Our body is managed by two systems. One is the nervous system while the other is the endocrine system. The endocrine system revolves around various glands found in the body which secrete substances called hormones. These glands are called endocrine glands meaning ductless glands. The cells in these glands form hormones which then diffuses through the endothelial wall and enters the blood. The hormones then travels around the body and takes effect in its target organs and any other organ which responds to it naturally. Each hormone serves its own purpose.
Endocrine glands and Exocrine glands
Endocrine glands are those glands which have no duct in it meaning it doesn’t have a tube to drop substances in to while exocrine glands do. Exocrine glands secrete specific substances while the endocrine secrete hormones into the bloodstream. There are some glands which have a duct but also secrete hormones. These include the Gonads and the pancreas. The cells of pancreas form a substance called the pancreatic juice which is a substance filled with enzymes. It is secreted out into the duodenum through the pancreatic duct. However the pancreas has a group of cells called the islets of Langerhans. These produce two hormones called insulin and glucagon which helps control blood glucose level.
The Main Endocrine Glands and their Functions
Hypothalamus – It produces hormones which controls other glands to release hormones.
Pituitary Gland – It also controls other glands to secrete hormones and secrets anti diuretic hormone (ADH) which controls water potential of the blood.
Thyroid Gland – produces thyroxine which controls the development and growth of the body.
Adrenal gland – found on top of the kidneys, these produce adrenaline which increases blood glucose concentration to provide energy to the muscles. Further it dilates the eye causing it to be more sensitive to movement. Blood vessels constrict and the erector muscles contract causing the hair to stand up. This hormone is connected to the nervous system. When we feel sad, angry or are excited the receptors sense a change in environment and sends nerve impulses to the central nervous system which then sends the impulses to the adrenal gland for secreting the hormone adrenaline. This forms a “fight or flight” situation.
Gonads – Gonads include the ovaries (in female) and testes (in male).
Ovaries – The ovaries secrete estrogen which is important for the development of female secondary sex organs. Further the ovaries also secrete progesterone during pregnancy which prepares uterus for implantation of embryo and swells the mammary glands.
Testes – Testes produce testosterone which develops the sperm cells in males and also develops the secondary male sex organs.