Cellular Responses to Stress, Injury, and Aging Flashcards
True or False
If a cell does not make adaptive changes as a result of stress, it will die.
True: adaptive changes allow the cell to survive and maintain some degree of function.
What occurs for cells to adapt?
change in #, size, or type.
What is atrophy?
a decrease in cell size. Occurs because of decrease of O2 consumption and organelle size.
What are some causes of atrophy?
disuse, denervation, loss of endocrine stimulation, inadequate nutrition, ischaemia (decreased blood flow).
What is hypertrophy?
increase in cell size and tissue mass. Occurs from normal physiological or abnormal pathologic.
what kind of cellular response occurs in cells incapable of mitotic division?
hypertrophy
What are causes of hypertrophy?
increased in workload: ATP depletion, increased membrane mechanical forces, or hormonal factors (IGF-1).
What is necrosis?
unregulated cell and thus tissue death
what results from an accumulation of bilirubin, usually due to liver disfunction?
jaundice
what is metastatic calcification?
occurs when hypercalcemia causes calcium to accumulate in healthy tissues.
What is autophagy?
The process whereby internal cell components are selectively destroyed through fusion with lysosomes.
What is an increase in cell number?
hyperplasia
What is ischemia?
a lack of blood flow to tissues that subsequently causes hypoxic tissue damage
What is cell growth that is dysfunctional or deranged?
dysplasia
What is metaplasia?
a reversible change of one cell type into another
What is the name of programmed cell death?
apoptosis
what cellular response is due to an increase in # of cells in an organ or tissue?
hyperplasia
what does physiologic mean?
normal changes
what does pathologic mean?
abnormal changes
What are physiologic and pathologic changes that occur during hyperplasia?
physiologic- hormonal: breast/uterine enlargement during pregnancy
compensatory- liver regeneration after surgery
pathologic- hormonal: benign prostate hyperplasia
growth factor related- HPV skin warts.
What is a reversible change cell response where one adult cell type is replaced by another?
metaplasia
What are causes of metaplasia?
chronic inflammation/irritation such as smoking. cells can return to normal
what is a deranged cell growth resulting in cells that vary in size, shape, and organization?
dysplasia
What are examples of dysplasia?
HPV caused cervical or oropharyngeal cancer
case study: a woman ruptured her left achilles tendon; 3 weeks later, you find:
1. left calf is smaller
2. circumference of right calf has increased
3. there are new callouses.
Which cell and tissue adaptations occured?
- atrophy
- hypertrophy
- hyperplasia
which intracellular accumulations occur in stressed cells that are normal body substances?
lipids, proteins, and pigments.
which intracellular accumulations of stressed cells are abnormal endogenous substances?
metabolic products- glycogen, lipds(NAFLD)
- bilirubin retention (jaundice)
-lipofuscin (wear-and-tear pigment)
what are some intracellular accumulations in a stressed cell that are abnormal exogenous substances?
tattoo pigment, coal dust, lead poisoning
What are the 2 types of pathological calcifications?
dystrophic calcification and metastatic calcification
what calcification occurs in injured tissue in areas of necrosis? is it more local or systemic?
dystrophic; more local
what is abnormal deposition of calcium salts in tissues?
calcification
what usually occurs in normal tissues due to hypercalcemia? is it local or systemic
metastatic calcification; more systemic
What are the types of cell injury?
physical, radiation, chemical, biologic agents, and nutritional imbalances
True or False:
If a cell is unable to maintain homeostasis in the face of injurious stimuli or stress, cells may not recover
false: cells may recover from certain types of damage or stress
what are examples of physical cell injury
trauma, heat and cold, electricity
what are examples of radiation cell injury?
ionizing, ultraviolet, nonionizing
why is ionizing radiation generally more dangrous?
physically disrupts DNA in cells
what are examples of chemical cell injury?
drugs, lead, mercury
what are examples of biologic agents that cause cell injury?
bacteria, viruses, parasites
what nutritional imbalances cause cell injury?
fats, minerals, vitamins and amino acids
what are 3 types of cell injury mechanisms?
ROS, hypoxia/ischemia, increase in intracellular calcium
what is hypoxia/ischemia?
when the cell is not provided with enough oxygen
How do reactive oxygen species cause injury?
free radicals cause oxidation of cell structures and nuclear/mitochondrial DNA
normal part of metabolism & intracellular signaling.
antioxidants are defense mechanism
how does hypoxia affect cells
aerobic metabolism stops and decreased ATP produced
- Na/K ATPase decreases which increases intracellular Na which causes swelling with water
- anaerobic metabolism used which decreases pH, this can lead to damaged cell membranes, intracellular structures and DNA
- exposure to acute hypoxia linked to increase to hypoxia induced factors’ (HIFs)
how does impaired Ca2 homeostasis affect the cell?
disrupts Ca2/Mg2- atpase-dependent membrane pumps
- excess Ca2 damages Ca2+ dependent phospholipases, proteases, ATPases & endonucleases
excess calcium can lead to ?
Exercise induced muscle damage (EIMD) and DOMS
What are the 3 outcomes of cell injury?
- reversible injury, cell recovery, and return to normal function.
- apoptosis and programmed cell removal
- cell death and necrosis
what is a normal & highly selective process that restructures tissues and replaces injured and aged cells?
apoptosis
what are the two pathways of apopstosis?
extrinsic (death receptor respondent)
intrinsic (death receptor independent)
What enzyme is required for both pathways of apoptosis?
caspase
what is autophagy?
internal cell components are engulfed and destroyed through fusion with lysosomes.
What are inhibitors of apoptosis linked to?
cancer and autoimmune diseases
what are senescent cells?
cells that are getting old and not working anymore
what is the process of apoptosis?
- shrinking of the cell
2-3. condensation and fragmentation of nuclear chromatin
4-5. separation of nuclear fragments and cytoplasmic organelles into apoptotic bodies - engulfment of fragments by phagocytic cells.
what is necrotic cell death?
unregulated death caused by injuries to cells
what occurs in necrotic cell death?
cells swell and rupture- lead to inflammation
various forms occur: liquefaction, coagulation, caseous necrosis
infarction- (tissue death)
gangrene occurs when large mass of tissue undergoes necrosis
why do cells change with aging?
programmed into cells because telomeres become to short;
accumlated epigenetic changes to DNA;
accumulated damage/error- DNA damage; oxidative free radical-mediated damage, glycation (AGE’s cause tissue stiffening.)
