Altered Cell Notes Flashcards
Cellular adaptation is
reversible, structural, or functional response
Cells adapt to stressors to maintain homeostasis by
- Conserving resources
- Decreasing or ceasing differentiated functions
- Focusing exclusively on their own survival
Cells adapt to increased work demands by changing in
- Size (atrophy & hypertrophy)
- Number (hyperplasia)
- Form (metaplasia)
How can hypertrophy or hyperplasia be helpful?
Increase organ size so it can function better
How can hypertrophy or hyperplasia be harmful?
Increased organ size requires more blood supply. If not available, it becomes ischemic.
Morphologic cell changes
Helps a cell recover structure and function in response to a reversible injury
Most significant adaptive/morphologic changes include
Atrophy, hypertrophy, hyperplasia, and metaplasia
Atrophy
Decrease in cellular size caused by aging, disuse or lack of blood supply, hormonal stimulation, or neural stimulation.
What decreases with atrophy?
ER, mitochondria, and microfilaments.
Decreases protein synthesis, increased protein catabolism, or both.
How is atrophy advantageous
Decreased organelles and size lowers oxygen requirements to survive
Hypertrophy
Increase in the size of cells caused by increased work demands or hormonal stimulation
What happens inside the cell with hypertrophy?
Increased amounts of proteins, ER, microfilaments, and mitochondria.
Hypertrophy can be classified as
Physiologic or pathologic
Hyperplasia
Increase in the number of cells caused by an increased rate of cell division.
What is hyperplasia classified as
Physiologic or pathologic
Physiologic Hyperplasia
Compensatory and hormonal
When does normal hyperplasia start/stop?
Stimulated by hormones or the need to replace lost tissues and ends when the stimulus is removed.
What is an example of hyperplasia?
Wound repair (increased cell division)
Endometrium/breast: cell death triggers mitosis
Dysplasia/Atypical Hyperplasia
Abnormal change in size, shape, and organization of mature tissue cells. Not considered a true adaptational change but rather atypical.
Is dysplasia reversible?
Yes, cells can revert to normal after the stimulus causing it is removed
Cervical Dysplasia
Mild dysplasia: most regress on their own, most common form.
Moderate & severe: Less likely to self-resolve and have a higher rate of progression to cancer.
Metaplasia
Reversible replacement of one mature cell type by another adult cell type
What does metaplasia allow for?
Substitution of cells that are better able to survive
What is an example of metaplasia?
Chronic smoking causing chronic irritation w/columnar tissue replaced by stratified squamous w/no cilia or mucus
What can cause hypoxia?
Free radicals, caustic or toxic chemicals, infectious agents, inflammatory and immune responses, genetic factors, insufficient nutrients, or physical or mechanical trauma
Hypoxia
Lack of oxygen to cells
Oxidative Stress
Free radicals
Toxic chemicals
alcohol, asphyxiants (cyanide)
Physical, mechanical, trauma
Blunt/penetrating trauma, temp.
Hypoxemia
Low oxygen in the blood
Initial insult in hypoxic injury is usually
Ischemia
Ischemia
Cessation of blood flow into vessels that supply the cell with oxygen and nutrients
Hypoxemic hypoxia
-Most common type
-PaO2 is below normal
Causes of hypoxemic hypoxia
- Alveolar PO2 is reduced - altitude sickness or decompression sickness
- Diffusion impairment (emphysema)
Ischemic/Stagnant Hypoxia
Tissue is not receiving enough oxygen because of decreased perfusion. Cardiac or vascular disorder
Anemic Hypoxia
Lungs can be in perfect working condition but the oxygen-carrying capacity of the blood is reduced.
-Anemia, or CO poisoning
Histoxic Hypoxia
Cells have been poisoned; oxygen gets to the tissue, but the tissue is unable to use the oxygen.
- Cyanide
Biochemical themes important to cell injury
- ATP depletion
- Mitochondrial damage
- Oxygen and oxygen-derived free radicals
- Membrane damage
- Protein folding defects
- Increased intracellular calcium and loss of calcium steady state.
What does hypoxia cause
Power failure in the cell & reduced ATP which can cause acute cell swelling
What happens to ions when Na+/K+ pump fails
IC K+ levels decrease while Na+ and H2O accumulate in the cell.
Vacuolization
Degeneration by water
Oncosis
Swelling
Form of cell death due to failure of Na+/K+ pump
What is oncosis caused by
ischemia
Is cell swelling reversible?
