M4: Make a flashcard/write a paragraph (1/2 page) for each of these hormones: Each flashcard/paragraph should describe how the hormone helps to control the body’s functions. Adrenaline Thyroxine Insulin Corticosteroids

Adrenaline Adrenaline is a hormone produced in the medulla of the adrenal glands, from where it is released into the bloodstream. It has many different actions depending on the type of cells it is acting upon. The overall effect of adrenaline is to prepare the body for the ‘fight or flight’ response in times of stress, i.e., for vigorous and/or sudden action. Key actions of adrenaline include increasing the heart rate, increasing blood pressure, expanding the air passages of the lungs, enlarging the pupil in the eye (see figure), redistributing blood to the muscles and altering the body’s metabolism, so as to maximise blood glucose levels (primarily for the brain). Adrenaline release is only increased at times of acute stress. Adrenaline is also used as a transmitter by some nerve cells to communicate with other cells (a neurotransmitter). Very little adrenaline is used in this way. How is adrenaline controlled? Adrenaline is mainly released in response to stressful events to prepare the body for the ‘fight or flight’ response. These events lead to the activation of nerves connected to the adrenal glands which trigger the secretion of adrenaline and thus increase the levels of adrenaline in the blood. This process happens relatively quickly, within two to three minutes of the stressful event being encountered. When the stressful situation ends, the nerve impulses to the adrenal glands are lowered, meaning that the adrenal glands stop producing What happens if I have too much adrenaline? Overproduction of adrenaline is rare. Symptoms may include rapid heart beat, high blood pressure, anxiety, weight loss, excessive sweating and palpitations. What happens if I have too little adrenaline? Suffering from too little adrenaline is very unusual. Among other things, it would result in an inability to prepare the body for action in response to a stressful or physically demanding situation. Source:

Thyroxine Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It is inactive and most of it is converted to an active form called triiodothyronine by organs such as the liver and kidneys. Thyroid hormones play vital roles in regulating the body’s metabolic rate, heart and digestive functions, muscle control, brain development and maintenance of bones. How is thyroxine controlled? The production and release of thyroxine is controlled by a feedback loop system which involves the hypothalamus in the brain and the pituitary and thyroid glands. The hypothalamus secretes a hormone which, in turn, stimulates the pituitary gland to produce thyroid stimulating hormone. This hormone stimulates the production of thyroxine by the thyroid gland. What happens if I have too much thyroxine? The release of too much thyroxine in the bloodstream is known as thyrotoxicosis. This may be caused by overactivity of the thyroid gland (hyperthyroidism), as in Graves' disease, inflammation of the thyroid or a benign tumour. Thyrotoxicosis can be recognised by a goitre which is a swelling of the neck due to enlargement of the thyroid gland. Other symptoms of thyrotoxicosis include intolerance to heat, weight loss, increased appetite, increased bowel movements, irregular menstrual cycle, rapid or irregular heartbeat, palpitations, tiredness, irritability, tremor, hair loss and retraction of the eyelids resulting in a ‘staring’ appearance. What happens if I have too little thyroxine? Too little production of thyroxine by the thyroid gland is known as hypothyroidism. It may be caused by autoimmune diseases, poor iodine intake or brought on by the use of certain drugs. Sometimes, the cause is unknown. Thyroid hormones are essential for physical and mental development so hypothyroidism during development or before birth and during childhood causes mental impairment and reduced physical growth.Hypothyroidism in adults causes a decreased metabolic rate. This results in symptoms which include fatigue, intolerance of cold temperatures, low heart rate, weight gain, reduced appetite, poor memory, depression, stiffness of the muscles and infertility. Source:

Insulin Insulin is a hormone made by an organ located behind the stomach called the pancreas. Here, insulin is released into the bloodstream by specialised cells called beta-cells found in areas of the pancreas called islets of Langerhans. Insulin can also be given as a medicine for patients with diabetes because they do not make enough of their own. It is usually given in the form of an injection.Insulin is released from the pancreas into the bloodstream. Insulin allows cells in the muscles, liver and fat (adipose tissue) to take up sugar (glucose) that has been absorbed into the bloodstream from food. This provides energy to the cells. This glucose can also be converted into fat to provide energy when glucose levels are too low. How is insulin controlled? When we eat food, glucose is absorbed from our gut into the bloodstream. This rise in blood glucose causes insulin to be released from the pancreas. In addition, hormones released in times of acute stress, such as adrenaline, stop the release of insulin leading to higher blood glucose levels. The release of insulin is tightly regulated in healthy people in order to balance food intake and the metabolic needs of the body.Insulin works in tandem with glucagon, another hormone produced by the pancreas. While insulin’s role is to lower blood sugar levels if needed, glucagon’s role is to raise blood sugar levels if they fall too low. Using this system, the body ensures that the blood glucose levels remain within set limits, which allows the body to function properly. What happens if I have too much insulin? Diabetic patients are given drugs including insulin treatment to lower their high glucose levels. However, if a person accidentally injects too much insulin, cells will take in too much glucose from the blood. This leads to abnormally low blood glucose levels (hypoglycaemia). The body reacts to hypoglycaemia by releasing stored glucose from the liver in an attempt to bring the levels back to normal. However, persistently low glucose levels in the blood can make a person feel ill.Unlike other cells in the body, nerve cells depend almost entirely on glucose as a source of energy. When the glucose level is too low, the majority of the symptoms result from these nerves not functioning properly. The brain is particularly affected by low glucose levels. Symptoms include dizziness, confusion and even coma in severe cases. Source:

Corticosteroids Corticosteroids are group of natural and synthetic analogues of the hormones secreted by the pituitary gland. Three types include: Glucocorticoids, which are anti-inflammatory agents with a large number of other functions; Mineralocorticoids, which control salt and water balance primarily through action on the kidneys; Corticotropins, which control secretion of hormones by the pituitary gland. Purpose Corticosteroids have multiple effects, and are used for a large number of conditions. They affect glucose use, fat metabolism, and bone development, and are potent anti-inflammatory agents. They may be used for replacement of natural hormones in patients with pituitary deficiency (Addison's disease), as well as for a wide number of other conditions including, but not limited to, arthritis, asthma, anemia, various cancers, and skin inflammations. Additional uses include inhibition of nausea and vomiting after chemotherapy, treatment of septic shock, treatment of spinal cord injuries, and treatment of hirisutism (excessive hair growth). The choice of drug will vary with the condition. Cortisone and hydrocortisone, which have both glucocorticoid and mineralocorticoid effects, are the drugs of choice for replacement therapy of natural hormone deficiency. Synthetic compounds, which have greater anti-inflammatory effects and less effect on salt and water balance, are usually preferred for other purposes. Source: