33. What are the functions of the endocrine system?
The main functions of the endocrine system are productive and regulative. Endocrine glands produce different hormones, which can be water- and lipid-soluble. With the help of such hormones endocrine system regulates the functions of other body organs.
34. Speak on the glands that make up the endocrine system and hormones they produce? Name some hormonal disorders.
The major glands, which make up the human endocrine system, are the hypothalamus, which is located in the lower central part of the brain and regulates the pituitary gland: The pituitary gland is located on the base of the brain and is called the “master gland”, because it controls other glands. It is divided into anterior and posterior lobes; Pineal gland is located in the middle part of the brain and is responsible for our wake-sleep cycle; Adrenal glands are located on the top of each kidney and is divided into adrenal cortex and adrenal medulla; Thyroid and parathyroid glands are located in the anterior part of the neck; Gonads, that produce androgens in men and estrogens in women; And endocrine part of the pancreas, that is responsible for carbohydrate metabolism.
Each glands of endocrine system produce different hormones.
Hypothalamus produces releasing and inhibiting hormones, which regulate anterior pituitary. Also it produces antidiuretic hormone, that regulates body water balance, and oxytocin, that triggers uterine contractions during labour.
The pituitary gland produces hormones, that control other glands; These hormones are: growth hormone (which stimulates protein synthesis and causes growth), follicle-stimulating hormone (that stimulates development and maturation of a follicle in a woman’s ovary), luteinizing hormone (that causes ovulation and the formation of corpus luteum), prolactin (which activates milk production in breastfeeding women), thyroid-stimulating hormone and corticotropin (which stimulate production of thyroid and adrenal hormones).
Adrenal cortex produces corticosteroids, which regulate salt and water balance, and metabolism. Adrenal medulla produces adrenalin and noradrenalin, which regulate the body’s response to stress, increase blood pressure, heartbeat, respiration and sweating.
Male gonads (testes) produce testosterone, and female gonads (ovaries) produce estrogen. These hormones regulate body changes associated with sexual development. Ovaries also produce progesterone that regulates menstrual cycle and pregnancy.
Thyroid gland produces calcitonin, thyroxine and triiodothyronine, which regulate calcium balance and metabolism. Parathyroid glands produce parathyroid hormone that also regulates calcium balance.
Pineal gland produces melatonin that regulates the wake-sleep cycle and skin pigmentation.
Pancreas produces insulin and glucagon, which regulate carbohydrate metabolism.
Excessive or insufficient amount of different hormones may result in hormonal disorders, such as:
Cushing’s syndrome, which is excessive amount of glucocorticoid hormones due to tumour in the pituitary gland;
Addison’s disease, that is deficiency of adrenal hormones, caused by autoimmune reaction or cancer;
Virilization, which is the development of exaggerated masculine characteristics due to excessive production of androgens;
Hypoglycaemia, that is abnormally low level of glucose;
Galactorrhoea, which is characterized by production of breast milk in men or women, who aren’t breastfeeding;
Precocious puberty, that is excessive production of gonadotropins leading to body changes at an abnormally young age;
Seasonal affective disorder, which is excessive production of melatonin, especially during winter.
35. What types of diabetes mellitus do you know? What are the causes, symptoms, treatment and complications of both diabetes types?
Diabetes mellitus is a disorder that is characterized by abnormally high level of glucose in the blood. There are two types of diabetes mellitus: type I diabetes mellitus (or insulin-dependent diabetes), and type II diabetes mellitus (or non-insulin-dependent diabetes). In type I most of insulin-producing cells are destroyed, and a patient must regularly inject insulin to survive. In type II the pancreas continues to produce insulin, but the body develops resistance to its effects.
Causes of diabetes mellitus include: viral infection or nutritional factor in childhood, genetic predisposition, high level of corticosteroids, pregnancy, drugs and poisons. Symptoms of diabetes are: polyuria, polydipsia (abnormal thirst), polyphagia (hunger), blurred vision, drowsiness, nausea, decreased endurance during exercise, susceptibility to infections. Treatment of diabetes include: keeping blood sugar levels within the normal range, weight control, exercise, diet, insulin replacement therapy, and oral hypoglycaemic medications. Complications may include: diabetic retinopathy, skin ulceration, ketoacidosis, hyperglycaemia, hypoglycaemia, diabetic coma, nephropathy, cardiomyopathy, neuropathy etc.
36. What are the complications?
A patient may develop diabetic coma if a level of glucose in his blood is extremely high or low.
The damage to small blood vessels leads to a microangiopathy, which can cause one or more of the following:
Diabetic cardiomyopathy, damage to the heart muscle.
Diabetic nephropathy, damage to the kidney which can lead to chronic renal failure.
Diabetic neuropathy, abnormal and decreased sensation starting with the feet but potentially in other nerves, later often fingers and hands. When combined with damaged blood vessels this can lead to diabetic foot (see below). Diabetic retinopathy, growth of friable and poor-quality new blood vessels in the retina which can lead to severe vision loss or blindness.
Diabetic encephalopathy is the increased cognitive decline and risk of dementia- including the Alzheimer's type- observed in diabetes.
Macrovascular disease leads to cardiovascular disease, to which accelerated atherosclerosis is a contributor:
Coronary artery disease, leading to angina or myocardial infarction
Peripheral vascular disease, which contributes to intermittent claudication as well as diabetic foot.
Diabetic foot, often due to a combination of sensory neuropathy (numbness or insensitivity) and vascular damage, increases rates of skin ulcers (diabetic foot ulcers) and infection and, in serious cases, necrosis and gangrene.
Stroke (mainly the ischemic type)
37. What are the risk factors for developing diabetes? How is it possible to prevent it?
Risk factors for type I diabetes mellitus include: genetic predisposition, environmental and nutritional factors. Risk factors for type II diabetes mellitus include: obesity, inactivity, genetic predisposition, age, race, high blood pressure and high cholesterol level. Prevention of diabetes includes: control level of sugars, weight control and physical activity.
38. What is diabetes insipidus? Speak on it.
Diabetes insipidus is a condition characterized by excessive thirst and excretion of large amount of urine. It is caused by a deficiency of antidiuretic hormone (central diabetes insipidus), by insensitivity of the kidneys to ADH (nephrogenic diabetes insipidus), or by drug use (iatrogenic diabetes insipidus). Symptoms of diabetes insipidus include: excessive urination, extreme thirst, dehydration, loss of appetite, weight loss, fever, vomiting, and diarrhea. Tests for diagnosing include: measurement of blood glucose, electrolytes, bicarbonate and calcium levels, urinalysis, a fluid deprivation test and pituitary hormone testing.