Physio Exercise 4 Endocrine System Physiology Review Sheet Match Each of the Hormones
Affiliate eleven: Introduction to the Body's Systems
11.iv Endocrine System
Learning Objectives
By the terminate of this section, yous volition be able to:
- List the dissimilar types of hormones and explain their roles in maintaining homeostasis
- Explain how hormones piece of work
- Explain how hormone production is regulated
- Describe the function of different glands in the endocrine system
- Explain how the dissimilar glands work together to maintain homeostasis
The endocrine system produces hormones that function to control and regulate many different torso processes. The endocrine system coordinates with the nervous system to control the functions of the other organ systems. Cells of the endocrine system produce molecular signals called hormones. These cells may compose endocrine glands, may be tissues or may be located in organs or tissues that accept functions in addition to hormone production. Hormones circulate throughout the body and stimulate a response in cells that have receptors able to demark with them. The changes brought well-nigh in the receiving cells affect the operation of the organ organisation to which they belong. Many of the hormones are secreted in response to signals from the nervous system, thus the two systems deed in concert to effect changes in the body.
Hormones
Maintaining homeostasis inside the body requires the coordination of many different systems and organs. One machinery of advice between neighboring cells, and between cells and tissues in distant parts of the body, occurs through the release of chemicals called hormones. Hormones are released into body fluids, ordinarily blood, which carries them to their target cells where they arm-twist a response. The cells that secrete hormones are often located in specific organs, called endocrine glands, and the cells, tissues, and organs that secrete hormones make up the endocrine organization. Examples of endocrine organs include the pancreas, which produces the hormones insulin and glucagon to regulate blood-glucose levels, the adrenal glands, which produce hormones such as epinephrine and norepinephrine that regulate responses to stress, and the thyroid gland, which produces thyroid hormones that regulate metabolic rates.
The endocrine glands differ from the exocrine glands. Exocrine glands secrete chemicals through ducts that lead exterior the gland (non to the blood). For example, sweat produced by sweat glands is released into ducts that comport sweat to the surface of the skin. The pancreas has both endocrine and exocrine functions considering too releasing hormones into the blood. It too produces digestive juices, which are carried by ducts into the small intestine.
Endocrinologist
An endocrinologist is a medical md who specializes in treating endocrine disorders. An endocrine surgeon specializes in the surgical treatment of endocrine diseases and glands. Some of the diseases that are managed past endocrinologists include disorders of the pancreas (diabetes mellitus), disorders of the pituitary (gigantism, acromegaly, and pituitary dwarfism), disorders of the thyroid gland (goiter and Graves' disease), and disorders of the adrenal glands (Cushing'south disease and Addison'due south affliction).
Endocrinologists are required to appraise patients and diagnose endocrine disorders through extensive use of laboratory tests. Many endocrine diseases are diagnosed using tests that stimulate or suppress endocrine organ functioning. Blood samples are then drawn to determine the outcome of stimulating or suppressing an endocrine organ on the production of hormones. For example, to diagnose diabetes mellitus, patients are required to fast for 12 to 24 hours. They are then given a sugary drink, which stimulates the pancreas to produce insulin to decrease blood-glucose levels. A claret sample is taken one to ii hours after the saccharide potable is consumed. If the pancreas is operation properly, the blood-glucose level will be within a normal range. Another instance is the A1C test, which can be performed during blood screening. The A1C exam measures boilerplate blood-glucose levels over the past two to three months. The A1C test is an indicator of how well blood glucose is existence managed over a long time.
In one case a illness such as diabetes has been diagnosed, endocrinologists can prescribe lifestyle changes and medications to care for the disease. Some cases of diabetes mellitus can be managed by exercise, weight loss, and a good for you diet; in other cases, medications may exist required to enhance insulin'southward production or upshot. If the disease cannot be controlled by these ways, the endocrinologist may prescribe insulin injections.
