Unit Eleven - The Endocrine System I. Introduction A. Overview: the endocrine system and nervous system work to control homeostasis within the body. The endocrine system operates at a much pace but the results are more widespread and longer lasting. The endocrine system releases chemicals called into the. Hormones enable the system to spread its control wherever blood goes and controls processes like growth, development, reproduction, blood pressure & metabolism. B. Structure of endocrine system 1. Made up of throughout the body that make chemicals (hormones) which carry messages. 2. Uses the for the transport of these chemicals. C. Function of endocrine system 1. Messages carried by hormones travel to different throughout the body looking for receptors to to. 2. Hormones will alter the metabolism of a target organ. D. Definitions 1. Endocrinology (endo=within, crin=to secrete, ology=study of) the study of the endocrine system. 2. Hormones: (hormone=set in motion) released into the bloodstream by the glands. Hormones can be divided into three groups: amino acid, peptide and protein, and steroid (lipid based). 3. Endocrine glands: glands that release their hormones into the space surrounding the producing cells. The hormones are then picked up by and spread throughout the body. Diagram comparing exocrine and endocrine glands:
II. Overview of the Endocrine System: Hypothalamus Pituitary gland Ovary (2) Testes (2) Thyroid gland Adrenal glands (2) Parathyroid gland Pancreas Thymus gland
III. Pituitary gland (hypophysis) A. Located at the bottom of the brain and controlled by the. Actually connected to the hypothalamus (a part of the brain) by a stalk called the. B. Only the size of a but controls many organs and body functions and therefore is often called the. C. Diagram of the pituitary gland: D. There are two parts to the pituitary gland: the anterior lobe and the posterior lobe. 1. Anterior lobe of the pituitary gland a. Responsible for the release of types of hormones. The release of these hormones is controlled by the. The hypothalamus will release chemical hormones that travel a short distance to the anterior pituitary causing the anterior pituitary to either release more or less of particular hormones.
B. The seven hormones released by the anterior pituitary will regulate different processes taking place in the body. (1) Growth hormone (GH): affects cause cells of and muscles to grow and divide. (2) Prolactin (PRL): (pro=for, lact=milk) after childbirth it stimulates the by the mother s breasts. (3) Melanocyte stimulating hormone (MSH): stimulates the production of melanin in the skin to increase in. (4) Thyroid stimulating hormone (TSH): influences the growth and activity of the. (5) Adrenocorticotropic hormone (ACTH): controls the production and secretion of hormones released by the adrenal gland. (6) Follicle stimulating hormone (FSH): stimulates the development of in the ovaries and in the testes. (7) Luteinizing hormone (LH) causes the ovary to actually the egg (ovulation) and prepares the uterus to accept the implantation of a fertilized egg. Stimulates the production of testosterone in the testes. Diagram of the female ovulation cycle:
1. Posterior lobe of the pituitary gland a. Not really an endocrine gland because it produce the hormones it releases. The hormones are made by the cell bodies of neurons found in the. After production, the hormones travel down the axons and are stored in the posterior pituitary until the time of their release. Because these neurons can secrete hormones they have the special name of. b. Diagram of hypothalamus and posterior pituitary: c. The two hormones released by the posterior pituitary will then regulate different processes taking place in the body. (1) (OT) (oxy=swift, tokes=birth): released in significant amounts only during childbirth and in nursing women. Causes of uterus during childbirth and milk ejection in a nursing mother. (2) Antiduretic hormone (ADH) (anti=against, diuretic=passing of urine): regulates fluid balance in the body by controlling the amount of produced.
