Endocrine system and diagnostic defects


The endocrine system refers to the collection of glands of an organism that secrete hormones directly into the circulatory system to be carried towards a distant target organ. The endocrine system is the collection of gland that produces hormones that regulate metabolism, growth and development. The major endocrine gland includes the pineal gland, pituitary gland, pancreas, ovaries, tastes, thyroid gland, parathyroid gland and adrenal gland.

The endocrine system is in contrast to the exocrine system which secretes its hormones using ducts. The endocrine system is an information signal system like the nervous system. The hypothalamus is neural control centre for all endocrine system. The endocrine system is derived from the Greek word “endo” meaning within and “crinis” meaning to secrete. The endocrine system affects almost every organs and cells in the body. The field of study dealing with the endocrine system and its disorder is endocrinology (Colombol et al, 2006).

The main function of endocrine gland is to secrete hormones directly into the blood stream. Hormones are chemical substance that affects the activities of the body. The hormones travel through the blood to other cells and help to co-ordinate the activities in the body. (Andrew, 2004)

Diseases of the endocrine system are common including condition such as diabetes mellitus, thyroid disease and obesity.

Broadly speaking, endocrine diseases or disorder may be sub-divided into groups;

  1. Endocrine gland Hyposecretion: When the gland is not producing enough, it can lead to hormone deficiency.
  2. Endocrine gland Hypersecretion: When the gland is over active and produce too much, it can lead to excess level of certain hormone.
  3. Tumour (benign or malignant) of endocrine gland

Below are some examples of diseases that may occur if a gland secretes too much or too little of its hormones.

  1. Adrenal gland hypersecretion may lead to over nervousness, sweating, raised blood pressure and cushing disease. Adrenal gland hyposecretion may lead to Addison’s disease and diabetes.
  2. Pancreas hypersecretion may lead to hyperinsulinism (too much insulin) and not enough glucose to the brain.
  3. Parathyroid gland hypersecretion may lead to brittle bones that facture easily, as well as store in urinary system.
  4. Parathyroid gland hyposecretion may lead to muscles tertany caused by low level of calcium in plasma.
  5. Thyroid gland hypersecretion may cause Grave disease, accelerated metabolism, sweating, weight loss and nervousness.
  6. Thyroid gland hyposecretion may lead to tiredness, weight gain, depression, abnormal bone development and mental retardation.
  7. Pituitary gland hypersecretion may lead to excessive growth.
  8. Pituitary gland hyposecretion may lead to slow bone growth (dwarfism).
  9. Thymus gland hypersecretion may lead to an over active immune system.
  10. Thymus gland hyposecretion may lead to a weakened immune system. (Kasper, 2005)

The endocrine system is one of the body’s communication system. It uses hormones to tell body what to do. The endocrine system composed of ductless glands. These are glands that release secretion directly into the blood and not into a duct (tube) like other type of gland such as the salivary gland. These ductless glands produce hormones, the body’s chemical messenger. Each gland produces specific hormones. Hormones control and affect many body function and organs as well as behaviour. The function of the endocrine system is closely linked to that of the nervous system (Hartenstein, 2006).


A hormone is a chemical messenger. It is secreted directly into the body by one of the gland in the endocrine system. When they are released, they trigger reaction of different part of the body. Some hormones are made of protein (example insulin) while others are steroids (adrenocorticoid), Glucoproteins (Thyroid stimulating hormones, follicle stimulating hormones and luteinizing hormones), or derivative of single amino-acids. Hormones are produced in the gland and are then transported in the part of the body (or organ) they control or affect.

Endocrine gland

Endocrine gland is a ductless gland which produces hormones. Ductless means that there is no separate canal or tube to transport the hormone to the blood.

Hormone travels straight into the blood stream from the glands, hormones in the body are produced by the endocrine gland. The gland helps to maintain homeostasis, cellular metabolism, reproduction, sexual development and heart rate. (Pedersen et al, 2008).

