Immune System Of Human
Immune system

The immune system is a system of biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.

Disorders of the immune system can result in autoimmune diseases, inflammatory diseases and cancer. Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections. In contrast, autoimmunity results from a hyperactive immune system attacking normal tissues as if they were foreign organisms.

The immune system protects organisms from infection with layered defenses of increasing specificity.
- In simple terms, physical barriers prevent pathogens such as bacteria and viruses from entering the organism. If a pathogen breaches these barriers, the innate immune system provides an immediate, but non-specific response. Innate immune systems are found in all plants and animals. If pathogens successfully evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system.
- The adaptive immune system is activated by the innate response. Here, the immune system adapts its response during an infection to improve its recognition of the pathogen. This improved response is then retained after the pathogen has been eliminated, in the form of an immunological memory, and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered.

Surface barriers : Several barriers protect organisms from infection, including mechanical, chemical, and biological barriers. for example
  • In the lungs, coughing and sneezing mechanically eject pathogens and other irritants from the respiratory tract.
  • The flushing action of tears and urine also mechanically expels pathogens, while mucus secreted by the respiratory and gastrointestinal tract serves to trap and entangle microorganisms.
 
Innate immune system

Microorganisms or toxins that successfully enter an organism encounter the cells and mechanisms of the innate immune system. The innate response is usually triggered when microbes are identified by pattern recognition receptors, which recognize components that are conserved among broad groups of microorganisms,or when damaged, injured or stressed cells send out alarm signals, many of which but not all are recognized by the same receptors as those that recognize pathogens.
 
Leukocytes
Leukocytes or white blod cells, are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist. They live for about three to four days in the average human body. Leukocytes are found throughout the body, including the blood and lymphatic system.

The number of leukocytes in the blood is often an indicator of disease. There are normally approximately 7000 white blood cells per microliter of blood and they make up approximately 1% of the total blood volume in a healthy adult.
 
Tonsil & Andenoid

Tonsil : The tonsils are two lumps of lymphoid tissue, each about the size and shape of a large olive, in the back of the mouth on either side of the tongue at the back of the human throat.These immunocompetent tissues are the immune system's first line of defense against ingested or inhaled foreign pathogens.

Adenoid : The adenoid is the the third lump of lymphoid tissue that sits between the tonsils, higher up behind the nasal cavity. Like lymph nodes, adenoids are part of the immune system and are made of the same type of lymphoid tissue. White blood cells circulate through the adenoids and other lymphoid tissue, reacting to foreign invaders in the body.
adenoid & tonsil
 
Thymus

The thymus is a specialized organ of the immune system. Thymus is a pyramid-shaped lymphoid organ that, in humans, is immediately beneath the breastbone at the level of the heart. The organ is called thymus because its shape resembles that of a thyme leaf.

The thymus is divided into two lobes, lying on either side of the midline of the body, and into smaller subdivisions called lobules. The thymus "educates" T-lymphocytes (T cells), which are critical cells of the adaptive immune system.

thymus
The thymus "educates" T-lymphocytes (T cells), which are critical cells of the adaptive immune system.

The thymus is largest and most active during the neonatal and pre-adolescent periods.
 
Spleen
The spleen is an organ in the upper far left part of the abdomen, to the left of the stomach it acts primarily as a blood filter. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock and also recycles iron.
spleen
 
 
 
Science

Change in state of water
Water and it's states
Spheres of the earth
Nutrients & Deficiency Of Nutrients & It's Effect
Interesting Facts About Human Organs
Circulatory system
Digestive system
Endocannabinoids system
Endocrine system
Excretory system
Integumentary system
Immune system
Lymphatic system
Nervous system
Respiratory system
Musculoskeletal system
Vestibular system

 
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