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Human Body Organs Overview

Jul 18, 2025

Overview

This lecture introduces the main internal human body organs and summarizes their primary functions.

Respiratory System

  • Lungs enable breathing, a process known as respiration.

Digestive System

  • Stomach receives food, mixes, breaks it down, and passes it to the small intestine.
  • Small intestine digests food further and absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water).
  • Large intestine absorbs water and electrolytes, produces and absorbs vitamins, and forms feces for elimination.
  • Liver removes waste and foreign substances from blood, regulates blood sugar, and creates essential nutrients.
  • Gallbladder stores and concentrates bile from the liver.
  • Pancreas regulates blood sugar levels and stimulates stomach acids.

Excretory System

  • Kidneys remove wastes and extra fluids from the body.
  • Bladder stores urine and contracts to expel urine via the urethra.

Circulatory System

  • Heart pumps and circulates blood throughout the body.
  • Spleen filters blood by removing old and damaged red blood cells.

Endocrine System

  • Thyroid gland controls metabolism, growth, and development.

Key Terms & Definitions

  • Respiration — the process of breathing in lungs to exchange gases.
  • Small intestine — the organ where digestion is completed and nutrients are absorbed.
  • Pancreas — gland that regulates blood sugar and aids digestion.
  • Spleen — organ that filters blood and removes old red blood cells.
  • Gallbladder — organ that stores bile for fat digestion.
  • Thyroid gland — gland that regulates metabolism, growth, and development.

Action Items / Next Steps

  • Review each organ's function for better understanding.
  • Be able to match each organ to its primary role in the human body.