- Physical Examination
- Surgical Examination
- Ophthalmology
- Clinical Skills
- Orthopedics
- Surgery Videos
- Laparoscopy
- Pediatrics
- Funny Videos
- Cardiothoracic Surgery
- Nursing Videos
- Plastic Surgery
- Otorhinolaryngology
- Histology and Histopathology
- Neurosurgery
- Dermatology
- Pediatric Surgery
- Urology
- Dentistry
- Oncology and Cancers
- Anatomy Videos
- Health and Fitness
- Radiology
- Anaesthesia
- Physical Therapy
- Pharmacology
- Interventional Radiology
- Cardiology
- Endocrinology
- Gynecology
- Emergency Medicine
- Psychiatry and Psychology
- Childbirth Videos
- General Medical Videos
- Nephrology
- Physiology
- Diet and Food Health
- Diabetes Mellitus
- Neurology
- Women Health
- Osteoporosis
- Gastroenterology
- Pulmonology
- Hematology
- Rheumatology
- Toxicology
- Nuclear Medicine
- Infectious Diseases
- Vascular Disease
- Reproductive Health
- Burns and Wound Healing
- Kidney Zone Podcast
- Other
Immune System
Video still from MedicalVideos.com: the immune system
The immune system is the distributed defence network of white blood cells, antibodies and the organs that house them — bone marrow, thymus, spleen, lymph nodes, tonsils and the lymphoid tissue of the gut and airways. It distinguishes self from non-self, fights infection, removes damaged cells and keeps watch for cancers, using a fast innate arm (barriers, phagocytes, inflammation) and a precise adaptive arm (T and B lymphocytes) that remembers past invaders — the basis of vaccination.
Key facts
- Neutrophils, the commonest white cells, live only days; some memory lymphocytes persist for a lifetime.
- Antibodies (immunoglobulins) are made by plasma cells derived from B lymphocytes — up to thousands of molecules per second per cell.
- About 70% of immune tissue is associated with the gut, sampling the body's largest surface of contact with the outside world.
- Fever is a deliberate immune strategy: higher temperature inhibits many microbes and speeds white cell activity.
What can go wrong
Immune problems divide into too little (immunodeficiency — from HIV, medicines, or inherited defects — causing recurrent or unusual infections), too much misdirected (allergy and autoimmune diseases such as rheumatoid arthritis and type 1 diabetes, where the system attacks the body's own tissues), and malignant change in its cells (leukaemia and lymphoma).
Related conditions
Related procedures & tests
Related symptoms
Watch: related videos
Frequently asked questions
How do vaccines train the immune system?
They present a harmless form of a microbe (or its blueprint) so the adaptive system builds memory cells; on real exposure, the response is fast and strong enough to prevent or blunt illness.
What is an autoimmune disease?
A condition where immune tolerance fails and lymphocytes or antibodies attack the body's own tissues — the target tissue determines the disease, from joints to thyroid to nerve insulation.
Educational information only. This atlas explains normal anatomy and describes conditions in general terms; it is not medical advice and does not replace assessment by a qualified clinician. If you have symptoms that worry you, seek medical care.
