- Causes of disease - microorganisms, physical agents, chemical factors, etc.
Sensation of illness such as pain, nausea and headache experienced by the patient.
Objective symptoms like diarrhea, fever and coughing which are perceptible to the senses of an observer.
A group of concurrent signs and symptoms of disease.
Step by step the process of the development of the lesion/disease.
The outcome/consequence of disease.
Statement of what the expected outcome of a condition is likely to be (good, guarded, poor/grave).
The two general causes of disease
Genetic or acquired
What is the cause of genetically determined disease and when does it manifest?
- Due to some abnormality of base sequence in the DNA of the fertilized ovum and the cells derived from it.
- It is inherited but will not necessarily manifest at birth, can manifest later in life.
Diseases which develop during fetal life and are present at birth.
That point when cell injury becomes irreversible
Two ways cell death occurs
- Necrosis (oncosis, oncotic necrosis)
Factors that characterize irreversibility
- Inability to reverse mitochondrial dysfunction
- Profound disturbances in membrane function
- Any biochemical or structural alteration that impairs the normal functional ability of the cell.
- May be mild, transient or reversible.
- May become irreversible.
Examples of cuases of cell injury
- Free radical mediation
Mechanisms of reversible cell injury
- Reducing ATP production -> ATPase in cell membrane decreased -> "sodium pump" failure -> Sodium is retained in the cell, water follows, causing acute cell swelling
- When oxygen levels are low, oxidative phosphorylation ceases and cells rely on glycolysis -> accumulation of lactic acid, lowering the pH of the cell
- Detachment of ribosomes from rough ER -> stoppage or lowering of protein synthesis -> accumulation of lipid in the cell
- If hypoxia continues -> increased membrane permeability and diminished mitochondrial function
What are effects of free radicals?
- Lipid peroxidation of membrances resulting in extensive membrane, organellar and cellular damage (permeability of cell membrane)
- Lesions in the DNA
- Cross linking of proteins
How are free radicals created?
- Absorption of radiant energy (x-ray, UV light)
- Reduction-oxidation reactions during normal physiologic processes
- Derived from enzymatic metabolism of exogenous chemicals
- Released by phagocytic cells in inflammation
3 ways chemicals can induce injury
- Binding to cell membrane causing increased membrane permeability and inhibition of ATPase dependent transport.
- Direct cytotoxic effects.
- Reactive free radicals.
What are the causes of acute cellular swelling?
- Loss of blood supply
- Toxins - bacterial, viral, fungal and poisons
- Mechanical injury
- Immune mechanism dysfunction