topic 2: pathology Flashcards
what are the different types of pathogen
bacteria
fungi
yeast
parasites
virus
protozoa
prions
what are the (special) structures of a bac
-capsule
-plasmids
-pilli
what is the function of pilus
(its a hair life structure)
function: help in adhesion to surface or other cells
sex pilus (specific type of pilus, only a few on a bac) : involved in exchange of genetic material during conjugation
function of capsule
caosule: production of a thick geletenous outlater outside cell wall
-made of polysaccharide proteins
function: protection agains
-phagocytosis by host immune cells
-desication (loss of water)
-help bacteria adgere to surfaces and invade immune responses
what is plasmid and its functions
plasmid: small circular DNA molecules that seprarate from bac chromosme.
function: carry additional gene that provides afv to 1. antibody resistance and 2. virulence factors (enable to cause disease)
plasmid can be trasferred between bac during conjugation -> genetic diversity anf adaptability
how can bac be classified into
- affinity to gram stain
gram positive bac: thick peptidoglycan layer retains purple colour of gram stain
gram negative: thin petidoglycan and has outer memberane made of lipopolysaccharides (LPS) -> more restsiant to antibodies
- predominant tissue effect
-pyogenic (produce pus-> attract leukocytes)
-toxigenic: secrete toxins that cause disease
-intracellular- replicates inside macrophage and host cells
what is fungi characterised as (U see this means its fungi)
vegetable struncture known as hyphae (branches)
what is the cell wall of fungi made of and its function
- made of chitin
structure : half flexible, water insouble polysaccharide
fucntion: give fungi structural integrity
protect them from environmental stress (eg harsh weather)
-play a role in fungi ability to grow and reporduce
what are fungi (cannot make theri own food) and how does it hahppen
heterotrophic (fungi produce enzymes that bread down complex organic matter into simpler compounds-> ontain energy)
what are the two ways fungi obtain nutrients
- saprophytic ( decomposer that feed on dead.decayed matter. how? they break down the dead plants/animals-> return nutrients back into ecosystem
- parasiticism; fungi obtain nutrient from living host cellshow? invade host cells-> abdorb nutrient directly ftom it-> disease causing
different types of parasites
-live in host (endoparasite) or on (ectoparasite) rely on host for nutrients and to reproduce themselves
what is protozoa and what is the type of rls they have with host when inside
unicellular eukaryotic organisms
mostly free living, but some lead to commensalistic (benefit, no harm to host), mutualistic (both benefit) or parasitic (protozoa benefit, host harm) exiistance
why do virus rely on host
mature infectious partilces are known as virions
-vririons do not contain ribosomes-> cannot synthesize protein-> rly on cellular organelles of the host to reporduce. host celluluar organells get replaced with viral proteins and its strucutre to form new virions
what are prions and its effect on other cells
-misfolden proteins
-associated with neurodegenerative diseased in human and animals
able to vnvert normal molecules of protien into abnormal strucutre
what are the different modes of diseases transmission
DAFOV
direct (physical contact through wounds/bodily fluid)
Aerosoles (droplets in close proximity)
Formites (contaminated inanimate objects)
Oral (ingestion of pathogenic agent)
Vector-borne ( insect aquire pathogen from one animal-> transfer to another)
what is pathology
- is a branch of medical science- stusy of the cuases of the diseases, how they develope and their effects on the body
aetiology
cause/origin of disease
pathogenesis
process/mechanism of disease developement
causes: structural changes in cells, tissues, organs
- functional changes → signs and symptoms
importance of pathology
Disease diagnosis
* Identify the causative agents
* Aids in treatment of patients
* Can be beneficial to human health too (eg. Zoonotic diseases)
* Research
* Understand animal disease better (progression
of diseases, transmission, mode of action,
pathways etc.,)
* Helps pharmaceutical research (develop drug
and treatment methods etc.,
what does general pathology refer to
The study of the basic mechanisms of disease, with emphasis on aetiology and
pathogenesis)
* No limiting discussion to a particular organ/ tissue.
* Eg. Inflammation (response of cell to injury )
general/basic/no specific organ
what is systemic pathology
Study of general pathology processes
* including special reference to specific tissue/ organ.
* involves aetiology, pathogenesis, epidemiology, macro- and microscopic appearance,
specific diagnostic features, natural history and sequelae (consequence of previous
disease/ injury).
* Eg. Dermatitis (inflammation in the skin
Describe the branches of pathology.
