The Endocrine system Glands and hormones Have you ever heard of an epinephrine rush? You might have had one without realizing it. Exciting situations, such as riding a roller coaster or watching a scary movie, can cause your body to release epinephrine. The Endocrine System The human body has two systems that regulate its activities, the nervous system and the endocrine system. The nervous system regulates most activities by sending nerve impulses throughout the body. The endocrine system produces chemicals that control many of the body’s daily activities. The endocrine system also regulates long-term changes such as growth and development. What is the Endocrine system? A collection of glands of that secrete hormones directly into the circulatory system to be carried toward specific target organs. The Endocrine System The endocrine system is made up of glands. A gland is an organ that produces or releases a special chemical messengers for you body. Some glands, such as those that produce saliva and sweat, release their chemicals into tiny tubes. The tubes deliver the chemicals to a specific location within the body or to the skin’s surface. Unlike sweat glands, the glands of the endocrine system d o not have delivery tubes. Endocrine glands (EN d uh k rin) produce and release their chemical products directly into the blood stream. The blood then carries those chemicals throughout the body. There are the main structure of the endocrine system. The Endocrine System What are hormones? Hormones are your body's chemical messengers made on one cell or tissue that causes a changes in another cell or tissue in another part of the body. They travel in your bloodstream to specific tissues or organs and work slowly, over time, affecting your growth, development, metabolism, reproduction, and mood. They are made in one location but travel to another to function. The chemical product of an endocrine gland is called a hormone. Hormones turn on, turn off, speed up, or slow down the activities of different organs and tissues. You can think of a hormone as a chemical messenger. Hormones are carried throughout the body by the blood. Therefore, hormones can regulate activities in tissues and organs that are not close to the gland s that produce them. The Endocrine System What causes the release of hormones? Often, nerve impulses from the brain make that happen. Suppose, for example, a person sees a deadly, knife-edged pendulum. Nerve impulses travel from the person’s eyes to the brain. The brain interprets the information and then sends an impulse to an endocrine gland . That gland , in turn, releases the hormone adrenaline into the blood stream. Adrenaline immediately makes the heart rate and breathing rate increase. The Endocrine System Hormone Action In contrast to the body’s response to a nerve impulse, hormones usually cause a slower, but longer lasting, response. For example, the brain sends a signal to an endocrine gland to release adrenaline into the bloodstream. When the adrenaline reaches the heart, it makes the heart beat more rapidly. The heart continues to race until the amount of adrenaline in the blood drops to a normal level. The Endocrine System Target Cells When a hormone enters the bloodstream, it affects some organs but not others. Why? The answer lies in the hormone’s chemical structure. A hormone interacts only with specific target cells. Target cells are cells that recognize the hormone’s chemical structure. A hormone and its target cell fit together the way a key fits into a lock. Hormones will travel through the bloodstream until they find the “lock”- or particular cell type-that they fit. Each endocrine gland releases different hormones and thus controls different processes. The endocrine glands include the hypothalamus, pituitary, thyroid, parathyroid, adrenal, thymus, and pancreas. They also include the ovaries in females and testes in males. The job depends on the gland they are made in . Major Glands of the Endocrine system Major Glands of the Endocrine System l Hypothalamus l Pineal Gland l Pituitary l Thyroid (AKA Parathyroid) l Adrenal Gland l Thymus l Pancreas l Ovaries / Testes Hypothalamus The nervous system and the endocrine system work together. The hypothalamus (hy poh THAL uh mus), a tiny part of the brain near the middle of your head, is the link between the two systems. Nerve messages controlling sleep, hunger, and other basic body processes come from the hypothalamus. The hypothalamus also produces hormones that control other endocrine glands and organs. The hypothalamus plays a major role in maintaining homeostasis because of the nerve impulses and hormones it produces. It controls the pituitary gland. Pineal Gland l Location > deep in brain as part of the hypothalamus l Hormones> Controls sleep body