endocrine

9.2

9.2

9.3

9.3

Type 2 diabetes

A chronic, lifelong condition of high blood sugar. non-insulin dependent form of diabetes because although some insulin is being produced, it is either an insufficient amount or ineffective in pushing the glucose out of the blood and into the cells. This is the most common type of diabetes mellitus and has been increasing in the population because of poor diets, obesity, and a lack of exercise. While it usually affects those older than 40 years of age, with the rise of childhood obesity, it is becoming more common in younger age groups. One reason the islets of Langerhans in the pancreas stop producing enough insulin or produce ineffective insulin is thought to be that the cells in the pancreas wear out from all of the carbohydrates (sugars) being consumed in mass quantities over a period of time. Unlike Type 1 diabetes, Type 2 usually does not require injections of insulin. Instead, this condition can be controlled with a healthy diet and exercise. If this lifestyle change isn't enough, the patient also can be given antidiabetic medication that will stimulate insulin secretion.

diabetes insipidus

A condition caused by a lack of antidiuretic hormone, causing frequent urination and thirst. and we will begin our discussion there.

Cushing's syndrome

A condition caused by too much cortisol in the body. is the result of the adrenal glands pumping too much cortisol hormone in the body for too long. Cushing's syndrome is caused by a variety of different conditions. An excessive amount of cortisol might be produced if a tumor positions itself on the adrenal glands, pituitary gland, pancreas, lungs, thyroid or thymus. In a healthy system, the pituitary gland releases adrenocorticotropic hormone (ACTH) to stimulate the adrenal glands to release more cortisol in the blood when needed. Tumors can increase the production of ACTH, signaling the adrenal glands to produce more cortisol. Tumors on the adrenal gland increase the levels of cortisol already being produced by directly causing the gland to secrete more cortisol. Cushing's syndrome most commonly is caused through prolong administration of steroid medications, the most common of which is prednisone. Cushing's syndrome sufferers experience two classic symptoms: a round, moon-shaped face, and a buffalo hump on the upper portion of his or her back. Other symptoms are fatigue, weakness, a large abdomen with thin arms and legs, high blood pressure, stretch marks, easy bruising, poor wound healing, osteoporosis, high blood sugar, and anxiety/depression. Symptoms that are specific to women are excess facial hair and irregular menstrual cycles; for men, symptoms include decreased fertility and sex drive

24-hour urine-free cortisol test

A diagnostic procedure used to measure the cortisol levels in urine over a 24-hour period.

diabetes mellitus

A group of diseases caused by too much sugar in the blood. which is a chronic condition that involves insulin and blood sugar

Addisonian crisis

A severe complication of Addison's disease. Patients experiencing an Addisonian crisis, a life-threatening complication of Addison's disease, have decreased blood sugar and blood pressure and increased potassium levels. This is a medical emergency and requires prompt medical treatment.

exophthalmos

Abnormal protrusion of the eyes. Other patients can develop an eye-opening symptom, literally. A condition called play audio exophthalmos causes the eyeballs to protrude outward in a wide-eyed appearance because of swelling of the vessels behind the patient's eyes. Exophthalmos can be so severe that the patient cannot close his or her eyelids.

Diagnosing and Treating Addison's Disease

Addison's disease can be diagnosed with blood samples. Blood tests can be used to measure the levels of adrenocorticotropic hormone and cortisol, as well as sodium and potassium. The physician also could measure the levels of antibodies that might be present causing the disease state. A test to see if the adrenal glands are producing cortisol properly is done by injecting the patient with a synthetic ATCH, which should prompt the body to increase cortisol levels. If there is adrenal insufficiency, cortisol levels will remain decreased or still not produce any at all. A CT scan can be performed to get a visual image of the adrenal glands to study for any anomalies. Addison's disease is treated with hormone replacement therapy to increase the patient's low hormones levels. This is accomplished by taking oral or injectable corticosteroids such as Cortef oral (hydrocortisone) and Solu-Medrol injection (methylprednisolone).

