Anatomy: Excretory system

Excretory system

  • Removal of waste products of metabolism, especially nitrogenous compounds from the body of insects is known as excretion. The excretion process helps the insect to maintain salt water balance and thereby physiological homeostasis. Following are the excretory organs.
  • Near the junction of the midgut and hindgut are long, thin structures called Malpighian tubules. These range in number from a few to hundreds, but only aphids (Order Homoptera) are currently known to have none. Malpighian tubules are creamy to yellow in color and work in conjunction with the ileum to provide the primary site for osmoregulation and excretion.
    1. Malpighian tubules: Thin, blind-ending tubules, originating near the junction of mid and hindgut, predominantly involved in regulation of salt, water and nitrogenous waste excretion. This structure was discovered by Marcello Malpighi.
    2. Nephrocytes: Cells that sieve the haemolmph for products that they metabolize (pericardial cells).
    3. Fat bodies : A loose or compact aggregation of cells, mostly trophocytes, suspended in the haemocoel, responsible for storage and excretion.
    4. Oenocytes: These are specialised cells of haemocoel, epidermis or fat body with many functions. One of the function is excretion.
    5. Integument: The outer covering of the living tissues of an insect.
    6. Tracheal system: The insect gas exchange system, comprising tracheae and tracheoles.
    7. Rectum: The posterior part of hind gut.
    Among the above organs, malpighian tubules are the major organ of excretion.

Last modified: Thursday, 17 November 2011, 12:06 PM