Pathoma: Cell Injury

Question 1

Injury

Answer 1

occurs when stress exceeds cells ability to adapt

Question 2

What does the likelihood of injury depend on?

Answer 2

The type and severity of the stress and the type of cell affected

Question 3

What type of cell is very susceptible to injury?

Answer 3

neurons–>hypoxia

Question 4

Common causes of injury

Answer 4

inflammation
nutritional deficiency or excess
hypoxia
trauma
genetic mutations

Question 5

Hypoxia

Answer 5

low O2 delivery to tissues

Question 6

Causes of hypoxia

Answer 6

ischemia
hypxemia
decreased O2 carrying capacity of blood

Question 7

Ischemia

Answer 7

decreased blood flow through an organ

Question 8

Why does ischemia occur?

Answer 8

because of a block in an artery or decreased flow of blood through a vein; shock

Question 9

Bud-Chiari syndrome

Answer 9

thrombosis of the hepatic V.; causes ischemia of liver

due to polycythemia vera or lupus anticoagulant

Question 10

Polycythemia vera

Answer 10

increase in the number of RBCs–>increased viscosity of blood; leads to Bud Chiari Syndrome

Question 11

Hypoxemia

Answer 11

low partial pressure of O2 in blood

PaO2 < 60 mm Hg, SaO2 < 90%

Question 12

PAO2

Answer 12

partial pressure of oxygen in alveolar air space

decreased by increased PACO2 (hypoventilation due to COPD)

Question 13

SaO2

Answer 13

percent of hemoglobin that has all of its spaces filled with O2

Question 14

How does decreased O2 carrying capacity occur?

Answer 14

Hb loss or dysfunction

Question 15

Anemia

Answer 15

decrease in RBC mass
PaO2 normal, SaO2 normal
SaO2 is normal because this number represents % of Hb bound by O2, not how much Hb is available

Question 16

CO poisoning

Answer 16

CO binds Hb more avidly than O2
PaO2 normal, SaO2 decreased
exposures include smoke from fires and exhaust from cars or gas heaters

Question 17

Classic finding of CO poisoning

Answer 17

cherry red skin

early sign of exposure is headache; significant exposure can lead to coma and death

Question 18

Methemoglobinemia

Answer 18

Iron in heme is oxidized to Fe3+, which cannot bind O2
PaO2 normal, SaO2 decreased
seen with oxidant stress (sulfa and nitrate drugs) or in newborns

Question 19

Classic finding of methemoglobinemia

Answer 19

cyanosis with chocolate-colored blood
treatment is IV methylene blue
helps reduce Fe3+–>Fe2+

Question 20

What does hypoxia impair?

Answer 20

oxidative phosphorylation

Decreased ATP–>increased Na+ in cell–>increased H2O in cell–>cell swells–>lysis

Question 21

Is the initial phase of injury reversible?

Answer 21

Yes
hallmark is cellular swelling
leads to loss of microvilli, membrane blebbing, and swelling of RER

Question 22

Late stages of injury

Answer 22

irreversible damage
hallmark is membrane damamge
plasma membrane–>enzymes will enter the blood
mitochondria–>ETC is disrupted, cytochrome C gets released into the cell cytoplasm
lysosomes–>digests cell instead of things inside the lysosome

Question 23

End result of irreversible damage of cell

Answer 23

cell death