cell injury Flashcards
define cell injury
injury to the smallest living unit in the body
what 4 factors does maintenance of cellular steady state involve.
1- preservation of genetic integrity
2- normal enzyme content.
3-intact membranes and transmembrane proteins.
4-Adequate supply of substrates and oxygen.
it a normal cell is put under stress what change will it undergo
adaptation
if a normal cell is put under injurious stimulus then what process will take place
cell injury
what 2 forms of cell injury are there
reversible
irreversible
is irreversible cell injury takes place what happens to the cell
apoptosis and necrosis.
If cells are put under stress due to increased cellular activity they often adapt by undergoing what 2 processes.
hyperplasia
hypertrophy
if cell are put under stress due to decreased cellular activity they adapt by undergo in what process
atrophy
metaplasia often occurs as a result of increased stress on a cell. what is metaplasia
change in cellular morphology
what changes morphologically occur in the cervix at puberty
at puberty the columnar cells replace some squamous cells at the squamouscoloumnar junction
What are the injurious stimuli which mean that a cell in unable to adapt and therefore becomes injured.
oxygen availability physical trauma chemical agents infectious organisms Irradiation Others- immunological, lack of essential nutrients/vitamin, genetic disorders and ageing.
Lack of oxygen delivery to cells is known as
hypoxia
no oxygen delivery to cells is known as
anoxia
Do loss of oxygen availability result in schema
Yes- if lest to long
No- cell can be reposed if condition causing hypoxia/annoxia is resolved within the given time frame.
what are the 2 main causes of physical trauma that cause cell injury
Mechanical trauma- disrupt cell structure, thrombosis, bullet shot through the head cause devascularisation.
Extremes of temperature- heat which denatures proteins and ice crystals.
what are the chemical causes which cause cell injury
alcohol, tobacco, drugs, poisons, environmental and occupational.
what are the 2 main modes of action of chemical agents in causing cellular injury
simple denaturation
interference with cellular metabolism
what are the 2 types of bacterial toxins which result in cell injury
exotoxins.
endotoxins.
how do virus cause cell injury
Hijacking of cell machinery
and collateral damage by inflammation.
how does irradiation cause cello damage.
e.g. X-rays, radioactive particles
Generation of free radicals and direct damage to macromolecules
which parts of the body are very highly sensitive to irradiation
bone marrow, gonads, intestines- parts of the body with high turnover rate
which parts of the body are very lowly sensitive to irradiation
uterus, pancreas, adrenal
what are the main targets for cell injury
mitochondrial function membrane integrity and function protein synthesis cytoskeleton genetic apparatus.
surplus of what 2 chemicals can cause swelling (known as cloudy swelling) and what symptoms is this associated with.
Na+ and H20 surplus c- associated with hypoxia, but can be due to fever or damage due to toxins.
what is the consequence of ribosome detachment
decreased protein synthesis in the mitochondria.
what causes decreased pH in injured cells
low glycogen and high lactic acid.
low pH results in less lipids being packaged and hence they build up- fatty change.
define a free radical
Highly reactive ions or molecules with single unpaired electron in outer orbital e.g. oxygen free radicals
what can cause membrane defects
bacterial toxins, viral proteins, complement, cytolytic lymphocytes, and various physical and chemical agents
what detoxifies free radicals
superoxide dismutase and antioxidants.
Loss of membrane barriers leads to the loss in what function
maintaining metabolite gradients
what enzymes does calcium activate and what is the consequence of this
deleterious effects of calcium increase.
ATPases (thereby hastening ATP depletion),
phospholipases (which cause membrane damage),
proteases (break down membrane and cytoskeletal proteins)
endonucleases (responsible for DNA fragmentation)
what are the types of cell death
necrosis
apoptosis.
what is necrosis
Cell death as result of lethal cell injury
is necrosis a passive or active process
passive
does necrosis have a inflammatory process
Yes
What are the 5 main forms of necrosis
coagulation- most common caseous- cheese like colliquative- liquifies gangrene- wet bacterial and dry fat/fibrinoid- fat becomes necrotic when injurged, lysis of necrotic fat releases fatty acids which chelate ca2+
when does coagulative encores occur
iscahemia or infarction
what bacterial infection causes caseous necrosis occur
TB
what organ undergoes colliquative necrosis and why
brain as it has no collagen.
what types of proteins are denatured in coagulative necrosis
Denaturation of intracytoplasmic protein
does coagulative tissue still have the basic microscopic structure
Yes
what happens to the dead cell in coagulative necrosis
become firm and slight swollen
what occurs at the site of colliqutive necrosis
cyst
does caseous tissue still have the basic microscopic structure
No
Cellular detail destroyed in this area, which is surrounded by granulomatous inflammation.
Dead tissue lacks any structure
Does caseous necrosis have granulomatous inflammation around the affected tissue
Yes
what causes wet gangrene
bacterial infection
what causes dry gangrene
type 2 diabetics- typically in the peripheries
define apoptosis
‘Programmed cell death’ or ‘apoptosis’
Is apoptosis a passive or active process
active
when does physiological apoptosis take place (give examples)
Embryogenesis, Involution, Elimination of self-reacting
lymphocytes
when does pathological apoptosis take place (give examples)
DNA/protein damage, Viral infections, Cell killing by cytotoxic T-cells, Chemo/radiotherapy
where are Apoptosis initiating factor (AIF) and cytochrome C normally found
inside the mitochondria
when Apoptosis initiating factor (AIF) and cytochrome C are relaxed in the cytosol what do they activate
caspases, which are the effector molecules of apoptosis
what actives p53, and what is its function
damaged DNA
causes the elimination of damaged cells by apoptosis
what does a mutation in p53 cause
unable to eliminate damaged cells by apoptosis, cell accumulate and develop genetic abnormalities and become malignant.
what is the function of bcl
sequesters cytochrome C and thus inhibits apoptosis.
what can mutations in over expression of bcl result in
tumours gain the ability to proliferate in an uncontrolled way.
is necrosis pathological or physiological
pathological
is apoptosis pathological of physiological
physicological
Is the cell size enlarged of reduced in necrosis
enlarged
Is the cell size enlarged of reduced in apoptosis
reduced
what happens to the plasma membrane and the contents of a cell in necrosis
plasma membran disruptes an enzyme digestion so they may leak.
what happens to the plasma membrane and the contents of a cell in apoptosis
plasma membrane intact cellular contents in tack and may be released into the apoptotic body
is there inflammation in necrosis
Yes
is there inflammation in apoptosis
No
how many cells are affected in apoptosis
1
how many cells are affected in necrosis
a group
in which subgroup of necrosis do cells lose their nucleus
coagulative
what happens to the nuclei in apoptosis
shrink
how is a appoptotic body removed
via phagocytosis.
