12. The Endocrine System: The Body’s Other Control System. Multimedia Asset Directory. Slide 66Hyperglycemia Animation Slide 67Hypoglycemia Animation Slide 71Pathology of Diabetes Video Slide 72Insulin Video Slide 73Hypothalmic Pituitary Axis Animation - PowerPoint PPT Presentation
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Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Introduction
• The nervous system and the endocrine system are totally interconnected and always monitor each other’s activities.
• The endocrine system also collects information and sends orders but it is a slower, more subtle control system. While it acts slowly, the effects last longer than those of the nervous system.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Hormones
• The chemical messengers released by endocrine glands are called hormones.
• Hormones are released into the blood stream and travel all over your body, some affecting millions of cells simultaneously. Their effects last for minutes or even hours or possibly days.
• Many hormones are secreted all the time, with the amount secreted changing as needed.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
How Hormones Work
• Hormones work by binding to receptors on target cells. They bind to not only sites outside the cell, like neurotransmitters, but also to sites inside the cell.
• If hormones bind to the outside of the cell, they can have several different effects, either changing cellular permeability or sending the target cell a message that changes enzyme activity inside the cell.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Steroids
• One special class of hormones, called steroids, is particularly powerful because steroids can bind to sites inside cells.
• Steroids are lipid molecules which can pass easily through the target cell membrane, allowing them to interact directly with the cell’s DNA to change cell activity.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Homeostasis and Negative Feedback
• Many of the chemical and physical characteristics of your body have a standard level, or set point, that is the ideal level for that particular value. Blood pressure, blood oxygen, heart rate, and blood sugar are examples.
• Your control systems (endocrine and nervous system) work to keep levels at or near ideal.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Homeostasis and Negative Feedback
• There is a way for your body to measure the variable, a place where the ideal level is stored, and a way for your body to fix levels that are not near ideal. For example, the hypothalamus stores the ideal set-point for temperature.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Homeostasis and Negative Feedback
• If any of your body’s dozens of characteristics become seriously abnormal, your control systems work to bring them back to set point via a process called negative feedback.
• Negative feedback counteracts a change. Thus, as blood pressure rises, your body works to bring it down to normal, the set point. If blood pressure falls, your body works to raise it back up to normal.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Positive Feedback
• Positive feedback increases the magnitude of a change.
• The flow of sodium into a neuron during depolarization is a real-life example we have already visited. The more depolarized a neuron becomes, the more sodium flows in, so it becomes more depolarized, so more flows in, etc. This kind of process is also known as a vicious cycle. Positive feedback is not a way to regulate the body, since positive feedback increases a change away from set point.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Childbirth and Positive Feedback
• Positive feedback is harmful if the vicious cycle cannot be broken, but is sometimes necessary for a process to run to completion. A good example is the continued contraction of the uterus during childbirth. When a baby is ready to be born, a signal tells the hypothalamus to release oxytocin from the posterior pituitary, increasing the intensity of contractions.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Childbirth and Positive Feedback
• As the uterus contracts, the pressure inside the uterus increases the signal to the hypothalamus and more oxytocin is released, causing the uterus to contract harder. This cycle of ever-increasing uterine contractions, due to ever-increasing release of oxytocin from the hypothalamus, continues until the pressure inside the uterus decreases when the baby is born.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Neural Control
• Some hormones are directly controlled by the nervous system. For example, the adrenal glands receive signals from the sympathetic nervous system. When the sympathetic nervous system is active, it sends signals to the adrenal glands to release epinephrine and norepinephrine as hormones, prolonging the effects of sympathetic activity.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Hormonal Control
• Other hormones are part of a hierarchy of hormonal control, where one gland is controlled by the release of hormones from another gland up the chain, which is controlled by another gland’s release of hormones up the chain. Orders are sent from one organ to another, like a relay race.
• Negative feedback controls the flow of orders via hormones from one part of the chain to the other.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Humoral Control
• Some endocrine organs directly monitor the body’s internal environment by monitoring body fluids, such as blood, and then respond accordingly.
