Blood and lymph in the human body perform important functions to maintain breathing and immunity. However, not all animals have these fluids separated, due to the structure of the body and the simplicity of organization. Such organisms include representatives of the type Arthropods (insects, spiders, crustaceans) and Mollusks. They are characterized by the presence of hemolymph, which has much in common with blood in composition and function.
Hemolymph - what is it?
Animals such as arthropods or mollusks are characterized by an open circulatory system. This means that the fluid that circulates through the vessels is ejected into the body cavity and washes all the tissues of the organs. This fluid is called hemolymph, because It combines the functions of blood and lymph.
What is hemolymph in insects and mollusks? This is a colorless, bluish or greenish liquid, which is responsible for the delivery of nutrients to organs and tissues, for metabolic metabolism and the immune response when a threat of a disease develops.
Hemolymph of invertebrate animals also contains uniform elements of one species, unlike human blood and other evolutionarily developed organisms. These cells are called hemocytes, and they can differ from each other in structure, shape and function.
The composition of hemolymph
What is hemolymph chemically? The composition of this solution is rather complicated, because It performs several functions in the body of invertebrate insects. Hemolymph has a neutral or slightly acidic environment, which is supported by the anions of certain acids. From 75 to 90% of the total solution is water, and the rest of the volume are formed elements and other dissolved substances.
The ionic composition of hemolymph is also diverse. It contains cations of sodium, potassium, magnesium and calcium. Of the anions, chlorine is most important, as well as phosphoric and carboxylic acid residues. The content of all ions is unstable and depends on the age and stage of development of the organism. For example, by the content of chlorine anions, one can distinguish an insect larva from an adult.
From organics, hemolymph contains proteins, fats and carbohydrates. Carbohydrates and proteins come from the digestive system through the diet, with glucose and fructose levels dependent on the amount of nectar consumed.
100 ml of hemolymph contains 1-5 g of protein. Proteins play an important role in the life of the body, so they are transported with fluid flow to organs and tissues. If hemolymph studies are carried out, up to 30 different fractions of proteins can be distinguished , and their amount depends on the sex of the body and age.
Lipids enter the hemolymph from the intestines and fat body, and in the latter they accumulate throughout life. The fat content varies, and most of them are esters of glycerol and fatty acids - glycerides. That's what hemolymph is in terms of chemistry.
Hemolymph functions
What is hemolymph and what functions does it perform in the body of invertebrate animals?
- The trophic function, which is the nutrition of tissues and organs, as well as the transport of substances throughout the body.
- Metabolic function, when metabolic products enter the hemolymph from tissues and are excreted through the excretory system.
- Immunological function. It is supported by certain types of hemocytes that are located on the surface of organs.
- Protective function. The hemolymph of some arthropods and mollusks contains poisons or other toxic substances, which protects them from predators.
Shaped elements
What is hemolymph in biology? This is a solution in which there are not only dissolved substances, but also specialized cells - hemocytes. There are 7 types of hemocytes, the main function of which is the immune response to the appearance of antigens. The shaped elements form special phagocytic structures on the surface of the tissues, which also serve as the lymph nodes of vertebrates.