Glands or gland-like cells release a substance into the body during secretion. The secretion is released either internally via blood pathways or externally via glandular pathways. Overproduction of certain secretions is called hypersecretion, whereas underproduction is called hyposecretion.
What is secretion?
Many secretions are also used for digestion, such as the secretion of digestive enzymes from bile. Figure shows bile and pancreas. During secretion, specialized cells release certain substances into the organism. In most cases, these specialized cells are glandular cells. There are different types of secretion. For example, exocrine secretion must be distinguished from endocrine secretion. In the endocrine form, the secretion is released into the blood system. This variant is the most common type of internal secretion. To be distinguished from this are autocrine and paracrine secretion. In the autocrine form, the secretion acts on the releasing cells themselves. Paracrine secretions, on the other hand, act on the cells in the environment. In the exocrine or external variant, the cells do not release the secretion internally, but into the glandular ducts or directly onto the surface of mucous membranes. Exocrine secretion can be further differentiated into eccrine, apocrine, and holocrine secretion. Additionally, the excretion of the end products of metabolism is sometimes referred to as secretion or, more specifically, excretion. Each secretion is irreplaceable to the organism, and the individual secretions perform entirely different functions.
Function and task
Secretion occurs involuntarily by glands or gland-like cells. Control of secretion is the responsibility of the autonomic nervous system and the endocrine system. Secretions fulfill various tasks. For example, metabolic products that are no longer needed in the body are secreted. Secretions such as nasal secretions, on the other hand, keep mucous membranes moist and bind pathogens. Many secretions also serve digestive purposes, for example the secretion of digestive enzymes from bile and the release of saliva or gastric juice. A nutritional function, on the other hand, is fulfilled by the secretion of the mammary glands, which ensures the supply of the offspring through the mother’s milk. The secretion of sweat via the sweat glands in turn serves thermoregulation. The release of fats from the sebaceous glands onto the surface of the skin serves to lubricate the skin and hair. Scent glands, on the other hand, secrete scent marks. In the animal kingdom, there are significantly more secretory functions. Snake venom, for example, serves to paralyze the prey animal. In mosquitoes, a secretion keeps the bite wound open, and animals such as the skunk are equipped with defensive secretions to drive away enemies. A glandular secretion can also serve several functions. In humans, for example, this is the case with bile secretions. The secretion can be released by different mechanisms. In avesicular secretion of bile, for example, the secretion is discharged via transport proteins. In eccrine secretion, on the other hand, small vesicles form and pass into the membrane, as in the case of sweat, for example. In apocrine secretion, the secretion is released together with parts of the cell and cell membrane.This type of secretion is operated, for example, by the mammary glands. In the holocrine secretion of the sebaceous glands, on the other hand, the entire secretion cell is released and dies. Depending on the anatomical structures on which a secretion acts, we speak of autocrine or paracrine secretion. Some glandular secretions act at the same time on the glandular cells themselves and on cells in the immediate vicinity. This phenomenon is present, for example, in the secretions of the testes. The consistency of a secretion may be between watery and mucilaginous or may take on mixed forms. Many secretory glands are hormonally controlled and function on the basis of feedback mechanisms. On the cellular level, the discharge of individual proteins can also be understood as secretion. This type of secretion occurs, for example, with immunoglobulins.
Diseases and disorders
Disorders in the secretion of glands correspond to either hypersecretion or hyposecretion. Hypersecretion is the overproduction of a particular secretion. For example, hyperhidrosis is the excessive production of sweat.Hyperlacrimation is increased secretion of lacrimal secretions and hypersalivation means excessive secretion of saliva. Salivary hypersecretion can occur, for example, in the context of poisoning or inflammation and infection. However, epilepsy and Parkinson’s disease are also possible causes of the phenomenon. If the reduced release of bodily secretions assumes pathological proportions, hyposecretion is present. This phenomenon often occurs in the context of an undersupply of certain hormones. Thus, the glands are stimulated to secrete only to an insufficient extent. The reduced hormone production in the pituitary gland is also called hypopituitarism. This phenomenon can occur in the context of tumor disease in the pituitary gland. Glands themselves can also be affected by disease and therefore alter their secretion. Diabetes, for example, is a disease of the endocrine gland system. Diseases of the thyroid gland are also referred to as endocrine diseases. In hypothyroidism, there is a deficiency of thyroid hormone in the body. Affected individuals gain weight, are sensitive to cold, and appear slowed in their reactions. In the case of hyperthyroidism, on the other hand, weight loss and nervousness set in. Excessive sweating also occurs as part of this.
