|
|
| (43 intermediate revisions by 4 users not shown) |
| Line 1: |
Line 1: |
| − | {{toplink
| + | #REDIRECT[[:Category:Protozoa]] |
| − | |backcolour =
| |
| − | |linkpage =Infectious agents and parasites
| |
| − | |linktext =INFECTIOUS AGENTS AND PARASITES
| |
| − | |pagetype=Bugs
| |
| − | |sublink1=Parasites
| |
| − | |subtext1=PARASITES
| |
| − | }}
| |
| − | | |
| − | ==Introduction==
| |
| − | [[Image:Balanditium.jpg|thumb|right|150px|Balantidium coli - trofozoite and cyst - Wikimedia Commons]]
| |
| − | [[Image:Flagella.jpg|thumb|right|150px|Flagella of ''E.coli'' - Nicolle Rager Fuller, National Science Foundation]] | |
| − | All protozoa are unicellular eukaryotic organisms which store their genetic information in chromosomes in a nuclear envelope. Protozoa are classified depending on their structure and life cycle. This reflects the similarities of the diseases which they cause.
| |
| − | | |
| − | Protozoa usually range from 10μm-50μm but can grow up to 1mm. Thus, they are usually observed and classified using a microscope.
| |
| − | | |
| − | Protozoa multiply sexually, asexually and can also use a combination of both, for example, the coccidia class. Replication can be by binary or multiple fission. Different protozoa use different forms of motility, including flagella, cilia, pseudopodia and gliding.
| |
| − | | |
| − | ==Structure and function==
| |
| − | | |
| − | *Motile
| |
| − | | |
| − | *Organelles and otehr cellular structures enable the protozoa to lead an '''independent exsistence'''
| |
| − | | |
| − | *Cilia
| |
| − | **Fine, short hairs covering the protozoal surface
| |
| − | **Hairs beat in unison to enable the protozoa to move
| |
| − | **Wafts food towards the cytostome (mouth opening)
| |
| − | **E.g. ''Balantidium''
| |
| − | | |
| − | *Flagellum
| |
| − | **Contractile fibre
| |
| − | **Contracts in a whip like motion to propel protozoa
| |
| − | **Attached to body of protozoa by an '''undulating membrane'''
| |
| − | **E.g. ''Trypanosoma''
| |
| − | | |
| − | *Pseudopodia
| |
| − | **Extensions of the cellular cytoplasm
| |
| − | **Cytoplasm flows into the pseudopodia allowing movement of the protozoa
| |
| − | **Also acts in a phagocytic manner surrounding food particles and enclosing it in a vacuole
| |
| − | **E.g. ''Entamoeba''
| |
| − | | |
| − | *Gliding
| |
| − | **No obvious means of locomotion
| |
| − | **E.g. ''Eimeria''
| |
| − | | |
| − | ==Nutrition and digestion==
| |
| − | [[Image:Pinocytosis.jpg|thumb|right|150px|Pinocytosis - Mariana Ruiz Villarreal]]
| |
| − | *Pinocytosis
| |
| − | **Droplets of fluid taken into the cell
| |
| − | **Generates small vesicles
| |
| − | **Usually used for extracellular fluid ingestion
| |
| − | **Requires ATP
| |
| − | | |
| − | *Phagocytosis
| |
| − | **Larger particles of matter taken into the cell
| |
| − | **Usually solid particles ingested
| |
| − | | |
| − | *Cell membrane envelops the fluid or food taking it into the cell
| |
| − | | |
| − | *Lysosomes fuse with the fluid/food initiating digestion
| |
| − | | |
| − | *Diffusion through the cell membrane allows excretion of metabolic products
| |
| − | | |
| − | ==Life Cycle==
| |
| − | | |
| − | *Most protzoal reproduction is asexual using binary fission, schizogony and sporogony
| |
| − | | |
| − | *Some protozoa also use sexual reproduction called gametogony
| |
| − | | |
| − | *In some species, sexual and asexual reproduction occurs in the same host, whilst in others asexual reproduction occurs in the vertebrate host and sexual reproduction in the arthropod vector
| |
| − | | |
| − | *Homogenous
| |
| − | **Parasite uses a single host species during its life cycle (direct)
| |
| − | **E.g. ''Eimeria''
| |
| − | | |
| − | *Heteroxenous
| |
| − | **Parasite uses more than one host during its life cycle (indirect)
| |
| − | **E.g. ''Trypanosomes''
| |
| − | | |
| − | *Facultatively heteroxenous
| |
| − | **Parasite '''may''' use more than one host during its life cycle but this is not essential
| |
| − | **E.g. ''Toxoplasma gondii''
| |
| − | | |
| − | ===Example Coccidian Life Cycle===
| |
| − | ''The following refers specifically to the life cycle of Coccidia spp.''
| |
| − | | |
| − | ==Protozoa of Veterinary Importance==
| |
| − | | |
| − | [[Coccidia]]
| |
| − | | |
| − | [[Tissue cyst-forming coccidia]]
| |
| − | | |
| − | [[Piroplasmida]]
| |
| − | | |
| − | [[Cryptosporidium]]
| |
| − | | |
| − | [[Babesia]]
| |
| − | | |
| − | | |
| − | ''Leishmania'' involved in [[Parasitic skin infections - Pathology#Protozoa|skin infections]]
| |