Internal Anatomy Physiology by cmb14063

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									 Internal Anatomy & Physiology
Hemocoel – insect body cavity
• filled with fluid, hemolymph
• lined with endoderm & ectoderm
• not a true coelom (no mesoderm)

Hemolymph
• bathes all internal organs
• delivers nutrients
• removes metabolites
• performs immune functions
Female Cockroach
                      Muscles
• insects have only striated muscles
  – overlapping of myosin and actin filaments
• muscles must attach to internal surface of
  external exoskeleton

  tonofibrillae –
  – fine connecting fibrils linking
  epidermal end of muscle to
  epidermal layer.
  – discarded with cuticle at
  each molt.
         Flight

direct
                  indirect
                   Wing Beats

               Insect        Wing-beats per second
        Ephemeroptera                 ---
        Odonata                    20 - 28
        Orthoptera                    ---
        Coleoptera                 46 - 91
        Diptera                   44 - 1,047
        Lepidoptera                 5 - 85
        Hymenoptera                108-250


Synchronous – one nerve impulse/beat (<100Hz)
Asynchronous – 100 - 1,000Hz
        How Fast Do Insects Fly?
            car
   sphinx moth
      dragonfly
migratory locust
           flies
          bees
       butterfly
   grasshopper
  4 minute mile
         beetle
     brisk walk
         mayfly


                   0   10   20   30 40   50   60   70
                                   mph
The Nervous System
     Central Nervous System
• primitively, 1 pr. of ganglia per body
  segment
• thoracic & abdominal ganglia of each
  segment fused
• ganglia of all head segments coalesced to
  form 2 ganglionic centers
  – brain
  – subesophageal ganglion
                  The Brain
the brain is composed of 3 pairs of fused ganglia:

• protocerebrum – associated with eyes and
  include optic lobes
• deuterocerebrum – innervating the antennae
• tritocerebrum – concerned with handling signals
  that arrive from the body

coalesced ganglia of the three mouthpart–bearing
  segments form the subesophageal ganglion.
               Additionally....
• Visceral (or sympathetic) nervous system
  – stomodeal (stomatogastric) subsystem
  – ventral visceral subsystem
  – caudal visceral subsystem
all of the above innervate fore– & hindgut,
   endocrine & reproductive organs & tracheal
   system

• Peripheral nervous system
  – motor neurons radiating to muscles from ganglia of the
    CNS and stomodeal NS
    Endocrine
     System
Neurosecretory Cells –
modified neurons producing
most insect hormones

Corpora cardiaca-
store prothoracicotropic
hormone (PTTH) that
stimulates secretory activity of
prothoracic glands

Prothoracic glands-
secrete ecdysone

Corpora allata-
secrete juvenile hormone
         Circulatory System
• Hemolymph – may be clear, yellow, blue,
  green or rarely red.
• rarely contains respiratory pigments
• Hemocytes –
  – phagocytosis - ingestion of small particles and
    substances
  – encapsulation of parasites & other large
    foreign materials
  – hemolymph coagulation
  – storage and distribution of nutrients
Series of muscular pumps
move hemolymph through
          body.

								
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