HUSAIN A. SATTAR Fundamentals of pathoma Latest Edition Ebook PDF

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HUSAIN A. SATTAR Fundamentals of pathoma Latest Edition Ebook PDF

 

HUSAIN A. SATTAR Fundamentals of pathoma Latest Edition Ebook  PDF daptations, Celfular Injury, and Cell Death
CELLULAR INJURY
I. BASIC PRINCIPLES
A. Cellular injury occurs when a stress exceeds the cell’s ability to adapt.
B. The likelihood of injury depends on the type of stress, its severity, and the type of
cell affected.
1. eurons are highly susceptible to ischemic injury; whereas, skeletal muscle is  relatively more resistant.
2. Slow·ly developing ischemia (e.g., renal artery atherosclerosis) results in atrophy;
whereas, acute ischemia (e.g., renal artery embolus) results in injury.
C. Common causes of cellular injury include inflammation, nutritional deficiency or excess, hypoxia, trauma, and genetic mutations.
II. HYPOXIA
A. Low oxygen delivery to tissue; important cause of cellular injury
1. Oxygen is the final electron acceptor in the electron transport chain of oxidative
phosphorylation.
2. Decreased oxygen impairs oxidative phosphorylation, resulting in decreased
ATP production.
3. Lack of ATP (essential energy source) leads to cellular injury.
B. Causes of hypoxia include ischemia, hypoxemia, and decreased 0 2 -carrying capacity of blood.
C. Ischemia is decreased blood flow through an organ. Arises with
1. Decreased arterial perfusion {e.g., atherosclerosis)
2. Decreased venous drainage (e.g., Budd-Chiari syndrome)
3. Shock-generalized hypotension resulting in poor tissue perfusion
D. Hypoxemia is a low partial pressure of oxygen in the blood (Pao2 < 60 mm Hg, Sao2 < 90%). Arises with
1. High altitude-Decreased barometric pressure results in decreased PAo2

2. Hypoventilation-Increased PAco2 results in decreased PA02

3. Diffusion defect-PAo2 not able to push as much 0 2 into the blood due to a
thicker diffusion barrier (e.g., interstitial pulmonary fibrosis)
4. V/Q mismatch-Blood bypasses oxygenated lung (circulation problem, e.g., right-to-left shunt), or oxygenated air cannot reach blood (ventilation problem,
e.g., atelectasis).
E. Decreased 0 2 carrying capacity arises with hemoglobin (Hb) loss or dysfunction.
Examples include
1. Anemia (decrease in RBC mass)-Pao2 normal; Sao2 normal
2. Carbon monoxide poisoning