chapter 3: cellular adaptation, injury, & death -

what is a cellular adaptation?

a cell’s response in order to escape and protect itself from injury

what is atrophy?

cells decrease in size, causing tissue size to decrease

what is physiologic atrophy? example?

normal process from a decrease in activity or age

ex) involution of the thymus at puberty

shrinkage of uterus following menopause

what is pathologic atrophy? example?

a result of a disease, or decrease in work load, pressure, blood supply, nutrition, or hormonal stimulation

ex) muscle loss from a nerve injury

what is hypertrophy?

an increase in cell size, causing an increase in tissue size

often caused from an increase in work load or hormonal stimulation

what is physiologic hypertrophy? example?

normal process

muscle mass increasing from weight lifting

what is pathologic hypertrophy? example?

caused from disease/chronic stress

left ventricular hypertrophy due to hypertension

what is hyperplasia?

an increase in cell number from increased cellular division

what are the 2 forms of physiologic hyperplasia? examples?

compensatory: tissue regeneration

liver regeneration following a partial removal

hormonal: replacing lost tissue or supporting new growth

ex) thickening of uterine lining to prepare for menstruation

what is pathologic hyperplasia? example?

excessive hormonal stimulation

increase in prostate size

what is dysplasia? what adaptation is it a form of?

abnormal changes in size, shape, and organization of cells due to deranged growth

a kind of atypical hyperplasia

does dysplasia indicate cancer?

no!!

what’s an example of dysplasia?

cervical dysplasia from HPV

what is metaplasia? example?

one mature cell type replaced by a different mature cell type, often as a result of chronic irrtation

barrett esophagus: chronic acid reflux causes typical esophageal cells to be replaced by intestinal cells

what is cellular injury?

cells exposed to harm beyond their adaptation abiliity

what is reversible cell injury?

the ability to recover after the stressor is removed

what is irreversible cell injury?

cell death

what are common causes of cell injury?

hypoxia, chemicals, and free radicals

how does ischemia/hypoxia lead to cellular injury?

1. mitochondria damage

2. ATP depletion

3. cells switch to anaerobic metabolism

   1. glycogen stores break down

   2. pumps stop working

   3. Na and water build up —> swelling

   4. ribosomes detach and protein synthesis decreases

how does free radical formation lead to cellular injury?

causes oxidation of integral cell structures

how does Ca increase lead to cellular injury?

enzymes are wrongly activated, causing damage to cell structures

what is an ischemia-reperfusion injury?

ischemia phase: low O2 causes cells to switch to anaerobic metabolism, decreasing ATP output

• This causes ion pumps to fail, leading to Ca build up and swelling

reperfusion phase: blood suddenly returns

• sudden O2 presence bursts ROS leading to membrane damage

what is a free radical injury?

increase in ROS causes lipid, protein, and nucleic acid oxidation

• membrane weakens

• proteins break down

• genes mutate

what is a toxin injury?

direct toxins cause membrane damage

• ex) lead causes direct harm to CNS and PNS

• CO2 intake causes hypoxia

what is necrosis?

uncontrolled cell death

what is coagulative necrosis?

• mechanism: protein denatures, dead cells remain on tissue

• morphology: cells become a gray, firm mass

• causes: ischemia

• damage: permanent structural damage and loss of function

what is liquefactive necrosis?

• mechanism: hydrolytic enzymes break down dead cells into liquid-filled cysts and pus

• morphology: often in glial cells/the brain

• causes: the digestion of dead cells by hydrolytic enzymes

• damage: destroys structure

what is caseous necrosis?

• mechanism: combo of coagulative and liquefactive necrosis

• morphology: looks like cheese (ew)

• causes: from TB

• damage: structure loss

what is fat necrosis?

• mechanism: lipases break lipids into fatty acids

• morphology: only occurs in adipose tissue

• causes: trauma, sudden ischemia

• damage: formation of scar tissue and cysts

what is gangrenous necrosis?

when an area of necrosis becomes large enough to be visible during an examination

what does dry grangrene look like?

skin shrinks, shrivels, and turns dark brown or black

what is wet grangrene?

dead tissue becomes infected by bacteria, leading to rapid break down and swelling

what is gas gangrene?

dead tissue becomes infected by Clostridium bacteria specifically

what is apoptosis?

programmed cell death and the digestion of old/damaged cellular parts (autophagy)

how does apoptosis and necrosis differ?

apoptosis is controlled cell death, whereas necrosis is accidental death caused by an injury

what is the biological schedule theory of aging?

our lifespan is regulated by genes, in that cells follow predetermined replication limits

what is the damage theory of aging?

aging is the result of accumulated cellular damage over time