How The Immune System Works
STARLOG.COM Health & Sickness
How The Immune System Works
The Two Parts of the Immune System
The immune system has two main parts: the innate immune system and the adaptive immune system.
The innate immune system is the first line of defense. It is present at birth and consists of physical barriers (such as skin and mucous membranes), chemical substances (such as enzymes and acids), and cells (such as white blood cells) that can quickly respond to any foreign substance. The innate immune system is not specific, meaning it does not distinguish between different types of invaders. It also does not have memory, meaning it does not remember previous encounters with the same invader.
The adaptive immune system is the second line of defense. It develops throughout life as the body is exposed to different microbes or chemicals released by microbes. The adaptive immune system is specific, meaning it can recognize and target specific types of invaders. It also has memory, meaning it can remember previous encounters with the same invader and mount a faster and stronger response.
The Cells of the Immune System
The cells of the immune system are called white blood cells or leukocytes. They circulate in the blood and lymphatic vessels, which are part of the lymphatic system. The lymphatic system forms a network of vessels, nodes, and organs that collect and filter excess fluid from the tissues and transport it back to the bloodstream.
There are different types of white blood cells that have different roles in the immune system:
Neutrophils are the most abundant type of white blood cells. They are part of the innate immune system and can quickly migrate to sites of infection or inflammation. They surround and absorb pathogens and break them down, effectively eating them. This process is called phagocytosis.
Eosinophils are part of the innate immune system and are involved in allergic reactions and parasitic infections. They release chemicals that can damage or kill pathogens.
Basophils are part of the innate immune system and are involved in allergic reactions and inflammation. They release chemicals such as histamine that can cause swelling, itching, and increased blood flow.
Monocytes are part of the innate immune system and can differentiate into macrophages or dendritic cells. Macrophages are large phagocytic cells that can engulf and destroy pathogens or debris. Dendritic cells are specialized cells that can capture antigens (parts of pathogens that trigger an immune response) and present them to other cells of the adaptive immune system.
Lymphocytes are part of the adaptive immune system and can be divided into two main types: B cells and T cells. B cells produce antibodies, which are proteins that bind to antigens and mark them for destruction by other cells or molecules. T cells can be further divided into helper T cells and cytotoxic T cells. Helper T cells activate other cells of the immune system by releasing cytokines, which are chemical messengers that regulate immune responses. Cytotoxic T cells kill infected or abnormal cells by releasing chemicals that induce apoptosis, which is programmed cell death.
How the Immune System Responds to an Infection
When a pathogen enters the body, it triggers an immune response that involves both the innate and adaptive immune systems.
The innate immune system responds first by activating physical barriers, chemical substances, and phagocytic cells that try to eliminate or contain the pathogen.
The adaptive immune system responds later by activating lymphocytes that recognize specific antigens on the pathogen.
The interaction between these two parts of the immune system is facilitated by cytokines, chemokines, and antigen-presenting cells.
Cytokines are molecules that regulate inflammation, cell proliferation, differentiation, and activation.
Chemokines are molecules that attract or repel certain types of cells to or from sites of infection or inflammation.
Antigen-presenting cells are cells that capture antigens from pathogens or infected cells and present them to lymphocytes.
The result of this coordinated response is the elimination or control of the pathogen and the development of immunological memory, which allows for a faster and stronger response in case of a future encounter with the same pathogen.
How the Immune System Can Malfunction
Sometimes, the immune system can malfunction or become dysregulated, leading to various diseases or disorders.
Comments
Post a Comment