Type 1 diabetes juvenile diabetes

Also called juvenile diabetes, caused by the pancreas' inability to produce insulin. Type 1 diabetes is caused by the body's inability to produce enough insulin, which can be caused by an autoimmune disease that attacks the pancreas and inhibits its ability to produce insulin. In the pancreas, insulin is produced by special beta cells in the islets of Langerhans. If not enough insulin is present, glucose will remain in the blood, and the body is unable to make energy to fuel its cells. The body then will attempt to use other substances such as proteins and fats to make energy. This will cause the body to store high levels of ketones in the bloodstream, creating a condition known as diabetic ketoacidosis. Both hyperglycemia and diabetic ketoacidosis cause life-threatening symptoms.

diabetic retinopathy

Blindness caused by high blood sugar. In the kidneys, renal vessels can be destroyed, causing kidney failure and death.

Ketoacidosis

Buildup of ketones (acid) in the blood when the body breaks down fat for energy Insulin, which is secreted by the pancreas, moves sugar from the bloodstream out into the tissues, where it is used to fuel the body and causes the blood sugar level to decrease. With a lack of insulin, the sugar remains in the bloodstream, causing an increase in blood sugar. In addition, because the sugar is not able to get out into the tissues to be used as fuel, the body will break down its own muscle and fat cells to produce energy. This causes a byproduct called ketones to build up in the body, leading to a condition called Ketoacidosis.

Central diabetes insipidus

Caused by the lack of antidiuretic hormone. develops as a result of not enough vasopressin being secreted by the pituitary gland. This form can develop as a result of a head injury or brain tumor.

hormones

Chemical signal that is secreted into the bloodstream to control bodily functions. secreted from various glands and organs throughout the body with the main purpose of keeping the body's organs working in a state of homeostasis. These endocrine glands and organs secrete their hormones into the bloodstream on an as-needed basis. This function is actually spelled in its name, endo- meaning into and -crine meaning to secrete. We do have other types of glands in our body, such as exocrine or sweat glands, but they secrete outside (exo) of the body. The endocrine system is made up of both glands and organs. Organs are made up of more than one type of specialized cell, which has the ability to secrete a substance and also perform other functions. For example, the pancreas is an organ that produces the hormone insulin to regulate blood sugar levels, but it also performs digestive functions. A gland is made up of just one type of cell and it secretes substances only inside the body

Myxedema

Condition associated with hypothyroidism. advanced form of hypothyroidism that usually occurs in middle-aged women. Congenital hypothyroidism, also called cretinism, occurs in newborns that do not have a properly developed thyroid. This condition causes both mental and growth development problems.

hypoglycemia

Condition of low blood sugar

Prediabetes

Condition of slightly higher than normal blood sugar that is not high enough to be considered diabetes.

diabetic gangrene

Dead tissue resulting from a loss of blood flow, peripheral artery disease caused by diabetes mellitus.

Diabetes insipidus causes

Diabetes insipidus causes an increase in the body's production of urine because of the kidneys inability to retain fluid. It can be caused by different situations, and each has a different name. Diabetes insipidus tends to affect men more than women and is likely to occur early in a person's life. The hormone involved in this condition is vasopressin, also known as antidiuretic hormone (ADH), which regulates the amount of urine released by the kidneys. For example, if vasopressin levels are increased, the kidneys will increase fluid reabsorption into the body and thus output less urine. On the other hand, if the vasopressin levels are decreased there will be less antidiuretic effect and the kidneys will eliminate large amounts of urine, a condition known as diabetes insipidus.

gestational diabetes

Diabetes that develops because of pregnancy.