In addition to clinical practice, endocrinologists may also be involved in primary research and evolution activities. For example, ongoing islet transplant inquiry is investigating how healthy pancreas islet cells may exist transplanted into diabetic patients. Successful islet transplants may let patients to stop taking insulin injections.
How Hormones Piece of work
Hormones crusade changes in target cells by binding to specific cell-surface or intracellular hormone receptors, molecules embedded in the prison cell membrane or floating in the cytoplasm with a binding site that matches a binding site on the hormone molecule. In this style, even though hormones circulate throughout the torso and come into contact with many different cell types, they merely affect cells that possess the necessary receptors. Receptors for a specific hormone may be establish on or in many dissimilar cells or may be limited to a modest number of specialized cells. For example, thyroid hormones human action on many different tissue types, stimulating metabolic activity throughout the body. Cells tin can have many receptors for the same hormone but oftentimes also possess receptors for different types of hormones. The number of receptors that respond to a hormone determines the cell's sensitivity to that hormone, and the resulting cellular response. Additionally, the number of receptors bachelor to respond to a hormone can alter over fourth dimension, resulting in increased or decreased cell sensitivity. In up-regulation, the number of receptors increases in response to ascension hormone levels, making the cell more sensitive to the hormone and allowing for more cellular activity. When the number of receptors decreases in response to rising hormone levels, called downwards-regulation, cellular activity is reduced.
Endocrine Glands
The endocrine glands secrete hormones into the surrounding interstitial fluid; those hormones then lengthened into blood and are carried to various organs and tissues inside the torso. The endocrine glands include the pituitary, thyroid, parathyroid, adrenal glands, gonads, pineal, and pancreas.
The pituitary gland, sometimes called the hypophysis, is located at the base of operations of the brain (Effigy 11.23a). It is attached to the hypothalamus. The posterior lobe stores and releases oxytocin and antidiuretic hormone produced by the hypothalamus. The anterior lobe responds to hormones produced by the hypothalamus by producing its own hormones, most of which regulate other hormone-producing glands.
The inductive pituitary produces six hormones: growth hormone, prolactin, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone. Growth hormone stimulates cellular activities like protein synthesis that promote growth. Prolactin stimulates the production of milk by the mammary glands. The other hormones produced by the anterior pituitary regulate the product of hormones by other endocrine tissues (Table eleven.1). The posterior pituitary is significantly dissimilar in structure from the anterior pituitary. Information technology is a part of the brain, extending down from the hypothalamus, and contains mostly nerve fibers that extend from the hypothalamus to the posterior pituitary.
The thyroid gland is located in the neck, simply below the larynx and in front of the trachea (Figure 11.23b). It is a butterfly-shaped gland with ii lobes that are connected. The thyroid follicle cells synthesize the hormone thyroxine, which is also known as T4 because it contains four atoms of iodine, and triiodothyronine, as well known every bit T3 because it contains three atoms of iodine. T3 and Tfour are released past the thyroid in response to thyroid-stimulating hormone produced by the anterior pituitary, and both T3 and T4 accept the effect of stimulating metabolic activity in the body and increasing free energy apply. A 3rd hormone, calcitonin, is as well produced past the thyroid. Calcitonin is released in response to ascension calcium ion concentrations in the blood and has the effect of reducing those levels.
Most people have iv parathyroid glands; however, the number can vary from ii to vi. These glands are located on the posterior surface of the thyroid gland (Figure 11.23b).
The parathyroid glands produce parathyroid hormone. Parathyroid hormone increases blood calcium concentrations when calcium ion levels fall below normal.
The adrenal glands are located on height of each kidney (Figure 11.23c). The adrenal glands consist of an outer adrenal cortex and an inner adrenal medulla. These regions secrete different hormones.
