Parasitism Flashcards
What is a realised niche
occupied in response to interspecific competition
What is competitive exclusion
when niches of 2 species is so similar one declines into LOCAL extinction
What does a parasite do
gains benefit in terms of nutrients at the expense of its host
What kind of niche does a parasite have and why
narrow (specialised) niche
they are very host specific only affecting a small no of host specific
Where are ectoparasites found
lives on surface of host
Where are endoparasites found
live within tissues of host
What is a definitive host
the organism in which the parasite reaches sexual maturity
What is an intermediate host
required for a parasite to complete it’s life cycle
no sexual stuff (haha sex)
What is a vector
plays an active role in the transmission of a parasite
What is malaria caused by
plasmodium
How do mosquitos infect humans
bite human
plasmodium enters bloodstream
asexual reproduction occurs in liver and rbc
rbc bursts and gametocytes released into blood
mosquito bites infected human and gametes enter mosquito
gametes rmature into male and female
sexual reproduction occurs
How is schistosomiasis caused
schistosomes are parasitic worms that reproduce sexually in intestines
fertilised eggs pooped into water where they turn into larvae
larvae infects water snails and asexual reproduction occurs
motile larvae produced which escapes snail and enters water
motile larvae penetrates skin entering bloodstream
Virus definition
parasites that only replicate inside a host cell
What do viruses contain
genetic material either in form DNA or RNA
What is a virus composed of
surrounded by phospholipid membrane
antigens that the host may not be able to detect is foreign
Viral cycle lyfe stages
host cell infected with genetic material of virus
Host cell enzymes replicate viral genome
viral genes transcribed
translation occurs producing viral proteins
viral proteins assembled and released to infect further host cells or additional hosts
What do RNA retroviruses do
injects RNA and reverse transcriptase which is used to form DNA in host cells
-inserted into genome of host cells
How are ectoparasites transmitted
through direct contact
how are endoparasites transmitted
through vectors or consumption of intermediate hosts
What is virulence
harm caused to the host by a parasite
Describe how endoparasites are transmitted.
Endoparasites of the body tissues are often transmitted by vectors or by consumption of intermediate hosts.
Explain factors that increase transmission rates of endoparasites.
overcrowding of hosts at high density
vectors and waterborne dispersal stages
-allows the parasite to spread even if infected hosts are incapacitated.
How do parasites exploit host behavior for transmission?
Parasites often exploit and modify host behavior to maximize transmission, making the host behavior part of the extended phenotype of the parasite.
Define the impact of parasites on host immune systems.
Parasites often suppress the host immune system, modifying host size and reproductive rate in ways that benefit the parasite’s growth, reproduction, or transmission.
Do overcrowding conditions affect endoparasite transmission?
Yes, overcrowding of hosts at high density increases transmission rates of endoparasites.
Explain the role of vectors in the life cycle of endoparasites.
allows them to spread even when infected hosts are incapacitated.
Describe the relationship between host behavior and parasite transmission.
Host behavior can be exploited and modified by parasites, which can enhance the likelihood of transmission.
How do parasites influence host reproductive rates?
Parasites can modify host reproductive rates in ways that benefit their own growth and transmission.
What are the two aspects of the immune response in mammals?
Non-specific
Specific
What are examples of non-specific defences?
Physical barriers
Chemical secretions
Inflammatory response
Phagocytes
Natural killer cells
What do cytokines do when tissues are damaged?
They increase blood flow, attracting white blood cells to the site of infection or tissue damage.
What are lymphocytes?
White blood cells that monitor tissues for pathogens.
What happens when an antigen binds to a lymphocyte’s receptor?
The lymphocyte is selected to divide and produce a clonal population.
What do some selected lymphocytes produce?
Antibodies
Induce apoptosis in infected cells
What is the role of the variable region in antibodies?
It provides specificity for binding to antigens.
What can the antigen-antibody complex result in?
Cell lysis stimulation
Inactivation of the parasite
Susceptibility to phagocytes
How do endoparasites evade the immune system?
Mimic host antigens
Modify host immune response
What is antigenic variation in parasites?
Allows change between different antigens during infection
What is the herd immunity threshold?
Density of resistant hosts needed to prevent an epidemic
What do vaccines contain?
Antigens that elicit an immune response
What is a challenge in finding drugs for parasites?
Similarities between host and parasite metabolism
What is the role of latency in viruses?
Integrate genome into host, remain inactive until conditions favor activation
What makes vaccine design challenging for some parasites?
Difficult to culture in the laboratory
What are effective control strategies for parasites?
Civil engineering for improving sanitation
Coordinated vector control
How does parasite control impact child development?
Reduces child mortality and improves intelligence growth and deelopment
