Causes of cell injury Flashcards
Is the most common cell injury. Caused by a lack of oxygen, respiratory disease (DVT deep vein thrombosis - lungs), ischemia, anemia (lower iron/ transportation of O2
Hypoxia (lung)
Effects:
Decreased 02 > impaired oxidative metabolism
> decreased ATP = cell swelling
OR
anaerobic metabolism > decreased lactic acid > decrease pH
Outcomes:
cell swelling, denaturation of enzymes, chromosome clumping, autolysis, coagulative necrosis
They are common causes of injury due to environmental exposure, occupational and transportation accidents, and physical violence and assault
Injury from physical agents
1) mechanical forces
2) extremes of temperature
3) electrical injuries
physical agents - injury
impact of body with another
these injuries split and tear tissue
ex. fracture of the bone, injury to blood vessel and disruption of blood flow
mechanical forces
physical agents - injury
Extremes of heat and cold cause damage to cells, its organelles and its enzyme systems
HOT
> Low intensity heat causes vascular injury, accelerates cell metabolism and disrupts cell membrane
> More intense heat causes coagulation of blood vessels and tissue protein
COLD
> Exposure to cold increases the blood viscocity and induces vasoconstriction.
Decrease in blood flow may lead to hypoxic tissue injury depending on the degree and extent of cold exposure
extremes of temperature
physical agents - injury
> leads to disruption of neural and cardiac impulses
> degree of damage depends of the voltage, duration of exposure…
> most severe tissue damage occurs at the site of entry and exit of current
electrical injuries
Radiation injury (3)
ionizing radiation
ultraviolet radiation
non-ionizing radiation
type of radiation injury
> immediately kills cells, interrupts cell replication, causes a series of genetic mutations (may or may not be lethal)
> used for cancer treatment
ionizing radiation
outcomes : direct > cell death, indirect > free radicals: division impairment, mutations, protein cross-linking, enzyme inactivation
Most vulnerable cells: GIT, bone marrow, effect on cells with high mitotic (reproductive) activity
type of radiation injury
> causes sunburn and increases risk of skin cancer
> damage is produced by REACTIVE OXYGEN SPECIES and damage to melanin producing process in the skin
ultraviolet radiation
UV radiation also damages DNA
type of radiation injury
> includes infrared light, ultrasound (deep heat), microwave and laser energy
> affect is produced by causing vibration and rotation of atoms and molecules (causing hyperthermia - elevated body temp)
> due to deep penetration, tend to involve dermal and subcutaneous tissue
non-ionizing radiation
type of injury
_____can injure the cell membrane and other cell structure, block enzymatic pathways, coagulate cell proteins and disrupt the osmotic and ionic balance of the cell.
ex: drugs
lead toxicity
mercury toxicity
Chemical injury
> They differ from other injurious agents in that they are able to replicate and can continue to produce their injurious effects
Agents vary from submicroscopic viruses to larger parasites (gastro intestinal - streptococus virus)
these injure cells by variable mechanism
Injury from biological agents
type of injury
Nutritional excesses/ deficiencies predispose cells to injury
Excesses > lead to obesity , higher risks for many diseases
EG. diets high in saturated fats can predispose person to atherosclerosis (coronary disease)
Deficiencies of protein can lead to malnutrition
> many diseases are associated with deficiencies of vitamins and minerals
eg. vitamin C=scurvy - lack of vitamin C
Vitamin1 (thymine)= Beri Beri - just rice diet
Injury from nutritional imbalances