Peripheral vascular disease (PVD)

Disease of the blood vessels outside of the heart often resulting in partial or complete blockages of blood flow

Antithyroid

Drug that stops the thyroid from producing T3 and T4 hormones. The main treatments for hyperthyroidism include medication, radiation, and a thyroidectomy. Antithyroid agents, also called thionamides, are used to bring thyroid levels back to normal. These drugs do not alter the thyroid gland as radiation would, and they also work faster than radiation therapy. Antithyroid medications decrease iodine levels in the body and thus decrease thyroid hormone production. Antithyroid hormones work best when treating mild cases of hyperthyroidism; however, this class also helps decrease the odds of experiencing worsening effects of hyperthyroidism. Commonly used antithyroid medications include Tapazole (methimazole) and Propacil (propylthiouracil). Tapazole is taken every eight hours, with or without food, and, if used in children, the dose will vary depending on their weight. Propacil is taken every eight hours with or without food and is not recommended for children. Pregnant women and those who are breastfeeding should take special precaution in taking these drugs. Propylthiouracil has fewer side effects than methimazole. Symptoms will not stop overnight. Instead, these drugs will take anywhere from one to eight weeks for symptoms to show improvements, and it may take up to six months to get the hormones back to normal levels. Common side effects of antithyroid drugs are nausea, achy joints, and a noticeable change in taste. Another drug called ThyroSafe (potassium iodide solution) can be used to block radiation therapy treatments from causing too much damage to thyroid tissue. Radiation iodide therapy is used by nuclear medicine to destroy thyroid tissue because patients who have benign thyroid nodules produce too much thyroid hormone.

antidiabetic drugs

Drugs used to control Type 2 diabetes.

different types of estrogen

Estradiol Estriol Estrone

Nephrogenic diabetes insipidus

Form of diabetes insipidus caused by kidney disease. is caused when the kidneys do not respond to the vasopressin hormone. This can be an inherited condition or caused by kidney dysfunction.

parathyroid glands

Four pea-sized regions in the posterior side of the thyroid. These four pea-sized glands on the posterior side of the thyroid secrete a hormone called parathyroid hormone. This hormone is important in regulating the levels of calcium and phosphates in the bloodstream. These minerals are needed for proper functioning of areas of the body such as the kidneys, bones, and small intestines.

anterior pituitary gland

Frontal portion of the pituitary gland. also called adenohypophysis, is located in the front portion of the pituitary gland. This gland is incredibly small, and yet is responsible for so much, which is why it is called the master gland. The anterior pituitary gland releases the following hormones:

adrenal glands

Glands located on top of each kidney. This gland is responsible for releasing three types of hormones: aldosterone, androgen, and cortisol. Each hormone has a specific role: Aldosterone maintains a balance of potassium and sodium levels in the blood; androgen hormone produces male sex traits, such as deepening of voice and body hair; and cortisol releases glucose to the brain

Atherosclerosis

Hardening of blood vessels. condition that causes fatty or waxy-like deposits on the walls of the arteries, causing them to thicken and harden. This condition is caused by lipids or fat cells going into the bloodstream to be used as energy instead of blood sugar. When a patient develops atherosclerosis, they are at greater risk of a myocardial infarction (heart attack), cerebral vascular accident (stroke), and peripheral vascular disease.

hyperglycemia

High blood sugar. It should be noted that diabetes and hyperglycemia are not the same. If a patient's diabetes is not controlled properly, their blood sugar can rise causing hyperglycemia. Hyperglycemia can be caused by other factors such as stress and medications, not just as a complication of diabetes mellitus

insulin

Hormone required to control blood sugar.

The final type of hormone level control is humoral control

Humoral means fluid, and one of the most important body fluids is blood. Some endocrine organs have the ability to monitor body fluids, such as blood, and then use the negative feedback mechanism to make any changes. For example, humoral control is used to keep our blood sugar levels properly balanced. If the body's blood sugar is too high, the pancreas will secrete the hormone insulin to decrease the elevated blood sugar. Insulin causes the sugar or glucose to be absorbed by tissues to decrease the total blood glucose level back toward normal.

Hypothyroidism

Hypothyroidism is most often caused by an autoimmune disease called Hashimoto's disease. It occurs more commonly in women than men and is thought to be caused by the destruction of the body's lymphocytes, resulting in less tissue to produce proper levels of thyroid hormones. Hypothyroidism also can be caused by over-treating hyperthyroidism, in which too much thyroid tissue was damaged, preventing the thyroid from producing enough hormones to maintain proper levels.

thyroid gland

Important structure located in the middle section of the neck that secretes thyroid hormones. is found in the anterior region of the neck. This gland releases three hormones that play very important roles in our body's function

list of possible signs and symptoms are

Increased weight gain Fatigue Weakness Hoarseness Constipation Muscle weakness Muscle aches and stiffness Joint pain Increased cholesterol Decreased fertility Depression Sensitivity to cold temperatures Slow heart rate Brittle nails Thinning hair Decreased memory The patient also might develop a goiter because of the continuous stimulation of the thyroid gland to create more hormones

adrenal medulla gland

Inner section of the adrenal gland. found in the inner region of the adrenal gland, which is encased by the adrenal cortex (outer core Two hormones secreted by the adrenal medulla are epinephrine and norepinephrine, which are released by the sympathetic system in response to high stress or danger.

Insulin pumps

Instead of using insulin injections to control blood sugar levels, an insulin pump can administer rapid-acting insulin 24 hours a day. This device can deliver three different dosage types under the skin via a catheter. Basal rate dosages are given at all times to keep the blood sugar level at proper levels (maintain a baseline) between meals and at night while you sleep. A bolus dose can be given by pushing a button on the pump to deliver an extra dose when you eat or any time you check your blood sugar level and the reading is too high.

thyroid storm

Life-threatening complication of hyperthyroidism. A life-threatening condition called a thyroid storm is an acute or sudden exacerbation of hyperthyroidism, which can happen to those with severe hyperthyroidism or after the thyroid has been removed (thyroidectomy). Symptoms include excessive tachycardia (possibly reaching a heart rate of 200 bpm), tachypnea, and a rapid onset of a high body temperature.

diabetic shock

Life-threatening condition caused by too much insulin in the body. This perfect storm occurs when an individual does not get enough food, exercises too much, or takes too much insulin (removing too much sugar from the blood

The different variations of diabetes

Nephrogenic diabetes insipidus Central diabetes insipidus

Normal blood

Normal blood sugar levels should be less than 100 mg/dL after fasting for eight hours. Diabetes can be diagnosed by a fasting plasma glucose test higher than 126 mg/dL. Another method called an oral glucose tolerance test is done by having a patient drink a sugary drink after fasting for eight hours. A reading of 200 mg/dL or higher is positive for diabetes.

A list of synthetic insulin injection preparations follows.

Novolin N, Humulin N, others (insulin isophane) is an intermediate-acting form that takes 2-4 hours to begin to work. It peaks at 4-12 hours, and can last 12-18 hours. Apidra (insulin glulisine) is a short-acting insulin that does not last long in the body. It begins to work 15 minutes after injection, peaks after a 1 hour, and has a 2- to 4-hour duration. NovoLog (insulin aspart) is a fast-acting insulin that also begins to work 15 minutes after injection, peaks at 1 hour, and has a 2- to 4-hour duration. Humalog (insulin lispro) is a fast-acting insulin that works 15 minutes after injected, peaks at 1 hour, and has a 2- to 4-hour duration. Lantus (insulin glargine) is a long-acting insulin that begins to work hours after the injection and continues to work for 24 hours. Levemir (detemir) is a long-acting insulin that begins to work hours after the injection and continues to work for 24 hours. Humulin 70/30, Novolin 70/30, others are mixtures of different types of insulin (70% human insulin isophane suspension and 30% human insulin injection). This is a mixture of intermediate- acting insulin with fast-acting insulin. Regular insulin also known as regular human refers to human forms of insulin.

Cortisol Issues

Our body's cortisol levels also must be kept at an acceptable level to function properly. Addison's disease is caused by the body having too little cortisol; Cushing's syndrome develops from too much cortisol production.

