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Transcript
Chapter 45 Worksheet Hormones and the Endocrine System Sy Ha An Introduction to Regulatory System 1. Compare the response times of the two major systems of internal communication: the nervous and the endocrine system. The response time of the nervous system is involved with high speed messaging as the body needs it quickly while the endocrine system is slower as it needs to do more activities such as connecting to a receptor, producing the required substances, releasing it, and the movement of the message. 2. Distinguish between the endocrine and exocrine glands. The endocrine glands are ductless glands that secretes hormones directly into the interstitial fluid, from which they diffuse into bloodstream and to wherever they need to go whereas the exocrine glands that is secreted externally through a duct. 3. Explain how neurosecretory cells, epinephrine, and the release of milk by a nursing mother illustrate the integration of the endocrine and nervous system. The neurosecretory cells, epinephrine, and release of milk illustrate the integration by creating a neurohormone pathway that regulates the release of milk. The neurosecretory cells work to create the hormone oxytocin which is stimulated from the suckling of the baby for milk. This nerve impulse starts the endocrine system in order to provide the baby with milk which is regulated by the oxytocin hormone. 4. Describe several examples of the essential roles of hormones in the maintenance of homeostasis. Hormones play an important role in maintaining homeostasis or keeping the body under normal conditions. For example, the control of blood glucose is controlled by insulin and glucagon. Insulin triggers uptake of glucose from blood decreasing glucose levels in blood when it is high and glucagon triggers release of glucose into blood increasing glucose levels when they are low. Another example is the temperature of the human body which is controlled by hypothalamus. The hypothalamus monitors the temperature and sends hormones to cell in order to tell them to take up more ATP or take up less ATP in order to raise heat or lower it. Chemical Signals and Their Modes of Action 5. Distinguish between the functions of local regulators and pheromones. Local regulators are secreted molecules that go short distances to reach target cells through diffusion while pheromones are chemicals released to outside environment in order for animals to communicate with other animals via smell. 6. Describe the diverse functions of growth factors, nitric oxide, and prostaglandins. Growth factors stimulate growth and cell production through the use of tropic and nontropic effects. Nitric oxide, which consists of nitrogen double-bonded to oxygen, serves as both a neurotransmitter and local regulator. For example, when oxygen levels fall in blood, NO is released which activates enzyme that relaxes smooth muscle cells, resulting in better blood flow. Prostaglandins, modified fatty acids, also have many modified activities. For example, during sex, prostaglandins are released in order to activate the smooth muscles of the females uterine wall to help sperm cells move through to egg and baby get out. In the immune system, prostaglandins promote fever and inflammation and also intensifies the sensation of pain. It also helps regulate the aggregation of platelets. 7. Define a signal transduction pathway, noting the mechanism and main components of action. Give several examples of its function. A signal transduction pathway are a series of changes in cellular proteins that converts extracellular chemical signal to a specific intracellular response. It occurs after binding to the receptor and goes through a series of steps in order to create the response needed. For example, epinephrine from the adrenal glands binds to G protein-coupled receptors in plasma membrane of liver cell to trigger a response to stress. It goes through a series of steps involving cAMP and activation of protein kinase A by cAMP to activate enzyme for glycogen breakdown and inactivation in order to provide fuel to handle the stress. 8. Describe the nature and locations of intracellular receptors for hormones that pass easily through cell membranes. Explain how their passage compares to the signal-transduction pathway noted just above. Hormones that pass easily through the cell membrane are lipid soluble hormones. Receptors for these types of hormones are located within the cell; therefore, these hormones pass through the plasma membrane of cell in order to bind to these receptors. On the other hand, signal transduction pathways bind to receptors located on the plasma membrane in order to activate these types of reactions. 