ENDOCRINE SYSTEM

The endocrine system is a system of ductless glands that produce hormones Hormones are chemical messengers that regulate growth, metabolism, reproduction, fluid balance, stress response, and homeostasis.

Hormones are secreted directly into bloodstream and act on target organs.

FUNCTIONS OF ENDOCRINE SYSTEM

1. Regulation of metabolism

2. Control of growth and development

3. Maintenance of homeostasis

4. Regulation of reproduction

5. Control of stress response

6. Regulation of blood glucose

7. Fluid and electrolyte balance

MAJOR ENDOCRINE GLANDS

1. Hypothalamus

2. Pituitary gland

3. Pineal gland

4. Thyroid gland

5. Parathyroid gland

6. Thymus gland

7. Pancreas (Islets of Langerhans)

8. Adrenal gland

1. HYPOTHALAMUS

Structure

• Located in brain below thalamus

• Connected to pituitary gland

• Part of diencephalon

Hormones produced

• Releasing hormones

• Inhibiting hormones

• ADH (stored in pituitary)

• Oxytocin (stored in pituitary)

Functions

• Controls pituitary gland

• Regulates temperature

• Controls hunger and thirst

• Maintains homeostasis

Nursing Importance

• Affects hormonal balance

• Regulates body temperature

• Controls stress response

  
  

2. PITUITARY GLAND (Master gland)

Structure

Small pea-sized gland located in sella turcica of skull

Parts

1. Anterior pituitary (adenohypophysis)

2. Posterior pituitary (neurohypophysis)

Hormones

Anterior pituitary hormones

• Growth hormone (GH)

• Thyroid stimulating hormone (TSH)

• Adrenocorticotropic hormone (ACTH)

• Follicle stimulating hormone (FSH)

• Luteinizing hormone (LH)

• Prolactin

Posterior pituitary hormones

• ADH

• Oxytocin

Functions

• Controls other endocrine glands

• Regulates growth

• Controls reproduction

• Regulates lactation

Nursing Importance

• Growth disorders

• Hormonal imbalance

• Diabetes insipidus

• Infertility issues

3. PINEAL GLAND

Structure

• Small pine cone shaped gland

• Located between two hemispheres of brain

Hormone

Melatonin

Functions

• Regulates sleep cycle

• Controls circadian rhythm

Nursing Importance

• Sleep disorders

• Mental health regulation

4. THYROID GLAND

Structure

• Butterfly shaped gland

• Located in neck below larynx

Parts

• Right lobe

• Left lobe

• Isthmus

Hormones

• Thyroxine (T4)

• Triiodothyronine (T3)

• Calcitonin

Functions

• Regulates metabolism

• Controls growth

• Maintains body temperature

Nursing Importance

• Hypothyroidism

• Hyperthyroidism

• Goiter

• Thyroid surgery care

5. PARATHYROID GLAND

Structure

• Four small glands located behind thyroid gland

Hormone

Parathyroid hormone (PTH)

Function

• Regulates calcium level

• Controls phosphate balance

Nursing Importance

• Calcium imbalance

• Tetany

• Bone disorders

6. THYMUS GLAND

Structure

• Located in upper chest

• Behind sternum

Hormone

Thymosin

Function

• Development of T lymphocytes

• Immunity

Nursing Importance

• Immune deficiency disorders

• Infection susceptibility

7. PANCREAS (Endocrine part)

Structure

• 
  

  

  Located behind stomach

Endocrine cells (Islets of Langerhans)

• Alpha cells → glucagon

• Beta cells → insulin

Functions

• Regulates blood glucose level

Nursing Importance

• Diabetes mellitus

• Insulin therapy

• Blood sugar monitoring

8. ADRENAL GLAND

Structure

Located above kidneys

Parts

1. Adrenal cortex

2. Adrenal medulla

Hormones

Cortex hormones

• Cortisol

• Aldosterone

• Androgens

Medulla hormones

• Adrenaline

• Noradrenaline

Functions

• Stress response

• Blood pressure regulation

• Electrolyte balance

Nursing Importance

• Cushing syndrome

• Addison disease

• Stress management

• BP monitoring

SUMMARY TABLE

Gland	Hormone	Function
Hypothalamus	releasing hormones	controls pituitary
Pituitary	GH, TSH	master gland
Pineal	melatonin	sleep cycle
Thyroid	T3, T4	metabolism
Parathyroid	PTH	calcium balance
Thymus	thymosin	immunity
Pancreas	insulin	glucose control
Adrenal	cortisol	stress response