Pathogenesis, Biology

Assignment Help:

The interactions between the human host and selected microorganisms that culminate in IE involve the vascular endothelium, hemostatic mechanisms, the host immune system, gross anatomic abnormalities in the heart, surface properties of microorganisms, and peripheral events that initiate bacteremia. Endothelial damage results in platelet-fibrin deposition, which in turn is more receptive to colonization by bacteria than is the intact endothelium. It is hypothesized that platelet-fibrin deposition occurs spontaneously in persons vulnerable to endocarditis and that these deposits, called nonbacterial thrombotic endocarditis (NBTE) are the sites at which micro organisms adhere during bacteremia to initiate IE. Bacteremia is the initiating event that ultimately converts NBTE to IE.  Bacteremia rates are highest for events that traumatize the oral mucosa, particularly the gingiva, and progressively decrease with procedures involving the genitourinary tract and the gastrointestinal tract.

The platelet-thrombin deposits are found at the valve closure-contact line on the atrial surfaces of the mitral and tricuspid valves and on the ventricular surfaces of the aortic and pulmonic valves, the sites of infected vegetations in patients with IE. Three hemodynamic circumstances may injure the endothelium, initiating NBTE: (1) a high velocity jet impacting endothelium (2) flow from a high to a low pressure chamber and (3) flow across a narrow orifice at high velocity.  Flow through a narrowed orifice, as a consequence of venturi's effect, deposits bacteria maximally at the low-pressure sink immediately beyond an orifice or at the site where a jet stream impacts a surface.

To cause IE, the organism must be able to persist and propagate on the endothelium. This requires resistance to host defenses. The complement-mediated bactericidal activity of serum limits the ability of susceptible aerobic gram-negative bacilli to cause IE. Those organisms that most frequently cause endocarditis adhere more vigorously in vitro to cardiac valves than do organisms that rarely cause IE.


Related Discussions:- Pathogenesis

Which type neurons work for spinal arch reflex, Q. Which are the kinds of n...

Q. Which are the kinds of neurons that participate in the spinal arch reflex? Where are their cell bodies situated? In the arch reflex first a sensory neuron located in the gan

Magnitude of healthcare needs, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Acid hydrolysis of non-reducing sugar, Q. Acid Hydrolysis of Non-Reducing S...

Q. Acid Hydrolysis of Non-Reducing Sugar? It involves the acid hydrolysis of non-reducing sugars to reducing sugars. It is also known as the process of inversion. Acid hydrolys

Define the absorption of vitamin a, Define the Absorption of Vitamin A? ...

Define the Absorption of Vitamin A? Vitamin A and carotenoid tend to aggregate with lipids into globules, which then pass into the small intestine. Dietary vitamin A (retinol)

#nervous system, 6. What is the function of the myelin sheath? Do all axons...

6. What is the function of the myelin sheath? Do all axons present a myelin sheath?

Explain risk assessment, Explain Risk Assessment Risk Assessment   :  ...

Explain Risk Assessment Risk Assessment   :  The scientific evaluation  of  known  or  potential adverse  health effects  resulting  from  human exposure to food borne hazards

Explain phylogenetically proximal species, Q. Do the phylogenetically proxi...

Q. Do the phylogenetically proximal species have cells with proximal chromosome counts? The number of chromosomes typical of each species is proximal for phylogenetically proxi

Loudness, The sound levels of power, intensity and pressure are the physica...

The sound levels of power, intensity and pressure are the physical effects which the human ear receives, it is not, however, what the person perceives. What is being perceived or h

Sperm which determines the sex of the offspring, a) In humans, is it the sp...

a) In humans, is it the sperm or the ovum which verifies the sex of the offspring? b) Give a reason for your answer.   (a) The sperm verifies the sex of the off

Integrated approach plus mastering, I recently rented Physiology, An Integr...

I recently rented Physiology, An Integrated Approach and I was looking online because I have to also get the A&P access code and realize I could have rented it too with my book. Is

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd