Endocrine System
- Introduction
• The endocrine system is a network of glands that produce and secrete hormones, chemical messengers that regulate many body functions.
• It controls growth, metabolism, reproduction, fluid balance, stress responses, and homeostasis.
• Works closely with the nervous system to maintain body balance. - Major Endocrine Glands and Their Functions
A. Hypothalamus
• Located in the brain, it links the nervous and endocrine systems.
• Controls the pituitary gland by releasing hormones that stimulate or inhibit its secretion.
• Regulates temperature, hunger, thirst, sleep, and emotional responses.
B. Pituitary Gland (Master Gland)
• Located below the hypothalamus at the brain base.
• Divided into:
• Anterior pituitary: secretes hormones like growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin.
• Posterior pituitary: releases oxytocin (stimulates uterine contractions and milk ejection) and antidiuretic hormone (ADH; regulates water balance).
C. Thyroid Gland
• Located in the neck, it produces thyroid hormones (T3, T4) that regulate metabolism, growth, and development.
• Also secretes calcitonin, which helps regulate blood calcium levels.
D. Parathyroid Glands
• Four small glands on the back of the thyroid.
• Secrete parathyroid hormone (PTH) which increases blood calcium by stimulating bone resorption.
E. Adrenal Glands
• Sit on top of each kidney.
• Consist of:
• Adrenal cortex: produces corticosteroids (cortisol for stress response, aldosterone for salt balance, and androgens).
• Adrenal medulla: produces adrenaline and noradrenaline for “fight or flight” response.
F. Pancreas (Endocrine part)
• Located behind stomach.
• Produces:
• Insulin (lowers blood glucose).
• Glucagon (raises blood glucose).
• Regulates blood sugar and energy metabolism.
G. Gonads
• Ovaries in females produce estrogen and progesterone (regulate menstrual cycle and pregnancy).
• Testes in males produce testosterone (controls male sexual development and sperm production). - Hormones: Chemistry and Mechanism of Action
• Hormones are chemical messengers released into the bloodstream.
• Two main types:
• Steroid hormones: lipid-soluble, can pass through cell membranes and influence gene expression.
• Non-steroid (peptide/protein) hormones: water-soluble, bind to receptors on cell surface and activate second messenger systems.
• Hormones act only on target cells that have specific receptors. - Functions of the Endocrine System
• Regulates growth and development.
• Controls metabolism and energy balance.
• Maintains fluid, electrolyte, and acid-base balance.
• Coordinates the body’s response to stress.
• Regulates reproduction and sexual function.
• Influences mood, behavior, and immune system. - Feedback Mechanisms
• Most hormone levels are controlled by negative feedback loops.
• When hormone levels rise, feedback signals reduce production.
• When hormone levels fall, the glands produce more.
• This maintains hormone levels within a narrow, healthy range. - Common Endocrine Disorders
• Diabetes mellitus (insulin deficiency or resistance).
• Hypothyroidism and hyperthyroidism (thyroid hormone imbalance).
• Addison’s disease (adrenal insufficiency).
• Cushing’s syndrome (excess cortisol).
• Pituitary disorders (e.g., gigantism, acromegaly).
• Polycystic ovary syndrome (PCOS).
• Goiter (enlarged thyroid). - Nursing Care and Considerations
• Monitor hormone levels and symptoms of imbalance.
• Administer hormone replacements or medications as prescribed.
• Educate patients about diet, lifestyle affecting endocrine health.
• Teach self-monitoring (e.g., blood glucose in diabetes).
• Support patients undergoing diagnostic endocrine tests.
• Promote mental well-being and coping strategies for chronic endocrine diseases. - Summary for Quick Review
The endocrine system consists of glands secreting hormones that regulate bodily functions including metabolism, growth, reproduction, and stress responses. Key glands include the hypothalamus, pituitary, thyroid, parathyroids, adrenal glands, pancreas, and gonads. Hormones act on specific target cells through complex mechanisms and are regulated by feedback loops. Nursing focuses on monitoring, managing hormonal disorders, educating patients, and supporting adherence to treatments.