IV. Thyroid gland A. Description: the thyroid gland is located just below the thyroid cartilage (Adam s apple) of the larynx (voice box) and in front of the trachea (windpipe). It consists of lobes lateral to the trachea, which are connected by a narrow band of the gland called the. B. Diagram of the thyroid gland: C. Structure of the thyroid gland 1. The thyroid gland is made up of an outer capsule and an inner area made up of secreting cells. 2. The thyroid produces hormones: a. Thyroxine (T4) and triiodothyronine (T3) both contain and increase the rate of metabolism. Thyroxine T4 has iodine atoms, T3 has iodine atoms. b. Thyroxine (T4) and triiodothyronine (T3) are very important hormones because they influence nearly every in the body. These hormones increase the rate at that glucose is broken down for energy, during. c. The third hormone produced by the thyroid gland is calcitonin (CT). Its main function is to the amount of calcium and phosphate in the blood. It inhibits the breakdown of bone. d. What might occur if the thyroid did not receive enough iodine to form proper thyroxine (T4) and triiodothyronine (T3)? e. What might happen in older age when glands tend to become less productive?
V. Parathyroid glands A. Description: total glands; two located on the posterior side of each lobe of the thyroid gland. B. Structure of the parathyroid glands 1. Each gland has an outer capsule and an inner area made up of cells. 2. The glands produce only one hormone. C. Function of the parathyroid glands 1. Produces parathyroid hormone (PTH) that is important in maintaining the calcium and phosphate levels in the blood. It the amount of calcium and lowers the level of phosphate. 2. Low levels of calcium in the blood will stimulate the release of the hormone. 3. Parathyroid hormone regulates the calcium level in the blood by: A. Increases the breakdown of bone. B. Increases the uptake of calcium from the digestive track. C. Diagram of the parathyroid glands:
VI. Adrenal glands A. Description: there are adrenal glands. Each one located on the top of a. B. Structure of the adrenal glands 1. Each adrenal gland is divided into parts the cortex and medulla. 2. The adrenal medulla produces principle types of hormones. C. Diagram of the adrenal gland: D. Function of the adrenal glands 1. The functions of the adrenal glands can be divided into those of the adrenal cortex and the adrenal medulla. A. Functions of the adrenal (1) Outer zone: responsible for the secretion of aldosterone. Basically, aldosterone acts upon the kidneys causing them to more sodium (Na+), which causes the retention of. Water follows sodium by the process of osmosis, so if more sodium is retained by the body then body fluid levels would increase. (2) Middle zone: responsible for the release of the glucocorticoids. The most important of these are cortisol and cortisone. When the body comes under these hormones will increase the levels of available by increasing the amount of glucose available to the cells of the body. This additional ATP will help the body combat stresses such as fright, temperature extremes and also inhibit allergic reactions and reduce inflammation. (3) Inner zone: responsible for the production and release of gonadocorticoids (adrenal sex hormones). These are (male sex hormones) and (female sex hormones).
B. Functions of the adrenal (1) It secretes two hormones called (adrenaline) and (noradrenaline). Both hormones function to act upon the body like the sympathetic nervous system does during the fight or flight response. Both hormones increase heart rate, raise blood pressure, accelerate breathing, dilates respiratory passages, increases glucose blood levels and other responses that will help the body deal with anything that might be causing stress. VII. Pancreas A. Description: the pancreas is located behind and below the stomach. It is a mixed gland because it produces enzymes for, as well as two important hormones. B. Structure of the pancreas 1. Located in clusters are cells designated the. 2. There are mainly two different types of cells: cells and cells. 3. Each type of cell produces a different type of hormone, each causing an opposite effect (but both helping to regulate the amount of sugar [glucose] in the blood). C. Function of the islets of langerhans 4. The alpha cells produce, a hormone responsible for the blood level of glucose. Basically, it does this by stimulating the liver to breakdown stores of glycogen (animal starch). 5. The beta cells produce, a hormone responsible for the blood level of glucose. It does this by increasing the transport of glucose into cells to be used for energy. VIII. Gonads A. Description: there are two types of gonads. The female gonads, called the are paired and located in the pelvic cavity. The male gonads, called are paired and lie in a sac outside the pelvic cavity. B. The ovaries C. The testes 1. Produce the hormones and, which are responsible for the development of the female sex characteristics. Ovaries are stimulated to release their hormones in a cycle by the anterior gonadotropic hormones (FSH and LH). 1. Produce the hormone, which is responsible for the development of adult male characteristics. Testosterone production is stimulated by luteinizing hormone (LH) from the anterior pituitary.