Lecture 1: Introduction Flashcards
What is a disease?
Any state in which the health of the human organisms is impaired. Disease is a consequence of a failure of homeostasis.
Homeostasis
the biological process that maintains a physiological steady state.
what is meant by “steady state” in homeostasis
Maintaining an appropriate steady state of the internal environment despite changes in the external environment.
Why is homeostasis usually desirable?
Allows consistency (constancy) in function of organs, tissues, cells, organelles, proteins.
Pathogenesis…
Biological mechanisms causing evident disease
Aetiology…
the specific cause of a disease
Predisposition…
A susceptibility or tendency to develop a disease, which depends on other risk factors to become clinically evident.
Risk factor…
A risk factor is a variable exposure or biological characteristic which makes a disease more likely
Genotype & Environment–>
Phenotype
Phenotype…
a physical or behavioural characteristic
Genotype…
the inherited, genetic constitution of an organism
Environment…
food availability, predators, competitors, climate, mate choice, environmental toxins, drugs
intrinsic =
natural
Genetic disease caused by intrinsic factor:
Sickle cell disease, CF
Metabolic disease caused by intrinsic factor:
Diabetes, gallstones
Cellular disease caused by intrinsic factor:
Autoimmune e.g. rheumatoid arthritis. Degenerative & raging e.g. Alzheimer’s
Structural disease caused by intrinsic factor:
Congenital e.g. spina bifida, Epstein’s anomaly
Acquired e.g. atheroma, osteoarthritis
Physical disease caused by extrinsic factor: (agent + Example)
Agent: Trauma, Radiation, Temperature.
Example: Bone Fracture, Cancer, Burns/Frostbithe (respectively)
Chemical disease caused by extrinsic factor: (agent + Example)
Agent: Toxic substances, Inflammatory agents. Example: Tobacco lung damage, Asthma
Biological disease caused by extrinsic factor: (agent + Example)
Agent: Bacterial, Virus, Fungi & Parasites.
Example: Various infections, AIDs, hepatitis, Athletes foot
Nutritional disease caused by extrinsic factor: (agent + Example)
Agent: Various
Example: Malnutrition
List diseases (CF, diabetes, traumatic head injury, breast cancer) from most affected by genetic factors to those affected by environmental factors
(Genetic) CF, diabetes, breast cancer, traumatic head injury (environmental)
Disability Adjusted Life Years (DALYs)…
the sum of years of potential life lost due to premature mortality and the years of productive life lost due to disability.
e.g of disease pathogenesis (skin abscess) steps.
Aetiology - artiologic agent e.g. bacterium
Pathogenesis - pathogenic mechanism
Morphological and functional features - pathological process
Complications and sequelae - Overt disease ad secondary consequences
Pathologic changes: What are the specific changes in function and structure that characterise each disease?
- Gross/macroscopic changes in organs
- Light microscopic level
- Electron- microscopic (EM) level
- Molecular level
What are the manifestations of disease?
the functional consequences of the morphologic changes that occur in the disease process
How would you detect manifestations of disease?
Clinical signs and symptoms tests may be needed such as -examination of urine/blood - X-ray, ultrasound, nuclear medicine - Examination of tissue samples (biopsies)
Pathobiology…
how does the disease process PRODUCE the morphologic changes?
Understanding the pathogenetic mechanisms…
provides the knowledge base for rational development and evaluation of interventions to PREVENT OR TREAT disease
To understand disease we need to:
- Understand the process for maintaining homeostasis
- Identify the agents and events that disrupt homeostasis
- Understand why homeostasis fails
- Understand the sequence of events that causes the development of a disease state
- Then we can evaluate the effectiveness and mechanisms of action
