- Endocrine glands – secretes hormones into the bloodstream.
- Exocrine glands – release their secretions such enzymes, mucus, sebum, sweat, etc. into a duct.
Important Glands in the human body
Adrenal gland
- Also known as the 3F gland & 4S gland.
- Cap-like triangular gland located above the kidney.
- The adrenal gland is made up of 2 parts
- Outer Adrenal cortex – makes hormones called corticosteroids that help control salt-water balance in the body, the immune system, metabolism, stress response, and sexual development and function.
- There are 3 types of corticosteroids:
- Glucocorticoids – Cortisol, Cortisone,
- Mineral corticoids – Aldosterone (regulates sodium loss in the body),
- Sex hormones
- Inner Adrenal medulla – makes epinephrine/adrenaline & Noradrenaline which increases blood pressure and heart rate when the body is under stress.
- Diseases –
- Addison's disease – deficiency of cortisol
- Cushing's syndrome – overproduction of cortisol
- Cons syndrome – the overdose of aldosterone
- Vitiligo & Gynecomastia – due to the formation of tumors in the Adrenal gland.
Hypothalamus
- Located at the lower central part of the brain.
- Links the endocrine system and nervous system.
- Made up of 3 parts –
- Anterior region – also known as the supraoptic region regulates body heat and maintains the circadian rhythm. It consists of
- Supraoptic nuclei.
- Paraventricular nuclei.
- Middle region – also known as the tuberal region. It consists of
- Ventromedial nuclei – controls the appetite.
- Arcuate nuclei – released the growth hormone responsible for the growth and functioning of the human body.
- Posterior region – also known as the mammillary region. It consists of
- Hypothalamic nucleus – cause shivering, blockage of sweat, and regulates the body temperature.
- Mammillary nuclei – related to the memory function.
Pituitary gland
- Also known as "master gland" & "hypophysis."
- A pea-shaped gland at the base of the brain, just below the hypothalamus, close to the optic nerve.
- Control & regulates other glands in the body.
- It is divided into three lobes:
- Anterior pituitary – synthesis and secretion of hormones like ACTH, FSH / LH, HGH, TSH, Prolactin, MSH
- Intermediate pituitary – absent in adults.
- Posterior pituitary – synthesis and secretion of hormones like ADH & Oxytocin
- Diseases –
- Acromegaly
- Empty Sella Syndrome
- Hypopituitarism
Thyroid gland
- Ductless endocrine gland.
- Butterfly shaped or bow-shaped gland located between C5 and T1 vertebrae in the neck.
- Play a vital role in the development of the brain and nervous system as well as bone development in children.
- Diseases –
- Goiter
- Hyperthyroidism – Overproduction of thyroxine hormone.
- Hypothyroidism – Underproduction of thyroxine hormone.
- Thyroid cancer –
- Anaplastic thyroid cancer
- Follicular thyroid cancer
- Medullary cancer
- Papillary thyroid cancer
Parathyroid gland
- Four tiny glands (3-5 mm in diameter & 30-60 mg in weight) attached to the thyroid gland.
- Controls and regulates the calcium levels in the blood in the range between 9.0 & 10.1.
- Releases 2 types of hormones – Parathormone & Calcitonin.
- Diseases –
- Hyperparathyroidism – high levels of parathyroid hormone in the bloodstream.
- Hypoparathyroidism – lower levels of parathyroid hormone in the bloodstream.
Pancreas
- Gland located below the stomach and surrounded by the spleen.
- Secretes digestive enzymes such as amylase, lipase & proteases.
- Releases three hormones – Insulin, Glucagon & Somatostatin
- Diseases –
- Pancreatitis
- Pancreatic Cancer
Pineal gland
- A small pinecone-shaped gland located in the middle of the brain.
- Also known as “the third eye.”
- Regulates the body’s Circadian rhythm.
- Produces white blood cells called T-lymphocytes that fight infection and hormone, Melatonin.
- Diseases –
- Pineal Gland Tumors
- Pineal Cysts
Reproductive Glands
- Male gonads aka testes –
- Located in Scrotum.
- Secretes male hormones called Androgens (Testosterone, Androstenedione & Inhibin).
- Female gonads aka ovaries –
- Located in Pelvis.
- Secretes female hormones called Estrogen & Progesterone.
Thymus gland
- Pinkish-grey gland located deep within the chest.
- Size varies according to age, larger in children, and smaller in adults.
- Secretes hormones called Thymosin.
- Diseases –
- Myasthenia gravis – abnormal enlargement of the thymus.
- Pure red cell aplasia – occurs when there is a tumor in the thymus and the body attack its own stem cells.
- Hypogammaglobulinemia – occurs when the body is producing not enough antibodies.
All these networks of glands and their secreted hormones together constitute the Endocrine System.
Glands & their hormones: In short
| Glands | Hormones |
|---|---|
| Adrenal gland | Adrenaline, Noradrenaline, Aldosterone & Cortisol |
| Hypothalamus | Vasopressin (aka Antidiuretic hormone), GnRH (Gonadotropin-releasing hormone) |
| Pancreas | Insulin, Glucagon & Somatostatin |
| Parathyroid gland | Parathyroid hormone |
| Pineal gland | Melatonin, Serotonin (precursor to Melatonin) |
| Pituitary gland |
|
| Ovaries | Estrogen & Progesterone |
| Testes | Testosterone, Androstenedione & Inhibin |
| Thymus gland | Thymosin |
| Thyroid gland | Thyroxine (T4), Tri-iodothyronine (T3) & Calcitonin |
📝SideNotes:
- Insulin shock – Lowering blood sugar level as far as 43mg / 100ml which leads to unconsciousness and sudden death.
- also known as Severe hypoglycemia.
- Vitiligo – a condition in which the skin loses its melanocytes, the pigment cells
- Gynecomastia – Manifestation of femininity in males.