Mechanisms of Cell Injury Flashcards
what are 5 categories of causes of cell injury’s
injury from: physical agent radiation injury chemical injury biological agent nutritional imbalances
first indication of cell injury is
biochemical lesion @ point of injury -:>lesion changes chemistry of metabolic reactions with in the cell
types of physical agents that cause cell injury
mechanical forces, extremes of temp,
electrical forces
mechanical injury forces occur (physical injury)
when body impacts with another object
tissue or bone tear, fracture, blood vessels can be injured to disrupt blood flow
extreme temp (physical injury)
causes damage to the cell, its organelles, and enzyme systems
low intensity heat causes (physical damage)
causes partial thickness burn or sever heat stroke
causes cell injury by causing vascular injury->accelerates cell metabolism, inactivates temp sensitive enzymes and disrupts cell membrane
more intense heat (physical damage)
coagulation of blood vessels and tissue proteins occur
cold exposure temp (physical damage)
increase blood viscosity, induces vasoconstriction as a reflex of sympathetic nervous system-> decreased blood flow may lead to hypoxic tissue injury
cold exposure temp can lead to (physical damage)
hypoxic injury due to capillary stasis and thrombosis
hypoxic means
deprived of adequate oxygen supply at tissue level
freezing (physical injury)
may result from a combo of ice crystal formation and vasoconstriction leads to edema
electrical forces (physical injury)
can affect body through ext. tissue injury and disruption of neural and cardiac impulses
much of damage caused by electrical injury is caused by
heat production in tissue that have highest electrical resistance
radiation injury types
ionizing radiation
UV and non-ionizing
ionizing radiation injury
causes release of free radicals that destroy cells->can kill cells or interrupt cell replication or cause variety of genetic mutations
example of ionizing radiation
cancer treatment
UV radiation
causes sunburns, increase risk of skin cancer
uv radiation damage caused
from reactive oxygen species (ROS) (free radicals) and damage to melanin producing processing the skin to damage DNA
non-ionizing radiation examples
infrared light, ultrasounds, microwaves, laser energy
non-ionizing radiation causes
direct break of chemical bonds caused by vibrations and rotation of atoms and molecules, energy converted into thermal energy, can burn skin and cause thermal injury to dermal subcut, and deeper tissue
types of chemical injury
drugs, lead toxicity, mercury toxicity,
examples of chemicals that can damage cells
carbon tetrachloride when ingested, tobacco when inhaled, preservatives, carbon monixde
drugs (chemical injury)
affects cells/tissue based on chemical nature of drug and how it is metabolized can impact cells, tissues, and organs
how does alcohol cause damage
can harm gastric mucosa, live developing fetus, can directly or indirectly damage tissue
acetaminophen damages (drug/chemical injury)
detoxed in liver- converted to toxic metabolite->detoxed by pathway that uses sub-> but when in large amounts, pathway is overwhelmed and toxic metabolite accumulates causing liver necrosis
lead toxicity (chemical)
one of most serious forms of chemical injury
lead is absorbed
in gastro tract and lungs then into blood stream
lead is eliminated
in kidneys
lead half life
hours->days but done deposits may maintain blood lead levels for months to years
major targets of lead toxicity
RBCs (decrease RBC lifespans), gastro tract, kidney damage
cardinal sign of lead toxicity
anemia
lead in nervous system
causes peripheral demyelinating neuropathy in adults and demyelinating of cerebral ad cerebrum white matter (breakdown of myelin sheath) and death of corticol cells
lead poisoning can also cause
acute encephalopathy, lead colic in adults, diffuse kidney damage, lead line
mercury toxicity (chemical injury)
can affect CNS and kidneys
main source of mercury exposure
is consumption of long-lives fish like tuna and swordfish recommended that pregnant women and children do not eat due to susceptible damage to brain
biological injury
biological injury agents differ from other injurious agents b/c they are able to replicate and can cont to produce their injurious effects
how do biological agents injure cell
by diverse mechanisms, and b/c (bacteria, viruses, fungi, etc.) can cont to replicate and continue to injure cell
injury from nutritional imbalances
excess and deficiencies predispose cells to injury
obesity->atherosclerosis
starvation->iron def anemia, scurvy, etc.
3 mechanisms where injurious agents exert their effects
free radical formation
hypoxia
impaired calcium homeostasis
free radical injury can lead to
can lead to production of free radicals
what are free radicals
unstable (extra electron) and highly reactive in that they react with molecules in the vicinity w/out purpose
free radicals react with
proteins, lipids, carbs
what do free radicals do
damage cells membranes, inactivate enzymes, and damage nucleic acids that make up DNA- can lead to mutations in cell structure and lead to premature cell death
cause ischemia->injury->cell death
free radicals derived from
oxygen and are known as superoxide and hydroxl radical
ROS=
oxygen containing molecules that include free radical
oxidative stress simple
and reperfusion injury to oxygen-> created oxygen free radicals (ROS)-> oxidative stress
oxidative stress book
occurs when gen. of ROS exceeds the ability of the body to neutralize and eliminate ROS-> oxidation of cell components-> activation of signal transduction pathways -> changes in gene and protein expression-> DNA mod and damage
oxidative stress associated with what disease/conditions
inflammation, ALS, cancer development
oxidative stress in inflammation or profusion (mycardial infarction, stroke, sepsis, shock)
free radicals are produced in response to inflammations= WBCs convert oxygen to free radicals b/c thinks it is fighting bacteria-> oxidative stress-> tissue damage
antioxidants
can decrease tissue damage from free radicals but replacing the missing electron on free radicals-> less free radicals
hypoxic cell injury mechanism
cell is deprived of oxygen->interrupts oxidative metabolism and generation of ATP
loss of oxygen in brain
with in 4-6 min causes perm damage
list causes of hypoxia
inadequate oxygen in air, resp. disease, ischemia, anemia, edema, inability of cells to use oxygen
ischemia
impaired oxygen delivery and impaired removal of metabolic end products creating lactic acid-> affects blood vessels an produces local tissue injury
simply put hypoxia
cause power failure in the cells-> effects cells structure and function
hypoxia- as oxygen falls
oxidative metabolism ceases and cell averts to aerobic metabolism-> using limited glycogen stores to maintain vital cell functions, lactic acid accumulated causing PH to FALL
hypoxia- > reduced ATP->
-> acute ccell swelling caused by failure of energy dependent NA+/K+ATPase membrane pump-> intracellular K+ decreased and NA+ AND water Increase
impaired calcium homeostasis cell injury mechanism
ischemia and certain toxins lead to increase in cytosolic calcium due to influx leading to release of CA+ from intracellular stores-> activates enzymes which can be damaging
CA+ levels in call are normally
extremely low compare to extracellular
2 patterns of reversible cell injury
cellular swelling and fatty changes
reversible cell injury- cellular swelling
occurs w/ impairment of ATP dependent NA+/K+ATPase membrane pump; usually a result of hypoxic cell injury
reversible cell injury- fatty changes
linked to intracellular accumulations of fat;;
what happens with reversible cell injury- fatty changes
small vacuoles of fat are dispersed through out cytoplasm and usually indicate sever injury
fatty changes may occur
b/c normal cells are presented with increased fat load or injured cells are unable to metabolize the fat properly
key diff. between reversible cell dealt and cell death
is removing the stimuli that is causing the injury before too much damage is done
