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Questions and Answers
What is the main function of the Malpighian tubules in insects?
What is the main function of the Malpighian tubules in insects?
- Excretion and osmoregulation (correct)
- Digestion of food
- Respiration
- Reproduction
What is the purpose of the peritoneal coat and muscle fibers surrounding the Malpighian tubules?
What is the purpose of the peritoneal coat and muscle fibers surrounding the Malpighian tubules?
- To filter out solutes from the haemolymph.
- To provide structural support and aid in peristalsis. (correct)
- To absorb water and solutes from the primary urine.
- To secrete enzymes for digestion.
What is the relationship between the Malpighian tubules and the alimentary canal in insects?
What is the relationship between the Malpighian tubules and the alimentary canal in insects?
- The Malpighian tubules are part of the alimentary canal.
- The Malpighian tubules are completely separate from the alimentary canal.
- The Malpighian tubules are connected to the mouth of the alimentary canal.
- The Malpighian tubules act in association with the rectum or ileum of the alimentary canal. (correct)
How many Malpighian tubules are present in different insects?
How many Malpighian tubules are present in different insects?
What is the relationship between the primary urine produced by the Malpighian tubules and the haemolymph (insect blood)?
What is the relationship between the primary urine produced by the Malpighian tubules and the haemolymph (insect blood)?
What is the primary function of the excretory system in insects?
What is the primary function of the excretory system in insects?
Which of the following is NOT considered a major excretory organ in insects?
Which of the following is NOT considered a major excretory organ in insects?
What is the primary function of the Malpighian tubules in the insect excretory system?
What is the primary function of the Malpighian tubules in the insect excretory system?
What is the function of the nephrocytes (pericardial cells) in the insect excretory system?
What is the function of the nephrocytes (pericardial cells) in the insect excretory system?
What is the role of the fat bodies in the insect excretory system?
What is the role of the fat bodies in the insect excretory system?
Which of the following is NOT considered an excretory organ in insects?
Which of the following is NOT considered an excretory organ in insects?
Which of the following describes the excretion process in terrestrial insects?
Which of the following describes the excretion process in terrestrial insects?
What is the primary function of osmoregulation in insects?
What is the primary function of osmoregulation in insects?
Which ions do both terrestrial and aquatic insects need to conserve?
Which ions do both terrestrial and aquatic insects need to conserve?
What is the role of chloride cells in the insect excretory system?
What is the role of chloride cells in the insect excretory system?
In freshwater insects, what is regulated in response to the loss of ions to the surrounding water?
In freshwater insects, what is regulated in response to the loss of ions to the surrounding water?
What is the major anion found in the isosmotic filtrate in malpighian tubules?
What is the major anion found in the isosmotic filtrate in malpighian tubules?
What generates an osmotic pressure gradient in malpighian tubules for the passive flow of water?
What generates an osmotic pressure gradient in malpighian tubules for the passive flow of water?
What type of excretion is seen in terrestrial insects such as coleoptera and lepidoptera larvae?
What type of excretion is seen in terrestrial insects such as coleoptera and lepidoptera larvae?
In aquatic insects, what is the excretory product that requires more water for waste removal?
In aquatic insects, what is the excretory product that requires more water for waste removal?
What holds the distal ends of the malpighian tubules in contact with the rectal wall?
What holds the distal ends of the malpighian tubules in contact with the rectal wall?
Which accessory function is NOT associated with malpighian tubules?
Which accessory function is NOT associated with malpighian tubules?
Study Notes
Excretory System of Insects
- The excretory system in insects is responsible for removing waste products of metabolism, particularly nitrogenous compounds, and maintaining salt-water balance and physiological homeostasis.
Malpighian Tubules
- Malpighian tubules are the main organ of excretion and osmoregulation in insects.
- They are thin, blind-ending tubules that originate near the junction of the mid and hindgut.
- Each tubule is covered with a peritoneal coat and supplied with muscle fibers that aid in peristalsis.
- The distal secretory region and proximal absorptive region of the tubules work together to produce a filtrate (primary urine) that is isosmotic but ionically dissimilar to the haemolymph.
Functions of Malpighian Tubules
- Remove nitrogenous wastes
- Regulate salt, water, and ion balance
- Produce a filtrate (primary urine) that is isosmotic but ionically dissimilar to the haemolymph
- Accessory functions include spittle secretion in spittle bugs and light production in Bolitophila
Other Excretory Organs
- Nephrocytes: cells that sieve the haemolymph for products they metabolize
- Fat bodies: loose or compact aggregations of cells that store and excrete waste products
- Oenocytes: specialized cells with many functions, including excretion
- Integument: outer covering of the insect body that aids in excretion
- Tracheal system: insect gas exchange system that also aids in excretion
- Rectum: posterior part of the hindgut that modifies urine to maintain fluid and ionic homeostasis
Excretion and Osmoregulation
- In aquatic insects, haemolymph composition is regulated in response to ion loss to the surrounding water.
- Special cells called Chloride cells in the hindgut absorb inorganic ions from dilute solutions.
- Active transport of ions generates an osmotic pressure gradient for the passive flow of water.
Nitrogenous Excretion
- Terrestrial insects excrete waste products as uric acid or urates (uricotelism), which requires less water for waste removal.
- Aquatic insects excrete ammonia, which requires more water for waste removal (ammonotelism).
- Cryptonephry is a specialized structure in some insects that aids in efficient dehydration of faeces or ionic regulation.
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Description
Learn about the excretory system in insects, focusing on the removal of waste products and maintenance of salt-water balance. Explore the functions and structures of excretory organs such as Malpighian tubules, nephrocytes, and more.
