Cell Injury and Inflammation Flashcards
Causes of Cell Injury
- ischemia (lack of blood flow or oxygen to an area)
- infectious agents (bacteria and virus kill cells)
- immune reactions (immune system becomes too excited and causes hypersensitivities or autoimmune)
- genetic factors
- mechanical factors
- nutritional factors
- physical factors
- chemical factors
-psychosocial factors
Factors Influencing healing
- physiological variables (age, growth factors, vascular sufficiency)
- general health of the individual, immunocompetency, psychological/emotional well being
- the presence of comorbidities (DM, decreased oxygen perfusion, hematologic disorders, cancer, incontinence, Alzheimers, neurologic impairment, immobility
- tobacco, alchohol, caffeine
- nutrition
- infections
- type of tissue
- medical treatment
Secondary Injury
complications after intial injury; usually the result of hypoxic-ischemia (brain cant get oxygen) injury caused by cerebral edema (swelling of brain) or intracranial hematomas (bleeding in brain)
Phases of healing
- hemostasis and degeneration
- inflammation
- proliferation and migration
- remodeling and maturation
Adaptation
the extent to which the cell is able to alter mechanisms and regain homeostasis in the altered environment
What does “reversible injury” depend on?
- mechanism of injury
- length of time the injury is present w/o intervention
- severity of the injury
Mild injury
- leads to sublethal alterations-may be reversible
Moderate or severe injury
- Leads to lethal alterations - likely irreversible - lead to cell death
Describe the pathway of Ischemia, one of the causes of cell injury
blood flow is insufficient (partial = hypoxia, total = anoxia) causing lack of ATP to be made which causes a build up of ions and fluid intracellularly, causing the cell to swell
Causes of Ischemia (what is it?) (know the condition names)
- obstruction of the respiratory tree (suffocation)
- inadequate transportation of O2 across the respiratory tract (pneumonia)
- arterial lumen obstruction and narrowing (atherosclerosis)
- intravascular clot (thrombus)
- inadequate transport of O2 in the blood (anemia)
- the inability of cell to use O2 (CO poisoning)
partial (hypoxia) or total (anoxia) reduction in O2 supply = loss of aerobic metabolism = reduction ATP synthesis = accumulation of ions and fluid = cells swell - comprised function
Infectious agents
- bacteria, viruses and others
immune reactions
overzealous in its activity, leading to hypersensitivities ranging from a mild allergy to life-threatening anaphylactic reactions or autoimmune disorders
Chemical factors
two catagories:
1. substances that can injure cells directly (heavy metals)
2. substances that require metabolic transformation into the toxic agent (carbon tetrachloride)
Production of reactive oxygen species (ROS)
- formation of free radicals
Free radicals
- natural by-product of using O2
- it is when a normal oxygen atom lose one of four paired electrons, becomes a chain rxn
- excessive amounts = oxidative stress = cell injury or death
Oxidation
when a molecule loses an electron
oxidation as a by product of metabolism damages cell membranes, leading to intrinsic cellular damage, a part of the normal aging process
Other causes for free radical formation
- exposure of toxic chemicals
-exposure to high level of oxygen - irradiation
- UV
- fluorescent light
- pollutants
- tobacco smoke
- pesticides
- drug overdose
- heat stress
-reperfusion injury - prolonged exercise
*intense or prolonged strenuous exercise leads to oxidative stress and may be harmful
Antioxidants
- they neutralize the extra free radicals and stop chain reaction
- endogenous antioxidants; enzymatic (scavengers) and nonenzymatic defense mechanisms
- exogenous antioxidants; 200 have been identified in food or plant substances (found outside the body)
- *moderate PA and exercise strengthen the antioxidant defense system
Genetic Factors
- alterations in the structure of number of chromsoomes that induce multiple abnormalities (down syndrome; 3rd chromosomes in the 21st pair)
- single mutations of genes cause changes in the amount or functions of proteins (sickle cell anemia, low-density lipoprotein receptor deficiency and a-antitrypsin deficiency)
- multiple gene mutations that interact with environmental factors to cause multifactorial disorders (hypertension and type 2 diabetes)
I would just remember structure/number alteration, single gene mutation, genes interacting with environment
Mechanical Factors
physical stress theory says changes in physical stress should cause a predictable adaptive response in tissue
- tissue response to physical stress includes decreased stress tolerance (atrophy), maintenance, increased stress tolerance (hypertrophy), injury and death
- soft tissues are influenced by the history of recent physical stresses so that the accumulation of individual stresses can cause injury
- trauma (bone fracture or ligaments rupture)
- other causes; repeated episodes of moderate-magnitude force, slow degradation of tissues tolerance, low loads sustained over long time
Nutritional Factors
imbalances in essential nutrients
- excessive nutrient intake, (leads to obesity)
- dietary deficiency (abnormal level or vitamins, kwashiorkor)
Physical factors
- blunt or penertrating trauma (brain contusions, internal organ damage, blood loss, delayed death of infections or organ failure)
- extremes of physical agents (temp; burn or frostbite), radiation and electricity
Psychosocial factors
feat, tension or anxiety may influence individual threshold values for tissue adaptation and injury
