4. Inflammatory responses- vasodilation and increased capillary permeability with resulting migration of phagocytic cells
Constitutive defense: non-specific; directed toward general defense; provide general protection against invasion, colonization, infection, etc; may not be sufficient to protect against pathogens
AKA natural/innate resistance
Inducible defense: specific; must be induced or turned on by host exposed to pathogen; are not immediately available after exposure
Define: immune, immunity, acquired immunity
Immune: the ability to resist infectious disease
Immunity: relative state of resistance of the host to a specific pathogen
Acquired immunity: inducible defenses that take time to develop after exposure.
Active immunity vs. passive immunity
Active immunity: the host undergoes an immunological response and produces cells/factors responsible for the immunity.
This immunity can persist a long time in the host (vaccines)
eg. host produces its own Abs and/or lymphocytes.
Passive immunity: the host acquires immune factors which were produced in another animal
eg. no time for vaccination, direct injection required
This immunity is short-lived (anti-venom)
Describe antigens and antibodies. Give details
Antigen: chemical substances that stimulate the immune system in animals
antigenic macromolecules (usually proteins) are present on parasites
Antibody: Protein synthesized by WBC in response to a foreign substance (At)
Can directly destroy, make easier for WBC to destroy, etc.
Antibodies and Antigens interact to form an Ab-At complex
*NOTE- Parasites can camouflage themselves to avoid antibody reactions
What is molecular mimicry? Give specific examples.
Molecular mimicry: parasite produces host-like molecules on its surface (or covers itself with host molecules) and is accepted as a host cell.
Trypanosoma- consistently express a new version of glycoprotein coat (VSG) (1/1000 at a time)
Plasmodium- resides in RBC and synthesizes proteins that appear on the RBC surface causing the RBC to anchor to the walls of the blood vessel. This prevents the infected cell from entering and being processed by the spleen.
Flukes- alter the behavior of their intermediate hosts in ways that increase their chances of moving on to a new definitive host (increased snail movement to attract birds)
What are the three types of destruction to host tissue w/ detail?
Necrosis: degeneration and death of cells or tissues from infection; tissues have opaque appearance.
encystment and calcification of Trichinella spiralis larvae in mammalian muscle cause tissue necrosis.
Fatty degeneration: this condition results in deposition of abnormal amounts of fat in cells. This type of degeneration imparts a yellowish color to the cells and is common among parasite-laden liver cells.
Albuminous degeneration: this condition results in swollen cells packed with albumin/fatty granules, indistinct nuclei, and pale cytoplasm. Affected organs can include liver, heart muscle, kidneys, etc
Define tissue transformation. What are the four types w/ examples?
Tissue transformation: parasites lead to changes in the growth pattern of the affected tissue
Hyperplasia: body repair activity follows shortly after parasitic infection and the resulting inflammation, Increased cell metabolism leads to increased cell division
eg. Liver fluke Fasciola promotes bile duct's thickening due to excessive division of the epithelial cells
Hypertrophy: an increase in cell or organ size due to presence of intracellular parasites
Plasmodium causes enlargement of the host's parasitized red blood cells and the spleen
Metaplasia: tissue conversion/transformation from 1 type to another
eg. Lung fluke Paragonimus converts lung tissue into fibroblast
Neoplasia: refers to abnormal cell growth in a tissue, forming a new structure (tumor).
benign if localized ith no invasion of adjacent tissues
malignant if invades adjacent tissues or metastasizes.
eg. Blood fluke Schistosoma may cause cancer of the urinary bladder.