General Review
A whole range of pathogens can affect us!
The study of the human immune system is called immunology. The immune system is highly organised system made up of biological structures and processes which are able to detect and destroy pathogen to protect us from diseases. Disease in biological terms is defined as something which impairs or upsets the natural balance in your body. A pathogen is an agent of disease which means that it can cause a disease. For our immune system to function and keep its integrity, it must identify 'self' from 'non-self' and then mount an attack on the 'non-self'. This is done by the 'self' cells carrying a recognition molecule usually a carbohydrate (glycoprotein) or a protein. The recognition in the immune system is highly co-ordinated. The cells involved:
Immune system is a major system of the body, it evolves to better detect and respond to pathogen, this is mainly caused by the evolving pathogen who longs to penetrate and cause harm to our body. As a result of this multiple defence mechanisms have evolved to recognize and neutralize pathogens. The human immune system is quite complex but even the simplest of living things such as the unicellular bacteria possess a rudimentary immune system, in the form of powerful enzymes which protect against bacteriophage infection
- 'Talk' by using chemical signals (cytokines)
- 'Listen' using surface receptors
- 'Hold hands' using adhesion molecules.
Immune system is a major system of the body, it evolves to better detect and respond to pathogen, this is mainly caused by the evolving pathogen who longs to penetrate and cause harm to our body. As a result of this multiple defence mechanisms have evolved to recognize and neutralize pathogens. The human immune system is quite complex but even the simplest of living things such as the unicellular bacteria possess a rudimentary immune system, in the form of powerful enzymes which protect against bacteriophage infection
Antibodies and antigens
The binding is like lock and key
Antigens (the bad guys)
These are molecules which are either proteins or carbohydrates, examples are cells such as bacteria and pollen. The modern view of antigens is that basically its any molecule or molecular fragment which can by bounded by a major histocompatibility complex (MHC markers) and be presented to a T-cell receptor. They are found on the surfaces of pathogenic cells and the outer coats of viruses. They can also be released by bacteria as toxins. When the body does recognize that the invading cell or pathogen is not 'self' it will launch an immune response to kill the antigens. When this happens, eventually an antigen binds to a T-cell receptor which eventually through a series of process stimulates the production of antibodies.
Antibodies (the good guys)
These are the fighting war machines of the immune system. they are produced by a plasma cell which in turn is a white blood cell. They are globular glycoproteins called immunoglobin (Ig) produced by the B-cells. Its worth while to note that antibodies are produced via the humoral immune system and released into the blood stream. Antibodies are are 'Y' shaped with two identical arms that bind to two antigen molecule. The binding is like lock and key. The antibodies bind to the antigens and form an antibody/antigen complex followed by coagulation and then its engulfed by a phagocyte.
These are molecules which are either proteins or carbohydrates, examples are cells such as bacteria and pollen. The modern view of antigens is that basically its any molecule or molecular fragment which can by bounded by a major histocompatibility complex (MHC markers) and be presented to a T-cell receptor. They are found on the surfaces of pathogenic cells and the outer coats of viruses. They can also be released by bacteria as toxins. When the body does recognize that the invading cell or pathogen is not 'self' it will launch an immune response to kill the antigens. When this happens, eventually an antigen binds to a T-cell receptor which eventually through a series of process stimulates the production of antibodies.
Antibodies (the good guys)
These are the fighting war machines of the immune system. they are produced by a plasma cell which in turn is a white blood cell. They are globular glycoproteins called immunoglobin (Ig) produced by the B-cells. Its worth while to note that antibodies are produced via the humoral immune system and released into the blood stream. Antibodies are are 'Y' shaped with two identical arms that bind to two antigen molecule. The binding is like lock and key. The antibodies bind to the antigens and form an antibody/antigen complex followed by coagulation and then its engulfed by a phagocyte.
Types of Defenses
There are two types of defenses:
- Non-specific: the immune response to any pathogen or antigen.
- Specific: highly specific, memory cells and antibodies involved.
Non-specific level one
Skin which serves as a barrier
These are ancient and innate adaptations to protect against a wide range of pathogens. The most simplest of them starts from external barriers to prevent entry to pathogens in the first place, these are skin, mucus secreting membranes in the nose and mouth which functions by trapping pathogen and ciliated membranes (air ways). The other is our external chemical barrier which also serves the same function as the external barriers does. For example these include toxic metabolites (e.g latic acid), tear which produced by the eyes and contains antibacterial substance within it which destorys the cell wall of bacteria, saliva which removes bacteria from our mouth and the acidity of our stomach which kills most germs what we ingest. Sweat also acts as a chemical barrier because of its high salt content which the bacteria find really hostile.
Level two
Inflammation
This level is all about the internal chemical responses to a penetrated pathogen. As soon as a cell from the 'self' is invaded, the cell release:
Cytokines (a molecule)
These are generally small glycoproteins which are also released by the lymphatic system as well. Once they have been released, they function by increasing the blood flow to the affected area to allow more defensive white blood cells to come to their help hence thats why you get swollen spots.
Interferons (a molecule)
These are anti-viral chemicals produced during a viral infection. They fight against virus infections by:
Complement (a system)
This is a system of about 20 large blood proteins. When they are normally in the blood stream its said to to be inactive but when an infection occurs in the body, these deadly protein are activated. Complements are produced in the liver. So in summary complement proteins are those which work and are activated by complement antibodies hence their name. Sometimes during an antigen/antibody complex; it doesn't perform any useful action unless its activated by an effector mechanism. The complement serves as the effector mechanism. It works by punching holes in the bacterial membrane which consequently releases the contents of the bacteria. This is known as lysing. This in turn attracts phagocytes. The complement proteins also bind to the bacterial cell causing the recognition of the cell to fairly easy for the phagocyte.