hyperthyroidism

Overproduction of thyroid hormones. also known as thyrotoxicosis, while some causes still remain unknown. Hyperthyroidism is a condition where the thyroid gland secretes T4 in excess. To produce hormones like T4, our body requires iodine, which can be found in table salt. Some causes of hyperthyroidism include hereditary, tumors, a diet high in iodine, and taking too much thyroid hormone medication. An autoimmune disease such as Graves' disease causes hyperthyroidism because antibodies stimulate the thyroid, causing the gland to become enlarged and overproduce hormones. Regardless of the cause, the thyroid becomes enlarged appearing as a lump called a goiter in the anterior region of the neck. The excessive production of T4 causes an increase in the body's metabolism rate, causing an increased appetite but no gain in weight because of the hypermetabolic state. Instead, the patient becomes very thin. Peristalsis is also stimulated by T4, and too much T4 increases peristalsis action, causing the bowel contents to move through the intestine at a faster pace than normal. This situation does not allow for proper fluid absorption and therefore causes diarrhea. The increased metabolism also causes an increase in body temperature, causing the patient to sweat excessively. Both diarrhea and increased sweating will cause an increase in fluid loss, leading to dehydration. Other symptoms are a high heart rate, hyperactivity, excessive excitability, weakness, and nervousness.

positive feedback loop

Physiological process that takes the body farther way from its normal point and will continue to do so until the cycle is broken. The second type of feedback is the positive feedback loop. Instead of maintaining homeostasis like the negative feedback does by bringing the change back toward normal, this feedback mechanism causes an increase in the change within the body. In most cases, positive feedback is a vicious cycle that can be harmful as it moves farther and farther away from normal. A good example, however, is uterine contractions during childbirth. The hypothalamus sends a signal releasing oxytocin, which causes contractions to begin. As the uterus contracts, the baby moves down the birth canal, which increases signals to the hypothalamus, causing even more oxytocin to be released, which increases the uterine contractions. This cycle continues to increase in intensity until the baby is born, thus relieving the pressure and signaling the hypothalamus to stop calling for more oxytocin

negative feedback loop

Physiological process used to bring the body back to its normal point. The majority of our homeostatic regulation is accomplished by a negative feedback loop. Negative feedback occurs when your body is trying to get itself back to its correct level of function, such as body temperature, by working in opposition to the out-of-range value. Keeping with the temperature theme, an example of negative feedback is the thermostat found in your home

Central diabetes insipidus conditions are treated with replacement hormones such as

Pitressin, Vasostrict (vasopressin), and Dyapid (lypressin). Another agent, desmopressin, is a synthetic analogue of antidiuretic hormone that comes in various forms, including oral, intravenous, intranasal, and subcutaneous. This medication can be given up to three times per day to help the patient's body maintain proper fluid requirements.

pancreas

Produces and secretes insulin. found behind the stomach and spans from the right side of the body where the duodenum is attached via the pancreatic duct to the left side of the abdomen the pancreas secretes glucagon from alpha cells of the islets of Langerhans and insulin is secreted from beta cells. The glucagon hormone is responsible for increasing the blood glucose level to produce energy for the body, while insulin is required to decrease blood sugar levels by enhancing cellular uptake

Radiation therapy

Radiation therapy can also cause extensive tissue damage and result in decreased hormone levels, as can a thyroidectomy that removes most, if not all, of a patient's thyroid tissue. This condition requires hormone replacement therapy. Some medications, such as lithium, are known to decrease thyroid hormone levels. Lithium is used to treat patients with psychiatric disorders.

posterior pituitary

Rear portion of the pituitary gland. or neurohypophysis gland, is responsible for releasing two hormones, oxytocin and antidiuretic (ADH) hormone. Oxytocin helps with lactation and uterine contractions. Antidiuretic hormone controls how much fluid the kidneys reabsorb, and therefore, the body's fluid balance. A diuretic causes fluid loss; an antidiuretic retains fluid within the body. This hormone is produced by the hypothalamus and is stored in the pituitary gland

late-night salivary cortisol level test

Salivary test done at night to measure cortisol levels. Finally, to check whether a tumor is the cause of raised cortisol levels, an MRI can evaluate the adrenal and/or pituitary gland.

endocrine system

System that produces and secretes hormones to control everyday bodily functions.

gonads

Testes in men and ovaries in women. Female gonads are located in the pelvic cavity and produce three types of hormones. Estrogen is produced in the ovaries and is the main sex hormone in women. The little bit of estrogen men have in their bodies comes about because the hormone is also made in the adrenal glands and even in fat tissue. While it can help maintain healthy bones in both sexes, it plays a major role in female development and pregnancy.

