Body defence Flashcards
What’s the function of the immune system?
- To deal with threats to normal function
2. To restore homeostasis
What is the immune system split up into?
External barrier (e.g. skin, mucous membrane, nasal hair) Internal protection, which is split into first and second line defence.
How does the immune system deal with threats?
It provides protection from pathogens (found in air, food and water- micro-organisms that cause disease)
It also detects antigens (toxins or other foreign substances which induce specific immune responses, especially the production of antibodies)
List some of the exterior defences
Saliva Skin Stomach acid Good gut bacteria Mucus linings Tears
How does the skin assist in the defence against pathogens?
It provides a barrier to entry
How does saliva assist in the defence against pathogens?
There are antibacterial enzymes in saliva
How does stomach acid assist in the defence against pathogens?
Low pH kills harmful microbes
How does good gut bacteria assist in the defence against pathogens?
They out-compete harmful bacteria
How do mucus linings assist in the defence against pathogens?
They trap dirt and microbes
How do tears assist in the defence against pathogens?
There are antibacterial enzymes in tears
Name the primary lymphoid organs
Bone marrow and the thymus gland
Why are the thymus gland and bone marrow primary lymphoid organs?
Primary lymphoid organs are where lymphocytes are formed and mature. They provide an environment for stem cells to divide and mature into B- and T- cells.
Name the secondary lymphoid organs
Lymph nodes, tonsils, spleen, Peyer’s patches, and mucosa associated lymphoid tissue (MALT).
What happens in secondary lymphoid organs?
Secondary lymphoid tissues are arranged as a series of filters monitoring the contents of the extracellular fluids. Secondary lymphoid tissues are also where lymphocytes are activated.
What is lymph?
A colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.
Name the immunological protection organs
Tonsils, lymph nodes, thymus, spleen, Peyer’s patches, appendix, bone marrow
What is the lymphatic system?
The lymphatic system is a system of lymph vessels and lymph nodes that run throughout the body. It also plays a role in:
fighting bacteria and other infections
destroying old or abnormal cells, such as cancer cells
What is the first line of defence?
The exterior non-specific defence
What’s the second line of defence?
The interior non-specific defence
What does the interior non-specific defence include?
Phagocytic white blood cells
Antimicrobial proteins
Inflammatory response
What’s the third line of defence?
The specific defence
What does the specific defence include?
Lymphocytes
Antibodies
Which is the innate defence system?
The non-specific defence (interior)
Which is the adaptive defence system?
The specific defence
Which is faster, the innate immunity or adaptive immunity?
The innate immunity because it can respond to anything
Cells that mediate the innate immunity
Macrophages
Natural killer cells
Neutrophils
Basophils
Cells that mediate the adaptive immunity
B cells
T cells eg CD4, CD8 T cells
Briefly describe neutrophils
Most abundant WBC (70%)
Important in fighting early phases of bacterial infections
Engulf and destroy microbes at infected sites
Briefly describe macrophages
Important in long-lasting infections
Pseudopodia, migration and phagocytosis
Largest phagocytes, long lived
Clean up dead neutrophils and tissue debris
Eg. lung alveolar; brain microglial cells; histiocytes in connective tissues, red pulp of spleen
Briefly describe natural killer cells
Not as differentiated
Involved in killing virus-infected cells, transplanted bone marrow cells and malignant tumour cells
Attack cells with surface membrane change (loss of MHC I molecule)
Pore insertion (perforin)
Cell lysis
When does the specific body defence develop?
It develops shortly after birth and during first months in response to pathogens you encounter
Why is it called the adaptive immune system?
Its responses are specific and targeted against particular pathogen
What are antigens?
A toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
How are antibodies produced?
B cell binds to antigen via membrane antibodies
Activated lymphocyte, assisted by helper T cells
Transforms into plasma cell (larger)
Secretion of antibodies into circulation
What are the different classes of immunoglobulin?
IgG (72%) IgA (8%) IgM (15%) IgD (1%) IgE (4%)
Active naturally acquired immunity
This comes from infection/ contact with a pathogen
Passive naturally acquired immunity
This comes antibodies that pass from mother to child via placenta/ breast milk
Active artificially acquired immunity
This comes from being vaccinated
Passive artificially acquired immunity
This comes from an injection of immune serum
