Medical Terminology Ch. 16

Endocrine System Overview

• Composed of glands that regulate bodily functions through hormones.
• Major glands include: pituitary, thyroid, parathyroid, adrenal, pancreas, gonads, and thymus.
• Functions include regulating metabolism, growth, and development.
• Endocrine glands release hormones directly into the bloodstream, classified as ductless glands.

Pituitary Gland

• Size of a pea and positioned at the base of the brain.
• Divided into anterior and posterior lobes; known as the "master gland" for its role in stimulating other endocrine glands.

Anterior Lobe

• Produces key hormones:
  • Growth hormone (GH) for body growth.
  • Adrenocorticotropic hormone (ACTH) to stimulate the adrenal cortex.
  • Thyroid-stimulating hormone (TSH) for thyroid activity.
  • Gonadotropic hormones (FSH and LH) for gonadal function.
  • Prolactin (PRL) for milk production post-birth.

Secreted Hormones

• Growth Hormone (GH): Regulates overall body growth.
• Adrenocorticotropic Hormone (ACTH): Targets adrenal gland to spur hormone production.
• Thyroid-Stimulating Hormone (TSH): Initiates thyroid gland hormone secretion.
• Gonadotropic Hormones: FSH and LH influence reproductive organs.
• Prolactin (PRL): Supports milk production and glandular development during pregnancy.

Posterior Lobe

• Stores and releases:
  • Antidiuretic Hormone (ADH): Aids kidney water reabsorption and constricts blood vessels.
  • Oxytocin: Stimulates uterine contractions and milk ejection during breastfeeding.

Hypothalamus

• Located above the pituitary gland; controls hormone release via "releasing" hormones that influence the pituitary.

Thyroid Gland

• The largest endocrine gland located in the neck, below the larynx.
• Produces triiodothyronine (T3) and thyroxine (T4), essential for metabolism; requires iodine for hormone production.

Parathyroid Glands

• Four small glands on the thyroid's posterior, producing parathyroid hormone (PTH).
• PTH regulates blood calcium levels impacting bones and kidneys.

Pancreas

• Contains islets of Langerhans, clusters of endocrine cells that produce insulin and glucagon for glucose metabolism.
• Exocrine cells produce digestive enzymes.

Adrenal Glands

• Located atop each kidney, divided into cortex (outer) and medulla (inner).
• Secretes hormones:
  • Cortisol: Energy regulation during stress.
  • Aldosterone: Maintains electrolyte balance in the body.
  • Epinephrine and Norepinephrine (Adrenaline and Noradrenaline): Increase blood pressure and heart rate during stress.

Key Hormones from Adrenal Glands

• Cortisol: Increases glucose levels for energy during stressful situations (also called hydrocortisone).
• Aldosterone: Essential for regulating electrolytes necessary for normal bodily function.
• Epinephrine: Increases physical readiness (fight or flight response).
• Norepinephrine: Works with epinephrine in stress response management.

This concise overview encompasses essential components of the endocrine system, summarizing the functions and characteristics of its glands and hormones.