type 1

Type 1 diabetes requires insulin injections to make up for the lack of insulin production, a situation that needs to be monitored to maintain the proper levels of blood glucose. The American Diabetes Association recommends a blood test to measure the level of glycated hemoglobin. The test is called hemoglobin A1c or HbA1c. This test gives medical providers an average of how well their patient has controlled his or her blood sugar over the past two to three months. Glycated hemoglobin forms when the hemoglobin in the blood is exposed to high blood sugar levels. This glycated change lasts throughout the duration of the hemoglobin's life span of two to three months. The higher the blood glucose level, the higher the level of HbA1c. For individuals that are not diabetic, HbA1c levels of 4% to 5.9% are considered normal, while those with diabetes who poorly manage their condition will have levels above 7%. Those able to decrease their HbA1c levels actually can decrease the likelihood of developing complications of diabetes. Type 1 diabetes is a serious medical condition and treatment will be required for the rest of the patient's life. Insulin injections are required to be given daily to control blood sugar levels. Insulin cannot be taken orally because it would be rendered ineffective by the stomach. To ensure blood sugar levels are normal, it can be checked both quickly and painlessly with a blood glucose monitoring device

Diabetic coma

Unconscious state caused by high blood sugar. another complication that arises when a person administers too little or too much insulin or if someone consumes too many carbohydrates, spiking their blood sugar levels. Those affected experience symptoms of excessive thirst, lethargy, and excessive urination, which result in dehydration. Also present is ketoacidosis, which can produce a noticeably sweet-smelling breath. This condition progresses slowly, but will eventually lead to coma. If this condition occurs, medical attention is needed to receive proper amounts of insulin and fluids.

Hypothyroidism

Underproduction of thyroid hormones. caused by an underactive thyroid, which decreases the body's normal production of T4

The symptoms of Addison's disease include

Vomiting Diarrhea Dehydration Salt cravings Hypoglycemia Darkening of skin (yellow to brown) Depression Irritability Joint and muscle pain Weight loss Decreased appetite.

Calcitonin

a hormone that helps to regulate proper levels of calcium and potassium in the blood. The parathyroid glands also play a role in regulating the calcium and potassium.

Growth hormone (GH

directly affects cellular growth and reproduction

Symptoms of hypothyroidism

do not usually occur suddenly. Instead, the patient will experience symptoms gradually and might even blame them on something else, such as old age. The severity of symptoms a patient experiences depends on how low the thyroid hormone levels drop

Estradiol

dominant form of estrogen found in women of child-bearing age.

Triiodothyronine (T3)

has an effect on our body temperature, heart rate, and growth

Thyroxine (T4)

helps to maintain appropriate metabolic processes

The second type of hormone produced in ovaries

is inhibin, which decreases FSH. The third hormone is progesterone, which also plays a major role in menstruation and pregnancy. In a pregnant woman, this hormone causes the endometrium to release proteins to prepare the body to nourish the fertilized egg.

The pineal gland

located between the two cerebral hemispheres of the brain and is attached to the thalamus. The hormones produced by this gland are melatonin and serotonin. Melatonin helps to regulate the body's sleep cycles or circadian rhythm. The pineal gland produces melatonin based on the light in the retina as sensed by photoreceptors. For example, if it is dark outside (night time), it will be dark in the retina causing the gland to produce melatonin. When it is day time, light will be sensed in the retina by photoreceptors causing a decrease in melatonin production. The hormone serotonin functions like a neurotransmitter and vasoconstrictor. Serotonin can cause the constriction of smooth muscles and the inhibition of gastric secretions.

T-cells

lymphocytes that are produced by the thymus gland and play a role in the body's immune system.

