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Disorders of Endocrine System

AIPMT-NEET Biology Aspirants, read out the next AIPMT-NEET Biology Study material/ Notes of Disorders of Endocrine System, important  for AIPMT-NEET Biology. Free online notes for AIPMT-NEET.

Endocrine system is the system of circulating hormones in our body which help to regulate the metabolism, growth and activity of target cells. Each hormone is released by specific endocrine gland and has specific target area which is discussed in detail under topic Endocrine hormones.

Endocrine system disorders or endocrine diseases often involve either hyposecretion i.e. inadequate release of a hormone, or hypersecretion means excessive release of a hormone. Other then this, hormone receptors can also be faulty,or there may be an inadequate number of receptors to receive the hormone. Any one of these conditions can lead to disorder of endocrine system. Below is the list of disorders retailed to endocrine hormones.

Anterior pituitary- Human growth hormone (hGH) HYPERSECRETION: During childhood causes Gigantism– abnormal increase in length of long bones, person becomes very tall, body ratio remains normal.

During adulthood it causes Acromegaly-  body tissues get thickened on face, hands feet bones, jawline get thickened, development of furrows on forehead and soles.

HYPOSECRETION:  Pituitary Dwarfism– slow growth of bones result in poor height, childlike appearance.

Posterior pituitary- Anti-diuretic hormone (ADH) or Vasopressin Diabetes insipidus – excretion of large volumes of urine which results in dehydration and thirst. This type of diabetes occurs due to any of the 2 reasons: due to hyposecretion of ADH from posterior pituitary or due to defects in ADH receptors and kidneys do not respond to ADH in both the cases.
Thyroid Gland- Thyroid hormone HYPERSECRETION: Condition is called Hyperthyroidism- Graves’ Disease– more common in females, it is an auto-immune disorder, person has 2 to 3 times enlarged thyroid gland, develops edema behind eyes (exophthalmos)i.e. protruding eyes.

HYPOSECRETION: Condition is called Hypothyroidism. Deficiency of iodine in diet leads to hypothyroidism and enlargement of thyroid gland called as Goitre.

Hypothyroidism during pregnancy causes defective development and maturation of the growing baby which results in stunted growth of baby (Cretinism), mental retardation, low I.Q. , abnormal skin, deaf-mutism, etc.

Hypothyroidism during adulthood causes disease Myxedema – patient develops bagginess under eyes, swelling of face due to accumulation of interstitial fluids. Hypothyroidism in women leads to irregular menstrual cycles.

Parathyroid gland- Parathyroid hormone HYPERSECRETION: Condition is called Hyperparathyroidism. High level of hormone leads to excessive resorption of Ca2+ from bones leading to high blood calcium level, bones become soft, prone to fracture, cause of kidney stones, person become lethargic.

HYPOSECRETION: Condition is called Hypoparathyroidism. Deficiency of hormone leads to deficiency of blood Ca2+ , which causes Tetany – maintained contraction of skeleton muscles, twitches, spasms.

Adrenal Gland-Adrenal cortex HYPERSECRETION: Hypersecretion of Cortisol (Glucocorticoid) causes a disease named Cushing’s Syndrome – causes breakdown of muscle proteins and redistribution of body fat from lower body to upper body parts, person has “moon face,” “buffalo hump” on the back, hanging abdomen, poor healing power, hyperglycemia, weakness. High ACTH also leads to high cortisol.

HYPOSECRETION: Hyposecretion of cortisol (glucocorticoids) and aldosterone (mineralocorticoid) causes Addison’s disease – autoimmune disorder: antibodies destroy adrenal cortex, or block binding of ACTH to receptors. Patient develops bronzed appearance of skin, mental lethargy, weight loss, low sodium and high potassium in blood, cardiac arrest.

Famous personality affected – American President John F. Kennedy

HYPERSECRETION of Aldosterone causes Conn’s syndrome (Primary Aldosteronism) . Patient suffers from hypokalemia (low potassium in blood), muscle spasms or paralysis.

Adrenal Gland-Adrenal medulla HYPERSECRETION of Epinephrine and Norepinephrine causes Pheochromocytomas due to tumor in adrenal medulla cells. Person shows elevated fight-or-flight response.
Pancreas- Insulin Diabetes mellitus caused by an inability to produce or use insulin.

Unavailability of insulin leads to rise in blood glucose level (Prolonged hyperglycemia), loss of glucose through urine (glucosuria) and formation of harmful compounds known as ketone bodies.

Disease has 3 “polys” symptoms: Polyuria – excessive urine production due to an inability of kidneys to reabsorb water; Polydipsia – excessive thirst; Polyphagia – excessive eating.   Diabetic patients are successfully treated with insulin therapy.

Two types of diabetes mellitus—type 1 and type 2. Type 1 diabetesInsulin-dependent diabetes mellitus (IDDM)– Person’s immune system destroys the pancreatic beta cells so insulin secretion decreases. As a result, the pancreas produces little or no insulin. Ketone bodies form in this case leading to fall in blood pH called as Ketoacidosis.

Type 2 diabetesNon-insulin-dependent diabetes mellitus (NIDDM)– more common than type 1. Disease occurs not due to shortage of insulin but because target cells become less sensitive to it due to down-regulation of insulin receptors (Insulin resistance). Obese people more prone to it.

Hyperinsulinism: Due to excessive production of insulin or when a diabetic person injects too much insulin. Leads to hypoglycemia (decreased blood glucose level). Severe hypoglycemia leads to mental disorientation, convulsions, unconsciousness, and shock.

Shock due to an insulin overdose is termed Insulin Shock. Sudden death can occur in this case unless blood glucose is restored to normal levels.

NOTE:  Thyroidectomy: Surgical removal of thyroid gland.

Gynecomastia: Excessive development of mammary glands in a male due to high secretion of estrogens in male.

Hirsutism: Presence of excessive body and facial hair like males in female due to high androgen production in females.

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