Anatomic Pathology
* A medical specialty that is concerned with the diagnosis of disease based
on the macroscopic, microscopic, biochemical, immunologic and molecular
examination of organs and tissues. (organ and tissues-mre deeper/smaller)
* For example, Histopathology; Fine Needle Aspiration, Autopsy
Clinical Pathology
* Supports the diagnosis of disease using laboratory testing of blood, urine
and other bodily fluids, tissues, and microscopic evaluation of individual
cells. (bodily fluids)
* For example, Hematopathology
classification of aetiologival agents (cause/ornigin)
1.internal factors (they already have it) CGIA
-chromosome abdnormalities (extra chromosomes)
-gene abnormalities (mutations, deletion )
-immune system (abnormal/defect)
age (natural process/premature aging)
- external factors PICE
-Physical agents – trauma, mechanical agents, radiation, heat, cold,
electrical
-infectious agents – bacteria, virus, parasites; protozoa, helminths,
arthropods, fungal
-Chemical agents – poison, toxin, acid, alkali
*-Environmental – Nutrition (deficiency or excess of nutrients)
Temperature
Hygiene
Radiation (UV light
effect of aetiology on diseases causing
- One aetiology causing one disease( Canine Distemper, Salmonellosis)
2.One aetiology causing many diseases
( Canine hyperadrenocorticism (cushings) → bacterial dermatitis; diabetes mellitus; hepatopathy; thromboembolism;)
3.Many aetiologies causing one disease
* Excess intake of sugar, lack of insulin, obesity → diabetes mellitus
3. Describe appropriate terminology in relation to
disease conditions.
Explain the differences between infectious and non-
infectious diseases.
Examples of Infectious (caused by pathogen, susceptable to transmission)
Diseases in Companion Animals
* Canine distemper virus (CDV)
* Canine parvovirus (CPV)
* Feline calicivirus (FCV)
* Feline herpesvirus (FHV)
Examples of Non-infectious Diseases (not casued by pathogen. lifestyle choces)
in Companion Animals
* Obesity
* Cardiac diseases
* Osteoarthritis
* Corneal Ulcers
host -orgnaism rls
they have a symbiotic rls- interaction/close living rls between organism of different species
Types of symbiosis
-Mutualism- both organisms benefit (Eg. Plants and pollinators (eg. Bees, bats, birds)
- Commensalism- one organism benefits, with neither harm nor benefit to the other
(Eg. Barnacles adhere to the skin of whales)
-Parasitism- The parasite benefits while causing harm to the host (Eg. Flea infestations)
Factors determining likelihood of contracting a disease
The animal:
* Health
* Immunity status
The pathogen
* Virulence- how toxic and invasive
criteria for pathogenicity (ability of infectious agent to cause disease) tell me about koch’s postulates
and the limitation on his postulates
his exp purpose: list of criteria to determine is an organism in the aetiological agent (causes the disease)
his exp:
➢ Agent must be isolated from every patient with the disease (prevent spread)
➢ Agent should be isolated from such disease and propagated serially in pure
culture, apart from its natural host (
➢ Upon introduction into an experimental host, the isolate produces the original
disease
➢ Agent can be re-isolated from this experimental infection
limitation:
If an organism cannot be grown in pure culture (some cannot grow outside host
* If there is no animal model for that organism (some only grow in humans)
* If the organism has gained virulence making it pathogenic
* If there is subclinical infection (doesnt show systoms despite being infected)
* If the organism affects an immunocompromised patient (may not be harmful in normal humans)
* It gains access to deep tissues via trauma, surgery, an IV line, etc. (for some, then only it becomes pathogenic)
- Elements in the production of infectious disease
1.Effective transmission: Modes, routes
- Attachment to host surface
Eg. Bacterial adhesins + host receptor
Prevented:
- by normal flora
- Mucosal antibody, other antibacterial
substance eg. lysozyme - Evasion of host defenses
❖Firm attachment
❖Repulsion of macrophages
❖Prevention of phagocytic digestion by capsules/cell walls - Dissemination (spreading)
❖Via blood, lymph, bronchial tree, bile ducts, nerve trunks, mobile
phagocytes
❖Direct extension into surrounding tissue with aid of bacterial
enzymes such as collagenase, hyaluronidase - Growth
❖Use host resources (nutients)
❖Create suitable microenvironment for its own benefit, including
temperature, pH, oxygen concentration, absorption of required
minerals like Fe (from heamoglobin in blood)
Host responses to infectious agents
physical barriers, chemical barriers
phagocytosis, natural killer cells
fever
acute inflammation
complement cascade
humoral immunity
cell mediated immunity
how sucessful infection can im=npact/har host
Endotoxin release (when bac break down-release LPS-endotoxin)
❖Trigger release of cytokines which cause fever, inflammation, hemorrhage
Exotoxins destroy cells and cellular contents (proteins released by bac)
❖Eg. Hemolysin, collagenase, hyaluronidases
❖Enter cell and disrupt biochemical reactions
- Viruses
❖Alter cell function & structure, destroy cells eg. Canine distemper virus,
feline panleukopenia virus destroy lymphocytes
❖Tumour formation - Parasites
❖Physical damage, interfere with normal function
