Pathology Flashcards
Define: Disease
Structural and/or functional disorder of the body which results in the development of discernible signs called symptoms.
(infectious disease) A physiologically impaired state resulting from microbial infection, microbial products or microbial activity.
Define: Pathogenicity
The ability of microorganisms to cause disease in the host on infection
Define: Infections
Growth of microorganisms within host tissues
Define: Pathogen
Organisms capable of causing disease.
Define: Host
Organisms on or in which parasitic organisms live.
Define: Parasite
Organisms that live on the body or in the tissue of another living organism, the host from which they obtain nutrients.
Define: Parasitism
Relationship of the parasite with their respective hosts.
Define: Pathogenesis
The series of events for the proper establishment of a pathogen in host cells/tissues.
Define: Endemic disease
Commonly occuring disease in a certain area
Define: Epidemic
Disease spread rapidly among many people.
Define: Pandemic
Diseases spread across the world.
Define: Epidemology
The science that deals with occurence, determination, distribution and control of diseases.
Define: Toxigenicity
Ability of microorganisms to cause toxins that disrupts normal function of cells.
Name some body sites inhabited by Staphylococcus
Skin
Eye
Genitourinary tract
Name some body sites inhabited by Lactobacillus
Gastrointestinal tract
Genitourinary tract
Small intestine
Large intestine
Name some body sites inhabited by Corynebacterium
Eye
Upper respiratory tract
Small intestine
Genitourinary tract
Name some body sites inhabited by Yeast
Tongue and buccal mucosa
Stomach
Site some examples of commensals infecting the host to cause disease when the host resistance drops.
Streptococcus aureus is commensal on skin which causes skin boils, acne when immunity is weak.
Streptococcus pneumoniae is a commensal of upper respiratory tract which moves to lower respiratory tract to cause pneumonia when it becomes a pathogen.
Escherichia coli lives as a commensal in large intestine but becomes a pathogen when it comes to the genitourinary tract.
What are the 2 factors which affect to cause a disease?
- Microbial virulence
2. Resistance of the host
Give an example of a microorganism that is less virulent?
E.coli
Give an example of a microorganism that is more virulent
Chicken pox virus
Virulence of a microorganism depends on 2 factors.What are they?
- Invasiveness
2. Intoxication
What is invasiveness?
Ability to invade human cells and tissues and to multiply within the tissues.
What are the 3 events of invasion of microorganism?
- Attachment and colonization
- Entry of the pathogen.
- Growth and multiplication of the pathogen
What are the ways in which pathogens enter deeper into epithelium after attaching to the surface of epithelium?
- Producing lytic substances and dissolving host tisues.
- Disrupting the cell surface.
3 Degrading carbohydrate protein complex between the cells.
Name 3 extracellular enzymes that contribute to invasiveness and state one function of each of these enzymes.
- Phospholipase - destroy (phospholipid component of) animal cell membranes.
- Lecithinase - Hydrolyse the lecithin component of lipid in the cell membrane.
- Hyaluronidase - Destroy body tissues by attacking the hyaluronic acid/cementing substances between cells.
What is toxigenicity?
Ability of microorganisms to produce biochemicals known as toxins that disrupt the normal function of cells.
What is Intoxication?
The condition that develop due to the release of toxins produced by the pathogen.
What is Toxemia?
Conditions resulted from a toxin.
What are the 2 main types of toxins?
- Endotoxins/LPS (lipopolysaccharide) toxins
2. Exotoxins
What are endotoxins?
Thermostable toxins which are part of the microbial cell.
What are exotoxins?
Thermolabile protein toxins, being inactivated by boiling.
Mention some features of endotoxins.
- Present in part of microbial cells such as lipopolysaccharide - protein complex, parts of cell wall of gram -ve bacteria.
- Only released when cell lyses or dies.
- Heat stable
- Not toxoids. Large lethal dosage presents.
Can affect the body in these ways:
1. Cause fever
2. Act as enterotoxins to cause diahorrea
3. Result rashes on skin
4. Due to increasing of the permeability of the blood vessels the host dies due to failing of blood pressure.
Mention some features of exotoxins.
- Water soluble
- Produced by gram +ve and gram -ve bacteria
- Heat labile and most are inactivated at 60 to 80 degrees C
- Small lethal dosage. Can act as toxoids.
- Excretion products of bacteria in some case substances are released upon autolysis and death of bacteria.
- Affect specific tissues.
What are the 3 types of exotoxins?
- Neurotoxins
- Enterotoxins
- Cytotoxins
What are neurotoxins?
Exotonins which interfere with normal transmission of nerve impulses.
Eg: Toxin produced by Clostridium tetani
What are enterotoxins?
Exotoxins which stimulate cells of the gastrointestinal tract in an ebnormal way.
Eg: Toxin produced by Vibrio cholerae
What are cytotoxins?
Exotoxins which kill host cells by enzymatic attack.
Eg: Toxin produced by Corynobacterium diphtheria.
Give some organisms responsible for infection due to production of endotoxins
Salmonella typhi
Give some organisms responsible for infection due to production of neurotoxins.
*Clostridium tetani - Block nerve impulse that permit relaxation of one skeletal muscle which the opposing muscle is contracting.
Clostridium botulinum - Precent transmission of nerve impulses. Flaccid paralysis results.
Give some organisms responsible for infection due to production of Enterotoxins.
*Vibrio cholerae - Includes diarrhea
Staphylococcus aureus
E.coli
Enterotoxigenic Escherichia coli and Shigella spp - Cause traveller’s diarrhea. Cause excessive secretion of ions and water, diarrhea results.
Give some organisms responsible for infection due to production of cytotoxins.
Corynebacterium diptheriae - Inhibit protein synthesis, especially in nerve, heart and kidney cells.
Streptococcus pyogenes - Scarlet fever. Cause vasodilation that results in the characteristic rash.
What are some portals of entry of pathogens into the human body?
- ->Gastrointestinal tract - Shigellosis, cholera, typhoid, hepatitis A, mumps, poliomyelitis
- ->Respiratory tract - diphtheria, measles, chicken pox, small pox, whooping cough.
- ->Genitourinary tract - Gonorrhea, Syphillis
- ->Wounds on skin/parenteral route- Tetanus, plagu, Hepatitis B, Rabies. malaria, yellow fever
What is host resistance?
The properties of healthy host to prevent the entry pf potential pathogens.
What are the 2 types of defense mechanisms?
- Non specific defense mechanism
2. Specific
