MedlinePlus Body Systems
Health topics organized by body location and system.
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Human body explorer
See how major systems work together, learn common symptom language, and connect body areas to trusted health topics.
Brain & nervous system
The brain, spinal cord, and nerves coordinate movement, sensation, thought, memory, emotion, and automatic body functions.
Symptoms often discussed
Headache, seizure, numbness, weakness, memory change, tremor, dizziness.
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StrokeMigraineEpilepsyAlzheimer’s diseaseParkinson’s disease
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Heart & circulation
The heart pumps blood through arteries, veins, and capillaries to deliver oxygen and nutrients and carry away waste.
Symptoms often discussed
Chest discomfort, palpitations, breathlessness, swelling, fainting, leg pain.
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High blood pressureCoronary artery diseaseAtrial fibrillationHeart failureStroke
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Lungs & breathing
The lungs exchange oxygen and carbon dioxide. The airways, chest muscles, and nervous system all contribute to breathing.
Symptoms often discussed
Cough, wheeze, shortness of breath, chest tightness, low oxygen.
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AsthmaCOPDPneumoniaSleep apneaPulmonary embolism
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Digestive system
The mouth, esophagus, stomach, intestines, liver, gallbladder, and pancreas digest food, absorb nutrients, and process waste.
Symptoms often discussed
Abdominal pain, reflux, nausea, vomiting, diarrhea, constipation, bleeding.
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GERDIBSCrohn’s diseaseUlcerative colitisLiver disease
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Hormones & metabolism
Hormone-producing glands regulate growth, energy, stress, reproduction, glucose, and many other processes.
Symptoms often discussed
Weight change, thirst, urination, temperature sensitivity, fatigue, menstrual change.
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DiabetesThyroid diseasePCOSAdrenal disordersOsteoporosis
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Immune & lymphatic
The immune system identifies threats, coordinates inflammation, remembers infections, and can sometimes react to harmless substances or the body itself.
Symptoms often discussed
Frequent infection, fever, swollen nodes, rash, joint pain, allergic symptoms.
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AllergiesAutoimmune diseaseImmunodeficiencyLupusRheumatoid arthritis
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Skin, hair & nails
The skin is a protective barrier that helps regulate temperature, sense the environment, and prevent fluid loss and infection.
Symptoms often discussed
Rash, itch, pain, discoloration, wounds, hair or nail changes.
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AcneEczemaPsoriasisSkin infectionSkin cancer
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Kidneys & urinary system
The kidneys filter blood, regulate fluid and minerals, help control blood pressure, and produce hormones.
Symptoms often discussed
Urinary change, blood in urine, swelling, flank pain, fatigue, high blood pressure.
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Kidney diseaseKidney stonesUTIIncontinenceProstate disorders
RememberSymptoms can involve more than one body system. A clinician uses history, examination, and testing to narrow the possibilities.
Systems, not silos
The body is a network
Health issues often cross systems. Diabetes can affect nerves, kidneys, eyes, and the heart; chronic stress can affect sleep, digestion, pain, and blood pressure.
Signals
Nerves and hormones carry messages that coordinate rapid responses and long-term regulation.
Supply
Breathing and circulation deliver oxygen and nutrients to tissues throughout the body.
Defense
Skin, immune cells, inflammation, and healing protect the body while limiting damage.
Balance
Kidneys, lungs, hormones, and the nervous system help maintain internal stability.
Movement
Muscles, bones, joints, nerves, and energy systems make activity possible.
Mind
Brain health, relationships, sleep, stress, and physical health influence one another.
Visible Human Project
Anatomical data resources from the U.S. National Library of Medicine.
Visit official source ↗NIH Health Information
Research-based information from NIH institutes and centers.
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