Humoral regulation, exocrine and endocrine glands - these are the concepts that you will learn about from this article. Together with the nervous system, they ensure the coordinated work of the whole organism. How does it happen?
Mechanism of action of humoral regulation
All physiological processes in the human body are carried out in two ways. The nervous system provides responses and a direct relationship with environmental factors.
Humoral regulation is carried out with the participation of special chemicals - hormones. They are produced by organs called glands. Hormones are carried by blood, tissue fluid or lymph. Under their influence, morphological and physiological changes occur, which are aimed at ensuring the normal functioning of the body. The action of hormones can be described as slow and prolonged, in contrast to the nervous regulation, which is carried out quickly and briefly.
Exocrine and endocrine glands: differences
There are several types of glands in the human body. They can be external or internal.secretions. In another way they are called exocrine and endocrine glands. The former secrete their products (secrets) into the external environment or body cavities. The functions of the exocrine glands are varied. The largest of them is the liver. It cleanses the body of toxins and is involved in the processes of hematopoiesis. Sweat provide thermoregulation, sebaceous moisturize and lubricate the skin. The bulbourethral glands also belong to this group. They are also called coopers. These are typical glands of external secretion, which belong to the male reproductive system. They secrete their secret, containing a large amount of mucus and enzymes, into the urethra. This substance promotes the movement of spermatozoa, neutralizes the acidic environment and prevents mucous membranes from irritation.
Like the exocrine glands, the endocrine glands secrete secretions. But they contain hormones - biologically active substances released directly into the blood. These substances have a number of specific features. They act in very small concentrations, change the rate of chemical reactions, and their effects are controlled by the nervous system.
Glands of mixed secretion
Besides the exocrine and endocrine glands, there is another group. They secrete two types of hormones. One of them enters the blood, the other - into the cavity of the internal organs. Examples of these are the sex and pancreas. Such secretion is called mixed.
Sex glands
Man is a dioecious organism. Men'sthe gonads (testicles) and female (ovaries) produce sex cells. They secrete gametes - eggs and sperm. The process of their fusion (or fertilization) occurs in the fallopian tube. This is how external secretion manifests itself.
Hormones are also formed in the gonads. Women's are called estrogens, and men's are androgens. They are released into the blood. During the period of embryonic development, these substances control the formation of the corresponding genital organs, and during adolescence - secondary sexual characteristics. This is the internal secretion of the gonads.
Pancreas
It is also an organ of mixed secretion. The exocrine part of the pancreas produces digestive juices. It is secreted into the duodenum. Gastric juice is a clear liquid, which includes hydrochloric acid, mucus mucin and enzymes - pepsin and lipase. As a result of the action of these substances, the breakdown of organic substances occurs, the neutralization of pathogenic bacteria and the stimulation of the motor activity of the stomach.
As an endocrine gland, the pancreas secretes the hormones insulin and glucagon, which regulate carbohydrate metabolism. The first promotes the conversion of glucose into glycogen, which is deposited in the liver. Glucagon has the opposite effect. If an insufficient amount of insulin is secreted in the body, this leads to an increase in the concentration of sugar in the blood and a violation of metabolic processes. This disease is called diabetes mellitus.
Pituitary
This gland is internalsecretion is located at the base of the brain. It secretes growth hormone. With its excess (hyperfunction), gigantism develops at a young age, and with a deficiency (hypofunction), dwarfism develops. If growth hormone is secreted in large quantities in an adult, this causes acromegaly - an exorbitant growth of certain parts of the body.
Thyroid
This organ is attached to the trachea and larynx with fibrous tissue. The thyroid is the largest endocrine gland. It secretes iodine-containing hormones - thyroxine and triiodopsin. They regulate the release of energy, growth and development of nervous tissue. Hyperfunction of the thyroid gland leads to the development of Graves' disease, which is manifested by excessive excitability, weight loss, trembling in the limbs. If the food contains insufficient amounts of iodine, this can lead to the appearance of endemic goiter. This is called an increase in the size of the thyroid gland.
Adrenals
You must have noticed that in a stressful situation, the body's forces are mobilized and muscle performance is increased. This is possible due to the action of adrenaline, a hormone secreted by the adrenal glands. The action of this substance leads to an increase in glucose levels. This provides the muscles with the necessary energy, increases their performance, and mobilizes the activity of the cardiovascular system.
Thymus gland (thymus)
This unpaired endocrine gland, formed by glandular cellsand reticular tissue. In humans, its formation is completed only by the period of puberty. After that, the reverse process begins. The reticular tissue of the thymus atrophies and is replaced by fatty tissue. A thymus hormone called thymosin affects the production of T-lymphocytes. These are blood cells that form humoral immunity. The essence of this process is the formation of specific antibodies that destroy foreign microorganisms.
So, humoral regulation in the human body is carried out with the help of the endocrine system. It includes the endocrine glands. Their examples are the thymus gland (thymus), the pituitary gland, the pineal gland, the thyroid gland. They secrete their secrets, containing hormones, into the blood. Exocrine glands include salivary, sweat, sebaceous, mammary, bulbourethral glands. They secrete their products outside or into the body cavity. In addition to the exocrine and endocrine glands, there are mixed glands in the body - the genital and pancreas. They secrete hormones into the blood, and gametes and digestive juice into the cavities of organs.
