BIOL 1344 Lecture 10Outline of Last Lecture I. Blood PressureA. Blood Pressure LevelsB. Mean Arterial PressureC. Blood Pressure RegulatorsII. Lymphatic System StructuresIII. Immune SystemOutline of Current Lecture IV. Endocrine System CommunicationA. Action and Graded PotentialsB. Chemical CommunicationV. Endocrine System ReleasesA. NeurotransmitterB. Neuro-hormonesC. Hormones VI. Functions of the Endocrine System A. HomeostasisB. ReproductionCurrent LectureEndocrine System: The endocrine system communicates through electrical signals which have a very fast generation, or propagation. It uses membrane potentials to pass voltage and responsesto this communication only last a short time. The endocrine system uses action potentials and graded potentials.Action Potentials: 1. Self-generating2. Short duration – about 1 milliseconds in neurons, 1-5 milliseconds in skeletal muscles 3. The energy doesn’t fade with time and distance4. Uses reversal of polarity or depolarization (this is when the inside of a cell becomes more positive)5. Excitable cells – neurons and musclesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Graded Potentials:1. Not self-generating2. Energy fades with time and distance3. Uses depolarizing or hyperpolarizing (This is when the inside of a cell becomes more negative)4. Several different types of cells including neurons and musclesThe endocrine system also uses chemical signals which differ from electrical signals in the following ways. They have a slow generation and a slower travel time through body tissues. However, their responses last for much longer, from minutes to even days. Chemical cells generate and terminate the signals. The endocrine system releases neurotransmitter, neuro-hormones and hormones. Ligand is the general name for anything that binds with a receptor, these can include neurotransmitters, toxins, etc. Once ligands bind with a receptor there will be a response in the body. 1. Neurotransmitters come from neurons and include 50-60 chemicals. These neurotransmitters can be chemicals, amino acids, and gases. Examples are acetylcholine,epinephrine, norepinephrine, dopamine, glycine, glutamic acid, carbon monoxide, nitrogen oxide, and ATP. 2. Neuro-hormones are also secreted from neurons in the hypothalamus. These include ADH and oxytocin.3. Hormones come from cells in different glands or tissues. They are released into the blood circulation from secretory cells and they travel to a target tissue which will respond to the hormone. Some hormones can control their own secretion through a feedback system. Functions of the endocrine system:1. Homeostasis- Osmoregulation is the maintenance of proper levels of water and electrolytes in the body and the hormones released from the endocrine system are extremely important for this. ADH is the main hormone responsible for this maintenance. If ADH is present, there is water reabsorption in the kidneys which means that urine is more concentrated and there is less volume. If there is no ADH, water is not reabsorbed and there is a large volume of undiluted urine. This can be a symptom of diabetes insipidus (insipidus means tasteless-the urine has no sugar). If a person is dehydrated, ADH should be released. Diuresis is the name for urinary loss of water and this can be caused by diuretics such as caffeine and alcohol. Diuretics can help to relieve high blood pressure. Aldosterone is another hormone released which maintainshomeostasis because it controls sodium reabsorption in the kidneys which results in water retention. 2. Reproduction – From the hypothalamus and pituitary glands, two hormones are released which are important in the reproductive system. Follicle stimulation hormone (FSH) and luteinizing hormone