Immune System
Antibiotics
Types of Pathogens
Vaccines
Types of Barriers
Methods of Transmission
Leukocytes
Antibodies
Antibodies (immunoglobulins) are a globular protein that recognizes a specific antigen and binds to it as a part of an immune response.
Pathogen: disease causing organism
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Fungi
Fungi can cause athlete's foot, mold, and ringworms. It can also cause allergic reactions and respiratory problems.
Fungi are eukaryotes, which primarily reproduce through spores.
Viruses
Viruses can cause variations of the flu, HIV/AIDS, smallpox, measles, the common cold, herpes, and ebola.
Viruses are acellular, which means that they are non living substances. they need a host, or another cell, organism to carry out the functions of its own life, which includes reproduction. Viruses can have DNA and RNA, or a combination of both. Viruses continuously are mutating, evolving, and recombining, which makes eradicating them, rather difficult.
Protozoa
Protozoa can cause diseases like malaria, leishmaniasis, and toxoplasmosis.
Protozoa are simple parasites. These can manifest and cause deteriorations of bodily systems.
Bacteria
Bacteria can cause food poisoning, ear and eye infections, cholera, and diarrhea.
Bacteria are prokaryotes, with no real nucleus. They divide by binary fission.
Bodily Fluids
Animal Vectors
Direct Contact
Blood Contact
Inhaled Droplets
Ingestion or Swallowing
Mucous Membranes
Skin
The sticky mucous acts to trap incoming invaders. Additionally, the pH is not favorable for the incoming pathogenic material, either. The lysosomes act as an enzymatic pathway to further breakdown any of the pathogens in the area. There is also competitive exclusion by non-harmful microbes that occurs in these membranes.
The skin is continuous, which means it is difficult to find an opening to physically go through for a pathogen. The skin is composed of multiple layers, which makes it physically difficult for a pathogen to penetrate. It is dry, and the pH is not favorable for pathogens, either. Lysozyme also act as enzymes that break down the pathogens. There are also natural organisms that live on the skin which allow for competitive exclusion by non harmful microbes.
Leukocytes are white blood cells.
Phagocytes
Lymphocytes
These are cell eating white blood cells. This means that the ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases.
Antigens are a substance or a molecule, often found on a cell or virus surface, that causes antibody formation (characteristic to the surface of a cell/cell type).
Chemotaxis is the movement in the response to various chemicals which attracts the phagocytes to the area of invasion as response to two main things: proteins produced by the pathogen and phospholipids released by damaged cells.
The phagocyte then attaches itself the pathogen's surface proteins and engulfs it completely. The fluids involved of the plasma membranes facilitate this.
A phagosome then forms, which is a vesicle that contains the pathogen in question. Then, the lysozomes, which are vesicles of digestive enzymes, deposit these specific enzymes into the phagosome.
The digestive enzymes then are tasked with breaking down the pathogen. The waste products are removed from the cell via exocytosis.
In summary, phagocytes are the types of cells that provide the body with a non-specific immune response to any of the materials assessed to be a foreign one. If this immediate response is not sufficient enough to deal with the pathogen, the introduced infection can become widespread. For this, a specific immune response is triggered handled by lymphocytes.
There are various types of lymphocytes all of which are responsible for the recognition of a specific antigen. When the immune system is compromised by an incoming pathogen, the specific lymphocyte responds.
The lymphocytes make clones of themselves which help produce numerous antibodies for the pathogens. This process is known as the clonal selection; the specific, right lymphocyte is chosen and then it is cloned.
As some cells are cloned, some remain as memory cells. These serve to protect the body if there is a secondary invasion by the pathogens. This system is known as immunity.
Antibiotics are drugs used in the treatment and prevention of prokaryotic bacteria. Eukaryotic and prokaryotic cells are vastly different; hence because of structural and functional differences, the drugs that act as inhibition for prokaryotes have little or no effect on eukaryotic cells.
The way that antibiotics are designed ensure a disruption to either cellular structures or metabolic pathways in the bacteria and fungis. This could include cell walls and membranes, protein synthesis, DNA/RNA synthesis, or a variety of other metabolic pathways or processes. Viruses do not have any of these structures, so antibiotics have no effect on them; viruses use the host cell's metabolism, protected by the host cell's structure, and use a very different structure than prokaryotes in general- just a capsid and genetic material.
Antibiotic resistance can also arise in bacteria. Generally, if the pathogenic bacteria evolves, it will no longer be effective in treating the infection. Bacteria mutate and develop a natural resistance to the prescribed antibiotic. Bacteria have the ability to divide quickly via binary fission, which makes the creation of a resistant strain of bacteria fast. These singular strains become multiple strains over a period of time. There are also other factors like the over prescribing of antibiotics, patients not completely finishing their prescribed medication rounds, the over use of antibiotics in livestock, poor infection control in populated environments, lack of hygiene, and new antibiotics being introduced to the environment.
Viruses lack metabolism which means that they cannot be treated with the antibiotic treatments.
