Pathology Flashcards
wk 12
what is pathology?
study of structural, biochemical and functional changes in cells, tissues and organs that UNDERLIE DISEASE
What is Aetiology?
Causes of disease
What is pathogenesis?
underlying mechansims of disease
What is morphological changes in terms of pathophysiology?
Structural alterations in cells or tissue = characteristics of disease OR diagnostic of aetiologic process
What are Functional abnormalities in terms of pathophysiology?
End result of genetic, biochemical and structural changes in cells and tissues
What are the five major aspects of disease processes?
Aetiology, Pathogenesis, morphological changes, functional abnormalities and clinical manifestations
What are clinical manifestations in pathology?
Functional consequences of morphological changes and functional abnormalities
When does cell injury occur?
When adaptive capability is exceeded or external stress is inherently harmful.
If stress to the cell is mild and transient what occurs?
reversible cell injury with limits
If stress is severe or persistent what occurs?
Irreversible cell injury
cell death
What can cells do in response to tress and stimuli before cell injury occurs?
Adaption- reversible actions that creates a new steady state to preserve viability and function.
What are the two types of adoptions that our cells can undergo when stress occurs?
Physiological and pathological adaptions
What is an example of a cell response to stress and noxious stimuli?
Myocytes of the heart:
adapt to increase load (hypertrophy)
cell injury: reversibly injury myocyte –> cell death
What are physiological adaptions?
Response to NORMAL stimulation by hormones and endogenous chemical mediators
What are pathological adaptions?
When cells module their structure and function to escape injury
What occurs in pathological hyperplasia
excessive hormonal or growth factor stimulation
What occurs in physiological hyperplasia?
Hormonal or compensatory (part of a tissue moved due to cancerous growth)
When does hypertrophy occur and what is it due to?
Occurs when cells are incapable of dividing and due to increased production of cellular proteins.
When does hyperplasia occur?
Adaptive response in cells capable of replication
What are the causes of atrophy?
decreased workload, loss of innervation, decreased blood supply, inadequate nutrition. Loss of endocrine stimulation and aging.
decreased protein synthesis and protein degradation
What is atrophy?
Reduction in size of organ or tissue
Due to decreased cell size and number
Function diminished but not dead
What is metaplasia?
One adult cell is replaced by another adult cell type that is better able to withstand adverse environment
How does metaplasia occur?
reprogramming of stem cells in normal tissues OR undifferentiated mesenchymal cells
What are the four cellular growth adaptions in response to stress?
Hypertrophy, hyperplasia, atrophy and metaplasia
What allows for reverisble cell injury and at what stage does it occur?
IF damaging stimulus is removed in: early stages or mild forms of functional and morphological changes
Is cell death normal?
Yes- it allows for maintenance of homeostasis but can be unintentional though injury
What is the main characteristics of cell injury hallmarks?
Reduced oxidative phosphorylation = depletion of ATP
What causes cellular swelling?
Changes in ion concentrations and water influx
Describe Necrosis
PATHOLOGICAL process
Main pathway for common insults (ischemia, toxins, infectious agnets and trauma) = when damage to membranes is SEVERE
Unregulated enzymatic digestion
What occurs in necrosis?
Unregulated enzymatic digestion
Initiates inflammation and enzymes leak out of lysosomes and into cytoplasm to digest cell
What is Apoptosis?
NORMAL process: eliminate cells no longer needed and maintain steady number of cell populations
enzymatic degradation of proteins and DNA
Is Apoptosis or Necrosis regulated? How?
Apoptosis
Tightly regulated - Mediated by activation of caspases
What are the morphological alterations in injured cells?
micro and macroscopic features in damaged cells
progresses as cells becomes more damaged
What are the reversible cell injuries?
Cell swelling (hydropic change)
Plasma membrane changes (blebbing, loss of microvilli)
Mitochondrial changes (swelling and appearance of clumps)
Dilation of ER (detachment of ribosomes)
Nuclear alterations (clumping of chromatin)
What are the Morphologic alterations that occur during necrosis?
Increases eosinophilia (pink dye staining)
Nuclear shrinkage, fragmentation and dissolution
Breakdown of plasma membrane and organelle membranes
Calcification
Leakage and enzymatic digestion of cellular
What are the Morphologic alterations that occur during Apoptosis?
Nuclear chromatin condensation
Formation of apoptotic bodies (fragments if nuclei in cytoplasm)
What does the cellular response to injurious stimuli depend on?
Nature of injury
Duration
Severity
What does the consequences of cell injury depend on?
Type, state and adaptability of injured cell
what are the causes of cell injury?
Ischemia/ hypoxia
Chemical agents/ toxins
Infectious agents
Immune reactions
Mutations
Nutritional imbalances
Physical agents/ radiation
Aging
What are the five mechanisms of cell injury?
ATO depletion
ROSs
ER Stress/misfolded proteins
DNA damage
inflammation
What does the mechanism of ATP depletion cause for cell injury?
ATP Depletion and chemical injury (toxins)
What does ROS’s cause in the body?
Chemcial agents/ toxins and aging
what does the biomedical mechanism of ER stress and misfolded proteins result in?
Infectious agents, immune reactions, nutritional imbalances, aging
altered or dysfunctional proteins or accumulation of proteins that create disorders
what does the biomedical mechanism of DNA damage result in?
Chemical agents/ toxins, Physical agents/ radiation, aging and mutations
what does the biomedical mechanism of inflammation result in?
Infectious agents, immune reactions and aging
How does the accumulation of misfolded proteins trigger apoptosis?
via the intrinsic pathway
What is the main cause of necrotic death. Explain.
failure of energy-dependent functions –> reversible injury –> necrosis
How does ATP depletion cause cell injury?
decreased activity of plasma membrane: Na/KATPase, changes I cellular energy metabolism, influx of Ca and reduction of protein synthesis.
How does ROSs result in cell death?
causes damage to cell membranes, proteins, inactivation of enzymes and nucleic acid damage = increased permeability of membranes = necrosis
What is autophagy?
Survival mechanism in times of nutrient deprivation in which cell eats its own contents
Describe the process of autophaghy.
Initiated by nutrient-sending proteins
Sequestration of cellular organelles —> autophagic vacuoles –> vacuoles fuse with lysosomes –> lysosomes digest enclosed material
What are the main mechanisms that result in cellular aging?
Accumulation of DNA damage and defective DNA repair mechanisms
Replicate senescence – reduced capacity of cells to divide
Defective protein homeostasis