Estriol

main type of estrogen found in pregnant women

Type 1&2 diabetes symptoms

more severe and have a faster (acute) onset. That being said, Type 1 and Type 2 (to be discussed soon) share some of the same symptoms. These symptoms include increased urination, thirst, hunger, blurred vision, fatigue, irritability, and recurring infections affecting the skin, vagina, and even the gums. Often people experience sweet-smelling urine caused by an increase in ketones in the urine. Also seen with this condition is impaired wound healing, causing a much slower healing time that often requires medical attention for even minor wounds.

Estrone

only form of estrogen found in women after they have gone through menopause.

Hormones work

ormones are released into our bloodstream, which transports them all throughout the body. Hormones function can last for various periods of time, ranging from several minutes to multiple days. To perform their duty, hormones must do more than just float around in our blood. Instead, they must seek out and bind to receptor cells. These receptors can be found both inside and outside of a cell. When a hormone binds to a target cell or receptor cell, it can change the cell's activity by causing the cell to make more protein, decrease the amount of protein production, or even stop the production of protein entirely. Two very powerful types of hormones are steroids and thyroid hormones, which have the ability to bind to receptors inside the body's cells. This means these two hormone types can enter a cell and cross over into the cell's DNA, where they can make changes to the cell. Steroids are released by the adrenal glands, while the thyroid gland releases thyroid hormones. Another difference from nervous system control is that endocrine glands secrete hormones on a continual basis. This means our endocrine glands are always at work to maintain our hormone levels at a proper level and to keep our bodies at a homeostatic state. Let's show how the two control systems work in a common situation, such as being in a cold environment well below the body's homeostatic body temperature of 98.6 degrees Fahrenheit. When the nervous system senses the body temperature dropping, the hypothalamus will be triggered by sensory neurons to produce body heat by shivering (neuromuscular control) and the hypothalamus stimulates the thyroid to release hormones to increase metabolism, which also generates more body heat.

Adrenocorticotropic hormone (ACTH)

regulates levels of cortisol, a steroid released by the cortex (the outer layer) of the adrenal gland. Cortisol is released when the body has low blood sugar, is used to regulate blood pressure, decrease inflammation, and monitor metabolism. When too much cortisol is in the body, whether caused by a tumor or drug, Cushing's syndrome can develop, while too little cortisol can cause Addison's disease. These two conditions will be discussed later in this chapter.

Addison's disease

relatively uncommon disease of the adrenal glands, is caused by the adrenal cortex not secreting enough cortisol and aldosterone. Addison's disease, also known as hypoadrenalism or adrenal insufficiency, can be life-threatening and can occur in patients of either gender at any age. A pituitary tumor, adrenal gland infection, cancer of the adrenal gland, tuberculosis, and steroid hormone therapy all are potential causes of Addison's disease. The most common cause, however, is autoimmune disease resulting in the inability of the adrenal glands to produce adrenocortical hormones. Symptoms of Addison's disease can range from mild to life-threatening, and can take several months to fully emerge

Thyroid-stimulating hormone (TSH)

released to control the thyroid in the body.

Luteinizing hormone (LH)

used along with FSH to control the female menstrual cycle. This hormone's level varies depending on the phase of the woman's cycle, as does FSH

Follicle-stimulating hormone (FSH)

used to produce eggs in the ovaries and plays a role in controlling the menstrual cycle. In men, it is used to produce sperm.

Male gonads are made up of two testes

which are found in the scrotum. Two hormones are produced by the testes: testosterone and inhibin. Testosterone generates male sex characteristics and helps with sperm maturation, while inhibin is used to increase sperm count when needed.

The second type of control comes from hormonal control

which follows a hierarchy chain of command. A hormone is released from a gland, which is controlled by the release from another gland, higher on the chain of command. This is like a relay race in which runners cannot take off until they are given the baton. This chain of command is a form of negative feedback, so that whenever the value returns to normal the stimulus to secrete more hormone is inhibited.

neural control

which is done through the nervous system. Reacting to danger, the nervous system initiates the fight or flight response. It increases the heart rate, dilates pupils, and increases the diameter of the airways so the body can bring in more oxygen by triggering the release of two hormones from the adrenal glands, which sit upon the kidneys. The two hormones, epinephrine and norepinephrine, cause the effects of the sympathetic nervous system, also known as the alert system.