9. Describe the several examples of different physiological reactions in animals exposed to the same hormone. Animals can react differently when exposed to the same hormone. Many hormones have multiple effects on animals and could also have different effects on different animals. For example, tissues in animals vary in their response to adrenaline. Adrenaline causes some of the tissues to contract and others to restrict blood flow. An example of a given hormone having a different effect for a different species is thyroxine. Thyroxine helps to regulate metabolism in many animals but frogs also use thyroxine in order to help them in the resorption of the tadpole’s tail to turn to adult. The Vertebrate Endocrine System 10. Explain how the hypothalamus and pituitary glands interact and how they coordinate the endocrine system. The hypothalamus and pituitary glands interact within the endocrine system. The hypothalamus sends signals to the pituitary glands in order for them to release these hormones. For example, if the hypothalamus sends the pituitary gland a signal to release the oxytocin hormone, then the posterior part of the pituitary gland will release it. 11. Describe the location of the pituitary. List and explain in detail the functions of the hormones released from the anterior and posterior lobes. The pituitary gland is located at the base of the hypothalamus. Anterior Posterior growth hormones - stimulates bone growth and metabolic functions oxytocin - stimulates contraction of uterus and regulation of milk release prolactin - stimulation of milk production and secretion antidiuretic hormone - promotes retention of water in kidney follicle stimulating hormone - stimulation of ova and sperm luteinizing hormone - stimulates ovaries and testes thyroid stimulating hormone - stimulates thyroid gland adrenocorticotropic hormone - stimulates adrenal cortex to secrete glucocorticoids 12. Describe the location of the pineal gland. Explain the significance of its secretion melatonine The pineal gland is a small mass of tissue located in the center of the brain. This gland helps secretes melatonin. Melatonin is significant because it regulates function related to light and to seasons marked by changes in daylight. Basically, it is controlled by the light/dark cycles of the seasons. If night is longer, then melatonin is released more. 13. List the hormones of the thyroid gland and explain their roles in development and metabolism. Explain the causes and symptoms of hyperthyroidism, hypothyroidism, and goiter. Triiodothyronine (T3) This helps to stimulate and maintain metabolic processes. thyroxine (T4) (same as above) Most of the time one iodine is removed from it to produce (T3) Calcitonin Lowers blood calcium levels Hyperthyroidism is caused by excessive secretion of the thyroid hormones. This causes high body temperature, profuse sweating, weight loss, irritability, and high blood pressure. Hypothyroidism results from having too little thyroid function. Symptoms include weight gain, lethargy, and intolerance to cold. Goiter results from the swelling of the thyroid gland. This results in the neck or voice box. 14. Note the location of the parathyroid glands and describe the hormonal control of calcium homeostasis. The parathyroid glands are located in the posterior surface of the thyroid. This plays a major role in calcium homeostasis because of the release of parathyroid hormone (PTH). Whenever calcium blood levels fall below set point, PTH is released and raises the calcium levels in blood through direct and indirect means. Directly, PTH stimulates calcium reabsorption through the renal tubules and indirectly influences it by promoting creation of Vitamin D. 15. Distinguish between alpha and beta cells in the pancreas and explain how their antagonistic hormones (insulin and glucagon) regulate carbohydrate metabolism. Alpha cells make glucagon whereas beta cells create insulin. These antagonistic hormones (insulin and glucagon) help regulate carbohydrate metabolism by having opposite effects. Insulin triggers the uptake of glucose from blood, decreasing blood glucose levels, while glucagon promotes release of glucose from blood, increasing blood glucose levels. These opposite effects balance the blood glucose levels; there won’t be too much or too little. 16. Distinguish between Type I diabetes mellitus and Type II diabetes mellitus. Type I diabetes mellitus occurs mostly during childhood. This autoimmune disorder occurs when the immune system destroys the beta cells of the pancreas, thus, causing a lack of insulin. This lack of insulin causes a high level of blood glucose levels. This can be treated through injection of insulin. Type II diabetes mellitus occurs during middle age. It occurs when target cells fail to respond normally to insulin. Insulin is still produced but cells fail to take in glucose. This causes blood glucose levels to remain. 