Nervous System

What are the three major divisions in the nervous system?

The central nervous system (CNS), the stomatogastric system, and the peripheral nervous system (PNS).

CNS (central nervous system):

Brain, subesophageal ganglion, ventral nerve cord, and segmental ganglia.

PNS (peripheral nervous system):

Sensory neurons and nerves connecting receptors and effects to the CNS.

Stomatogastric/visceral system:

Innervates gut, heart, and associated internal organs.

What does the connection of ganglia in the CNS create?

A ladder-like organization system.

CNS ancestral plan:

One pair of ganglia per body segment, connected top-to-bottom by connectives.

CNS Brain:

Protocerebtum, deutocerebrum, and tritocerebrum.

What are the CNS brain regions broadly associated with?

Visual processing, antennal input, and integration to mouthpart and foregut related systems.

What is the protocerebrum associated with?

Vision, innervates compound eyes and ocelli.

What does the protocerebrum include?

Mushroom bodies (learning, memory, sensory integration), the central complex (spatial orientation and motor coordination), and optic lobes (paired structures connected to and processing input from eyes).

What is does the deutocerebrum do?

Process input from the antennae, especially mechanosensory and olfactory.

What does the tritocerebrum do?

Links the anterior brain functions with the subesophageal ganglion and stomatogastric system.

What is the ventral nerve cord?

Ladder-like chain of paired ganglia, connected by pairs longitudinal nerve tracts.

Where is the subesophageal ganglion located?

Below the brain and esophagus.

What does the subesophageal ganglion innervate?

Mouthparts (mandibles, maxillae, labium, hypopharynx), salivary glands, and neck muscles.

What is the subesophageal ganglion for?

Feeding, the manipulation of food, and coordinated head movement.

Subesophageal ganglion examples:

Coiling/uncoiling the proboscis and mandible + maxillae movements.

How many thoracic ganglia are there?

One pair per thoracic segment ancestrally.

What do the thoracic ganglia innervate?

Legs, wings, and associated sensory receptors.

What do thoracic ganglia play a major role in?

Walking, jumping, flying, and posture.

Thoracic ganglia examples:

Rapid aerial turns and flight movements, leg movement for prey capture, and sensory information from halteres for flight stabilization.

What do abdominal ganglia control?

Abdominal muscles, spiracle related functions, and posterior sensory integration.

What do terminal ganglia innervate?

Genitalia, the anus, and sensory structures such as tarsi.

What are posterior ganglia important for?

Reproduction, ventilation, and escape responses.

Abdominal and terminal ganglia examples:

Ovipositioning and control of cerci.

Where is fusion of ganglia common?

In more derived groups.

What can the fusion of ganglia increase?

Integration (like tagmatic specialization of body regions).

What is the function of the stomatogastric nervous system?

Nerve control of internal organs.

What does the stomatogastric nervous system innervate?

The foregut, portions of the gut, heart, and endocrine structures.

What does the stomatogastric nervous system regulate?

Swallowing, food transport, and aspects of visceral control.

What is the function of the PNS?

To link receptors and effectors.

What does the PNS link?

External and internal receptors to the brain and ganglia, allowing insects to detect stimuli and produce coordinated responses.

What information does the PNS carry and to where?

From sensory receptors toward the CNS and efferent output from the CNS to muscles and glands.

What is chemoreception?

When chemical cues are detected with specialized cuticular sensilla, concentrated on the antennae, mouthparts, and tarsi.

What is chemoreception critical for?

Food, mates (via pheromones), oviposition sites, and avoiding predators/toxins.

What are examples of chemoreception?

Olfaction and gustation.

What are mechanoreceptors?

Structures that detect physical deformation through touch, air movement, vibration, and body position/proprioception.

What are the common types of mechanoreceptors?

Tactile hairs (bend), campiliform sensilla (dome-shaped, movement/flight), and tympana organs (hearing).

Where can tympanal organs be located?

Katydid leg and moth thorax.

What are photoreceptors?

Compound eyes and ocelli.

Where are photoreceptors?

Optic lobes and protocerebrum.