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ACP-2 Lesson Six Endocrine System The endocrine system plays a vital part in every aspect of our health. It is made up of a series of glands which secret hormones to influence every one of the bodily systems. The glands which are involved in system are: Adrenal glands Pituitary Hypothalamus Thyroid Thymus Parathyroid Pineal Ovaries and testes Islet of Langerhans An initial danger signal is processed in the brain by the hippocampus, which is then passed onto to theamygdala. There, the signals are changed to pictures and sounds and is then sent to thehypothalamus which triggers the HPA axis. The HPA axix stands for: hypothalamus, Pituitary and Adrenals. The Adrenals These small glands sit on top of each of your kidneys and are in charge of the body’s responses to danger signals or excitement. We call this the “Fight and Flight” Syndrome. It works extremely quickly and can result in reactions like a person jumping out of the way of the car without even realizing they even saw it coming. The adrenals then secrete epinephrine or what you may be more familiar with as adrenaline. This causes the heart rate to increase, flushing the muscles with blood, while breathing gets shallower filling the blood with oxygen. Tiny muscles in the hair follicles called erector pili are activated causing the hairs on your skin to stand on end. Once the initial stress response has passed, the parasympathetic nervous system then applies the brakes and the hormones return to normal. The reason for this chain of responses enables to rise to a fight very quickly if we need to protect ourselves and/or supercharge us to give our best performance. In fact, the adrenals are responsible for activating over a 100 different hormones. Another hormone, you as an aromatherapist should be concerned with is called cortisol. This particular hormone controls: • Blood sugar (glucose) levels • Fat, protein and (gluconeogenesis) carbohydrate • Immune responses • Anti-inflammatory actions • Blood pressure metabolism to maintain blood glucose • Heart and blood vessel tone and contraction • Central nervous system activation The problem a person face’s is that long term, the parasympathetic system is no longer able to apply the brakes and the body is flooded with cortisol needlessly which affects all of the above. You can see why stress-related illnesses can become not only problematic, but also diverse. Pituitary Scientists originally thought the pituitary was responsible for the control of the endocrine system. We now know that, in fact, the hypothalamus is the big boss. The pituitary is about the size of a pea and is located close to the base of the brain. The pituitary secretes many hormones, but they do not all exclusively pertain to sexuality and fertility. ACTH - Stimulates the adrenal gland to produce a hormone called cortisol. TSH – (thyrotrophin) Stimulates the thyroid gland to secrete its own hormone, which is called thyroxine. FSH Follicle stimulating hormone- stimulates the ripening of ova to be released in ovulation. Encourages maturation of testosterone in men. LH Luteinising hormone –triggers ovulation in women and in men helps with the production of testosterone Testosterone- Controls reproductive functioning and sexual characteristics. While this is in higher concentration in men, it is also found in women. Prolactin – Stimulates the breasts to produce milk. This hormone is secreted in large amounts during pregnancy and breast feeding, but is present at all times in both men and women. Growth hormone or Somatotropin – Stimulates growth and repair in every cell of the body. MSH Vasopressin- Controls the blood fluid and mineral levels in the body by affecting water retention by the kidneys. This hormone is also known as argenine vasopressin (AVP). Oxytocin Affects uterine contractions in pregnancy and birth and subsequent release of breast milk. These hormones will be covered in more detail in the lesson about reproduction. Melanocyte-stimulating hormones – stimulates the growth of nails and hair Hypothalamus As you know, this is the CEO of the endocrine system which not only controls everything, but it also communicates the messages from the brain into the physical body. It is located right at the very base of the brain and merges with the top of the spinal cord. It joins with the pituitary gland by a thin stalk of neurons and works like a valve to regulate the pituitary hormones. Every message coming from the brain passes through the hypothalamus. It governs the process we call homeostasis, which means it monitors the body to make sure it is ticking along as it should. It regulates: body temperature thirst hunger sleep circadian rhythm moods sex drive water levels Working from a benchmark set point, the hypothalamus is always checking levels of the above and then releasing other hormones to try to balance out to ensure everything is working