Week 1 - Cell Injury and Adaptations Flashcards
Types of growth
Multiplicative, auxetic, accretionary, combined
Multiplicative growth
Increase in number of cells
Auxetic growth
Increased size of individual cells
Accretionary growth
Increase in intracellular tissue components
Tissue growth depends on balance between
Cell proliferation, apoptosis and differentiation
Labile tissue
High regenerative ability & rate of turnover
Stable tissue
Good regenerative ability but usually low turnover rate
Permanent tissue
Limited regenerative ability
Factors affecting differentiation
Genes, hormones, position within fetus, growth factors, matrix proteins
Morphogenesis
Development of the shape and form of organs, limbs, facial features etc from primitive cell masses during embryogenesis
Physiological adaptation
Adaptation that involves a body part’s job of controlling a life process
Types of physiological adaptation
Structural and metabolic
Examples of physiological metabolic adaptation
Mobilise fatty acids from adipose tissue for energy (fasting), mobilise calcium from bone matrix (lack of calcium), liver metabolising drugs
Mechanism of structural physiological adaptation
Increase/decrease in hormonal stimulation or functional demand -> increase/decrease in cell size/number
Pathological adaptation
Modifications that allow the cells to cope with changed conditions, structural and functional change
Hypertrophy
Increase in cell size without cell division
Physiological cardiac hyperthrophy
Characterised by normal organisation of cardiac structure and normal/enhanced cardiac function
Pathological cardiac hypertrophy
Commonly associated with up-regulation of fetal genes, cardiac dysfunction and increased mortality
Hyperplasia
Increase in cell number
Example of physiological hyperplasia
Red blood cells in people living at high blood pressure, breast tissue during puberty, pregnancy and lactation, thyroid hyperplasia due to increased metabolic demands of puberty and pregnancy
Autonomous hyperplasia
Cells proliferate rapidly without a clear stimulus or control mechanism
Examples of pathological hyperplasia
Psioriasis, Paget’s disease, Fibromatosis
Psioriasis
Marked epidermal hyperplasia
Paget’s disease
Hyperplasia of osteoblast/osteoclast => thick but weak bone
Fibromatosis
Proliferation of myofibroblasts
Angiogenesis
New blood vessels grow into damaged tissues to supply oxygen/nutrients for cells
Benign prostatic hyperplasia
Too many cells/increased cell growth in transition zone
Atrophy
Decrease in cell size/number/both
Physiological atrophy
Adaptive response to decrease functional requirement for a cell/organ
Example of pathological atrophy
Immobilised limb -> decreased function -> loss of innervation & decreased blood supply -> decreased oxygen & nutrients
Mechanisms of atrophy
Production and destruction of cellular constituents, reversible restructuring of cell activities to facilitate survival/adapt to conditions of diminished use, decreased protein synthesis, increased protein degradation
Causes of atrophy
Decreased function (disuse atrophy), loss of innervation (denervation atrophy), inadequate blood/O2 supply, pressure atrophy, lack of nutrition, systemic atrophy
Metaplasia
Altered differentiation, mature cell differentiates into another type
Mechanisms of metaplasia
Adaptive response to chronic, persistent injury/altered cellular environment => tissue change structure to better adapt to environment/stress
Can metaplasia be reversed?
Yes, when stimulus to change is removed e.g. stop smoking
Change in respiratory epithelium in smokers
Chronic irritation -> normal respiratory epithelium change to squamous epithelium -> lose functions of mucus secretion & movement
Barrett’s oesophagus
Replacement of normal squamous epithelium in the oesophagus by glandular columnar epitheium
What is general pathology?
Mechanisms and characteristics of principle types of disease processes
What is systemic pathology?
Descriptions of specific diseases as they affect individual organs or organ systems
What does epidemiology study?
Incidence, prevalence, distribution, prevention
What is aetiology?
Cause
What is pathogenesis?
Mechanism causing the disease
What is prognosis?
Likely outcome for patient
What are the causes of disease?
Entirely genetic, multifactorial, entirely environmental => not always linear
What is the latent period?
Time lag after exposure before signs and symptoms appear
What are structural abnormalities?
Space occupying lesions, storage disease, loss of healthy tissue, obstruction, distension or rupture of hollow structure
What are functional abnormalities?
Excessive secretion of cell product, insufficient secretion, impaired neuromuscular function
What does pathognomonic mean?
Absolute diagnostic feature
What is morbidity?
Patient effects
What is mortality?
Rate of death
Why do we study epidemiology?
Providing aetiological clues, planning preventive measures, provision of adequate medical facilities, population screening for early diagnosis
What is incidence rate?
Number of new cases of the disease occurring in a population of defined size during a defined period
What is prevalence rate?
Number of cases of the disease to be found in a defined population at a stated time
What is remission rate?
Proportion of cases of the disease that recover
What is mortality rate?
Number or percentage of deaths from a disease in a defined population
