The circulatory system of insects is open and consists of hemolymph that bathes the organs rather than being contained in vessels. The main circulatory organ is the dorsal vessel, a tube located along the midline that functions like a heart to circulate the hemolymph. Hemolymph carries nutrients and wastes but does not transport oxygen. Accessory pulsatile organs help circulate hemolymph to appendages and tissues.

1. Circulatory system of insets
Submitted by: Submitted to:
Manish Kumar Pal Mr. Rajendra Regmi
ENT-03M-2017 Assisstant professor of AFU
Department of Entomology
AFU, Rampur
10th Ashoj,2075

2. 0 Insects have an open circulatory
system.
0 The hemocoel is filled with
hemolymph that bathes the organs
0 Insects have local pulsatile organs at
the bases of appendages that pump
hemolymph
0 It does not carry oxygen along its
circulation.
0 Movement of nutrients, salts,
hormones, and metabolic wastes
throughout the insect’s body
10th Ashoj, 2075

3. Insect Circulatory Organs
DORSAL VESSEL
0 principal organ responsible for blood
circulation
0 lies along the dorsal midline of the
insect body
0 open anteriorly and closed posteriorly
except in larval mayflies
0 anterior part may be called aorta and
the posterior part the heart
0 The heart is usually restricted to the
abdomen, but may extend upto prothorax
in cockroaches.
10th Ashoj, 2075

4. Insect Circulatory Organs
HEART
0 usually closed at its posterior end
and bears a number of valvular
openings (ostia)
ALARY MUSCLES
0 fibromuscular innervated structures
attached laterally to the body wall and
vary in number from 1-13 pairs
0 contraction causes blood to flow into
the pericardium from the perivisceral
cavity and then into the heart
10th Ashoj, 2075

5. The Insect Circulatory System
10th Ashoj, 2075

6. Insect Circulatory Organs
HEMOCOEL
0 The main body cavity of
invertebrates, such as insects
0 The compartmentalized structure
of this cavity is due to the
presence of one or two
fibromuscular septa
0 an arrangement of blood
vessels in mammals is replaced
by Haemocoel
. 0 organs of the insect are
suspended in this cavity.
10th Ashoj, 2075

7. Insect Circulatory Organs
Dorsal Diaphragm
0 Separates the upper pericardial sinus
from the lower perivisceral sinus.
0 formed by alary muscles of the heart
and related structures
Ventral Diaphragm
0 separates the perineural sinus from
the main perivisceral sinus
0 helps in perfusing the ventral nerve
cord of insects
10th Ashoj, 2075
To facilitate circulation of hemolymph, the body cavity is divided into three compartments
(called blood sinuses) by two thin sheets of muscle and/or membrane known as the dorsal
and ventral diaphragms.

8. Insect Circulatory Organs
Accessory Pulsatic organs
• located at the base of the
appendage
• In case of wings, is present in
both wing-bearing segments of
most adult insects.
• Also found at the base of the each
antenna
• pulsatile leg organs with muscular
attachment to the diaphragm
• have a longitudinal septum in
legs, which divides the lumen into
two sinuses
10th Ashoj, 2075

9. Insect Circulatory Organs
HEMOLYMPH
0 Colorless liquid that bathes the insect tissues
0 Only about 10% are hemocytes and the rest of the
hemolymph content is watery plasma
0 analogous to the blood in vertebrates
0 circulates in the interior of the arthropod body remaining
in direct contact with the animal's tissues.
0 transfers nutrients from the insect gut to the organs, takes
away waste and also transmits hormones
10th Ashoj, 2075

10. Insect Circulatory Organs
HEMOLYMPH COMPOSITION:
0 90% Water
0 Inorganic ions
0 Nitrogenous wastes
0 Carbohydrates
0 Lipids
0 Proteins and enzymes
0 Pigments
0 Hormones
10th Ashoj, 2075

11. Insect Circulatory Organs
HEMOLYMPH FUNCTIONS:
0 Lubricant for tissues and internal organs
0 Hydraulic medium (caterpillars, wing expansion, etc.)
0 Transport medium for nutrients, wastes and hormones
0 Storage (amino acids, water, and glycerol)
0 Heat exchange
0 Immune response
10th Ashoj, 2075

12. Circulation
0 When the heart contracts,
the valves of the ostia are
closed by the pressure and
the hemolymph is moved
forward and dumped into
the head area.
0 Alary muscles aid the
contractions of the heart.
10th Ashoj, 2075

13. Circulation
0 The blood circulation is also aided by the presence of
the dorsal and ventral diaphragms, which consists of
sets of muscles that divide the hemocoel into various
sinuses.
10th Ashoj, 2075

14. 10th Ashoj, 2075

15. Overview
VERTEBRATES INSECTS
0 Closed circulatory
system
0 Blood
0 Heart
0 Oxygen
Transportation
0 Open circulatory
system
0 Hemolymph
0 Dorsal Vessel
0 Transport of other
substances
10th Ashoj, 2075