Cell Injury and Death Flashcards
Some examples of Injurious agents to cells
- Hypoxia
- Heat and cold
- Electricity
- Chemical agents
- Biologic agents
- Radiation
- Nutritional imbalances
Which type of gangrene results in crepitus (bubbles that can be felt under the skin)?
Gas
The only type of gangrene that causes crepitus is gas grene. The bubbles are the result of gas produced by the Clostridium infection
Pyknosis
Nucleus shrinks in size in necrosis
Facts about Free Radicals
- Molecules with an unpaired electron in the outer electron shell
- Extremely unstable and reactive
- Can react with normal cell components:
- Damaging them
- Turning them into more free radicals
- Normally removed from body by antioxidants
T/F If a cell does not make adaptive changes as a result of stress, it will die.
True.
Adaptive changes allow the cell to survive and maintain some degree of function. If the cell makes no changes or makes maladaptive changes as a result of stress, the cell will not survive.
Cell death resulting from severe hypoxia, most commonly caused by loss of blood supply (ischemia)
A large area of necrotic tissue
Gangrene
Two types of Cellular Death
Necrosis and Apoptosis
Examples of causes of cell death (Necrosis)
- Trauma: mechanical stresses, temperature extremes, electrical forces, radiation
- Intoxication: chemical injury (drugs, lead, mercury poisoning) or biological agent injury
- Deficiency: lack of an essential nutrient
Programmed Cell Death
Apoptosis or “cell suicide”
- Removes cells that are being replaced or have “worn out”
- Turn on their own enzymes inside the cell, especially caspases
- Digest their own cell proteins and DNA
- Are then destroyed by white blood cells
- energy dependent programmed cell death that helps maintain homeostasis
- Normal process in the body
Results from autolysis or heterolysis, involves digestion of cell remains, typical abscess (pus) formation
Liquifactive Necrosis
_____ allows cells to survive in the short-term
Adaptation
Cell Changes with Aging.. Why??
- Is it programmed into the cells?
- Telomeres become too short; cell can no longer divide
- Is it the result of accumulated damage?
- Older cells have more DNA damage
- Older cells have more free radicals
- Cells can lose the ability to repair their telomeres
Karyolysis
change in nucleus where DNA is degraded in necrosis
Karyorrhexis
Nucleus becomes fragmented
Ischemic Cell Injury and Death
(Slide)
Importance of Calcium in the Cell
“Calcium Cascade”
- Cell usually maintains low intracellular calcium
- When calcium is released into the cell, it:
- Acts as a “second messenger” inside the cell
- Turns on intracellular enzymes, some of which can damage the cell
- Can open more calcium “gates” in the cell membrane
- Letting in more calcium
- “Calcium cascade”
Excess ROS causes …
- Cellular Damage
- Leaking membranes
- Calcium influx
- Ultimately -> CELL DEATH
Stress Damages Cells by causing….
- Direct damage to proteins, membranes, and DNA
- ATP depletion
- Free radical formation
- Increased intracellular calcium
Has been associated with a predispositon to cancer
Is most often found in epithelial and connective tissue
Metaplasia
Anti-Oxidant Systems
(Slide)
Hallmark of irreversible cell injury or cell death is massive _____
Calcium Influx
Cell death due to physiological turn over of cells is called _____
Apoptosis
Damage due to unpaired electrons that react with lipids and proteins
Free radical injury
- damages cell membrane
- is very unstable
- may be formed in normal physiological processes
- oxygen free radicals
- can do significant harm if produced at a high rate
- can form damaging reactive oxygen species (ROS)
T/F Necrotic tissue may be reversed using high concentrations of oxygen
False
Necrotic tissue is already dead, so it cannot be restored to functional tissue.
Stressed cells may fill up with ______
- Unused foods
- lipids
- glycogen
- Abnormal proteins
- Pigments
- Calcium Salts
Intracellular Accumulations
- may interfere with metabolic functions of cells
- may interfere with physical functions of tissues
- may initiate an inflammatory response that can lead to organ enlargement
Slide explaining the injurous agents
How does the body protrect from reactive oxygen species
Superoxide dismutase (SOD) converts superoxide into hydrogen peroxide and then catalase converts hydrogen peroxide into water and oxygen
_____ include excessive cell swelling, and dramatic changes to cellular organelles
Morphologic characteristics
Apoptosis is associated with which disease states
- Cancer
- Myocardial Infarction
- HIV
- Others
Hypoxia causes _______
ATP depletion or “Power Failure”
- Aerobic metabolism stops → less ATP is producedNa+/K+ ATPase cannot run fast enough
- Cell swells up with water
- Anaerobic metabolism used → lactic acid produced
- Acid damages cell membranes, intracellular structures, and DNA
Which of the following is correct: How does hypoxia cause cell damage?
- Directly damages DNA
- Diminishes ATP production
- Forms free radicals
- Increases intracellular calcium
Diminishes ATP production
Oxygen is a key ingredient for the majority of ATP production. With less oxygen, less ATP is produced, and the cell cannot function at the same level. If hypoxia is severe or prolonged, the cell will die.