properly. Thyroid The thyroid is a butterfly-shaped organ found in your neck just above the windpipe. Normally, it is not visible from outside of the throat but certain conditions such as goitre will cause it to enlarge. The functions of the thyroid are: Regulation of appetite Regulation of temperature Metabolism Growth and development The main hormones secreted by the thyroid are: thyroxine (T4) triiodothyronine (T3) In the blood, T4 is a precursor to T3 and is found in quantities which outstrip T3 by around 20 to one. This is mainly because T4 has a far longer half-life (the time it takes for the chemical to break down) than T3. T4 and T3 are mainly, but not exclusively concerned with metabolism and so if there is a deficiency you are likely to see weight gain and conversely if there is an excess, you may struggle to gain weight. A deficiency also will case the patient to feel cold. For the thyroid to function effectively, it must have enough iodine in the blood. If it doesn’t, it becomes enlarged and goitre presents itself. Nowadays this is a condition rarely seen, but it used to be referred to as Derbyshire Neck because it was so prevalent in this region of England. It was only when the authorities discovered their water was iodine deficient that a correlation was drawn. Should a person have an over-enthusiastic thyroid, it is possible they could develop Graves’ Disease. Thyroid problems cause an especial threat to newborns and most children are now routinely checked. Problems with this gland can lead to problems with growth, in particular dwarfism or with mental retardation with the extremely unkind name of cretinism. A child with an inactive thyroid is unusually quiet, has very little appetite and will sleep for very long periods. Thymus The thymus is found posterior to the sternum in the middle of the chest just in front of the heart. The role of this gland sits squarely in the immune system. It is here the important T-Cells mature. Parathyroid Parathyroid is found just behind the thyroid gland and is responsible for looking after the bone density in your body through regulation of calcium and phosphorous. In fact, there are four of these glands, typically about the size of a grain of rice, and sometimes as big as a pea. They are mustard yellow in color. Calcium, in fact, is the only mineral in the body which has its own built-in regulator. This is because it provides the electrical impulses which transmit along nerves, as well as contributes to bone density and a person’s mood. Phosphorous helps keep our teeth strong, but also helps with how the body processes glucose and with how it metabolizes calcium and protein. Pineal Many of you will have seen pictures of the third eye in the center of the brow. This is the location of the pineal. In fact, it is hidden deep inside the brain where the two hemispheres meet. Its function is to produce melotonin which regulates the body’s circadian rhythms. One particular problem with this might be SAD or seasonal affective disorder, producing too little, leading to anxiety, too little sleep and depression. Ovaries and Testes The male and female hormones will be covered in more detail in the reproduction lesson, but at this point it is enough to know they are endocrine glands. Islets of Langerhans Like the thymus, this is mainly immunity related. The islets (pronounced eye-lets) are actually lots of clusters of cells, around 4000 clusters in total. Their job predominately, is to recognize and regulate sugar in the blood stream. They are -2% of mass of the pancreas. There are 5 component cells. Alpha cells producing glucagon (15–20% of total islet cells) Beta cells producing insulin and amylin (65–80%) Delta cells producing somatostatin (3–10%) PP cells (gamma cells) producing pancreatic polypeptide (3–5%) Epsilon cells producing ghrelin (<1%) Glucagon Glucagon is a hormone in the blood stream which increases blood sugar concentration. It does the opposite to insulin. Insulin Insulin, which many are familiar with, regulates carbohydrates and fats in the body. It absorbs blood sugar into the skeletal muscles and into the blood. Amylin This works in tandem with insulin, slowly reducing gastric sugars. Somatostatin Somatostatin regulates glucogen and insulin. Pancreatic polypeptides Pancreatic polypeptides regulate the secretions from the pancreas and also influences how the liver processes glycogen as well as the secretions in the gastric processes. Ghrelin Ghrelin is known as the hunger hormone and directly communicates with nerves in the system. It also plays an important role in how efficiently our body uses the energy we give it. In summary, the cell clusters also influence each other through hormonal feedback in a continuous loop. Glucose/Insulin: activates beta cells and inhibits alpha cells Glycogen/Glucagon: activates alpha cells which activates beta cells and delta cells Somatostatin: inhibits alpha cells and beta cells