Lecture

• Smooth ER fxns: lipid and steroid hormones creation, stores calcium and detoxification(lots in the liver)
• 3 ways a cell can respond to environmental changes/injury: survival, adaptation and death
• Survival is reversible and its a response that's used in the short term. When the stressor is dealt with, it returns back to normal as if nothing had happened
• Adaptation is usually reversible
• Hypertrophy is an increase in cell size and it signals gene activation, protein synthesis and organelle proliferation
• Example of metaplasia: monocytes turning into macrophages
• Metaplasia is reversible if stressor is removed
• Pathologic hyperplasia often leads to dysplasia
• Dysplasia is reversible if the stressor is removed
• Cellular injury is affected by these types of stress: physical, infectious and immune
• Direct chemical damage occurs when there's no need for metabolism for damage to occur while indirect requires metabolism of the chemical
• Hallmark sign of reversible cell injury is hydropic swelling
• the 2 types Irreversible cell injuries: necrosis and apoptosis; the hallmark sign is membrane damage while the terminal sign if the loss of the nucleus
• Necrosis: occurs externally and consists of messy membrane rupture, everything swells and enzymes break down cell contents
• Necrosis from the outside may leak out cytochrome c which causes apoptosis from the inside
• Necrosis is always followed by inflammation
• Cell accumulations consist of excess normal, abnormal and indigestible materials; normal is too many fats/carbs/proteins, abnormal is glycogen/protein, indigestible is bilirubin/heavy metals/mineral dust
• Apoptosis is an ATP dependent process
• Hypoxemia is considered if FIO2 is lower than 90%
• Air trapping caused by pulmonary diseases causes an increased PaCO2 which causes a decreased PaO2
• SaO2: refers to O2 loaded on to hemoglobin
• Hypoxia can occur because of increased demand or decreased supply
• Stagnant/Ischemic Hypoxia: decreased blood through your organs which leads to shock and hypoxia
• Anemic Hypoxia: impaired O2 carrying capacity; CO poisoning is an example
• Hypoxemic hypoxia: decrease in PaO2 and occurs because of V/Q mismatch; examples are high altitude and hypoventilation
• Histotoxic hypoxia: aka cellular hypoxia; Inability of the cell to use the O2 delivered. Examples are cyanide poisoning or Hydrogen sulfide
• Different types of hypoxia are: Hypoxemic, Anemic, Ischemic and Histotoxic
• Generally systemic hypoxia causes vasodilation but has selective vasoconstriction and shunting
• Shunting blood flow occurs through closing precapillary sphincters
• Oxygen Demand/Myogenic theory: smooth muscle requires O2 to remain contracted because it requires ATP.
• Vasodilator/Metabolic theory: vasodilator substances affect precapillary sphincters and arterioles directly; an increase in metabolic rate or decrease in availability of nutrients/O2 causes an increases in vasodilator substances
• Clubbing of the digits occurs because of chronic hypoxia
• Different tissues react to hypoxia differently
• Neurons are extremely sensitive to hypoxia
• CNS hypoxia causes increased permeability of cerebral capillaries
• Hypoxia causes vasoconstriction in pulmonary vessels
• Hypoxia has a systemic vasodilation effect but pulmonary vasoconstriction effect
• Cardiac conduction tissue has a very high O2 consumption rate; occurs due to its leaky gates
• Initially, hypoxia effects the cardiovascular thru inducing tachycardia and then bradycardia follows if not treated
• Hypoxia irritates cardiomyocytes which makes them more likely to conduct impulses on their own which can cause dysrhythmias