The adrenal cortex produces mineralocorticoids, glucocorticoids, and androgens. The main mineralocorticoid is aldosterone, which regulates the concentration of ions in urine, sweat, and saliva. Aldosterone release from the adrenal cortex is stimulated by a decrease in blood concentrations of sodium ions, blood book, or blood force per unit area, or past an increase in blood potassium levels. The glucocorticoids maintain proper claret-glucose levels betwixt meals. They also command a response to stress past increasing glucose synthesis from fats and proteins and collaborate with epinephrine to cause vasoconstriction. Androgens are sexual practice hormones that are produced in small amounts by the adrenal cortex. They do not normally affect sexual characteristics and may supplement sex activity hormones released from the gonads. The adrenal medulla contains ii types of secretory cells: i that produces epinephrine (adrenaline) and another that produces norepinephrine (noradrenaline). Epinephrine and norepinephrine cause firsthand, short-term changes in response to stressors, inducing the and so-called fight-or-flying response. The responses include increased center rate, breathing rate, cardiac muscle contractions, and blood-glucose levels. They too accelerate the breakdown of glucose in skeletal muscles and stored fats in adipose tissue, and redirect blood flow toward skeletal muscles and away from skin and viscera. The release of epinephrine and norepinephrine is stimulated by neural impulses from the sympathetic nervous system that originate from the hypothalamus.
The pancreas is an elongate organ located between the stomach and the proximal portion of the pocket-sized intestine (Effigy xi.23d). It contains both exocrine cells that excrete digestive enzymes and endocrine cells that release hormones.
The endocrine cells of the pancreas form clusters chosen pancreatic islets or the islets of Langerhans. Among the cell types in each pancreatic islet are the alpha cells, which produce the hormone glucagon, and the beta cells, which produce the hormone insulin. These hormones regulate blood-glucose levels. Blastoff cells release glucagon every bit claret-glucose levels decline. When blood-glucose levels rising, beta cells release insulin. Glucagon causes the release of glucose to the blood from the liver, and insulin facilitates the uptake of glucose by the body's cells.
The gonads—the male testes and female person ovaries—produce steroid hormones. The testes produce androgens, testosterone existence the virtually prominent, which permit for the evolution of secondary sex characteristics and the production of sperm cells. The ovaries produce estrogen and progesterone, which cause secondary sex activity characteristics, regulate production of eggs, control pregnancy, and set the body for childbirth.
There are several organs whose primary functions are non-endocrine but that also possess endocrine functions. These include the center, kidneys, intestines, thymus, and adipose tissue. The heart has endocrine cells in the walls of the atria that release a hormone in response to increased blood volume. Information technology causes a reduction in blood volume and blood pressure, and reduces the concentration of Na+ in the blood.
The gastrointestinal tract produces several hormones that aid in digestion. The endocrine cells are located in the mucosa of the GI tract throughout the tum and minor intestine. They trigger the release of gastric juices, which aid to break down and digest food in the GI tract.
The kidneys also possess endocrine office. Two of these hormones regulate ion concentrations and claret volume or force per unit area. Erythropoietin (EPO) is released by kidneys in response to low oxygen levels. EPO triggers the formation of red blood cells in the bone marrow. EPO has been used by athletes to improve operation. But EPO doping has its risks, since it thickens the blood and increases strain on the heart; it besides increases the take a chance of blood clots and therefore center attacks and stroke.
The thymus is plant backside the sternum. The thymus produces hormones referred to every bit thymosins, which contribute to the development of the immune response in infants. Adipose tissue, or fat tissue, produces the hormone leptin in response to nutrient intake. Leptin produces a feeling of satiety after eating, reducing the urge for further eating.
