Download - Exocrine and Endocrine Glands
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AGR 254 ENTOMOLOGY
EXOCRINE GLANDS
AND
ENDOCRINE GLANDS
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DTypes of glands
1. Exocrine glands system
2. Endocrine glands system
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Exocrine Glands
Send chemicals/signals outside body-cuticle layer.
They may be single cells or small aggregates of secretory cells; or can be complex glands
Exocrine glands are generally of ectodermal origin and are widely scattered over the insect.
Examples of exocrine glands:A. Simple unicellular gland
B. Unicellular cell with ductule cell
C. Simple aggregations of gland cells
D. Aggregation of gland cells with common duct
E. Complex aggregation of glands with common duct
Glands that secrete their products into ducts that lead directly into the external or lumens of various organs.
SITI NURAREFANIE,SUHANAH,SYAMRIZAL,WILFRED
Examples of Exocrine Glands
Simple unicellular
Unicellular with ductule
Simple aggregation
Aggregation –same duct Complex-
same duct
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DFunction of exocrine
1. Defense
venoms, alarm pheremones Nastute soldiers of termite produce
sticky defensive material – from the enlarged frontal gland
2. Intraspecific Communication
Glands in many insects produce chemicals that serve as signals of various sorts for other members of the same species
These are called “pheromones”
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DFunction of exocrine
3. Building Structural Material Structural materials include wax and silk
In honeybee wax is secreted by epidermal glands – to construct honey combs
4. Transport of Materials in Liquid State Salivary glands
Accessory gland and spermathecal gland – assist transport of spermatozoa
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DEndocrine Gland Typically ductless and their secretions
are usually released directly into the Hemolymph(like blood of human).
Endocrine system – involved with the secretion of “ hormones” .
Commonly function in close coordination with one another.
In insects, the largest and most obvious endocrine glands are found in the Prothorax-just behind the head.
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DEndocrine Gland & The Nervous system-(coordinate)
Hormones are involved with long term adjustments to changes in the external and/or internal environment
Nerves system only provide short-term adjustments to changes in the external and/or internal environment
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DMajor endocrine structures are:
Corpora allata
Corpora cardiaca
Thoracic glands
Insects have special cells called Neurosecretory cells that secrete neurohormones.
act as the link between the nervous and endocrine systems
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DNeurosecretory cells location:
Protocerebrum
Subesophageal and other ventral chain ganglia
Corpus cardiacum
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Corpora allata produces and secretes juvenile hormones-it plays a crucial role in metamorphosis.
The thoracic gland or Prothoracic gland– secrete hormones that initiate the “molting process”- Ecdysal Hormone.
Prothoracic glands are only found in immature insects.
In many Diptera species, the corpus allatum is fused with the corpus cardiacum, forming a "ring gland", also known as Weismann's ring.-wiki
In Lepidoptera species, the corpus allatum acts a release site for prothoracicotropic hormone which is generated by the brain.-wiki
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Corpora allata
Thoracic gland
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DFunction Of the endocrine glands:
Regulation of molting
Determination of form at metamorphosis
Polymorphism
Regulation of diapause
Involvement in reproduction
Regulation of metabolic activities and general body functions
Regulation of behavior
Regulation of preprogrammed cell death
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