Search results
slideshare.net
- The immune system mounts a response against pathogens as they infect an individual and replicate. The response includes both an immediate innate response and a slower adaptive response, which are explained in greater detail in the following sequence.
onlinelearning.hms.harvard.edu › hmx › immunityHow The Body Reacts To Viruses - HMX | Harvard Medical School
People also ask
How does the body fight bacterial pathogens?
What are the primary mechanisms against viruses?
How do pathogens spread?
Apr 23, 2020 · The main tasks of the body’s immune system are. to fight disease-causing germs (pathogens) like bacteria, viruses, parasites or fungi, and to remove them from the body, to recognize and neutralize harmful substances from the environment, and. to fight disease-causing changes in the body, such as cancer cells. Go to:
- Overview
- Infectious disease
- Nonspecific defense: the innate immune system
- First line of defense
- Second line of defense
- Specific defense: the adaptive immune system
- Humoral immunity
- Cell-mediated immunity
- Vaccines
- Viral structure
Key Terms
Infectious disease
Infectious diseases are caused by viruses, bacteria, fungi, protists, and other pathogens.
Pathogens are often spread through coughing, sneezing, and physical contact between people. They can also be spread through contamination of water supply, or through the exchange of body fluids, including sexual intercourse or
[blood transfusion.]
Nonspecific defense: the innate immune system
Infectious diseases are caused by viruses, bacteria, fungi, protists, and other pathogens.
Pathogens are often spread through coughing, sneezing, and physical contact between people. They can also be spread through contamination of water supply, or through the exchange of body fluids, including sexual intercourse or
The human body has a series of nonspecific defenses that make up the innate immune system. These defenses are not directed against any one pathogen but instead, provide a guard against all infection.
The body's most important nonspecific defense is the skin, which acts as a physical barrier to keep pathogens out. Even openings in the skin (such as the mouth and eyes) are protected by saliva, mucus, and tears, which contain an enzyme that breaks down bacterial cell walls.
If a pathogen does make it into the body, there are secondary nonspecific defenses that take place.
An inflammatory response begins when a pathogen stimulates an increase in blood flow to the infected area. Blood vessels in that area expand, and white blood cells leak from the vessels to invade the infected tissue. These white blood cells, called phagocytes engulf and destroy bacteria. The area often becomes red, swollen, and painful during an inflammatory response.
When pathogens are able to bypass innate immune defenses, the adaptive immune system is activated.
Cells that belong in the body carry specific markers that identify them as "self" and tell the immune system not to attack them.
Once the immune system recognizes a pathogen as "non-self," it uses cellular and chemical defenses to attack it. After an encounter with a new pathogen, the adaptive immune system often "remembers" the pathogen, allowing for a faster response if the pathogen ever attacks again.
Specific immune responses are triggered by antigens. Antigens are usually found on the surface of pathogens and are unique to that particular pathogen. The immune system responds to antigens by producing cells that directly attack the pathogen, or by producing special proteins called antibodies. Antibodies attach to an antigen and attract cells that will engulf and destroy the pathogen.
Humoral immunity relies on the actions of antibodies circulating through the body.
Humoral immunity begins when an antibody on a B cell binds to an antigen. The B cell then internalizes the antigen and presents it to a specialized helper T cell, which in turn activates the B cell.
Antibodies alone are often not enough to protect the body against pathogens. In these instances, the immune system uses cell-mediated immunity to destroy infected body cells.
T cells are responsible for cell-mediated immunity. Killer T cells (cytotoxic T cells) assist with the elimination of infected body cells by releasing toxins into them and promoting apoptosis. Helper T cells act to activate other immune cells.
Vaccines work by taking advantage of antigen recognition and the antibody response. A vaccine contains the antigens of a pathogen that causes disease. For example, the smallpox vaccine contains the antigens specific to smallpox. When a person is vaccinated against smallpox, the immune system responds by stimulating antibody-producing cells that are...
Viruses are infectious particles that reproduce by hijacking a host cell and using its machinery to make more viruses.
There are many kinds of viruses, differing in structure, genome, and host specificity. However, viruses tend to have several features in common. All viruses contain a protective protein shell, or capsid, that houses their nucleic acid genome (either DNA or RNA).
Think of a primary infection as a race between the pathogen and the immune system. The pathogen bypasses barrier defenses and starts multiplying in the host’s body. During the first 4 to 5 days, the innate immune response will partially control, but not stop, pathogen growth.
- Lindsay M. Biga, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Mat...
- 2019
Jul 30, 2022 · Think of a primary infection as a race between the pathogen and the immune system. The pathogen bypasses barrier defenses and starts multiplying in the host’s body. During the first 4 to 5 days, the innate immune response will partially control, but not stop, pathogen growth.
The immune system mounts a response against pathogens as they infect an individual and replicate. The response includes both an immediate innate response and a slower adaptive response, which are explained in greater detail in the following sequence.
Nov 22, 2023 · Summary. The immune system is the body’s tool for preventing or limiting infection. Its complex network of cells, organs, proteins, and tissues enable the immune system to defend...
