Insect Circulatory System Overview

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Questions and Answers

What is the primary function of the dorsal vessel in insects?

To regulate body temperature

To aid in gas exchange

To pump hemolymph throughout the body (correct)

To provide structural support to the abdomen

What term is used to describe the blood in insects?

Serum

Hemolymph (correct)

Plasma

Circulatory fluid

How does hemolymph flow into the dorsal vessel?

Via segmental openings known as ostia (correct)

Through a series of muscular contractions directly from organs

By diffusion through body tissues

Through capillaries connected to arteries

Which structure supports the dorsal vessel in insects?

Alary muscles Signup and view all the answers

What separates the compartments in an insect's circulatory system?

Fibromuscular septa and membranes Signup and view all the answers

What prevents backflow of hemolymph within the dorsal vessel?

Valves in the ostia Signup and view all the answers

What happens during the muscular relaxation phase in an insect's heart?

Hemolymph enters the dorsal vessel from the pericardial sinus Signup and view all the answers

What is the role of ostia in the insect circulatory system?

To allow one-way flow of hemolymph Signup and view all the answers

What condition is caused by a higher concentration of amino acids?

Aminoacidemia Signup and view all the answers

Which type of haemocyte is primarily involved in phagocytosis?

Plasmatocyte Signup and view all the answers

Which of the following is NOT a function of haemolymph?

Dissolving carbohydrates Signup and view all the answers

What is the role of glycerol in insects at high altitudes?

Antifreeze agent Signup and view all the answers

Which haemocyte type is involved in blood coagulation?

Cystocyte Signup and view all the answers

Which function of haemolymph assists during the ecdysis process?

Hydraulic medium Signup and view all the answers

What is the primary nitrogenous waste product excreted by insects?

Uric acid Signup and view all the answers

How does haemolymph contribute to thermoregulation?

By transporting heat within the body Signup and view all the answers

What is the primary role of the ventral diaphragm in the insect circulatory system?

To aid in the circulation of haemolymph Signup and view all the answers

How do the accessory pulsatile organs contribute to circulation in insects?

By pumping haemolymph through various tubes Signup and view all the answers

In what way is the circulation of haemolymph in the wings of young adult insects different from other areas?

It is sustained by air influx rather than pulsatile organs Signup and view all the answers

Which statement correctly describes haemolymph in insects?

It includes a component called plasma Signup and view all the answers

What function does the perineural sinus serve in the context of haemolymph circulation?

It aids in the lateral direction of haemolymph flow Signup and view all the answers

Which ions are typically found in the plasma of the hemolymph, specifically in predators and parasites?

Sodium and Magnesium Signup and view all the answers

What is the typical pH level of haemolymph?

Acidic, usually around 6.7 Signup and view all the answers

What is the primary function of haemocytes within the haemolymph?

To act as a defense against pathogens Signup and view all the answers

Study Notes

Insect Circulatory System

Unlike humans, insect circulatory systems are "open"
Hemolymph flows freely throughout the hemocoel
The only vessel is the dorsal vessel (heart)
Posteriorly, the dorsal vessel pumps hemolymph forward (to head/thorax)
Anteriorly, it acts as an aorta, then returns hemolymph to the dorsal vessel via ostia.
Ostia are small slits in the heart region of the dorsal vessel, allowing hemolymph uptake
The dorsal vessel is very thin, located on the dorsal side of the body
The circulatory system is maintained by muscular pumps (the dorsal vessel).

Components and Function of the Dorsal Vessel

The dorsal vessel acts as the heart portion, and aorta portion
Composed of one layer of myocardial cells
Segmentally arranged openings called ostia
Valves prevent backflow of hemolymph
Thoracic ostia (3 pairs) and abdominal ostia (9 pairs)
Supported by alary muscles, forming the pericardial sinus
Pericardial sinus is a compartment above the dorsal diaphragm (fibromuscular septum).
Waves of contraction in dorsal vessel pump hemolymph.
Hemolymph is pumped to appendages, and returns to the pericardial sinus.

Ventral Diaphragm

An important component of insect circulation
Fibromuscular septum located in the floor of the body cavity
Associated with the ventral nerve cord
Active peristaltic contractions aid hemolymph flow backwards and sideways in the perineural sinus.
Facilitate rapid exchange of chemicals between the ventral nerve cord and hemolymph (e.g. thermoregulation.)

Haemolymph Composition and Function

A watery fluid containing ions, molecules, and cells.
May be clear or colored (e.g., red due to hemoglobin).
Main function: Transport of nutrients, hormones, and gases. Removes waste.
Maintains osmotic pressure (important for physiology).
Serves as a metabolic medium facilitating conversion of trehalose to glucose.
Plays a role in lubrication
Plays a role in various processes like ecdysis, wing expansion, and appendage movement.
Includes cellular components (haemocytes) that play roles in defense, wound healing, etc.

Accessory Pulsatile Organs

Muscular pumps located at the base of antennae and legs
Release neurohormones that influence sensory neurons.
Aid unidirectional circulation to appendages.

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Description

Explore the unique features of the insect circulatory system, which operates as an open system with hemolymph flowing freely throughout the body. Learn about the structure and function of the dorsal vessel, its components, and how it efficiently pumps hemolymph to sustain insect physiology.