is mechanical digestion?

  Cutting and crushing food by teeth
• What role do digestive enzymes play in digestion?

  They contribute to the breakdown of food
• What is egestion?

  Elimination of waste not made by the body
• What is the function of the mouth in digestion?

  Ingestion and digestion of starch
• What is the role of the oesophagus?

  Carriage of food to the stomach
• What does the stomach primarily digest?

  Protein
• What is digested in the duodenum?

  Carbohydrates, fats, and proteins
• What is the function of the ileum?

  Digestion and absorption of food
• What is the role of the rectum?

  Storage of feces
• What is the anus responsible for?

  Egestion
• What are the four tissue layers of the gut wall?

  1. Serosa: Tough connective tissue
  2. Muscular layer: Inner circular and outer longitudinal muscles
  3. Submucosa: Connective tissue with blood vessels
  4. Mucosa: Innermost layer lining the gut
• What is the function of the serosa layer in the gut wall?

  Protects the gut wall and reduces friction
• How do the inner circular and outer longitudinal muscles work together?

  They coordinate peristalsis to move food
• What does the submucosa contain?

  Blood and lymph vessels, and nerves
• What is the function of the mucosa layer?

  Lines the gut and secretes enzymes
• What are the modes of nutrition?

  • Autotroph: Synthesizes organic molecules
  • Heterotroph: Consumes other organisms
  • Saprotroph: Digests dead or decaying material
  • Holozoic: Involves ingestion, digestion, absorption, assimilation, and egestion
• What is an autotroph?

  An organism that synthesizes its own food
• What is a heterotroph?

  An organism that consumes other organisms
• What is a saprotroph?

  An organism that digests dead material
• What does holozoic nutrition involve?

  Ingestion, digestion, absorption, assimilation, egestion
• What is peristalsis?

  Rhythmic waves of muscular contraction
• What are the key terms related to modes of nutrition?

  • Autotroph
  • Heterotroph
  • Saprotroph
  • Holozoic
• What type of digestion do multicellular organisms perform?

  Extracellular digestion
• Why do multicellular organisms have digestive systems?

  To digest a wider range of foods efficiently
• What is the digestive sac in Hydra called?

  Gastrovascular cavity
• How does Hydra digest food?

  Through extracellular and intracellular digestion
• What is the role of mechanical digestion in Hydra?

  It helps break down food into fragments
• How are food fragments absorbed in Hydra?

  By phagocytosis and pinocytosis
• What is the main characteristic of flatworms' digestive system?

  Single gut cavity
• How does the gastrovascular cavity of flatworms differ from that of Hydra?

  It is highly branched for better absorption
• What type of gut do more complex animals have?

  Tube gut
• What are the functions of different regions of the tube gut?

  Mechanical and chemical digestion
• How does the human gut adapt to different food types?

  It is adapted for both plant and animal material
• What is the role of the buccal cavity in digestion?

  Mixes food with saliva and prepares for swallowing
• What enzyme is found in saliva, and what does it do?

  Salivary amylase breaks down starch
• What is the function of the oesophagus?

  To carry food to the stomach