Function of the immune system:
The immune system is the organs of the body and the processes they carry out that protect against infection and disease. In a healthy body, it does this by detecting foreign disease-causing agents known as pathogens (and recognising them from its own cells) and neutralizing them using white blood cells that are produced in the bone marrow. White blood cells are also known as leukocytes.
The immune system is able to distinguish between 'self' (describes agents that are recognised by the immune system of an organism as being part of that organism) and 'non-self' (describes agents that are not recognised by the immune system as being part of the organism itself; they are foreign), and therefore knows which cells are harmful to the body and can target and destroy them.
The lymphatic system is a part of the immune system. It consists of organs (such as the thymus, bone marrow, spleen, lymph nodes, network of vessels) and lymph fluid, and together they work to transport lymphocytes (white blood cells) and remove foreign material.
Organs and tissues that make up the immune system, and their roles:
The immune system is the organs of the body and the processes they carry out that protect against infection and disease. In a healthy body, it does this by detecting foreign disease-causing agents known as pathogens (and recognising them from its own cells) and neutralizing them using white blood cells that are produced in the bone marrow. White blood cells are also known as leukocytes.
The immune system is able to distinguish between 'self' (describes agents that are recognised by the immune system of an organism as being part of that organism) and 'non-self' (describes agents that are not recognised by the immune system as being part of the organism itself; they are foreign), and therefore knows which cells are harmful to the body and can target and destroy them.
The lymphatic system is a part of the immune system. It consists of organs (such as the thymus, bone marrow, spleen, lymph nodes, network of vessels) and lymph fluid, and together they work to transport lymphocytes (white blood cells) and remove foreign material.
Organs and tissues that make up the immune system, and their roles:
The immune system consists of three lines of defence:
1. The first line of defence 2. The second line of defence 3. The third line of defence A summary of the three lines of defence can be found at right. |
Cellular pathogens:
1. Bacteria - cause disease to their hosts in a variety of ways. Large numbers of bacteria can alter the normal functioning of the host's tissues, other bacteria can directly attack and destroy the tissues of the host, and some can produce toxins that can harm or kill the normal functioning of the host's cells.
They can be transmitted from one host to another by direct contact with an infected host, contact with objects that are contaminated
or inhalation of dust/water droplets that have been in contact with an infected host.
Diseases caused by bacteria include: salmonella poisoning, gonorrhoea, leprosy and scarlet fever.
2. Protists - can be spread through parasitic species (called vectors) and contamination of foods or water.
Diseases caused by protists include: malaria, African sleeping sickness and dysentery.
3. Fungi - can attack living plant or animal tissues
Non-cellular pathogenic agents:
1. Viruses - can only reproduce once they have gained access to the host's cells. Their nucleic acid (either DNA or RNA) must be inserted into the chromosomal material of the host.
Can be spread via air/nasal droplets (such as influenza) or bodily fluids (such as AIDS virus).
Diseases caused by viruses include: chicken pox, mumps and rabies.
2. Prions - composed of a protein that has the ability to propagate and kill brain cells
Types of Immunity
1. Bacteria - cause disease to their hosts in a variety of ways. Large numbers of bacteria can alter the normal functioning of the host's tissues, other bacteria can directly attack and destroy the tissues of the host, and some can produce toxins that can harm or kill the normal functioning of the host's cells.
They can be transmitted from one host to another by direct contact with an infected host, contact with objects that are contaminated
or inhalation of dust/water droplets that have been in contact with an infected host.
Diseases caused by bacteria include: salmonella poisoning, gonorrhoea, leprosy and scarlet fever.
2. Protists - can be spread through parasitic species (called vectors) and contamination of foods or water.
Diseases caused by protists include: malaria, African sleeping sickness and dysentery.
3. Fungi - can attack living plant or animal tissues
Non-cellular pathogenic agents:
1. Viruses - can only reproduce once they have gained access to the host's cells. Their nucleic acid (either DNA or RNA) must be inserted into the chromosomal material of the host.
Can be spread via air/nasal droplets (such as influenza) or bodily fluids (such as AIDS virus).
Diseases caused by viruses include: chicken pox, mumps and rabies.
2. Prions - composed of a protein that has the ability to propagate and kill brain cells
Types of Immunity
1. acquired natural immunity: develops when an organism comes into contact with a particular pathogen and develops memory B and T cells to the antigens of that pathogen. The contact with the pathogen occurs naturally. Typical way that humans gain immunity to pathogens.
2. acquired artificial immunity: immunity acquired from immunizations/vaccines
3. passive immunity: transfer of humoral immunity - ready-made antibodies either supplied naturally (maternal antibodies) or artificially (antibodies from other sources)
2. acquired artificial immunity: immunity acquired from immunizations/vaccines
3. passive immunity: transfer of humoral immunity - ready-made antibodies either supplied naturally (maternal antibodies) or artificially (antibodies from other sources)
Differences and similarities between specific and non-specific immune responses
Similarities:
- both immune responses require white blood cells
Differences:
- non-specific retains no memory of foreign antigens whereas specific does
- non-specific is apart of the first and second line of defence whereas specific is the third
- non-specific responds to foreign antigens the same whereas specific has a specific response to antigens
- non-specific generates the same level of response when exposed to an antigen whereas specific causes a greater response when exposed to already experienced antigen