Human Body Systems: Functions of Major Organs

Key Organs and Their Roles

• Brain – controls thought, memory, emotion, movement.
• Heart – pumps blood, delivering oxygen/nutrients.
• Lungs – gas exchange (O₂ in, CO₂ out).
• Stomach – digests food, breaks down nutrients.
• Intestines – absorb nutrients and water.
• Liver – filters blood, produces bile for fat digestion.
• Kidneys – filter waste, produce urine.
• Pancreas – digestive enzymes, blood sugar hormones (insulin, glucagon).
• Skin – protection, temperature regulation, vitamin D synthesis.
• Bones – support, organ protection, blood cell production.
• Muscles – movement, heat, posture.
• Nerves – signal transmission for coordination.
• Blood vessels – transport blood, nutrients, hormones, waste.
• Lymphatic system – fluid balance, immunity, fat absorption.
• Reproductive organs – produce gametes, enable reproduction.