• Humoral is the term that pertains to body fluids or substances and therefore this is called humoral control. For example, the pancreas secretes insulin in response to rising blood sugar levels.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Endocrine Glands:The Hypothalamus
• The hypothalamus, located in the diencephalon, is an important link between the two control systems.
• The hypothalamus controls much of your physiology, including hunger, thirst, fluid balance, and body temperature to name a small number of its functions.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Endocrine Glands:The Hypothalamus
• The hypothalamus also acts as a “commander in chief” for the other glands in the endocrine system since it controls the pituitary gland, and thus, most other glands in the endocrine system.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Pituitary
• The pituitary, also a part of the diencephalon, has been commonly known as the “master gland” because of its role in controlling other endocrine glands.
• The pituitary gland really acts only under orders from the hypothalamus.
• If the hypothalamus is the “commander in chief,” the pituitary is a high-ranking general.
• The pituitary is split into two segments, the posterior pituitary and the anterior pituitary.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Posterior Pituitary
• The posterior pituitary is an extension of the hypothalamus. Hypothalamic neurons, specialized to secrete hormones instead of neurotransmitters, extend their axons through a stalk in the posterior pituitary.
• These neurons secrete two hormones, antidiuretic hormone (ADH) and oxytocin. While they are secreted by the pituitary, they are made by the hypothalamus.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Anterior Pituitary
• The anterior pituitary makes and secretes a number of hormones under hormonal control of the hypothalamus.
• The hypothalamus secretes a hormone that controls hormone secretion by the anterior pituitary, which usually controls the secretion of hormones by another endocrine gland (growth hormone is an exception).
• The hormone levels are controlled by negative feedback to both the pituitary and the hypothalamus.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Stature Disorders
• Stature disorders are those that result in well below normal (dwarfism) or well above normal (gigantism or giantism) height. Some are caused by abnormalities in skeletal development or nutritional deficiencies, but growth hormone (GH) problems are often implicated.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Stature Disorders
• If GH secretion is insufficient during childhood, children don’t grow to normal height. If GH deficiency is diagnosed before closure of the growth zones of the long bones it can be treated with GH supplements, otherwise these children grow to be undersized adults.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Stature Disorders
• Oversecretion of GH during childhood results in very, very tall people. Robert Wadlow, one of the tallest men to ever live, according to The Guinness Book of World Records, was more than 8 feet tall. People with gigantism have many health problems, including a skeleton that can’t support them. Surgery and medication are the only treatments.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Stature Disorders
• If the oversecretion of GH starts after the bones have stopped growing the person doesn’t get taller but the tissue of the hands, feet, face, and many internal organs will continue to grow out of control causing pain and organ dysfunction. Most oversecretion is due to noncancerous pituitary tumors.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Thyroid Gland
• The thyroid gland is located in the anterior portion of the neck and is butterfly-shaped.
• The thyroid gland secretes the hormones triiodothyronine (T3) and thyroxine (T4) under orders from the pituitary. The third hormone is calcitonin, involved in calcium storage.
• T3 and T4 contain iodine and control cell metabolism and growth.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Thyroid Gland
• Over- or under-production cause a variety of clinical symptoms, because the level of these hormones is essential in controlling growth and metabolism of body tissues, particularly in the nervous system.
• Table salt contains iodine to ensure people get enough iodine in their diets to make thyroid hormones.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Parathyroid Glands
• The thyroid gland has two small pairs of glands, called the parathyroid glands, embedded in its posterior surface.
• They produce parathyroid hormone (PTH), which regulates the levels of calcium in the blood stream.
