Cell Injury Flashcards
How do extreme temperatures injure cells?
-Inducing vascular injury -accelerating cell metabolism -inactivating temp-sensitive enzymes -disrupting cell membrane
What happens with more intense heat?
Coagulation of blood vessels and tissue proteins occurs
What happens with exposure to cold?
-increases blood viscosity and induces vasoconstriction by direct action and through reflex of sympathetic nervous system. -hypoxic tissue injury due to low blood flow -ice crystal formation and vasoconstriction
Why does edema occur with lower temperatures?
Decreased blood flow lead to capillary stasis and arteriolar and capillary thrombosis. Edema results from increased capillary permeability.
What is considered ionizing radiation?
Radiation energy above the UV range. Photons have enough energy to knock e- off atoms and molecules.
What is non ionizing radiation?
Radiation energy at frequencies below those of visible light.
How does ionizing radiation affect cells?
Causes ionization of molecules and atoms in the cell, by directly hitting the target molecules in the cell, or by producing free radicals that interact with critical cell components.
What can occur to a cell if exposed to ionizing radiation?
-Immediately kill it -interrupt cell replication -cause variety of genetic mutations
Where do we see most ionizing radiation injuries?
Caused by localized irradiation that is used in Ca Tx.
When might be a “normal” to expose patients to high doses of irradiation?
Pt. precedes bone marrow transplantation.
Which cells are more susceptible to ionizing radiation?
Bone Marrow and Intestine (because they have rapidly dividing cells) (as opposed to bone or skeletal muscle)
What can we expect with occupational exposure of ionizing radiation?
-skin ca -leukemia -oteogenic sarcomas -lung cancer
Clinical manifestations of radiation injury:
-acute cell injury -changes in blood vessels that supply irradiated tissue -fibrotic tissue replacement
What is cell’s initial response to radiation injury?
-swelling -disruption of the mitochondria -cell membrane alterations -changes in nucleus
Which cells more sensitive to rad injury in vasculature?
endothelial cells
What are signs of radiation related acute reversible necrosis injury?
-radiation cystitis -dermatitis -diarrhea from enteritis
What are chronic effects or radiation?
-fibrosis -Scarring of tissues and organs in the irradiated area
What type of cellular damage does tylenol OD produce?
Tylenol metabolized in liver - one metabolite highly toxic - if OD present - large amounts of metabolite causes massive liver necrosis.
Where can a child be exposed to lead?
-ingestion of peeling paint -breathing lead paint dust -playing in contaminated soil
How is lead absorbed into the body?
Through GI or lungs.
What deficiency makes lead absorption easier?
-Calcium -Iron -Zinc
What is the most common route of lead absorption in children?
Lungs
Does lead cross placenta into fetus?
Yes
When absorbed, where is lead stored?
Bone
How is lead excreted?
Kidneys
How does lead poison?
-inactivate enzymes -compete with calcium in bone incorporation -interfere w/ nerve transmission/brain development
What are the major targets of lead toxicity?
-red blood cells -GI tract -kidneys -nervous system
Cardinal sign of lead poisoning?
Anemia -red cells are coasely stippled and hypchromic, resemebling those of iron-deficiency anemia.
Main symptom source in adults of lead posining?
Abdominal pain. Lead line - along gingival margins (not seen in children)
Does lead poisoning lead to HTN?
Yes
How does lead affect the nervous system?
Demyelination of cerebral and cerbellar white matter and death of coritcal cells.
What serious manifestation of lead poisoning affecting nervous system?
Acute encephalopathy: -persistent vomiting -ataxia -seizure -papilledema -impaired consciousness -coma
Drugs and Cell Injury
Left Blank
Accidental Hypothermia
Unintentional drop in core body temperature below 35C (95F).
At these temps - comp mechanisms that conserve temperature start to fail.
Primary accidental hypothermia
Physiologic result of a previously healthy person to the changes that occur with cold.
Secondary hypothermia
Consequence of serious systemic disorder (i.e. endocrine disorder)
Has much higher mortality rate.
Why are neo nates at higher risk for heat loss?
Increased surface to mass ratio
lack of shivering
lack of other behavioral responses
Hyperthermia
Uncontrolled increase in body temp that exceeds body ability to lose heat
Three types of heat injury:
Heat cramps - tx w/ Na replacement
Heat stroke - life threatening temp 106F (41C) - peripheral vasodilation and decrease in circulating blood volume
Heat Exhaustion - happens when enough salt and water loss - results in hemoconcentraiton - Hypotension r/t to fluid loss - feels weak, nauseated / can collapase from hypovolemia. MOST COMMON HEAT INJURY
Factors affecting high altitude sickness
Rate of altitude ascent
Final altitude reached
Altitude at which person sleeps
Individual physiology
Other risk factors:
CV/Pulm conditions
Residence at low altitude
Hx of altitude sickness
Level of exertion at altitude
Acute Mountain Sickness
Nonspecific symptoms
Present few hours after ascent
H/A
Loss appetite
N/V
Weakness
Lassitude
Dizziness
Difficulty sleeping
Relatively Benign - does not include abnormal neuro symptoms, if so, think HACE
Hight Altitude Cerebral Edema
Onset of ataxia, ALOC, Severe lassitude
Severe h/a, n/v
In AMS and HACE what produces h/a?
Hypoxemia-induced cerebral vasodilation, w/ significant increase in blood flow.
What is HAPE?
High Altitude Pulmonary Edema
Discuss HAPE
non cardiogenic pulmonary edema associated with pulm. HTN and elevated capillary pressure
Related to rate of ascent, ultimate alt. reached, and individual suceptability
