Chapter 43: The Immune System Flashcards
Pathogen
Bacterium, fungus, virus, or other disease disease-causing agent
Immune System
The body’s defenses that enables an animal to avoid/inhibit infection
Innate Immunity
- Includes barrier defenses
- Recognition relies on a small set of receptor proteins that bind to molecules/structures absent from animals but common to a group of viruses, bacteria, or other molecules
Adaptive Immunity
Molecular recognition relies on a vast arsenal of receptors, each of which recognizes a feature typically found only on a particular molecule in a particular pathogen
Lysozyme
Enzyme that breaks down bacterial cell walls
Phagocytosis
- Type of endocytosis
- Large particulate substances or small organisms are taken up by a cell
- Carried out by some protists and by certain animals
Toll-Like Receptor
- Membrane receptor on a phagocytic white blood cell
- Binds to fragments of molecules normally absent from the vertebrate body but characteristic of a set of pathogens
Neutrophil
- Phagocytic cell
- Circulates in the blood
- Attracted by signals from infected tissues
- Engulf and destroy infecting pathogens
Macrophages
- “big eaters”
- Larger phagocytic cells
- Some migrate throughout the body
- Some reside permanently in organs and tissues
Dendritic Cells
- Mainly populate tissues that contact the environment
- Stimulate adaptive immunity against pathogens they engulf
Natural Killer Cells
- Circulate through the body
- Detect abnormal array of surface proteins characteristic of some virus-infected and cancerous cells
- Release chemicals that promote cell death
Interferons
Proteins that provide innate defenses by interfering with viral infections
Complement System
- About 30 proteins in blood plasma
- When activated, cause a cascade of biochemical reactions that can lead to lysis
Inflammatory Response
Changes brought about by signaling molecules released upon injury or infection
Histamine
Inflammatory signaling molecule found in connective tissue
Mast Cells
- Densely packed vesicles
- Produce histamine and other molecules that trigger inflammation in response to infection and in allergic reactions
Lymphocytes
- Type of white blood cell
- Mediates immune responses
- Main classes are B cells and T cells
Thymus
- Organ in the thoracic cavity above the heart
- Where T cells mature