B5 Immune system Flashcards
Name the type of leucocyte shown in the picture.
(It has been stained purple)
Phagocyte
Name the type of leucocyte shown in the picture.
(It has been stained purple)
Lymphocyte
What is a foreign antigen?
Glycoprotein on the cell surface membrane of a pathogen.
Describe the process of phagocytosis
- Phagocyte moves towards pathogen
- Phagocyte engulfs pathogen to form phagosome.
- Phagosome fuses with lysosomes to form a phagolysosome
- Lysozymes/enzymes digest pathogen
- Phagocyte absorbs products from pathogen
- Pathogen antigen displayed on cell membrane
Name the 2 types of specific immune response
Humoral
Cell mediated
Outline the process of cell mediated response
- T lymphocyte activated by a foreign antigen on antigen presenting cell
- Causes mitosis producing a clone of T cells.
Killer T cells cause lysis of pathogen/antigen presenting cells.
Helper T cells activate B lymphocytes and produce an antibody response
Memory cells remain dormant until host is next exposed to antigens
Activate B cells to produce cytokines
Outline the process of the humoral response
- Specific B lymphocyte activated by a specific antigen binding with its receptors
- Specific lymphocyte divides rapidly by mitosis.
- B cells differentiate into plasma cells and memory cells
- Plasma cells secrete antibodies into blood
- Antibodies cause agglutination forming a antigen-antibody complex and efficient phagocytosis
What is an antibody?
Proteins secreted by plasma cells
Y shaped protein
Binds to antigens on pathogens
Name the type of specialised cell that can make the molecule shown in the diagram
Plasma cell
How do antibodies lead to the destruction of a pathogen?
Formation of antigen-antibody complex results in agglutination which enhances phagocytosis
What are memory cells?
Specialised B and T cells produced from primary immune response
Remain in low levels in the blood
Can divide rapidly by mitosis if organism encounters the same pathogen again.
What is a primary response to an infection?
Specific B cells are activated
Produce plasma cells.
Release antibodies to form antigen-antibody complexes
Efficient phagocytosis of pathogen.
Memory cells produced
What is the difference between a primary and secondary response?
Secondary response produces antibodies more rapidly
Secondary response produces more antibodies
Explain the principles of vaccination
Vaccine contains dead/inactive form of a pathogen/antigen
Triggers primary immune response
Memory cells are produced and remain in the blood so secondary response is rapid and produces higher concentration of antibodies
Pathogen is destroyed before it causes symptoms
What is immunity?
When a body’s defences are able to kill a pathogen before it causes harm
List the non-specific defences against infection
Skin - dead barrier
Scab - seal wound in skin and prevent blood loss
Tears and saliva - contain lysozymes
Mucus in trachea and bronchus
Stomach acid
Phagocytosis
What is a pathogen?
A microorganism that causes infectious disease
Which type of immunity are T lymphocytes mainly involved in?
Cell mediated
B lymphocytes can develop into which types of cells during an immune response?
Plasma cells
Memory cells
What is the function of a plasma cell?
Produce antibodies which destroy pathogens
Name the type of molecule shown in the diagram
Antibody
Describe how the presentation of a viral antigen leads to the secretion of antibodies against the viral antigens.
T cells bind to antigen on phagocyte
T cells are activated to form T helper cells
T helper cells stimulate SPECIFIC B cells
B cells stimulated to divide by mitosis
Form plasma cells which release antibodies
