Endocrine System Overview Quiz

Gonads

• The testes produce testosterone, which maintains reproductive organs and develops secondary sex characteristics in males.
• The ovaries create estrogen and progesterone, responsible for female reproductive organ maintenance and secondary sex characteristic development.

Prostaglandins

• Prostaglandins are lipid molecules produced by cells throughout the body.
• They act locally, influencing neighboring cells.
• They play a vital role in various bodily functions, including:
  • Pain
  • Inflammation
  • Fever
  • Blood clotting
  • Vasodilation/constriction

Thyroid Hormones

• Thyroxine (T4) is the primary thyroid hormone, promoting energy and metabolism.
• Triiodothyronine (T3) also increases energy and metabolism.
• Calcitonin regulates blood calcium levels. When calcium levels are high, it triggers calcium deposition in bones.

Parathyroid Glands

• They are four small glands found in the thyroid gland's posterior capsule.
• The glands secrete parathyroid hormone (PTH), the primary hormone responsible for maintaining calcium blood levels.

Parathyroid hormone

• Its main function is to regulate blood calcium levels.
• PTH inhibits new bone formation and stimulates the breakdown of old bone to release calcium into the bloodstream.
• It encourages the kidneys to reabsorb calcium and activate vitamin D, crucial for calcium absorption in the intestines.

Pancreas

• It has both endocrine and exocrine functions.
• Endocrine cells (Islets of Langerhans) secrete hormones.
• Exocrine cells secrete digestive enzymes.

Islets of Langerhans

• These pancreatic cell clusters contain alpha and beta cells.
• Alpha cells release glucagon, which increases blood glucose levels.
• Beta cells produce insulin, which lowers blood glucose levels.

Regulation of Blood Glucose

• The pancreas plays a vital role in regulating blood glucose levels.
• Insulin lowers blood glucose levels by promoting glucose uptake in cells.
• Glucagon elevates blood glucose by stimulating glycogen breakdown in the liver.

Organs of the Endocrine System

• The endocrine system includes various organs producing and releasing hormones.
• These organs include:
  • Hypothalamus
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal
  • Pancreas
  • Ovaries (females)
  • Testes (males)

Endocrine System vs. Nervous System

• Endocrine System
  • Utilizes hormones as messengers.
  • Hormones travel through the bloodstream to target cells and tissues.
  • Slow-acting, with long-lasting effects.
  • Adapts slowly to continuous stimulation.
• Nervous System
  • Employs neurotransmitters as signaling molecules.
  • Neurotransmitters are released directly into synapses, affecting neighboring cells.
  • Fast-acting, with short-lived effects.
  • Adapts quickly to continuous stimulation.

Hormones

• Hormones are chemical messengers that regulate cellular or organ functions.
• Some act on many tissues, while others target specific ones.
• Hormones travel through the bloodstream until they encounter their designated receptor.
• Receptor binding triggers changes in the target cell or tissue.

Hormone Classifications

• Steroid Hormones
  • Are made from cholesterol.
  • Synthesized in cells of the adrenal cortex (e.g., aldosterone) and sex glands (e.g., estrogen, testosterone).
  • Can easily pass through cell membranes.
• Nonsteroid Hormones
  • Are derived from proteins or amino acids.
  • Unable to penetrate cell membranes.
  • Bind to receptors on the cell surface.
  • Examples include insulin, anti-diuretic hormone (ADH), epinephrine, and norepinephrine.