| Endocrine Gland | Associated Hormones | Effect |
|---|---|---|
| Pituitary (anterior) | growth hormone | promotes growth of trunk tissues |
| prolactin | promotes milk production | |
| thyroid-stimulating hormone | stimulates thyroid hormone release | |
| adrenocorticotropic hormone | stimulates hormone release past adrenal cortex | |
| follicle-stimulating hormone | stimulates gamete production | |
| luteinizing hormone | stimulates androgen product by gonads in males; stimulates ovulation and product of estrogen and progesterone in females | |
| Pituitary (posterior) | antidiuretic hormone | stimulates water reabsorption by kidneys |
| oxytocin | stimulates uterine contractions during childbirth | |
| Thyroid | thyroxine, triiodothyronine | stimulate metabolism |
| calcitonin | reduces blood Ca2+ levels | |
| Parathyroid | parathyroid hormone | increases blood Ca2+ levels |
| Adrenal (cortex) | aldosterone | increases blood Na+ levels |
| cortisol, corticosterone, cortisone | increase claret-glucose levels | |
| Adrenal (medulla) | epinephrine, norepinephrine | stimulate fight-or-flight response |
| Pancreas | insulin | reduces blood-glucose levels |
| glucagon | increases blood-glucose levels |
Regulation of Hormone Production
Hormone production and release are primarily controlled past negative feedback, every bit described in the discussion on homeostasis. In this way, the concentration of hormones in blood is maintained within a narrow range. For example, the anterior pituitary signals the thyroid to release thyroid hormones. Increasing levels of these hormones in the blood then give feedback to the hypothalamus and anterior pituitary to inhibit further signaling to the thyroid gland (Figure xi.24).
Section Summary
Hormones cause cellular changes by binding to receptors on or in target cells. The number of receptors on a target cell can increment or decrease in response to hormone action.
Hormone levels are primarily controlled through negative feedback, in which rising levels of a hormone inhibit its further release.
The pituitary gland is located at the base of the brain. The anterior pituitary receives signals from the hypothalamus and produces six hormones. The posterior pituitary is an extension of the brain and releases hormones (antidiuretic hormone and oxytocin) produced by the hypothalamus. The thyroid gland is located in the neck and is composed of two lobes. The thyroid produces the hormones thyroxine and triiodothyronine. The thyroid as well produces calcitonin. The parathyroid glands prevarication on the posterior surface of the thyroid gland and produce parathyroid hormone.
The adrenal glands are located on top of the kidneys and consist of the adrenal cortex and adrenal medulla. The adrenal cortex produces the corticosteroids, glucocorticoids and mineralocorticoids. The adrenal medulla is the inner part of the adrenal gland and produces epinephrine and norepinephrine.
The pancreas lies in the abdomen between the breadbasket and the small intestine. Clusters of endocrine cells in the pancreas grade the islets of Langerhans, which contain blastoff cells that release glucagon and beta cells that release insulin. Some organs possess endocrine activeness as a secondary function just take another chief function. The heart produces the hormone atrial natriuretic peptide, which functions to reduce blood volume, pressure, and Na+ concentration. The gastrointestinal tract produces various hormones that aid in digestion. The kidneys produce erythropoietin. The thymus produces hormones that aid in the development of the immune system. The gonads produce steroid hormones, including testosterone in males and estrogen and progesterone in females. Adipose tissue produces leptin, which promotes satiety signals in the brain.
Glossary
adrenal gland: the endocrine gland associated with the kidneys
downwardly-regulation: a decrease in the number of hormone receptors in response to increased hormone levels
endocrine gland: the gland that secretes hormones into the surrounding interstitial fluid, which then diffuse into blood and are carried to diverse organs and tissues within the body
exocrine gland: the gland that secretes chemicals through ducts that lead to skin surfaces, torso cavities, and organ cavities.
hormone: a chemical released by cells in one area of the torso that affects cells in other parts of the trunk
intracellular hormone receptor: a hormone receptor in the cytoplasm or nucleus of a cell
pancreas: the organ located between the breadbasket and the small intestine that contains exocrine and endocrine cells
parathyroid gland: the gland located on the surface of the thyroid that produces parathyroid hormone
pituitary gland: the endocrine gland located at the base of the encephalon composed of an anterior and posterior region; also called hypophysis
thymus: the gland located behind the sternum that produces thymosin hormones that contribute to the development of the immune system
thyroid gland: an endocrine gland located in the cervix that produces thyroid hormones thyroxine and triiodothyronine
up-regulation: an increment in the number of hormone receptors in response to increased hormone levels
Source: https://opentextbc.ca/biology/chapter/11-4-endocrine-system/
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