17. Describe the development of the adrenal medulla. List the hormones of the adrenal medulla, describe their functions, and explain how their secretions are controlled. The adrenal medulla is the central portion of the adrenal glands. This develops from neural tissues during embryonic development. The adrenal medulla produces epinephrine and norepinephrine. These hormones are created in response to stress. These hormones help create more energy by increasing the availability of energy sources in order to deal with the stress. This is controlled by neurons which send them impulses to activate whenever stress appears. 18. List the hormones of the adrenal cortex, describe their functions, and explain how their secretions are controlled. The adrenal cortex produces the glucocorticoids and mineralocorticoids. The glucocorticoids is a steroid that raises blood glucose levels. The mineralocorticoids are steroids that promote reabsorption of Na+ and K+ in kidneys. Glucocorticoids is regulated by ACTH, Adrenocorticotropic hormone, and the mineralocorticoids are regulated by K+ in blood and angiotensin II. 19. List the hormones of three categories of steroid hormones produced by the gonads. Describe variations in their production between the sexes. Note the functions of each category of steroid and explain how secretions are controlled. Androgens Produced by testes (males) mainly testosterone and functions by helping develop male secondary sex characteristics during puberty Estrogens Mainly estradiol; responsible for maintenance of female reproductive system and development of female sex characteristics Progestins Mainly progesterone; function is to prepare and maintain tissues of uterus for growth and support of embryo Secretions are controlled through cascade pathways. They are synthesized by gonadotropins (FSH and LH) from the pituitary glands which is in turn controlled by the hypothalamus. Key Terms hormone - molecule that is secreted into the extracellular fluid, circulates in the blood or hemolymph, and communicates regulatory messages throughout the body target cell - cell that has receptors for a hormone to latch on and give signal to the cell endocrine system - body system that is used for communication and regulation of the body endocrine glands - ductless regions that hold endocrine cells nuerosecretory cells - cell in the nervous system that produces a hormone ecdysone - hormone that is released by the prothoracic glands that promotes molting during metamorphosis of insects (ex: caterpillar into a butterfly) brain hormone (BH) - A hormone, produced by neurosecretory cells in the insect brain, that promotes development by stimulating the prothoracic glands to secrete ecdysone. juvenile hormone - signaling molecule secreted by the corpora allata that indirectly influences development by modulating the activity of ecdosine growth factor - substance that stimulate cell proliferation and differentiation nitric oxide (NO) - gas that consists of nitrogen double bonded to oxygen that serves as a nuero transmitter and local regulator prostaglandins (PGs) - group of local regulators (fatty acids) that serve various actvities such as stimulating smooth muscles of female’s uterine wall to contract in order to help sperm reach egg, etc. signal-transduction pathway - series of changes in cellular proteins that converts extracellular chemical signal to a specific intracellular response tropic hormones - hormones that regulates the function of endocrine cells or glands hypothalamus - endocrine gland located in the brain that plays important role in integrating endocrine and nervous system pituitary gland - gland located at base of hypothalamus anterior pituitary - gland that develops from fold of tissue at the roof of the embryonic mouth and grows upward towards brain and releases hormones adenohypophysis - another name for the anterior pituitary releasing hormone - hormone that is released by hypothalamus that speeds up secretion of a given hormone by anterior pituitary inhibiting hormone - hormone that is released by hypothalamus that inhibits secretion of a hormone posterior pituitary - extension of hypothalamus that grows downward toward mouth and secretes two hormones made by hypothalamus neurohypophysis - another name for the posterior pituitary oxytocin - hormone that is released by posterior hormones that regulates milk release during milking antidiuretic hormone (ADH) - hormone that is released by posterior hormones that helps regulate blood osmolarity growth hormone (GH) - hormone secreted by anterior pituitary that stimulates growth through tropic and nontropic