Yes
Movement of water and ions into the cells is associated with
- Dilation of the ER & other organelles
- Increased membrane permeability
- Decreased mitochondrial function
Without restoration of oxygen
- Loss of enzymes, proteins, and RNA through hyperpermeable membrane continues
- Injury to the lysosomal membranes cause enzymatic digestion of cell components
- Leakage of the intracellular enzymes through the permeable membrane
Cellular tolerance to hypoxia could involve:
- Reduction in the metabolic rate
- Increased extraction of oxygen from the blood and surrounding tissues.
- Adaptations of enzymes to allow metabolism at low partial pressures of oxygen
Sequence of events leading to cell death
Decreased ATP production, failure of active transport mechanisms, cellular swelling, detachment of ribosomes from ER, cessation of protein synthesis, mitochondrial swelling from calcium accumulation, vacuolation, etc.
Oxidative stress
An imbalance between the production of reactive oxygen species (free radicals) and the ability of the body to counteract, their effects with antioxidants.
Reperfusion Injury
Restoration of oxygen causing further injury with free radicals.
Antioxidants
Natural and synthetic molecules that either inhibit the reactions responsible for production of ROS or neutralize ROS.
Acute abuse of ethanol/alcohol affects
RAS & brainstem, motor & intellectual dysfunction, depresses medulla oblongata decreases respiration
Chronic abuse of alcohol
Hepatitis and cirrhosis, gastritis & pancreatitis
Frostbite causes
Vasoconstriction causing hypoxia
Heat/burns causes
Increased metabolism, denaturing, coagulation of BV
Contusion
Bleeding into the skin or underlying tissues as the result of a blow.
Hematoma
Collection of blood in soft tissues or an enclosed space
Abrasion
Results from the removal of the superficial layers of the skin caused by friction between the skin and injuring object.
Laceration
Tear or rip resulting when the tensile strength of the skin or tissue is exceeded
Incised wound
Cut that is longer than it is deep
Stab wound
Penetrating sharp force injury that is deeper than it is long.
Puncture Wound
Objects with sharp point rather than sharp edges
Penetrating Gunshot Wound
Bullet remains
Perforating Gunshot Wound
Bullet exits
Contact range entrance
Muzzle on skin, block-back and muzzle imprint
Intermediate range entrance
Tattooing and stippling
Indeterminate range entrance
No gunshot residue (GSR)
Asphyxial injury
Caused by a failure of cells to receive or utilize oxygen
4 categories of asphyxial injuries
- Suffocation
- Strangulation
- Chemical
- Drowning
Suffocation Types
Choking & traumatic
Clinical manifestations of endothelial impairment
Edema, hypertension, abnormal vasoconstriction or vasodilation, hypercoagulability
Autophagy
“Eating of self” and a recycling factor.
Necrotic cell death
Pathological/unregulated cell death with inflammation.
Infarction
Tissue death
Five major types of necrosis
- Liquefactive
- Coagulative
- Caseous
- Fat necroses
- Gangrenous necrosis
Liquefactive necrosis
Dead cells digested by own NZ’s - leak out- tissue is walled off from healthy cells as cysts
Coagulative necrosis
Acidosis denatures proteins and albumin changes from gel to hard & opaque
Caseous necrosis
Dead cells disintegrate, tissues soft and granular, creates cheesy look
Fat necroses
Interlobular adipocytes are necrotic and surrounded by inflammation cells
Gangrene
Large area of necrotic tissue caused by hypoxia and the subsequent bacterial invasion.
Dry gangrene
Lack of arterial blood supply but venous flow can carry fluid out of tissue
Symptoms of dry gangrene
Slow progression
Skin shrinks & wrinkles
Black, brown, dry
Usually from coagulative necrosis
Clear line of demarcation
Extremities only
Wet gangrene
Lack of venous flow lets fluid accumulate in tissue
Wet gangrene symptoms/sign
Tissue tends to liquefy and becomes infected
Black, moist, cold, swollen, pulseless
Fast progression
No clear line
Due to blocked vein
Location is internal organs or extremities
Foul odor
Gas gangrene
Caused by infection or injured tissue by anaerobic clostridium bacteria
Death is by shock
Frailty
Wasting syndrome of aging leaving a person vulnerable to falls, functional decline, disease, and death
Somatic death
Death of the entire organism
Pallor mortis
Face becomes sharp and pale as blood drains away
BP in retinal BVs decrease causing muscle tension to decrease and pupils to dilate
Algor mortis
Reduction in body temp
Rigor mortis
Happens within 6 hours ends by 36 hours
Acids build up in muscles and interferes with ATP detachment of myosin from actin
12-14 hours
Putrefaction
24-48 hours after death
Enzymes leak from cells and dissolve tissues and organs
Green discoloration of skin
Skin slips and loosens from underlying tissue
Swelling and bloating
Decomposition
Organic matter of body is broken down into elemental matter by body’s own enzymes
