Cell injury Flashcards
True or False, a cell can modify its organization and function in response to stress
True. this is called adaptation, and will preserve the health of the cell to a certain point. When the cells adaptive capability is exceeded, cell injury develops.
true or false, cell injury is reversible
true. up to a certain point it is reversible, but in the case of persistent, severe stress the cell suffers irreversible injury and dies
which lives longer, aerobic or anaerobic cells?
anaerobic cells can live much longer than those that need O2
7 causes of cell injury
- hypoxia (#1)
- physical agents
- chemical agents and drugs
- infectious agents
- immunological reactions
- genetic defects
- nutritional imbalances
causes of cell injury - Hypoxia
definition-1
causes -3
- def- decreased availability of O2, which leads to a spectrum of changes, including cell injury to death
causes: - ischemia (obstruction of blood flow) - most common
- cardiopulmonary failure- venous drainage is obstructed by vascular disease =>loss of O2 supply to tissues
- loss of O2 carrying capacity of the blood as in anemia or CO poisoning
causes of cell injury- Physical Agents (5 examples)
- mechanical trauma (getting beat up)
- extreme heat or cold
- sudden changes in atmospheric pressure
- ionizing radiation => formation of OH radicals (ie atomic bombs)
- electrical energy
causes of cell injury- Chemical agents and drugs
def
parts of cell chemical agents can affect -3
examples -5
def- any chemical agent may generate cell adaption, injury or death by acting on vital cell functions such as:
1. membrane permeability
2. osmotic homeostasis, or
3. integrity of different enzymes
examples of chemical agents:
poisons, air pollutants, pesticides, herbicides, and drugs
causes of cell injury- infectious agents (5)
sizes from submicroscopic -> macroscopic forms
- viruses
- rickettsiae
- bacteria
- fungi
- parasites (worst medical problem world wide)
causes of cell injury- immunologic reactions
explanation/ definition (1)
types (3)
def- contradictory to main role of immune system which serves in defense against biological agents, immunologic reactions may cause the following cell injury:
- anaphylactic reaction to foreign proteins
- immune complexes deposition (things join together to fight virus but complex can precipitate out and cause inflammation)
- autoimmune reactions
causes of cell injury- genetic defects
explanation/ definition (1)
types (2)
def- results in gross defects in protein structure which are responsible for inborn errors of metabolism
eg:
1. congenital malformations
2. chromosomal- insertions, deletions, translocations or point mutations
causes of cell injury - nutritional imbalances (4)
- protein/calorie deficiencies
- vitamin deficiencies (hypovitaminoses)
- vitamin excess (hypervitaminoses)
- dietary excess
most common cause of cell injury and how it works
ischemia is the most common cause of cell injury. Causes injury by reducing cellular O2 supplies. Usually starts as reversible but if it persists => irreversible injury.
reversible cell injury def -1 characteristics - 6
if stress is removed in time, full cell integrity can be restored. characteristics of acute injury are:
- cell swelling- because it cannot maintain homeostasis
- mitochondrial swelling
- dilation of endoplasmic reticulum
- plasma membrane alterations
- nuclear alterations
- fatty changes- manifested by appearance of lipid vacuoles. occurs in hepatocyte and myocardial cells
irreversible cell injury def -1 characteristics - 5
persistent, sufficient, severe stress leads to irreversible injury and the cell dies. associated with:
- extensive damage to cell membrane
- vacuolization of mitochondria
- swelling of lisosomes
- massive Ca2+ influx into cell
- release of O2 free radicals
scientific wordy characteristics of irreversible cell injury whats happening with enzymes (3) nuclear changes (3)
1. the main characteristic of lethally injured cells is progressive degradation of enzymes followed by enzymic digestion of cell and denaturation of proteins. nuclear changes that also occur: 2. pyknosis (nuclear shrinkage) 3. karyorrhexis (nucleus fragmentation) 4. karyolysis (nucleus degradation)
three potential causes for cell membrane damage
- progressive loss of membrane phospholipids- due to activation of endogenous phospholipases by increased cytostolic Ca2+
- cytoskeletal abnormalities - increase of intracellular Ca2+ enzymes => detachment of cell membrane from cytoskeleton => membrane susceptible to stretching and rupture
- toxic O2 radicals - these are increased in ischemic tissues especially after restoration of blood flow, may be the cause of reperfusion injury.
what is the central factor in irreversible injury?
cell membrane damage