temperature, reproduction and aging l Other Info > size of pea, sensitive to light Pituitary Gland Just below the hypothalamus at the base of the brain, above the roof of the mouth is an endocrine gland about the size of a pea. The pituitary gland (pih TOO ih tehr ee) communicates with the hypothalamus to control many body activities. In response to nerve impulses or hormone signals from the hypothalamus, the Pituitary gland releases its hormones. Some of those hormones act as an “on” switch for other endocrine glands. For example, one pituitary hormone signals the thyroid gland to produce hormones. Other pituitary hormones control body activities directly. Growth hormone regulates growth from infancy to adulthood, which includes sexual development. Another pituitary hormone directs the kidneys to regulate the amount of water it takes from blood . Pituitary Gland FUNCTION: - Stimulates specific glands and tissues in the body: thyroid, ovaries, testes, mammary glands, and adrenal glands. - “Master gland” - Stimulates growth/repair of cells - Regulates blood pressure HORMONES: Produces seven hormones: -Human growth hormone(HGH) -Thyroid-stimulating hormone(TSH) Things that can go wrong… l Giantism- oversecretion of somatotropin before puberty l Dwarfism- undersecretion of somatotropin. Cause: tumor, injury, infection, genetics l Diabetes insipidus- decreased ADH Thyroid LOCATION: Throat, under Adam’s apple FUNCTION: Controls rate at which the body produces energy from nutrients inside cells-known as your metabolism. Regulation of calcium in blood. HORMONES: -Triiodothyronine (T3) -Thyroxine (T4) OTHER INFO: Must have iodine to function. Parathyroid LOCATION: Throat, under Adam’s apple FUNCTION: Produce hormones that regulate calcium and phosphorous levels which help in bone development. HORMONE: Parathyroid hormone Thyroid Problems Hypothyroidism - An underactive thyroid. Hyperthyroidism - An overactive thyroid. Goiter - An enlarged thyroid, not enough iodine Thyroid Nodules - Lumps in the thyroid gland. Thyroid Cancer - Malignant thyroid nodules or tissue. Thyroiditis - Inflammation of the thyroid. Autoimmune Hashimoto's Disease - an autoimmune disease that causes the thyroid to become underactive. Autoimmune Graves' Disease - an autoimmune disease that causes the thyroid to become overactive. Adrenal Glands LOCATION: Top of the kidneys FUNCTION: Helps to react to danger -fight or flight response Regulates body’s response to: -Stress -Blood sugar levels - Salt and water balance in kidneys -Cardiovascular function -Gastrointestinal function HORMONES: About 30 different ones -Adrenaline/Epinephrine -Steroid hormones (Cortisol) OTHER INFO: hormones from here give you a quick burst of energy and fight allergies. Thymus LOCATION: In your chest cavity between lungs FUNCTION: -Increases white blood cell function -Increases immune response -Stimulates certain pituitary hormones HORMONES: Thymosin and Thymulin OTHER INFO: Slowly gets smaller over time, important to circulatory and immune systems. Pancreas LOCATION: Beneath stomach, connected to small intestine FUNCTION: Lowers blood glucose levels after meals by stimulating the absorption of glucose in the liver and muscle tissue Pancreas HORMONES: Insulin and glucagon (regulate the amount of glucose in blood) OTHER INFO: Important in digestive system too, diabetes if it doesn’t work right. Glucose Feedback Control Two hormones control the level of glucose in the blood. Insulin lowers blood-glucose levels by telling the liver to convert glucose into glycogen and to store glycogen for future use. Glucagon has the opposite effect. It tells the liver to convert glycogen into glucose and to release the glucose into the blood. Disease and Disorders Growth Hormone Deficiency – the pituitary gland doesn‛t make enough growth hormone, so the body doesn‛t grow properly. Growth is stunted but treatable. If too much the child may grow taller than expected. Treatments – if detected early, growth hormone can be prescribed and the child‛s growth monitored. Diabetes Mellitus – when a person‛s body does not use insulin properly or whose pancreas does not make enough insulin. Treatments -daily injections of insulin to keep blood glucose levels at safe limits. Diabetes Cause- decreased secretion of insulin Symptoms Excessive thirst, excessive urination, hyperglycemia, slow healing of skin infections Affects 21 million in US: 7% of population Estimated 1/3 of people who have diabetes don’t know it 225,000 die each year 132 billion/year- 10% of our health care spending Insulin was the first hormone identified (late 1920's) which won the doctor and medical student who discovered it the Nobel Prize (Banting and Best) 1982 – Human Insulin - First ever approved genetically engineered human therapeutic by Genentech