effects insulinlike growth factors (IGFs) - hormone released by liver that is responsible for building muscle prolactin (PRL) - nontropic hormone that has diversity of various effects among vertebrate species such as stimulating gland growth and milk synthesis follicle-stimulating hormone (FSH) - tropic hormone that stimulates activities of the male and female gonads luteinizing hormone (LH) - tropic hormone that stimulates activities of the male and female gonads thyroid-stimulating hormone (TSH) - hormone released by anterior pituitary that helps regulate function of thyroid gland gonadotropins - group of hormones secreted by pituitary that stimulates activity of gonads adrenocorticotropic hormone (ACTH) - tropic hormone that stimulates secretioni and production of steroid hormones by adrenal cortex melanocyte-stimulating hormone (MSH) - nontropic hormone that regulates activity of pigmentcontaining cells in skin of amphibians as well as fish and reptiles endorphin - group of hormones produced in brain and anterior pituitary that inhibits pain perception pineal gland - small gland that is located on the dorsal surface of brain that secretes melatonin hormone melatonin - hormone released by pineal gland that regulates body functions related to seasonal day length thyroid gland - gland consisting of two lobes on ventral surface of trachea that regulates homeostasis and development triiodothyronine (T3) - hormone consisting of three iodine atoms that is produced by the thyroid gland and play a role in development and maturation thyroixine (T4) - hormone containing four iodine atoms (one atom removed to make T3) and plays a role in development and maturation calcitonin - hormone released by thyroid gland that inhibits bone resorption and enhances calcium ion (Ca2+) release by kidney parathyroid glands - set of four small structures embedded in posterior surface of thyroid that plays major role in blood calcium ion (Ca2+) regulation parathyroid hormone (PTH) - hormone released by parathyroid glands when blood Ca2+ falls below set point vitamin D - steroid molecule that is obtain from food or synthesized in skin from exposure to sunlight and helps stimulate uptake of Ca2+ from food and helps augment effects of PTH pancreas - gland that has following functions: the nonendocrine portion functions by helping in digestion, secretion of enzymes, and alkaline solution into small intestine via a duct; the ductless endocrine portion function by helping in homeostasis by secreting hormones of insulin and glucagon into blood islets of Langerhans - endocrine cells located in pancreas that uses alpha and beta cells that make insulin and glucagon alpha cells - cells that help make glucagon in pancreas glucagon - hormone released from pancreas that promotes release of glucose into blood increasing blood glucose concentration beta cell - cells that make insulin in pancreas insulin - hormone released by pancreas that triggers uptake of glucose into blood decreasing blood glucose concentrationconra Type I diabetes mellitus - autoimmune disorder that mostly occurs during childhood that destroys person’s ability to make insulin Type II diabetes mellitus - disorder that occurs when there is a failure of target cells to respond normally to insulin adrenal gland - glands located in kidneys that contains adrenal cortex and adrenal medulla adrenal cortex - gland in kidney that releases corticosteroids such as glucocorticoids, mineralocorticoids, and sex hormones adrenal medulla - gland in kidney that releases epinephrine and norepinephrine in response to stress epinephrine - hormone (adrenaline) released by adrenal medulla that stimulates fight-or-flight response in response to short term stress norepinephrine (noradrenaline) - hormone that functions similarly to adrenaline and acts as a hormone or nuerotransmitter catecholamines - class of amine hormones synthesized from amino acid tyrosine (epinephrine and norepinephrine is part of this class) corticosteroids - any steroid hormone produced and secreted by adrenal cortex glucocorticoids - steroid hormone that is secreted by adrenal cortex and influences glucose metabolism and immune function mineralocorticoids - steroid hormone that is secreted by adrenal cortex and regulates salt and water homeostasis androgens - any steroid hormone that stimulates development and maintenance of male reproductive system and secondary sex characteristics testosterone - steroid hormone required for development of male reporductive system, spermatogenesis, and male secondary sex characteristics estrogens - any steroid hormone that stimulates development and maintenance of female reproductive system and secondary sex characteristics progestins - steroid hormone with progesterone like activity