Function of the hormone and endocrine system

They are involved in behavioural and functions in different areas of the body. For example some hormones are responsible for correct growth in children and changes to the body in puberty. Other controls the menstrual cycle, pregnancy or cause menopause. Some are responsible for response to stress and anger and the proper functioning of the kidney and digestive system. (Brouwers et al, 2006)

Physiology of the endocrine system

The endocrine system works alongside the nervous system to form the control system of the body. Nervous system provides a very fast narrowly targeted system to turn on specific gland and muscles throughout the body. The endocrine system on the other hand, is much slow acting, but has very wide spread, long lasting, and powerful effects. The hormone is distributed by glands through the blood stream to the entire body, affecting any cell with a receptor for a particular hormone. Most hormones affect cells in several organs or throughout the entire body leading to many diverse and powerful responses (Schollon et al, 2013).

The gland and the hormones they produce

Pituitary gland is situated at the base of the brain sitting in a cup-shaped depression of the skull. It is closely connected to the hypothalamus. The pituitary gland has 2 hormone secreting lobes, the anterior and posterior.

Human growth hormone (HGH)

Function: It regulates height and growth, along with genes. It is the main controller of final height of a person.

Melanocyte stimulating hormone (MSH)

Function: Stimulate production of brown pigment melanin in the skin

Prolatin or lactogenic hormone (LTH)

Function: Production of breast milk during lactation

Follicle stimulating hormone (FSH)

Function: Stimulate ovaries to produce estrogens and to ovulate (release an egg for fertilization).

Oxytocin hormone (OH) (the birth hormone)

Function: Studies shows that raised level of oxytocin help human bonding trust, it stimulate the secretion of breast milk for feeding and tells the muscle of uterus to contrast for child birth.

Thyroid gland is shaped like a bow-tie and position at the front of the neck, just below the larynx (voice box)

Calcium hormone

Function: Maintain calcium and phosphate balance in the body.     

Thyroxin hormone

Function: To stimulate the consumption of oxygen and the metabolism of all cell and tissues in the body.    

Para-thyroid gland are 4, two either side behind the thyroid gland

Parathyroid hormone

Function: Maintain calcium level in plasma, stimulate calcium resumption by the kidney and activate vitamin D.

Adrenal gland: There is one sitting on top of each kidney. Each gland is split into two parts, the adrenal cortex and the adrenal medulla.

Adrenal cortex


Function: Regulate salt in the body, especially sodium chloride and potassium. It also stimulates the absorption of sodium (Na+) by the kidney.

Adrenal medulla: The adrenal medulla function to support the sympathic nerves system.

Adrenal and noradrenalin hormone

Function: They are usually called stress hormones. They prepare the body for fight, by speeding up heart beat, slowing digestion system, increasing blood pressure and blood sugar.

Pancreas is located slightly below and behind the stomach.

Hormone: Insulin

Function: Its function is to allow others cells to transform glucose into energy throughout the body. It also helps to store energy.


Function: It elevate the concentration of glucose in the blood by promoting gluconeogenesis and glycogenolysis, it also regulate the rate of glucose production in the liver.

Ovaries: There are two ovaries, one on each side of the womb (uterus)


Function: It regulate the menstrual cycle, it also affect the reproductive tract and sexual development in women.

Progesterone (female sex hormone)

Function: To regulate the inner lining of the uterus, it prepares the wall of the uterus so that the lining is able to accept a fertilized egg and the egg can be implanted and develop.

Testis is located inside the scrotum behind the penis.

Testosterone (male sex hormone)

Function: Responsible for male sexual characteristic thus, sperm production, changes at puberty, voice breaking, pubic, facial and under arm hairs, growth, increase muscles.

Pineal gland is also called the pineal body; it is located at the centre of the brain.

Melatonin hormone

Function: Control body rhythms (tell us when to sleep and wake up)

Thymus gland is in the upper parts of the chest.

Hormone: Thymic factor (tf), thymic humoral. factor (thf), thymosine, and thymoporatin.

