Immunity Flashcards
What do viral cells do once they have entered the body?
Identifies susceptible cells, determined by specific receptors on the cell surface which act as molecular doorways, and viruses have adapted to recognize and bind to them
Penetrates the cellular barrier either through cell membrane fusion or engulfing the cell entirely
Sheds its protective layers to expose its genetic material, commandeering the host’s cellular machinery to synthesize viral proteins
Cell’s viral genome is replicated
Newly synthesized viral components assemble into complete virions
The assembled virions navigate through the host cell and are released to infect new cells
What do bacterial cells do once they have entered the body?
Attach to surfaces within the body either through adhesin or structural adaptations that allow the cells to adhere to surfaces
Colonize
Some cause tissue destruction through by-products from growth
Some release toxins that causes degradation of cells or trigger destructive immune responses
Components that make up cell walls in some cells can set off the immune system
What are the body’s first line of defence mechanisms?
Skin which acts as a barrier towards pathogens
Airways filter out harmful particles
Mucous membranes are covered with secretions that fight off pathogens
What system is responsible for fighting infection?
Immune system
What type of cell helps fight off infection?
White blood cells (leukocytes)
What two types of white blood cell help fight infection?
Phagocytes
Lymphocytes
What is a phagocyte?
A type of white blood cell that performs phagocytosis
Define the term ‘phagocytosis’.
The process by which a cell engulfs a particle and digests it
What is step 1 of phagocytosis?
Chemotaxis may occur
Immune cells pick up chemical signals and migrate toward invading pathogens
Phagocytes are activated by inflammatory mediators
Define the term ‘chemotaxis’.
The movement of phagocytes toward a concentration of molecules
What is step 2 of phagocytosis?
Phagocyte attaches to the pathogen
What is step 3 of phagocytosis?
Phagocyte ingests the pathogen
Pathogen is enclosed in a vesicle (a sphere of cell membrane with fluid in it) called a phagosome
The phagosome transports the pathogen into the cell
What is step 4 of phagocytosis?
A lysosome fuses with the phagosome and the pathogen is digested
What is a lysosome?
A vesicle that contain hydrolytic enzymes that break down molecules
What is step 5 of phagocytosis?
Cellular waste is discharged from the cell by the process of exocytosis
Define the term ‘exocytosis’.
When cellular waste products travel in vesicles to the surface of the cell membrane and are released
What is a lymphocyte?
A type of white blood cell that fight infection and disease
How do lymphocytes protect the body against pathogens?
Recognise proteins on the surface of pathogens called antigens
Detect that the antigens are foreign and produce antibodies that cause pathogens to stick together making it easier for phagocytes to engulf them
Also produce antitoxins to neutralise toxins produced by pathogens
Define the term ‘active immunity’.
When a specific type of lymphocyte called a memory lymphocyte can ‘remember’ the antigens from an infection by a previous pathogen
Antibodies will be produced much faster
Define the term ‘passive immunity’.
When an offspring receives antibodies from it’s mother either
