INSECT INTERNAL ANATOMY

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INSECT INTERNAL ANATOMY
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Major Internal Systems of the Insect Body

• Respiration Reproduction
• Digestion Nervous System
• Circulation Hormones
• Excretion

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Insect Muscles

• Most muscles attach to the inside walls of the
  exoskeleton.
• These muscles control movement
• Mouthparts, legs and wings
• Air through the trachea
• Food through the digestive system
• Most muscle activity is controlled by the nervous
  system (just as with humans).

http//www.cals.ncsu.edu/course/ent425/library/tut
orials/external_anatomy/locomotion.html
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Insect Respiratory System

• Insects breathe through small openings called
  spiracles that are found along the thorax and
  abdomen

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University of Nebraska-Lincoln
Air travels throughout the body through tubes
called tracheae
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Drain fly larvae
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Insect Respiratory System

• Some aquatic insects breathe through gills

discoverlife.org
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Insect Respiratory System

• Mosquitoes larvae breathe through siphons

photobucket.com
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Respiratory Video
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Digestive System

• The digestive system is a tube that is divided
  basically into three sections
• Foregut
• Midgut
• Hindgut

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Digestive System

• Foregut mostly used for temporary storage,
  mixing and grinding.

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Digestive System

• Midgut - where most digestion and absorption of
  food occurs

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Digestive System

• Hindgut - where wastes are removed.

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Insect Digestive System
University of Nebraska-Lincoln
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Insect Digestion of Food

• Most insects digest carbohydrates, proteins and
  fats.
• Some insects, such as termites, have
  microorganisms called symbionts in their gut
  that digest cellulose or other materials for them
  to use as nutrients.

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Insect Circulatory System

• Insects have an open circulatory system.
• Their blood is about 90 liquid (plasma)
• Blood travels through some blood vessels, then
  dumps into an open cavity.
• Insects have a dorsal blood vessel that serves as
  their heart.
• Accessory pulsating organs help push the blood
  through the legs, wings and antennae

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Dorsal Blood Vessel
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Circulatory Video
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The Insect Circulatory System

• With most insects, blood is not used to transport
  oxygen
• Bloodworms - Hemoglobin binds and holds a reserve
  supply of oxygen for times when oxygen in water
  is low.

Flyguys.net
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The Insect Circulatory System

• Transports nutrients and waste products
• Transports chemicals that are important for
  insect growth and development (hormones).
• Certain cells in the blood heal wounds and also
  dispose of bacteria and other organisms
• Maintains or changes the pressure inside the body

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Insect Excretory System

• Malpighian tubules insect kidneys located at
  the junction of the midgut and hindgut
• Purpose - similar to our kidneys
• Remove wastes from the blood and digestive
  systems.
• Filter out water for recycling through the body.

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Insect Excretory System
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Reproductive System

• Most insect species have two genders (sexes) -
  male and female
• Some insects can control the gender of their
  offspring. For example - bees
• unfertilized eggs produce males (drones)
• fertilized eggs produce females
• they may produce males at certain times of the
  year only

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Reproductive System

• Parthenogenesis - reproduction without mating
• All offspring from one female are genetically
  identical to her. (Example aphids and
  whiteflies)
• Can increases the likelihood of pesticide
  resistance developing.

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Nervous System

• Insects have a ventral nerve cord (the opposite
  of mammals and other vertebrates)
• They have a collection of nerve cells that
  compose a brain
• They have a pair of nerve centers in each body
  segment, called ganglia

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Nervous System

• Role of the nervous system
• Collect and transmit sensory information such as
• Temperature, light, chemicals, etc.
• Control responses (movement, molting, eating,
  etc.)

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How the Nervous System Works

• Nerves control the muscles
• A nerve impulse moves along the nerve cell
  (neuron).
• The impulse then travels across a gap (synapse)
  between the neuron and the muscle that it
  controls

University of Nebraska-Lincoln
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How the Nervous System Works

• Acetylcholine acts as chemical bridge across
  the gap.
• Acetylcholinesterase - resets the synapse

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How the Nervous System Works

• Organophosphate pesticides (e.g, Dursban and
  diazinon, Orthene) inhibit or interfere with
  acetylcholinesterase and prevent the nerves from
  resetting.
• Result
• nerve keeps sending signals (doesnt reset)
• muscles keep twitching
• insect dies
• Same affect on human nervous systems

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Hormone Production

• HORMONE - a chemical formed in an organ or body
  tissue that travels through the body and causes
  some effect on another body part.
• Some hormones control
• Molting
• Growth and maturation to adulthood

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Hormone Production

• Some insecticides mimic these hormones - prevent
  the insect from molting or maturing or cause it
  to become an adult too quickly.

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INSECT GROWTH METAMORPHOSIS
ADULT
NYMPH
EGG
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Questions?