• If calcium levels get too low, the parathyroid glands are stimulated to release PTH, which stimulates bone dissolving cells and releases calcium into the blood stream.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Hyperthyroidism
• Jenny was a healthy 25-year-old school teacher starting her first job when she began having strange symptoms, including a rapid heart rate, profuse sweating, and constant hunger. Initially, she thought the symptoms were caused by the stress of her new job and moving from home, but then other, more alarming, symptoms appeared.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Hyperthyroidism
• Jenny became irritable and restless, developed insomnia, and couldn’t concentrate. Soon she couldn’t focus long enough to read the newspaper or get through a half hour sitcom. Her thoughts became so scattered she thought she might be going crazy so she made an appointment with her doctor and found out she had Graves’ disease, a disorder that causes oversecretion of the thyroid hormone.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Figure 12-9 The hypothalamus controls the anterior pituitary, which in turn controls the thyroid gland. Negative feedback loops prevent the oversecretion of hormones.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
The Pineal Gland
• The tiny pineal gland is found within the diencephalon of the brain.
• Its full function remains unknown.• It has been shown to produce the
hormone melatonin which rises and falls during the waking and sleeping hours. It is believed that this hormone triggers our sleep by peaking at night and causing drowsiness.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Diabetes Mellitus
• Diabetes mellitus (DM) is a condition characterized by abnormally high blood glucose levels. Type 1 diabetes is caused by destruction of insulin-producing cells of the pancreas, resulting in inadequate insulin production. These patients require daily insulin injections.
• Type 2 diabetes is caused by insensitivity of the body’s tissues to insulin and can be treated with a carefully controlled diet and a weight loss regimen.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Diabetes Mellitus
• In either type of DM, elevated blood sugar must be controlled because high glucose levels cause the kidneys to work overtime to secrete the excess sugar. Increased urination (polyuria), dehydration leading to increased thirst (polydipsia), and hunger are the most common symptoms.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application:Diabetes Mellitus
• Untreated diabetes leads to weight loss as the body searches for other sources of energy. As abnormal cell metabolism breaks down muscle, acid is produced and blood acidity worsens, leading to tissue and organ damage. Lack of treatment will lead to coma and death.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Adrenal Cortex
• The adrenal cortex makes dozens of steroid hormones, known collectively as adrenocorticosteroids, which are released under the direct stimulation of the anterior pituitary.
• Many of these hormones are so important that a decrease in production could be fatal relatively quickly.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Adrenal Cortex
• Each of these hormones has a specific function, including regulation of fluids, electrolytes, blood sugar, reproduction, secondary sex characteristics, cell metabolism, growth, and immune system function.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Prednisone
• Prednisone is clinically important in the treatment of inflammation, organ rejection, and immune disorders. Prescription steroids are a two-edged sword because they have dangerous side effects including bone loss, weight gain, hair growth, fat deposits, and delayed wound healing.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Clinical Application: Prednisone
• This drug cannot be discontinued suddenly because the drug decreases adrenal cortex production. The adrenal cortex must be allowed to resume normal functions gradually – gearing up to secrete the proper amount of steroids.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Hashimoto’s Disease
• Hashimoto’s disease is a form of hypothyroidism caused by an autoimmune attack of the thyroid gland.
• The cause is unknown. The body attacks the thyroid gland, causing inflammation and damage to the gland, leading to decreased production of thyroid hormones (hypothyroidism).
• The thyroid may swell, causing painful swallowing. It is most common in women 30 to 50-years-old and is treated with a daily synthetic hormone treatment.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Graves’ Disease
• Graves’ disease is an autoimmune disorder affecting the thyroid, stimulating an increased production of hormones, called hyperthyroidism.
• Symptoms include insomnia, bulging eyes, and jitteriness.
• Treatment involves decreasing hormone secretion by destroying the thyroid with radioactive iodine, or surgery if this is not effective. After treatment, patients will need synthetic thyroid hormone because the thyroid no longer functions properly, if at all.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Pheochromocytoma
• A pheochromocytoma is a tumor of the adrenal gland causing increased epinephrine secretion.
• The symptoms are similar to an adrenalin rush, including severe headaches, excess sweating, racing heart, anxiety, abdominal pain, heat intolerance, and weight loss.
