The Glandular System

There are many kinds of glands in the human body. These glands are made up of special kinds of cells. All these glands and their functions comprise the glandular system.

The glands found in the body are of two types. They are as follows:

1. Exocrine glands, and

2. Endocrine glands.

Exocrine Glands

       Exocrine glands pour their secretions out through a duct, for example, salivary gland and liver. The secretions of exocrine glands are called enzymes. The enzymes secreted by exocrine glands produce chemical changes when they come in contact with other substances.

Endocrine Glands

       Endocrine glands are usually a group of cells and glands without ducts. They produce special substances called hormones, which are poured directly into the blood stream from the glandular cell. So, they are also known as ductless glands. The endocrine system consists of a number of distinct glands. The main endocrine glands are:

a) Pituitary glands,                                  b) Pineal glands,

c) Thyroid glands,                                   d) Parathyroid glands,

e) Thymus glands,                                   f) Adrenal glands,

g) Pancreas, and                                      h) Gonads.

a) Pituitary Glands: The pituitary gland is a small, oval-shaped body like a big pea. It is located in the base of the brain. It controls all the glands as the master. It has great influence on skeletal growth. It also affects the functions of ovaries and testes.

b) Pineal Gland: The pineal gland is a small body resembling a pine cone, which is situated under the brain.

c) Thyroid Gland: The thyroid gland is located in the neck where the larynx joins the trachea. This gland helps to regulate the rate of metabolism. The thyroid gland secretes thyroid hormones called ‘Thyroxin’ and ‘Tridothyroxin’. An overactive thyroid gland will cause a bulging of the eyes and other symptoms. The thyroid gland requires a certain amount of iodine. When there is too little iodine in the water supply or in the food, a swelling called goiter may appear in the neck.

d) Parathyroid Glands: The parathyroid glands are small oval bodies, and are about the size of a pea. There are four parathyroid glands. The secretion of the parathyroid glands is called parathormone, which influences calcium and phosphorus metabolism, and controls the excretion of phosphate.

        Over secretion of parathormone causes loss of calcium, which goes from the bones into the blood, and from there it is excreted in the urine. The bones become porous and brittle and the increased level of blood calcium may cause the formation of kidney stone.

        Under-secretion of this hormone leads to a sharp decrease of calcium in the blood plasma. This condition is characterized by intense spasm of many of the muscles.

e) Thymus: The thymus gland is located in the thoracic cavity behind the sternum. It is believed that it is related to the production of antibodies.

f) Adrenal Glands: The adrenal glands are paired organs each of which is located at the top of each kidney. The hormones secreted from the adrenal glands regulate the level of glucose in the blood, and influence fat, carbohydrate and protein metabolism. Under-secretion of these hormones causes the disturbance in metabolism, loss of weight, muscular weakness, low-blood pressure, etc. whereas; over-secretion causes change in the genital system. In women, it may result in secondary male characters.

g) Gonads: The sex glands, the testes in male and ovaries in female are known under the common name of gonads. These glands internally secrete sex hormones which are delivered into the blood and influence the various functions.

         The ovaries secrete estrogen and progesterone, which influence the sexual maturation of the female organs, regulate the monthly period, prepare the uterus for ovulation, and influence the normal course of pregnancy.

h) Pancreas: The pancreas lies across the posterior abdominal wall behind the stomach. It is a mixed gland composed of lobules. Pancreas produces pancreatic juice, which is delivered to the duodenum. It also secretes a hormone known as insulin. In case of insulin deficiency, only a portion of carbohydrate is used by the body. The remaining carbohydrate is secreted in the form of sugar in urine. Thus, the deficiency of insulin results in diabetes.

Glands and Health

          Glands of our body secrete various enzymes and hormones, which are essential for the proper growth, development and regulation of our body. Over secretion or under secretion of these glands may create physiological disturbances in the body which is the sign of ill health. In fact, these glands only work efficiently in a healthy situation, and the healthy condition can be maintained only through the balanced diet, maintenance of personal hygiene, healthy habits and proper exercise.