Hemolymph
Hemolymph, or haemolymph, is a fluid, analogous to the
Oxygen-transport systems were long thought unnecessary in insects, but ancestral and functional hemocyanin has been found in the hemolymph.[3] Insect "blood" generally does not carry hemoglobin, although hemoglobin may be present in the tracheal system instead and play some role in respiration.[4]
Method of transport
In the
Coordinated movements of the body muscles gradually bring the hemolymph back to the dorsal sinus surrounding the hearts. Between contractions, tiny valves in the wall of the hearts open and allow hemolymph to enter. Hemolymph fills all of the interior (the
The hemolymph of lower arthropods, including most
Constituents
Hemolymph can contain nucleating agents that confer extra cellular freezing protection. Such nucleating agents have been found in the hemolymph of insects of several orders, i.e., Coleoptera (beetles), Diptera (flies), and Hymenoptera.[6]
Inorganic
Hemolymph is composed of water, inorganic salts (mostly sodium, chlorine, potassium, magnesium, and calcium), and organic compounds (mostly carbohydrates, proteins, and lipids). The primary oxygen transporter molecule is hemocyanin.[7][3]
Amino acids
Arthropod hemolymph contains high levels of free amino acids. Most amino acids are present but their relative concentrations vary from species to species. Concentrations of amino acids also vary according to the arthropod stage of development. An example of this is the silkworm and its need for glycine in the production of silk. [8]
Proteins
Proteins present in the hemolymph vary in quantity during the course of development. These proteins are classified by their functions: chroma proteins, protease inhibitors, storage, lipid transport, enzymes, the vitellogenins, and those involved in the immune responses of arthropods. Some hemolymphic proteins incorporate carbohydrates and lipids into the structure.[9]
Other organic constituents
Nitrogen metabolism end products are present in the hemolymph in low concentrations. These include ammonia, allantoin, uric acid, and urea. Arthropod hormones are present, most notably the juvenile hormone. Trehalose can be present and sometimes in great amounts along with glucose. These sugar levels are maintained by the control of hormones. Other carbohydrates can be present. These include inositol, sugar alcohol, hexosamines, mannitol, glycerol and those components that are precursors to chitin.[1]
Free lipids are present and are used as fuel for flight.[10]
Hemocytes
There are free-floating cells, the hemocytes, within the hemolymph. They play a role in the arthropod immune system. The immune system resides in the hemolymph.
Comparisons to vertebrates
This
Specialist uses
In some species, hemolymph has other uses than just being a blood analogue. As the insect or arachnid grows, the hemolymph works something like a hydraulic system, enabling the insect or arachnid to expand segments before they are
See also
References
- ^ a b Chapman 1998, p. [page needed].
- S2CID 218693.
- ^ PMID 14715904.
- PMID 12048208.
- ISBN 0-412-61390-5.
- PMID 7083885.
- PMID 16861020.
- ^ Chapman 1998, p. 108.
- ^ Chapman 1998, p. 111.
- ^ Chapman 1998, p. 114.
- .
- ^ Genus Leptanilla Australian Ants Online
Sources
- Chapman, R.F. (1998). The Insects: Structure and Function (4th ed.). Cambridge: Cambridge University Press. ISBN 978-0-521-57890-5.
External links
- "Do insects have blood?". Boston Globe. October 17, 2005. Archivedfrom the original on October 2, 2022.
- Bolstad, Kat (May 2, 2008). "Blue Squid Blood - Murky Water". Te Papa Tongarewa Museum of New Zealand. Archived from the original on April 2, 2015.