How does the complement system guard against microbes?
Complement protects against infection in three ways. Firstly, it activates a large number of complement proteins that bind to pathogens so that they can be engulfed by phagocytes. Second, fragments of complement proteins can act as chemoattractants to recruit phagocytes.
What line of defense is the complement system?
The Complement System Complement system represents a major part of the innate immunity. It is a cascade of soluble proteins and membrane expressed receptors and regulators (Figure 1), which operates in plasma, in tissues, on cell surface, and even within the cell.
How are host cells protected from the action of complement?
The constant arbitrary tick-over activation within the complement cascade marks a potential hazard to any surface. Preformed complement regulators on self-cells ensure that, even after initial opsonization, host surfaces are not affected by the actions of the AP amplification loop.
What are the four major functions of the complement system?
The complement system has four major function, including lysis of infectious organisms, activation of inflammation, opsonization and immune clearance. There are three different complement pathways, the classical complement pathway, the alternative complement pathway, and the mannose-binding lectin pathway.
What is the function of complement?
The main function of complement proteins is to aid in the destruction of pathogens by piercing their outer membranes (cell lysis) or by making them more attractive to phagocytic cells such as macrophages (a process known as opsonization).
How does complement system work?
The complement system is made up of a large number of distinct plasma proteins that react with one another to opsonize pathogens and induce a series of inflammatory responses that help to fight infection. A number of complement proteins are proteases that are themselves activated by proteolytic cleavage.
What activates complement system?
Complement can be activated through three pathways: classical, lectin, and alternative. The classical pathway is activated when C1q binds to antibody attached to antigen, activating C1r and C1s, which cleave C4 and C2.
What organ produces complement proteins?
The bulk of the complement proteins that are present in serum are produced and secreted by the liver, in particular by hepatocytes.
What are the three outcomes of complement activation?
Its activation results in three major potential outcomes for microbes: cell lysis upon assembly and insertion of the terminal membrane attack complex (MAC), complement mediated opsonization, and the release of anaphylatoxins that enhance local inflammation.
Which organ is responsible for producing most of the plasma proteins known as the complement system?
B. Liver: The liver is the major organ responsible for synthesizing proteins of the complement system. In addition, it contains large numbers of phagocytic cells which ingest bacteria in the blood as it passes through the liver.
What is the main component of blood plasma by weight?
Plasma. Plasma is the liquid component of blood, in which the red blood cells, white blood cells, and platelets are suspended. It constitutes more than half of the blood’s volume and consists mostly of water that contains dissolved salts (electrolytes) and proteins. The major protein in plasma is albumin.
Do mast cells produce complement proteins?
These cells produce complement proteins of the classical pathway (including C1q, C1r, C1s, C4, and C2) and alternative pathway (C3, FB, FD, P, and FH).
What is the fluid that is carried through the lymphatic system?
lymph
What are the 6 lymphatic organs?
Lymphoid organs
- Bone marrow. Bone marrow is a sponge-like tissue found inside the bones.
- Thymus. The thymus is located behind the breastbone above the heart.
- Lymph nodes. Lymph nodes are small bean-shaped tissues found along the lymphatic vessels.
- Spleen.
- Tonsils.
- Mucous membranes.
How does lymph leave the body?
The lymph fluid carries the waste products and destroyed bacteria back into the bloodstream. The liver or kidneys then remove these from the blood. The body passes them out with other body waste, through bowel movements (poo) or urine (pee).
Does removal of lymph nodes affect immune system?
Lymph nodes play a key role in filtering out bacteria and other harmful substances while also exposing them to infection-fighting white blood cells and triggering an immune response. The more lymph nodes you have removed, the greater the disruption to your immune system.