2 common types of necrosis
Coagulative and liquefactive
A reversible process in which mature cell types are replaced by less mature cell types
Metaplasia
- Is seen in smokers: columnar ciliated epithelial cells are replaced with flat squamous epithelial cells
Explain what happens in hypoxic cell injury
- is caused by limited oxygen (hypoxia) as a result of reduced blood flow (ischemia)
- can lead to a state of hypoglycemia that impairs energy production
- makes body switch from aerobic to anaerobic metabolism, increasing the production of lactic acid
- changes the pH, which leads to damage
- limits ATP production due to the now anaerobic metabolism
An increase in the number of cells
Hyperplasia
- Depends on whether a cell type can divide or not
- nondividing cells (cardiac myocytes) cannot divide and undergo hypertrophy
- dividing cells (epithelial cells) can divide and may undergo hyperplasia and hypertrophy
A disordered growth and maturation of the cellular components of a tissue
Dysplasia
- Disrupts the homogenous appearance of tissue by causing
- change in cell size and shape
Cell Injury causes…
CELL INJURY
- Reversible injury > Cell recovery > and return to normal function
- Apoptosis and programmed cell removal
- Cell death and necrosis
Initiated by pathologic stimuli from outside the cell and results in the dissolution or removal of that cell
Necrosis
Necrosis involves activation of enzymes that digest cellular components
Autodigestion
This process may stimulate an inflammatory response
Apoptosis can be Caused By:
- Signaling factor attached to “death domains” of cell surface receptors
- Mitochondrial damage inside the cell
- Protein p53 activated by DNA damage
Loss of homeostasis forms the basis of most _____ states
disease
Is associated with the potential for cancer
Dysplasia
- may also be found in ulcerative colitis
- can persist and proceed to a cancer state
- can mimic precancer states
- usually seen in cervical cancer
Why do cells change with aging?
- Is it programmed into the cells?
- Telomeres become too short; cell can no longer divide
- Is it the result of accumulated damage?
- Older cells have more DNA damage
- Older cells have more free radicals
- Cells can lose the ability to repair their telomeres
Allows the stressed tissue to survive or maintain function
Examples:
- Atrophy
- hypertropy
- hyperplasia
- metaplasia
- dysplasia
Cellular Adaptation
Explain what happens in free radical injury
- Is caused by unpaired electrons, especially reactive oxygen species (ROS)
- are highly reactive and interact with lipids and proteins in the cell, especially cell membrane
- creates activity that compromises the cell
- Is normally prevented by the cell’s protection systems
- Superoxide dismutase (SOD), which converts superoxide into hydrogen peroxide - Enzyme
- form of molecular oxygen that has been radicalized
- Catalase, which converts hydrogen peroxide into water and oxygen - Enzyme
- Superoxide dismutase (SOD), which converts superoxide into hydrogen peroxide - Enzyme
- Is brought on by excess ROS, which forms when oxygen is limited
The shrinkage of tissue or organ size due to a reduction in cell size
Atrophy
- Physiologic comes from changes to the functional demands on the cell
- Pathologic comes from stimuli
Examples
- Disuse atrophy (decreased workload)
- Denervation atrophy (loss of nerve connection)
- Ischemic atrophy (loss of blood supply)
- Mr. X Had a Stroke …
- Blood flow to part of his brain was cut off
- His wife can understand why they gave him an anticoagulant, but she does not comprehend why he was also put on:
- Oxygen
- A calcium channel blocker
Question:
- What is the explanation?
We are preventing an influx of calcium, placed on oxygen so ATP production doesn’t stop and become acidotic
3 special types of necrosis that involve coagulative and liquefactive processes
- Caseous necrosis
- Fat necrosis
- Gangrene
An increase in cell size in response to stress, usually results in the increase of cell components
Hypertrophy
- May be caused by
- Hormonal stimulation (pregnancy)
- Increrased functional demand (muscle)*heart
- Initially increases functional capacity of the affected organ
- results in eventual inability of the organ to compensate for the increased workload
Cell death due to injury is called _____
Necrosis
Gas Gangrene
Clostridium infection produces toxins and H2S bubbles, an anaerobic bacteria that damages the connective tissues
Can happen from injury or infection
Unregulated death caused by injuries to cells
Necrotic cell death
- Cells swell and rupture
- cell contents often released
- Inflammation results
- Cells may undergo
- Liquefaction
- Coagulation
- Infarction
- Caseous necrosis
Fine granular golden brown pigment formed from phospholipids and proteins derived from degenerating membranes
Lipofuscin
- Lack of arterial blood supply but venous flow can carry fluid out of tissue
- Tissue tends to coagulate
- Coagulative necrosis as a result of ischemia
Dry Gangrene
A deprivation of oxygen that inhibits energy production in the cell
Hypoxic cell injury
- Lack of venous flow lets fluid accumulate in tissue
- Tissue tends to liquefy and infection is likely
- Occurs when tissue is infected with bacteria and phagocytic cells are recruited, releasing enzymes that lead to a liquefactive process
Wet Gangrene
