week 12 CTL Flashcards
what are the major aspects of disease processes
1) Aetiology - the cause of the disease can be genetic or acquired
2) Pathogenesis - the sequence of biochemical or molecular events that occurs in cells or tissues after the exposure of the injury-causing agent
3) Morphological changes - the structural changes that occur in cells or tissues that are characteristic of the disease or diagnostic of aetiological process
4) Functional changes - the end result of genetic, biochemical structural changes in cells or tissue, this lreads to
5) clinical manifestations: the functional consequences of thse changes
Outline the stages in cellular responses to noxious stimuli
- Normal cells normally maintain stay within homeostatic range
- When they are physiologically or pathologically stressed the undergo ADAPTATIONS that help it to preserve its function
- If the cells adaptive capability is exceeded or if external stress in inherently harmful CELL INJURY develops
- if the cell injury is mild or transient it is reversible and the cell can revert to a normal functioning cell
- If the cell injury is severe or progressive it will lead to IRREVERSIBLE CELL injury which is either necrotic or apoptosis
What are physiological adaptations
The changes that occur in cells in response to normal stimulation by hormones or endogenous chemical mediators
Pathological adaptations?
The responses of the cells that allow them to modulate their structure and function in order to escape injury.
Define describe and give example of hypertrophy
- Hypertrophy is the increase in size of a cell or organ
- Occurs when cells that are incapable of reproducing
- This can be physiological e.g. skeletal muscle hypertrophy in response to increased load or the uterus growth during pregnancy
- Or pathological e.g. cardiac ventricular muscle hypertrophy in response to high blood pressure
- Due to overproduction of cellular proteins
Define describe and give example of hyperplasia
- Hyperplasia is the increase in cellular proliferation or cell number in a tissue or organ
- It is an adaptive response in cells that are capable of dividing
- Physiological hyperplasia e.g. compensatory hyperplasia when a portion of tissue is removed or hormonal hyperplasia
- Pathological hyperplasia e.g. benign prostate hyperplasia (BPH)
Define describe and give example of atrophy
Atrophy is the decrease in cell or tissue size and number
It can be physiological e.g. skeletal muscle hypertrophy with inactivity or inadequate nutrition etc.
Pathological e.g. loss of innervation to muscle during stroke, blood flow
Define describe and give example of metaplasia
This is the replacement of an adult cell of one cell type with another adult cell of another cell type (e.g. epithelial or mesenchymal)
- This allows for adaption to functional demands e.g. in the airways when there is an infection the columnar epithelial cells that are mucous secreting convert to stratified squamous cells that do not secrete
OR
during reflux the keratinous squamous epithelium of oesophagus becomes mucous secreting to protect oesophagus from damage
Hallmarks of reversible cellular damage
1) Reduced oxidative phosphorylation and therefore depleted ATP
2) Cellular swelling due to changes in ion concentrations and water efflux (NA/K-ATPASE pump can’t function without ATP)
3) Intracellular organelles show changes e.g. mitochondria and cytoskeleton
Compare and contrast the two types of cell death NECROSIS and APOPTOSIS
NECROSIS VS APOPTOSIS
NECROSIS: this is an unplanned, unregulated and pathological process of cell death. It occurs in response to severe cellular membrane damage. Enzymes leak out of lysosomes and digest the cell. There is cellular swelling, severe damage to the cellular membrane, cell contents are enzymatically digested and may leak out of the cell, there is frequently associated inflammation. The whole process is pathological culmination of irreversible cell innjury.
VS
APOPTOSIS: this is planned and highly regulated cell death. IT is not always associated with pathological causes and often has a physiologic role in elimination cells that are no longer needed. It occurs in specific situations and serves many normal functions. It is mediated by activation of caspases and stimulus for apoptosis is when cells are deprived of growth factors or DNA/proteins are damaged beyond repair.
- cells shrink instead of swell
- the plasma membrane is in tact
- the cellular contents are also intact but they may be released into apoptotic bodies
- Overall has a more of a physiological role.
what are some morphological processes that occur in reversible cell damage
- Cell swelling
- Dilation of ER and detachment of ribosomes
- Mitochondria swell and clumps appear
- Nuclear alterations e.g. clumping of chromatin
What are some morphological process that occur in necrosis and apoptosis
NECROSIS
- oesinophillia (pink die staining)
- cell swelling
- nuclear shrinking, fragmentation and dissolution
- breakdown of plasma and organelle membrane
- calcification
- leakage and enzymatic digestion of contentiosn
APOPTOSIS
- Apoptic bodies form
- Nuclear chromatin condenses
List with examples the main cuases of cell injury
1) HYPOXIA (e.g. ischemic stroke/ hypoventilation)
2) chemical agents (e.g. HCL damages GIT)
3) infectious agents e.g. bacteria causing infection leads to necrosis
4) immune reactions e.g. anaphylaxis
5) nutritional defects e.g. starvation
6) genetic defects e.g. sickle cell anaemia, cystic fibrosis causes damage to airways
7) physical agents e.g. burns
8) Aging
What are the main mechanisms of cellular damage
1) ATP DEPLETION - usually due to hypoxia and chemical injury. It is the main cause of necrotic cell death. Leads to failure of energy dependent celular functions. Decreased activity of NA/K ATP ase and Calcium pump therefore calcum influx.
2) Mitochondrial cell damage: damaged by cytosolic accumulation of calcium, ROS, oxygen deprivation. Leads to depletion of ATP –> ultimately necrosis.
3) ROS: highly unstable free radicals that cause damge t cell membranes proteins and inactivate enzymes and damage nucleic acids. They increase permeability of cellular membrane and plasma membrane, lysosomal and mitochondrial membranes.
4) Calcium influx: cellular calcium is tightly regulated. Increased calcium alteres mito membrane, damge cellular components including membrane and cytoskeleton.
What is autophagy
cell eating its own contents, it is a survival mechanism during nutrient deprivation. Plays a role in cancer!