• They are rarely cancerous but must be removed or the effects of excessive epinephrine production will be fatal.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Addison’s Disease
• Addison’s disease is caused by insufficient production of the adrenocorticosteroid cortisol. The deficiency causes weight loss, muscle weakness, fatigue, low blood pressure, and excessive skin pigmentation.
• Aldosterone may also be deficient. • Many cases of Addison’s are autoimmune.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Cushing’s Syndrome
• Women may have excessive facial hair and irregular periods while men have decreased fertility and sex drive. It may be a side effect of medical use of steroids, like prednisone, or may be due to primary tumors, lung tumors, adrenal tumors, or one of several genetic disorders.
• Treatment depends on the underlying cause. Hormone replacement may be required.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Figure 12-15 (continued) Examples of Endocrine Disorders. (C) A patient with exophthalmos, a symptom of hyperthyroidism (Graves’ disease). (Source: Custom Medical
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• The endocrine system works together with the nervous system to regulate the activities of all the body systems. The endocrine system is linked to the nervous system but works very differently. The endocrine system secretes hormones that act very slowly on distant targets. Their effects are long lasting. Some organs, like the pancreas and the thyroid gland, function mainly to release hormones.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• However, many other organs, like the heart and stomach, can also release hormones. They aren’t considered endocrine glands because hormone release isn’t their primary role.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• Most hormones act on cells by binding to external receptors, causing changes in enzyme activity inside the target cell. Steroids, however, can enter cells and interact directly with DNA, which makes steroids very powerful.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• Hormone levels are controlled largely by negative feedback. When hormone levels rise, signals are transmitted to the endocrine organ releasing the hormone, telling the organ to decrease the amount of hormone released. Hormone levels will then decrease. The optimal level of the hormone is called the set point.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• If the signal brings a hormone back to set point, the action is called negative feedback. If the signal causes the hormone to get further away from set point, the action is positive feedback.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• Hormone levels can be regulated via three mechanisms: changes in the body’s internal environment (humoral), control by hormones released by another endocrine gland (hormonal), and direct control by the nervous system (neural).
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• The pituitary gland has two parts: the posterior pituitary, which is part of the hypothalamus and actually secretes hypothalamic hormones (ADH and oxytocin), and the anterior pituitary, which secretes several different hormones under the influence of hormones from the hypothalamus.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• Several other endocrine glands have important control functions. The thyroid gland secretes the iodine-containing hormones triiodothyronine (T3) and thyroxine (T4), which control growth and cellular metabolism. The pancreas secretes two hormones: insulin, which lowers blood sugar, and glucagon, which raises blood sugar.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Snapshots from the Journey
• The adrenal glands are split into two parts. The adrenal medulla is an extension of the sympathetic nervous system, releasing epinephrine and norepinephrine as hormones during fight-or-flight response. The adrenal cortex releases many different adrenocorticosteroid hormones, which control reproduction, inflammation, tissue growth, and immunity.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Case Study
A 40-year-old patient presents to the emergency department with the following symptoms:– Recent weight loss– Generalized weakness– Excessive thirst and urination
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
Case Study
• Portions of his lab values show a blood glucose of 150 mg/dl and acidic urine and blood. He has a family history of diabetes, but this is the first time he’s presented with these symptoms.
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
From the Streets
You are called to the home of the 40 year-old patient who presented to the ED 1 month ago. Family states that he did not follow up for diabetic treatment. You find him lying in bed slow to respond with rapid & deep breathing, hypotension, tachycardia, severely incontinent of urine, and pale, cool, & clammy skin. His breath has a fruity odor. His blood glucose is 600 mg/dl (normal range 60—120 mg/dl).
Essentials of A&P for Emergency CareBruce J. Colbert • Jeff Ankney • Karen T. Lee • Bryan E. Bledsoe
End of ChapterReview Questions
7. If an adult patient is treated for gigantism by removal of their pituitary gland, which hormone would have to be replaced with drug therapy.a. Cortisolb. Melatoninc. Thyroid-stimulating hormoned. Insulin