Read the summary and the most important questions on H15 - Foerageer gedrag en darm morfologie

• 1 -

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• What is suspension feeding?

  Suspension feeders use ciliated surfaces to produce currents that draw drifting food particles into their mouths.

• What is filter feeding? Name examples of filter feeders.

  • A form of suspension feeding.
    
  • They have filtering devices that strain food from water as it passes through (kieuwen). 
  • Examples are whales, herring, flamingos, sharks.

• What are the 4 different types of teeth mammals have and what is their function?

  1. Incisors: for biting, cutting and stripping.
  2. Canines: for seizing, piercing and tearing.
  3. and 4. Molars and premolars: for grinding and crushing. 

• Explain the structure of a tooth.

  
  A tooth consists of 3 layers, namely:
  

  1. Outer layer: enamel. 98% mineral and the hardest in the body.
  2. Middle layer: dentine. Composes the mass of the tooth and is 75% mineral.
  3. Third layer: cementum. Forms a thin covering over the dentine in the root of the tooth and is very similar to dense bone in composition.

  
  Then there is the pulp cavity. It contains loose blood vessels, nerves and tooth-building cells.

• What types of animals practice fluid feeding?

  Most common among internal parasites (endoparasites) and external parasites (ectoparasites) like leeches, fleas, mosquitoes, ticks and mites.

• Explain how intracellular digestion works.  Which animals do this?

  • Food particle is enclosed within a food vacuole by phagocytosis.
  • Digestive enzymes are added.
  • Products of digestion are absorbed into the cell cytoplasm to be used or transferred to other cells.
  • Food wastes are extruded from the cell by exocytosis.

  
  This only occurs in protozoa and sponges.

• What are the limitations of intracellular digestion?

  Only particles that are small enough to be phagocytized can be engulfed, and every cell must be capable of secreting all necessary enzymes and of absorbing the products into the cytoplasm.

• What type of enzymes are used in chemical breakdown of food particles? Where are these enzymes located?

  • Hydrolitic enzymes, or hydrolases. They split the food molecules by hydrolisis, breaking the chemical bond by adding water components.
    
  • They are located in specific regions of the GI tract in an "enzyme chain". 

• 2 -

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• How is food moved through the GI tract?

  By cilia or specialized muscles.

• What are segmentation and peristalsis?

  • Segmentation is the alternate constriction of rings of smooth muscle of the intestine that constantly divide and squeeze contents back and forth. It mixed food, but does not move it through the gut.
    
  • Peristalsis moves food down the gut with waves of contraction of circular muscle behind and relaxation in front of the food mass.