ENT Final

Foregut

forms from stomodeal invagination, lined with chitin, very little digestion

Midgut

formed from mesentral growth, not lined with chitin, main area of digestion

Hindgut

formed from proctodeal invagination, lined with chitin, permeable to some substances

Preoral cavity

Salivary glands open here, grinding of food

Cibarium

important in food ingestion, food storage pouch in front of mouth

Esophagus

Conducts food rearward

Crop

pre-digestive storage

Proventriculus

Valve at end of foregut used for grinding

Ventriculus

Secretes enzymes into stomach

Gastric caeca

tubes that aid in digestion and house microbes

Stomach

main area of midgut, lined with peritrophic membrane

Intestine

receives waste from midgut, excretions from the malphigian tubules

Rectum

Reabsorbs water and salts from waste prodcuts

Anus

Exit for fecal pellet

Peristalsis

Series of muscle contractions moving food down esophagus into crop for storage

Enzymatic digestion

carbohydrases, lipases and proteinases (many insects have specialized enzymes)

Food absorbed from midgut to hemolymph

Peritrophic membrane

Membrane lining midgut that protects epithelial cells from damage

Encloses food, continually formed as digestion occurs, moves along the midgut and into hindgut where it breaks down

Diverticulum

Modified pouch off of the esophagus that allows for liquid storage in some insects

Filter Chamber

allows for passive diffusion of water out of gut

Fat Body

Yellow/white tissue in abdomen with many metabolic functions (storage, synthesis and regulation of blood sugars, synthesis of hemolymph proteins)

Trophocyte

Cell found in fat body, responsible for all metabolic and storage functions

Produced only when needed

Symbionts

Many insects ingest compounds that they can’t digest, these bacteria/yeast digest for them

Malphigian tubules

Small tubes used for liquid excretion, bathed in hemolymph and close in proximity to fat body

Uric Acid

Common nitrogenous waste product, nontoxic and soluble, conserves water

Ammonia

Rare nitrogenous waste product, poisonous and highly soluble, does not conserve water

Circulation

Open circulatory system, 3 major sinuses separated by 2 diaphragms, Aorta and Heart

Sinuses

channel flow of hemolymph

Diaphragms

Propel hemolymph through undulations

Aorta

in head, thorax and anterior abdomen, simple conduit for oxygenated hemolymph to get to head

Heart

In abdomen, chambers that draw in hemolymph and pump it towards head

Accessory Pulsate Organs

Contractile, help drive hemolymph to hard to reach areas

Plasma

Aqueous solution of salts and organic compounds that is part of the hemolymph

Hemocytes

Blood cells, phagocytize small particles, encapsulates invaders, coagulates

Hemolymph Function

• Transportation of food/waste

• Storage

• Cellular defense

• Wound healing

Tracheal System

System of tubes allowing for direct diffusion of air into almost all body cells

Spiracles

Openings for tracheal system into integument

Trachaea

Air filled tubes that conduct gas into tracheoles and eventually cells

Tubes

Extension of body to water surface for respiration

Bubble

Air is captured at surface and carried under water for respiration

Plastron

Air bubble acts as gills, oxygen diffused in as co2 diffuses out

Blood Gills

Oxygen diffuses through gill integument to hemolymph then to a respiratory system

Tracheal Gills

O2 diffuses through gill integument into tracheal system

Cuticular Gills

O2 diffuses through integument into air pocket then to tracheal system

Muscular Bundles

Skeletal muscles, origins and insertions on integument

Muscular Sheets

circular and longitudinal muscles wrapped around gut

Muscle Networks

Branching network of muscle units spread around the esophageal diverticulum

Tergo-sternal muscles

Muscles that run from the tergum to the sternum

Dorsal longitudinal muscles

Muscles that run longitudinally along the dorsal length of the body

Ventral longitudinal muscles

Muscles that run longitudinally along the ventral length of the body

Direct muscle control

Muscles connected directly to wings; contraction and relaxation of muscles results in movement of wings

Indirect muscle control

Muscle contraction and relaxation causes movement of thorax and movement of flight muscles

Dendrite

Part of neuron that receives signal

Axon

Part of neuron that transmits signal

Sensory Neurons

Receive stimuli from environment, transmits to nervous system

Interneurons

Receive information, transmit to other neurons

Motor Neurons

Receive information from interneurons, transmit to muscles

Neuroendocrine cells

Modified neural cells that produce hormones

Neurotransmitters

transmit impulses between neurons and from neurons to muscles

Reflexes

Transmit impulses from sensory to motor neurons

Central Nervous System Components

Brain, main ventral nerve cord, all ganglia

Peripheral Nervous System Components

Skeletal and Visceral System

Protocerebrum

innervates compound eyes and ocelli

Dueterocerebrum

Innervates antennae

Tritocerebrum

Connects to the visceral nervous system

Frontal Ganglion

helps to process stimuli; innervates labrum

Subesophageal ganglion

innervates mandibles, maxillae and labium

Thoracic ganglia

innervate muscles, legs, wings

Abdominal Ganglia

innervate musculature and genitalia

Skeletal System

innervates sensory organs and muscles related to the integument

Stomodeal System

Innervates heart, foregut, and midgut

Ventral nerves

innervate spiracles

Caudal System

Innervates hindgut and reproductive organs

Neuroendocrine system

system that controls molting, excretion, metabolic rate, etc

Neurosecretory Cells

Excrete brain hormones into hemolymph

Thoracic glands

Release Ecdysone into hemolymph

Ecdysteroids

Any steroid with molt promoting activity obtained from food

Juvenile Hormones

Control metamorphosis, regulate reproductive development

Neurohormones

Master regulators of insect development, metabolism, reproduction, regulate Juvenile Hormone and ecdysone

Tormogen Cell

Forms Socket for sensory neuron

Trichogen Cell

Forms the seta within the socket

Sensory neuron

Dendrite rests directly on seta

Stimulation of seta causes movement of dendrite and stimulation of axon

Mechanoreceptors

Sense touch, hearing

Chemoreceptors

Sense smell, taste

Hygroreceptors

Sense humidity

Thermoreceptors

Sense radiant, convective heat

Sensillum Trichoidea

seta in socket, innervated by a single sensory neuron

Sensillum Basiconica

Sensory pegs in socket; innervated by many sensory neurons

Sensillum Coeliconica

Like Basiconica except the peg is sunken into a cavity

Sensillum Campaniformia

External area is dome-like; innervated by a single sensory neuron

Sensillum Placodea

External area is a thin cuticular plate; innervated by many sensory neurons

Taste

Located on mouthparts and tarsi, chemoreception

Smell

Located on antenna, airborne chemoreception

Sensillum Basiconica allows entry of many volatile chemicals

Johnston’s Organ

in 2nd antennal segment of male mosquitos to pick up on wing frequency

Tympanal organs

made of thin cuticular membrane stretched across thin airspace

Stemmata

Visual organs of larval homometabolous insects

Can discriminate between light and dark, low resolving powers

Ommatidia

Small repeating units that make up compound eye compose of a lens, cone, pigment cells and sensory neurons

Ocelli

light sensing organs

thin cuticle allows light to pass through to sensory neurons which relay directly to brain

Help navigate, can discriminate between light and dark

Compound eye

Made of apposition (daylight) and superposition (nighttime) ommatidium

Forms composite images

Can discriminate between color, distance and direction and very sensitive

Pheromones

Hormones transmitted through air to attract opposite sex

Visual Displays

Use to attract via long distance visual signals (ex. fireflies)