Causes of disease - microorganisms, physical agents, chemical factors, etc.
Symptoms
Sensation of illness such as pain, nausea and headache experienced by the patient.
Clinical signs
Objective symptoms like diarrhea, fever and coughing which are perceptible to the senses of an observer.
Syndrome
A group of concurrent signs and symptoms of disease.
Pathogenesis
Step by step the process of the development of the lesion/disease.
Sequel
The outcome/consequence of disease.
Prognosis
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.
Congenital anomalies/defects
Diseases which develop during fetal life and are present at birth.
Cell death
That point when cell injury becomes irreversible
Two ways cell death occurs
Necrosis (oncosis, oncotic necrosis)
Apoptosis
Factors that characterize irreversibility
Inability to reverse mitochondrial dysfunction
Profound disturbances in membrane function
Cell injury
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
Hypoxia
Free radical mediation
Chemicals
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.
