Introduction to Endocrine System

Cellular functions are controlled by two mechanism:

• Neural control mechanism
• Endocrine control mechanism

Neural vs Endocrine System

Neural control mechanism involves the nerves through which impulses are transmitted to certain group of cells to control its function. The action is rapid and short lived.

Endocrine control system involves hormones which are secreted directly into the blood stream and controls the function of number of cells. The action is show and long lived.

The hormones are secreted into the bloodstream by ductless glands called Endocrine glands.

Important endocrine glands are

• The hypothalamus
• The Anterior pituitary (Adenohypophysis)
• The Posterior pituitary (Neurohypophysis)
• The islets of Langerhans in the Pancreas
• The Adrenal cortex
• The Adrenal medulla
• The Thyroid
• The Parathyroid
• The Kidney
• The Ovary and the Testis

Endocrine Glands

Definition of a hormone

Hormones are secretory products of ductless (endocrine) glands released directly into the circulation in small amounts in response to a specific stimulus and on delivery in circulation produce response on the target cells or organs.

Characteristics of a Hormone

Hormones interact with the target cells via receptors which are large protein molecules.

Hormones bind to receptor to form a hormone receptor complex which through second messenger system controls the functions of target cells.

The second messenger systems are:

1. Cyclic Adenosine Mono-Phosphate (cAMP)
2. Cyclic Guanosine Mono-Phosphate (cGMP)
3. Inositol Triphosphate (IP3)
4. Calcium Calmodulin
5. Tyrosine Kinase

Second messenger system

Hormones regulate the body process, but will not initiate the cellular reactions

Hormones as a regulator controls the functions of target cells by controlling the enzymes.

Hormones are metabolized rapidly and inactivated by liver and kidney

Application and implication in Nursing

Q. What are the common symptoms found in the most of the endocrine disorders?

A. 

• Fatigue and weakness
• Weight changes
• Blood glucose level fluctuation
• Abnormal cholesterol level
• Mood changes