Function: Part of immune system, appears to promote development of T-Lymphocytes in the thymus gland. This fight infection in the body (Pedersen et al, 2003)

Diagnosis of endocrine system

The endocrine system can be diagnosed by measuring the blood level of endocrine hormones. Endocrine system is diagnosed for several reasons which include:

  1. To measure the level of various hormone in a patient body
  2. To learn if the endocrine gland are working correctly
  3. To determine the causes of an endocrinological problems
  4. To confirm an early disease or disorder of the endocrine system

Method of diagnosis of endocrine system

Glucose estimation method:

This method determines the amount of glucose present in the blood, which is regulated by the hormones insulin and glucagon. Insulin is provided with in the body to remove excess glucose from the blood, when blood glucose level fall below a certain levels, the body begins to used stored glucose for energy, Which break down the glycogen stored in the liver and muscle into glucose. Glucagons on the other hand increase the production of glucose in the liver. When control of insulin fails and the body lack insulin, its lead to a disease condition known as diabetes mellitus. The symptom of high blood sugar, (diabetes) include frequent urination, increased thirst and increased hunger, there are three main types of diabetes mellitus: Type I DM, Type II DM, and Gestational diabetes (Maria et al, 2013).

Type I DM: Diabetes mellitus results from the pancreas’ failure to produce enough insulin.

Type II DM: Diabetes mellitus begins with insulin resistance, a condition in which cells fail to respond to insulin properly.

Gestational diabetes: occurs when pregnant women without previous history of diabetes develop a high blood sugar level. The blood glucose can be diagnosed by

  1. Oral glucose tolerance test
  2. Fasting blood sugar
  3. Random blood sugar
  4. 2 hour post pandral

24 hour urine collection method

This method is used to measure the levels of various hormones in a patient’s body; the 24 hour urine specimen is required for the quantitative analysis of substance such as hormones steroid, phosphate calcium and protein. Hypo-secretion occur when the gland is not producing enough hormone and hyper-secretion occur when the gland secrete too much hormone. 24 hour urine collection estimate the level of hormone the gland secretes. A condition in which the adrenal gland produces too much cortisol may suggest that the patient may have Cushing’s syndrome. The sign and symptoms of Cushing syndrome may include high blood pressure, abdominal obesity with thin arms and legs, reddish stretch marks, weak muscle, weak bones and women may have more hair and irregular menstruation (Forbis, 2005).

Hormonal assay method

Hormones can be measured (assayed) in the blood to give an indication of metabolic processes and condition; these include male and female sex hormones, and parathyroid and adrenal gland. The hormone estrogens and progesterone are necessary to prepare the uterus for menstruation and the development of breast, fat distribution in the hips, legs and development of productive organs.

The estrogens and progesterone deficiency result in osteoporosis and bone loss; when estrogens is not balance by progesterone, can produce weight gain, headaches, loss of interest in sex, development of breast cancer, menstrual irregularities or menopause and infertility. The hormonal assay test is diagnosed if there is a suspicion of endocrine problem relating to the function of many glands in the body. Hormone test give the concentration of specific hormone in the blood stream. These results are compared to a reference range of “hormone” values obtained. The hormone level may therefore below normal or high (Nussey, 2001).

Fine-needle aspiration biopsy method

In fine-needle aspiration biopsy, a small needle is used to remove a sample of cell from a thyroid nodule, the sample is diagnosed to determine whether the nodule is malignant (cancerous). Fine needle aspiration biopsy tell if a thyroid nodule is benign (non-cancerous or malignant (cancerous). The process only takes about 20 minutes; he or she insert a thin needle into the neck, and into the thyroid nodule , in some cases the ultra sound is use to guide the needle, with the needle several sample are then evacuated  under a microscope by a pathologist. (Ullal, 2014).


In conclusion, the endocrine system has many functions. There are many organs throughout the body that secrete hormones which travel throughout the blood stream, and then attached to their target cells and activate them. There are many different types of hormones as well as, local regulator and they have different ways of travelling such as diffusion, moving through lipids etc. Hormones have been maintaining homeostasis in calcium, glucose using hormone such as insulin and glucagons. Hormone also maintains metabolism, development and behaviour. The endocrine system is an important player in the regulation of all activities of the body. The only way to diagnose the activity of endocrine gland is by a blood test to determine how much hormone is being secreted.


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