Insect Endocrine System

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Questions and Answers

What is the primary function of juvenile hormones in insects?

To regulate metabolic functions

To stimulate adult characteristic development

To promote larval growth and prevent metamorphosis (correct)

To initiate molting processes

Which glands are responsible for producing molting hormones in insects?

Neurosecretory cells

Prothoracic glands (correct)

Corpora allata

Corpora cardiaca

What role do neurosecretory cells play in the insect endocrine system?

They secrete ecdysone.

They coordinate bodily functions such as feeding and reproduction. (correct)

They store juvenile hormones.

They are responsible for metamorphosis.

Which hormone is primarily released by the corpora allata?

Juvenile hormone Signup and view all the answers

What stimulates the production of ecdysone in insects?

Prothoracicotropic hormone Signup and view all the answers

Which of the following is NOT a component of the insect endocrine system?

Corpus striatum Signup and view all the answers

What is the significance of the critical period in the insect endocrine system?

It denotes when brain hormones exert their influence. Signup and view all the answers

Which hormone is known to inhibit the development of adult characteristics?

Juvenile hormone Signup and view all the answers

What hormone is primarily responsible for initiating the molting process in insects?

Ecdysone Signup and view all the answers

Which hormone is secreted by the brain neurosecretory cells to stimulate the prothoracic glands?

Prothoracicotropic hormone Signup and view all the answers

What is the role of juvenile hormone in insect development?

Prevents premature metamorphosis Signup and view all the answers

Which hormone is responsible for tanning the insect cuticle?

Bursicon Signup and view all the answers

What triggers the behavior associated with ecdysis?

Eclosion hormone Signup and view all the answers

What happens to the corpora allata during the last larval or nymphal stage?

It becomes atrophied and stops producing juvenile hormone Signup and view all the answers

Which of the following best describes the action of ecdysteroids in plants?

They act as toxins or antifeedants against herbivorous insects Signup and view all the answers

What is the primary role of ecdysone in terms of epidermal cells?

Promotes synthesis of new cuticle Signup and view all the answers

Study Notes

Insect Endocrine System

Comprises parts responsible for hormonal regulation and bodily functions in insects.
Involves chemical messengers called hormones secreted directly into the bloodstream.

Types of Hormones in Insects

Brain Hormones: Regulate various physiological processes.
Molting Hormones: Control the shedding and renewal of exoskeleton.
Juvenile Hormones (JH): Important for growth and development.

Hormonal Control of Molting and Metamorphosis

Sir Vincent Wigglesworth studied Rhodnius prolixus to discover that JH inhibits adult characteristics, allowing continued larval development.
Critical Period: A specific timeframe where brain influence is essential for hormonal effects to manifest.

Endocrine Glands

Neurosecretory Cells: Found in the protocerebrum, coordinate functions like feeding, metabolism, reproduction, and development.
Corpora Cardiaca: Stores and releases hormones from neurosecretory cells, associated with the aorta.
Corpora Allata: Secretes juvenile hormones, connected to the corpus cardiaca and subesophageal ganglion.
Prothoracic Glands: Stimulated by brain hormones to produce molting hormone (ecdysone).

Key Hormones

Prothoracicotropic Hormone (PTTH): Secreted from the corpus cardiacum; stimulates ecdysone production.
Juvenile Hormone (JH): Promotes larval growth, preventing metamorphosis. Secreted by corpora allata and active during larval molts.
Ecdysone (Molting Hormone): Secreted by prothoracic glands, initiates molting by stimulating epidermal cells; also found in some plants as a protective agent.
Eclosion Hormone: Triggers ecdysis (molt behavior) as ecdysteroid levels fall.
Bursicon: Causes sclerotization (hardening) of the exoskeleton through cross-linkages in the cuticle.

Hormones Involved in Insect Development

Prothoracicotropic Hormone (PTTH): Stimulates the secretion of ecdysone from prothoracic glands.
Ecdysone/Ecdysteroids: Promote synthesis of new cuticle in response to hormonal signals.
Juvenile Hormone (JH): Regulates cuticle type and inhibits premature metamorphosis.
Eclosion Hormone (ETH): Activates secretion of hormones necessary for ecdysis.
Bursicon: Promotes tanning of the cuticle following molting, ensuring structural integrity.

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Description

Explore the intricate components and functions of the insect endocrine system in this quiz. Learn about various hormones such as brain hormones, molting hormones, and juvenile hormones, and their roles in insect development and population control.