Exam 1: Altered Cellular Biology Flashcards
Define compensation:
Body’s attempt to maintain homeostasis under stress
Define cell injury:
Result of stimulus *in excess* of cell’s adaptive response
Types of cell injury:
Reversible and irreversible
Describe reversible cell injury:
Causes cells to adapt for next time stress is applied True at the cellular level, but not at the tissue level
Describe irreversible cell injury:
Cell death
Tissues that hypertrophy/atrophy:
Cardiac Skeletal
Tissues that become hyperplastic:
All beside cardiac/skeletal
Describe metaplasia:
Change in type of cell present when current type is not adequate to deal with stress/irritant
Examples of metaplasia:
- Barrett’s esophagus
- Cilia converting to stratified squamous in smokers
Describe dysplasia:
Abnormal cells (not physiologically normal for any tissue)
Describe neoplasia:
Abnormal cells lacking organization/structure
What causes hypertrophy of the heart?
Hypertension Aortic stenosis Conditions that require more force to pump the same volume
What type of athletes need hypertrophied hearts?
Power athletes - weightlifters, sprinters, rowers, etc Need high flow under high pressure
Difference between hypertrophy in athletes and sick patients:
Sick patients: stress is 24/7, heart cannot rest and remodel properly Athletes: stress is transient, heart can rest and remodel in healthy way
Is the metaplasia seen in smokers reversible?
Yes
What parts of the brain form new cells regularly?
The hippocampus (memory center) and olfactory neurons
What are four common themes in cell injury?
ATP depletion Free radicals/reactive oxygen species Increase in Ca++ in the cell Defects in the plasma membrane
What does high Ca++ in the cell do?
Signals for it to die
How is Ca++ removed from the cell?
ATP powered pump
Embolus vs. thrombus:
Embolus: mobile, gets stuck Thrombus: occludes in situ
Describe the chain of events that occurs within the ischemic cell:
Hypoxic mitochondria switch to anaerobic metabolism Low ATP signals cell to deplete glycogen in order to phosphorylate ADP Lactate production increases pH Acidic environment causes DNA clumping and lysosome swelling Lysosome rupture leads to autodigestion
Describe the chain of events that occurs at the ischemic cell membrane:
Low ATP can’t pump out Na+ and Ca++, can’t return leaked K+ Osmotic effect means water trapped in cell (Ca++ leads to muscle contraction, using more ATP) Dilated ER can’t synthesize proteins Membrane becomes unrepaired and damaged More Ca++ in Cell contents out
What are the clinical signs of cell damage?
Cytoplasmic proteins: troponin, CK, CK-MB, LDH
Define hypoxia:
Low O2 in tissue
Define hypoxemia:
Low blood O2
Define ischemia:
Insufficient blood supply to tissue
Define infarct:
Ischemia with necrosis
What can cause localizes hypoxemia and hypoxia?
Embolus
What can cause hypoxia without hypoxemia?
Anemia
What causes reperfusion damage?
Production of reactive oxygen species
How does the endogenous antioxidant system neutralize free radicals?
O2- converted to H2O2 by SOD; catalase converts H202 to H2O *or* glutathione converts H2O2 to H2O
Why do frequent exercisers have so little risk of heart attack?
Cells adapt to the insult of free radicals produced during exercise
How does necrosis affect neighboring cells?
Leakage of cell contents is signal for inflammatory process to clean up the mess
How does apoptosis affect neighboring cells?
No cell content leakage into ECF; apoptotic bodies consumed by phagocytes without affecting rest of tissue
Where does coagulative necrosis occur? What causes it? How does it happen?
Everywhere but the brain Caused by ischemia Cells die in place
Where does liquefactive necrosis occur? What causes it? How does it happen?
In the brain Caused by ischemia Cells are obliterated by inflammation and enzymes dissolve them
Where does caseous necrosis occur? What causes it? How does it happen?
In the lungs Caused by tuberculosis Cellular debris is cheese-like
Where does fat necrosis occur? What causes it? How does it happen?
In the omentum/mesentery fat Pancreatic enzymes leak (pancreatitis) and saponify the abdominal fat
Three types of gangrenous necrosis:
Dry Wet Gas
Describe dry gangrene:
Typically diabetic in origin; neuropathy dulls warning pain Loss of blood flow means loss of immune response to infection
Location of wet gangrene:
Internal organs or bedsores
Cause of gas gangrene:
From c. perfringens
What are telomeres?
6 nucleotide repeats on the end of chromosomes that limit number of replications
What is replicative senescence?
When telomeres are exhausted and cells can no longer divide
What opposes the natural shortening of telomeres?
Telomerase
What cells normally have telomerase turned on?
Germ cells