HIV & AIDS
HIV is the human immunodeficiency virus which attacks the body's immune system. Infected people find it harder to fight immune diseases and infections. AIDS is a syndrome which is caused by the HIV condition. This is known as the last stage of HIV. There is no cure for HIV; yet with treatment, people can live long and healthy lives.
HIV attacks the immune system. It is a retrovirus. It inserts its own RNA into the host well, which helps incorporate the HIV's RNA into the DNA. HIV attacks T-helper cells by binding to the protein on their surface. Once it is inside the cell, the RNA is inserted into the macrophage genome. Through the processes of transcription, it now has HIV's genetic code, resulting in more output RNA and HIV particles. This weakens the immune system as it inhibits the antibody production.
Blood Clotting)
If there is a cut in the skin, it is sealed by blood clotting. For this to happen clotting factors are released from the platelets. Wounds on the skin can cause openings through which pathogens could potentially enter. Platelets, with other damaged tissue, releases clotting factors, which cause a series of biochemical reactions which end with a protein mesh forming around the wounded site. In these processes, thrombin, fibrinogen (soluble and fibrous) are involved.The fibers then capture these blood cells that continue to come outwards and form a blood clot. The air dries to form a scab.
Immunity is defined as having sufficient biological defenses against an infection. Active immunity is immunity due to the production of the antibodies by the organism. This would be after the immune response has been used by a pathogen. Passive immunity is the acquisition of antibodies from another organism, which means that an artificial source is being used- placenta, colostrum, direct injection, or antibodies.
There are two main lymphocytes in mammals. The helper T cells are the driving force and the regulators of the immune defense. Their main task is to activate the B cells and the killer T cells. The B cells are responsible for searching for matching the antigen with the receptor.
Initial Attachment to Antigen
Neutralization: In this step, the attachment stops the toxins from entering the cells, or effecting them in any way- like viruses from entering the cells or bacteria from efficiently functioning. This essentially stops the pathogen from attacking the cells completely.
Opsonization: Through the attachment of different antibodies marking the pathogen, it makes it easily identifiable by the other immune cells so that it can be engulfed later in the process.
Agglutination: The antibodies then attach to each other which causes a clumping of the pathogen, which acts to further enhance the effects of the first two steps.
Complement Activation: The antibodies then are encouraging other components to attach to the pathogen itself. This means that the pathogen is being attacked causing a variety of reactions to terminate the pathogen.
Histamines
White cells release histamines in response to allergens. Histamines can cause allergic symptoms. A histamine is an organic molecule produced by the two types of leukocytes: basophils and mast cells. Since mast cells are in connective tissue, if the area is stimulated, there is an allergic reaction. Histamines increase the permeability of the skin and the capillaries to white blood cells and some proteins, allowing the components of the immune system to be brought into question rather early on in the infection.
The loss of fluid from those capillaries into the surrounding tissues as prescribes can cause a variation of physical responses including inflammation or hives, itching, sneezing, or watery eyes. Antihistamines are a type of drug that opposes the activity of histamine receptors.
ABO blood type classification systems help us understand how the presence or absence of specific antigens in erythrocytes affects the antibodies and blood types. While Type O is the universal donor, Type AB is the universal acceptor. Type A blood has Anti-B antibodies which means it cannot have B or AB blood. Type B blood has Anti-A antibodies, which means it cannot have type A or AB blood. Type AB blood has neither antibody which means it can accept any blood, while type O blood has both antibodies, which means it can only have O blood. The antigens act as the determining factor as to what the blood type can accept or donate to.
Vaccines allow for an individual to become immune to a pathogen or disease without actually experiencing it. Vaccines also contain antigens which do not cause serious health symptoms in a healthy person. Vaccines are administered either orally or by injection.
The vaccine is a primary immune response. This means that it is slow to build up and not very strong. Then via the processes of immunity, the body fights off the infection and only the memory cells remain. Then the secondary response is much stronger and rapid in comparison that the primary response, if the pathogen is introduced to the body.
One of the first vaccines to be developed was for the smallpox disease, caused by the virus variola- it was infectious. Though the terms through which it was developed was unethical, it was groundbreaking for science.
While some pathogens only affect humans, like polio, measles, or syphilis, others are zoonosis- a disease or infection that is naturally transmissible from vertebrate animals to humans. Examples include the flu, ebola and salmonella.
When there is an immune response in the body, antibodies specific to the pathogen are produced, By producing these in larger quantities it can have greater applications. When there is an immune response, it could be polyclonal, which means that the B cells could respond to multiple epitopes.
An animal is injected with an antigen, it tends to respond with specific plasma cells. These plasma cells are harvested from the spleen of the organism. They are then fused with tumor cells, which are capable of divisions, which then form hybridoma cells. These are screened to determine which ones are useful in terms of actually producing useful antibodies. Once selected, they are allowed to divide to produce clones. They are often used to synthesize large quantities of a single antibody for usage in diagnostic tests and treatments, like pregnancy tests.
