The Circulatory System

which led to an early suggestion that they segregated and stored waste products (hence their 519

alternate name of nephrocytes). The usual view is that the cells accumulate and degrade large molecules such as proteins, peptides, and pigments, and the products are then used or excreted. However, their structure includes much rough endoplasmic reticulum and well-developed Golgi complexes, characteristics of cells producing protein for export. Indeed, Fife et al. (1987) demonstrated that the pericardial cells synthesized and secreted several proteins into the hemolymph.

3. Physiology 3.1. Circulation

Contractions of the dorsal vessel and accessory pulsatile organs, along with movements of other internal organs and abdominal ventilatory movements (coelopulses), serve to move hemolymph around the body (Miller, 1997). In Periplaneta larvae, for example, circulation time is 3-6 minutes; in Tenebrio the time for complete mixing of injected radioisotope is 8-10 minutes. Generally hemolymph is pumped rapidly through the dorsal vessel but moves slowly and discontinuously through sinuses and appendages.

The direction of hemolymph flow in most insects is indicated in Figure 17.4A-C. Hemolymph is pumped anteriorly through the dorsal vessel from which it exits via either excurrent ostia of the heart or mainly the anterior opening of the aorta in the head. The resultant pressure in the head region forces hemolymph posteriorly through the perivisceral

FIGURE 17.4. Diagrams showing direction ofhemolymph flow. (A) Longitudinal section; (B) transverse section through thorax; and (C) transverse section through abdomen. Arrows indicate direction of flow. [After V. B. Wigglesworth, 1965, The Principles of Insect Physiology, 6th ed., Methuen and Co. By permission of the author.]

FIGURE 17.4. Diagrams showing direction ofhemolymph flow. (A) Longitudinal section; (B) transverse section through thorax; and (C) transverse section through abdomen. Arrows indicate direction of flow. [After V. B. Wigglesworth, 1965, The Principles of Insect Physiology, 6th ed., Methuen and Co. By permission of the author.]

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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