Inflammation (a process)
This is a powerful non-specific defense mechanism which is activated by the presence of a pathogen or damaged tissues. Inflammation is usually red, swollen and painful experience due to the fluids in the tissue. The inflammation is mainly triggered by substances released from damaged cells and by histamins which are stimulated by mast cells. Mast cells occur in the walls of vessals and it is the mast cell which releases the chemical hstamins. The inflammation functions by bring abundant blood flow which brings with it phagocytic cells to destroy the pathogen.
Cytokines (a molecule)
These are generally small glycoproteins which are also released by the lymphatic system as well. Once they have been released, they function by increasing the blood flow to the affected area to allow more defensive white blood cells to come to their help hence thats why you get swollen spots.
Interferons (a molecule)
These are anti-viral chemicals produced during a viral infection. They fight against virus infections by:
- Preventing the synthesis of viral RNA
- Making the unaffected cells nearby more resistant
- Stimulating macrophages (phagocytic white blood cells, note phagocytes are monocytes and macrophages, those cells capable of performing phagocytosis are called phagocytes) to destroy infected cells.
Complement (a system)
This is a system of about 20 large blood proteins. When they are normally in the blood stream its said to to be inactive but when an infection occurs in the body, these deadly protein are activated. Complements are produced in the liver. So in summary complement proteins are those which work and are activated by complement antibodies hence their name. Sometimes during an antigen/antibody complex; it doesn't perform any useful action unless its activated by an effector mechanism. The complement serves as the effector mechanism. It works by punching holes in the bacterial membrane which consequently releases the contents of the bacteria. This is known as lysing. This in turn attracts phagocytes. The complement proteins also bind to the bacterial cell causing the recognition of the cell to fairly easy for the phagocyte.
Inflammation (a process)
This is a powerful non-specific defense mechanism which is activated by the presence of a pathogen or damaged tissues. Inflammation is usually red, swollen and painful experience due to the fluids in the tissue. The inflammation is mainly triggered by substances released from damaged cells and by histamins which are stimulated by mast cells. Mast cells occur in the walls of vessals and it is the mast cell which releases the chemical hstamins. The inflammation functions by bring abundant blood flow which brings with it phagocytic cells to destroy the pathogen.
Non-specific Cellular defense
These includes the white blood cells (leukocytes). There are five types of white blood cells:
4. Easinophils
- Lymphocytes (B and T cells)
- Phagocytes
- Monocytes
- Neutrophils
4. Easinophils
Specific Adaptive Immunity cell mediated and humoral system
Simple diagram summing the overall immune system
The ability of this type of immune response is that its specific being able to target specific pathogens and it can create memory cells which 'remembers' the primary exposure to a pathogen and then mounts a rapid secondary response. However its slower than the innate response and is only due to antibodies and memory cells. How it works is best explained by diagrams (below.)
References
http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/carbohydrates/
http://en.wikipedia.org/wiki/Carbohydrate
http://dl.clackamas.edu/ch106-07/carbohyd1.htm
http://en.wikipedia.org/wiki/Aldehyde
http://ghr.nlm.nih.gov/handbook/basics/dna
http://en.wikipedia.org/wiki/Sterol
http://dl.clackamas.edu/ch106-07/carbohyd1.htm
http://en.wikipedia.org/wiki/Protein
http://en.wikipedia.org/wiki/Phospholipid
http://chemistry.about.com/od/biochemistry/a/proteinstructur.htm
http://en.wikipedia.org/wiki/Cofactor_(biochemistry)
http://bacteriamuseum.org/cms/How-We-Fight-Bacteria/our-immune-system-fights-against-bacteria.html
http://en.wikipedia.org/wiki/Enzyme#.22Lock_and_key.22_model
http://en.wikipedia.org/wiki/Immune_system
http://biology-pictures.blogspot.com/search/label/Active%20Transport
http://en.wikipedia.org/wiki/Antibody
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Complement.html
http://science.howstuffworks.com/environmental/life/human-biology/immune-system8.htm
http://en.wikipedia.org/wiki/Transcription_(genetics)
http://en.wikipedia.org/wiki/DNA_replication
http://en.wikipedia.org/wiki/Carbohydrate
http://dl.clackamas.edu/ch106-07/carbohyd1.htm
http://en.wikipedia.org/wiki/Aldehyde
http://ghr.nlm.nih.gov/handbook/basics/dna
http://en.wikipedia.org/wiki/Sterol
http://dl.clackamas.edu/ch106-07/carbohyd1.htm
http://en.wikipedia.org/wiki/Protein
http://en.wikipedia.org/wiki/Phospholipid
http://chemistry.about.com/od/biochemistry/a/proteinstructur.htm
http://en.wikipedia.org/wiki/Cofactor_(biochemistry)
http://bacteriamuseum.org/cms/How-We-Fight-Bacteria/our-immune-system-fights-against-bacteria.html
http://en.wikipedia.org/wiki/Enzyme#.22Lock_and_key.22_model
http://en.wikipedia.org/wiki/Immune_system
http://biology-pictures.blogspot.com/search/label/Active%20Transport
http://en.wikipedia.org/wiki/Antibody
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Complement.html
http://science.howstuffworks.com/environmental/life/human-biology/immune-system8.htm
http://en.wikipedia.org/wiki/Transcription_(genetics)
http://en.wikipedia.org/wiki/DNA_replication