CHAPTER 2: CELL ADAPTATION, INJURY, & DEATH Flashcards
Cellular Adaptation is..
cell response to stressors to maintain homeostasis
- change in size, number, phenotype, metabolic activity, function
Atrophy: physiologic vs. pathologic
DECREASE in cell size due to DEC in DEMAND
physio: occurs w early development, age-related changes (ovary atrophy post menopause)
pathologic: occurs result of decrease in WORKLOAD
use it or LOSE IT!
Pathologic Atrophy
disuse: dec in skeletal musc from dec workload
denervation: dec musc in paralzed limbs
ischemia: dec blood supply
additional:
- loss encodrine stimulation
- inadequate nutrition
Hypertrophy: physiologic vs pathologic
INC cell size and function from INC workload
physiologic: inc demand, stimulation by hormones and growth factors
pathologic: chronic hemodynamic overload
Physiologic Hypertrophy
inc in skeletal muscle mass from inc workload/exercise
Pathologic Hypertrophy
adaptive: myocardial hypertrophy (from hypertension)
compensatory: enlargement of remaining organ/tissue after portion has been removed
Hyperplasia
INC in # of cells, requires mitosis
(epidermis, intestinal epithelium, etc..)
Physiologic Hyperplasia
hormonal: in organs that respond to endocrine hormonal stimulation
compensatory: enables organs to regenerate (epidermis, intestinal epi, hepatocytes)
Pathologic Hormonal Hyperplasia
excessive hormonal stimulation
ex) thyroid enlargement, benign prostatic hyperplasia, endometrial hyperplasia
Dysplasia
aka atypical hyperplasia
- abnormal changes in size, shape, organization of mature cells
Metaplasia
1 cell type replaced by another dude to stress/injurious stimuli
ex) chronic smoker will change from ciliated columnar epithelial cells in trachea TO stratified squamous epithelium
- NO mucus or cilia=lost protective mech.
ex) GERD
Cell Injury/Death occurs…
when the cell is unable to maintain homeostasis
- reversible if stimulus is mild or transient
Cell Injury: Hypoxia
cell is deprived of oxygen, interrupts oxidative metabolism and ATP generation
Hypoxia may result in
- power failure in cell
- acute cellular swelling –> edema
- induces inflammation
Hypoxemia
PaO2 below normal due to environmental or resp disease
- high altitude or emphysema
Ischemia
dec perfusion (vasoconstrict) due to cardiac or vasc disorder
- arteriosclerosis or embolus
Anemia
O2 carrying capacity is reduced due to loss of Hb or Hb function
- dec RBC production.
Hypoxic Cell injury results in…
aerobic metabolism stopping –> dec ATP—> active transport mechanisms stop working
Ischemia-Reperfusion Injury
restoration of blood flow and oxygen to ischemic tissues
Free Radicals and ROS
free radical: uncharged atom has unpaired electron
reactive oxygen species: formed natural oxidant species during respiration
Lead Toxicity
- sources: flaking paint, lead contaminated water/pipes
- absorbed into blood through GIT, resp tract
- causes lead colic/abdominal pain, pigmented gums, nervous system
Infectious Injury
viruses enter cell and incorporate into DNA synthetic machinery
- bacteria produce endotoxins that interfere w ATP production
Xeroderma Pigmentosum
dry pigmented skin
- rare autosomal recessive disorder
- result of nucleotide excision repair enzymes being mutated –> unable to repair UV damage to DNA
Lipids and Carbs
Accumulation of lipid in liver
- steatosis (fatty changes of liver)
Water
cellular swelling
- reversible, in hypoxic injury
Calcification
cellular calcification
- calcium salts accumulate in injured, dead tissues
- dystrophic calc: in DEAD or dying tissue (pulm TB, damaged heart valves)
- metastatic calc: in NORMAL tissue (renal tubules, blood vessels)
Hypercalcemia causes
- hyperparathyroidism
- vit D intox
- hyperthyroidism
- addison disease
Antioxidants
molecules that inhibit oxidation of other molecules
- inactivate free radicals
ex) vit A, C, E, CoQ10, Zinc, Glutathione
Xenobiotics
toxic, mutagenic, and carcinogenic chemicals
- cause direct toxicity to the cell
- ex) drugs (alc), carbon monoxide, lead tox, mercury
Radiation Injury
ionizing (xrays, gamma)
- dsDNA breaks, free radicals released, vasc damage
UV radiation
- sunburn, inc risk of cancer, DNA damage
Cell Death
Apoptosis: cell suicide
Necrosis: cell murder (programmed)
Necrosis
liquefactive, coagulative, caseous, fat
Gangrene
dry: from coagulative necrosis, skin dry and shriveled
wet: tissue swollen, black color, rapid spread
