The endocrine system controls the body through chemical messengers called hormones. Glands such as the pituitary, thyroid, pancreas and ovaries secrete hormones that travel through the bloodstream and trigger responses in target cells. Hormones can be proteins that bind to cell surface receptors or lipids that pass into cells to regulate gene expression. Conditions like Cushing's syndrome and Addison's disease occur when the endocrine system produces too much or too little cortisol and other hormones.
2. Main Fuction/Structure/Purpose The endocrine system controls the body by means of chemical messengers, which bring slower, long-lasting responses and changes. Even before you were born, the endocrine glands and the hormones they secrete were functioning in the homeostatic control of your body. Some examples of endocrine glands at work is the amount of growth you experience, the regulation of blood sugar levels, the regulation of the calcium level in your bones and blood, and how fast you metabolize your food.
3. Vocabulary GLANDS : a cell, group of cells, or organ producing a secretion PITUITARY GLAND : releases hormones that control other endocrine glands HYPOTHALAMUS : part of the brain that controls blood pressure, body temperature, and emotions. It’s connected to the pituitary and controls the release of hormones by the pituitary. HORMONES : organic compound made and released by one part of an organism in order to affect another part of an organism
4. Hormones Hormones travel to all parts of the body, individual hormones don’t have an effect until they reach their target organs. When it is there, the hormone binds with specific molecules in target cells. Hormones fit with their target cells like a lock and key. The way in which a hormone affects a cell depends on the type of hormone. There are two types…
5.
6.
7. Types of Glands THYMUS : makes thymosin, which stimulates the development of T cells ADRENAL GLAND : adrenal cortex produces epinephrine and nor epinephrine, which cause the fight-or-flight response TESTIS : makes testosterone, which develops and maintains the male reproductive system and the male secondary sex characteristics OVARY : makes estrogen and progesterone. Estrogen develops and maintains the female reproductive system and the female secondary sex characteristics. Progesterone prepares and maintains the uterus during pregnancy. PINEAL GLAND : secretes melatonin, which helps control body functions in response to daylight and seasonal changes THYROID GLAND : makes thyroxine, which speeds up metabolism and helps control growth and development PARATHYROID GLAND : makes parathyroid hormone, which regulates the level of calcium in the blood PANCREAS : makes insulin and glucagons. Insulin lowers blood sugar level; glucagon raises blood sugar level
8.
9. How are hormones transported from one area of the body to another? Hormones are hydrophobic and therefore don’t dissolve in the plasma, they require proteins to travel through the blood stream. Once they reach their target cells they easily diffuse through the cell membrane due to their hydrophobicity and bind to their receptor within the cytoplasm. This complex travels to the nucleus to regulate transcription to alter the amount of protein that is made.
10. Endocrine System vs. Nervous System There are two control systems that regulate the human body: the nervous system and the endocrine system. These two systems, together, monitor all the other systems in order to maintain homeostasis. The nervous system controls the body through high-speed nerve impulses. As I said before, the endocrine system controls the body by means of chemical messengers.
11. Control of Endocrine Glands One way in which hormones regulate the body is through feedback control. This is the regulation of the rate of a process by the last step in the process. In negative feedback control, the last step in the process stops the first step. In positive feedback control, the last step in a process accelerates the first step.
12. control of bLood sugar Blood sugar levels are controlled by two hormones secreted by the pancreas. The pancreas contains patches of endocrine tissue called the islets of Langerhans. Special cells in the islets of Langerhans, called beta cells, produce insulin. It also causes the liver and skeletal muscles to convert blood sugar to glycogen. Therefore, insulin lowers the amount of glucose in the blood. Another hormone, called glucagon, is produced by alpha cells in the islets of Langerhans. Therefore, glucagon raises the amount of glucose in the blood. In some people, the blood sugar level is difficult to regulate. Diabetes mellitus is a disorder in which the body is unable to control blood sugar levels. Diabetes can lead to a dangerously high level of glucose in the blood. There is no cure, but there are effective treatments. Scientists are always looking for better treatments and a cure for diabetes.
13. Control of Reproduction The hypothalamus and the pituitary gland indirectly control the growth, development, and activities of the reproductive system. They affect the reproductive system by stimulating the testes and ovaries to secrete sex hormones. These sex hormones control the development of sex characteristics. The site of most sex hormone secretion changes during a person’s lifetime. Before birth and during childhood, the development of the sex organs is controlled by the secretion of sex hormones from the adrenal glands. These glands secrete only small amounts of the sex hormones. At some point between the ages of 10 and 16, the hypothalamus begins stimulating the pituitary to release two hormones: LH and FSH. LH also stimulates the release of the egg from the ovary in girls. The release of LH and FSH from the pituitary mark the beginning of puberty. Now, instead of the sex hormone secretion being in the adrenals, it’s in the testicles or ovaries.
