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Pathogen invasion is the prime emphasis of this sqadia.com medical V-learning lecture. Starting off with epithelial barriers, breaches in epithelial barrier, mechanism to overcome epithelial barriers, intracellular and extracellular pathogens also comes under debate. Then discussion continues on viral invasion in conjunction with bacterial and parasitic invasion.
Thick covering of skin protects human body from pathogen invasion. Breaches in epithelial barrier such as wounds gives direct access to pathogens. However, primary pathogens do not require wound to gain access. Moving onward, Zain Arfeen discusses epithelium colonizing pathogens. Also, mechanism to overcome epithelial barriers is conversed about.
Intracellular and Extracellular Pathogens
Mechanisms of extracellular pathogens disturb host cells without entering them. Next, Bordetella Pertussis comes under consideration. Enteropathogenic E. coli (EPEC) causes diarrhea in young children and uses type III secretion system rather than exerting its effect through toxins. Mechanisms of intracellular pathogens is also pursued in this section along with advantages of life inside host cell.
Viruses bind to surface receptors and the first virus receptor identified was E. coli surface protein t. Discussion continues on exploitation of cell surface receptors. Some viruses use more than one type for instance HIV-1 uses two types of receptors for entry i.e. primary receptor and co-receptor. Mode of entry of enveloped and non-enveloped viruses is also delineated later on.
Bacterial and Parasitic Invasion
Mechanisms of bacterial invasion is reported in the beginning of this section. Subsequently, zipper mechanism and trigger mechanism are elaborated through diagram. Intracellular eukaryotic parasites invade host cells through a variety of complex pathways. Moreover, comprehensive elucidation is given on Toxoplasma Gondii which protrudes an unusual microtubule-based structure called a conoid and facilitates entry into the host.