Malpighian tubules from an adult mosquito

Insect Physiology and Morphology

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1. Integument -- Coat of Armor
   1. Cuticle
   2. Epidermis
2. Muscular system
   1. Striated muscles
   2. Muscle attachment to apodeme
3. Circulatory System
   1. Open vs. closed system
   2. Hemocoel - insect body cavity
   3. Dorsal vessel (aorta, heart)
   4. Hemolymph
      1. Plasma

         Functions - lubricant for tissues, hydraulic medium, transport of substances (hormones), ventilation of tracheal, thermoregulation.

      2. Hemocytes (blood cells)
         1. Types
         2. Functions - phagocytosis, encapsulation, coagulation (wound healing), and storage and distribution
4. Tracheal System (Respiratory System)
   1. Spiracles
   2. Trachea (tracheal trunks to tracheoles)
   3. Gas exchange vs. respiration
   4. Modifications (tracheal gills)
5. Digestive System
   1. Mouthparts
      1. Types
      2. Modifications
   2. Foregut (esophagus, crop, proventriculus)
   3. Midgut - peritrophic membrane, uptake of nutrients
   4. Hindgut
   5. Fat Body
      1. Within hemocoel
      2. Multiple functions (metabolism, storage, synthesis of blood sugar, synthesis of proteins)
6. Excretory System
   1. Malpighian tubules
   2. Rectum
7. Reproductive System (Separate lecture on Reproduction)
   1. Ovary
   2. Testis
   3. Associated reproductive structures
8. Nervous System (Aspects in lecture with Metamorphosis and Molting)
   1. Brain
   2. Ganglia (In primitive insects, each segment has ganglion)
   3. Neurosecretory cells (hormone production)
9. Derivation of scientific terms

   Apodeme - (Gr. apo, away; demas, body) An invagination of the cuticle that serves for muscle attachment and for strengthening of the body wall.

   Chitin - (Gr. chiton, tunic) A linear polysaccharide that resembles cellulose and constitutes one-fourth to one-half of the dry weight of the exo- and endocuticle.

   Epidermis - (Gr. epi, upon; derma, skin) The cellular layer of the insect integument.

   Hemocoel - (Gr. haima, blood; koilos, hollow) The main body cavity.

   Hemocytes - (Gr. kytos, container) Blood cells of insects.

   Hemolymph - (L. lympha, water) Fluid within the hemocoel.

   Peritrophic membrane - (Gr. peri, around, trophe, food) - a thin, but selectively porous, chitin membrane that separates the midgut cells from the food particles and other materials in the gut lumen.

   Phagocytosis - (Gr. phagein, to eat; kytos, container) The ingestion of solid particles by a cell; usually of a forgein particle for host defense.

   Taenidium - (L. taenia, band or ribbon) A spiral chitinous thickening, strengthening the inner wall of the trachea.

   Trachea - (L. trachia, windpipe) The larger tubes of the respiratory system, supported by taenidia, that opens to the outside through the spiracles and terminates internally in the tracheoles.

   Tracheoles - The fine intracellular terminal branches of the respiratory tubes.

Suggested Readings: Gullan, P.J. and Cranston, P. S. (1994)
pp. 22-28, Section 2.1; pp. 55-58, Sections 3.1, 3.1.1, 3.1.2
pp. 61-65, Section 3.2; pp. 69-93, All of sections 3.4-3.8.

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