Earthworm Excretory system

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Earthworm Excretory system
http//image.tutorvista.com/content/excretion-and-
osmoregulation/earthworm-cross-section.jpeg
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New Vocabulary

• Coelom Body cavity, space
• Nephridia unit of the excretory system in
  earthworms
• stome mouth like opening

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• Earthworm belongs to Phylum Annelida (higher
  invertebrates)
• Excretory systems consists of nephridia which are
  small, coiled tubes along the body.

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3 types of nephridia depending on location

• Septal (behind the 15th segment)
• Integumentary( along the inner side of body)
• Pharyngeal(4th, 5th, 6th segments only)

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• A typical nephridium consists of a ciliated
  funnel or nephridiostome which opens into the
  coelomic cavity.

http//shs.westport.k12.ct.us/mjvl/biology/dissect
/earthworm_images/earthworm_nephridia.gif
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• This is followed by a short and narrow tube
  called the neck which is bent on itself and opens
  into the main body of the nephridium.

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• The cells lining the nephridiostome and the
  nephridial tube bear cilia in some lengths. The
  lashing movements of the cilia help in the flow
  of the excretory matter.

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Process of Excretion

• Since the nephridia are richly supplied with
  capillaries, n_ _ _ _ _ _ _ _ _s
  wastes are removed from the blood.

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• The rhythmic beating of the cilia of the
  nephridiostomes drives a steady stream of
  coelomic fluid containing metabolic waste
  materials, such as u_ _a,
• a_ _ _ _ _ a and remains of dead cells, into
  and through the nephridial tube.

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• The excretory wastes are then finally discharged
  into the gut. Only waste matter is excreted from
  the capillaries with which they are richly
  supplied. Thus water is conserved by these
  nephridia.

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