Pathology Flashcards
Define pathology.
Normal physiological processes in healthy tissues start to go wrong, there is altered function and structure of cells, tissues and organs beyond the physiological range. These changes are a state of disease and so pathology is the study of these changes/of disease.
List the typical events in the development of a disease.
- Stimulus
- Cellular injury or altered demand
- Cellular response
- Structural and functional changes
- Clinical signs
Define stimulus.
Stimulus – something that causes a reaction or a change in cells. When these changes are outside of physiological range, this is recognised as disease.
Define aetiology/aetiological agents.
The cause of disease. Very broad and includes large groups such as:
- Infectious agents
- Physical forces – trauma, heat/cold, chemicals and toxins
- Immunological factors
- Nutritional factors
- Genetic abnormalities
All of these cause disease by causing a stimulus to a cell.
What is cellular injury and altered demand?
Cellular injury can arise through a variety of different mechanisms or may alter the demand and work load of the cell.
What is cellular response?
The cell will respond in some form and may involve signalling toother cells to try and recruit their help in part of the wider host response to injury or the aetiological agent.
- Degeneration, including cell detah
- Altered growth or differentiation (non-neoplastic)
- Inflammation and healing
- Blood flow and circulatory changes
- Neoplasia
When do clinical signs develop in disease?
Could be at the level of the cell, tissue or organ. Depending on which, we may need a form of a biochemical test in order to detect them, such as microscopic analysis and inspection of tissues/histological examination, or even imaging at a gross level.
It is these changes that cause the clinical signs of disease.
What is aetiopathogenesis?
The events that occurs over time during the development and evolution of a disease are known together as the pathogenesis of the disease. And if the cause is known, the aetiology and the pathogenesis can be combined together to discuss the aetiopathogenesis, the cause and the way in which it develops and changes over time.
Why is understanding aetiopathogenesis important?
- Explain the clinical signs observed in patients
- Allows you to make a list of differential diagnosis – possible diseases that may cause the functional and morphological changes and clinical signs
- And decide which diagnostic tests are required to make a definitive diagnosis
- Helps predict the prognosis
- Provides the basis for treatment, control and prevention of disease
List 3 general pathological processes that may occur in different diseases.
Cell death, non-neoplastic alterations in growth or differentiation, inflammation and healing, blood flow and circulatory changes, and neoplasia.
Define congenital malformation.
Structural, functional, metabolic or behavioural disorder that occur during intrauterine life and are present at birth, some of which may not be apparent until later in life.
What are the possible causes of congenital malformations?
Genetic errors – inherited or acquired, single or multiple gene mutations or at the level of the chromosome. Chromosomal abnormalities can either be structural or numerical in tehir nature, forming in meiosis.
Environmental factors – a large number of agents:
- Infectious agents: Schmallenberg virus, border disease virus, bovine viral diarrhoea virus and feline parvovirus
- Nutritional deficiencies: copper, iodine, vitamin A
- Chemicals, drugs, toxins and hormones – so be careful when treating pregnant animals
- Physical: trauma, abnormal pressures in uterus from malpositions, ionising radiations from X-rays, heat from incubation
Define teratogens?
Foreign agents that interfere with normal development in the embryo or foetus giving rise to congenital malformations.
What factors can influence whether a teratogen will cause congenital malformation?
- Agent factors: dose, frequency of exposure, route of exposure
- Species factor: species susceptibility
- Maternal factors: genetic makeup and metabolism
- Embryo/foetus: stage of development, genetic makeup and metabolism. This is the most critical factor.
What are the 3 stages within embryonic development and their sensitivities to teratogenic agents?
- Embryonic period, organogenesis (organs created from germ cell layers) has the highest sensitivity to teratogenic agents. Injury at this time may result in death and abortion, or major morphological abnormality in 1 or more organs.
- Foetal period, histogenesis and functional maturation (growth and maturation of organs) has a lower sensitivity to teratogenic agents. Injury at this time may result in death and abortion, or growth retardation or minor morphological abnormalities of organs.
- Organs develop at different times during these periods and so each organs has its own sensitivity.
