Pathophys Test 2

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  1. Review blood flow through the heart and the mechanical events that take place. (p.2)
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  2. Preload
    • End-diastolic volume
    • Blood in each ventricle at end of diastole
    • Normal = 110-120 mL
    • Venous return to heart = major factor regulating end-diastolic volume
    • Preload = degree of tension or distending force on ventricular muscle when it begins to contract
  3. End-systolic volume
    • Volume of blood in ventricle after contraction
    • Usually 40-50 mL
  4. Afterload
    • Pressure or resistance against which ventricle has to pump
    • Anything that increases pressure (aortic stenosis or peripheral vascular disease) increases afterload
  5. Stroke Volume
    • Amount of blood ejected from ventricles during contraction
    • Usually 40-50 mL
  6. Cardiac Output
    (Stroke volume) x (Heart rate)
  7. How is Frank-Starling mechanism related to cardiac output?
    Greater stretch of muscle fibers = stronger contraction
  8. How does the sympathetic nervous system influence heart rate and force of contraction? (p.6)
    • Sympathetic nervous system – supplies both atria and ventricles
    • Sympathetic stimulation –
    • o Can increase cardiac output 2-3 fold
    • o Increase rate and force of contractions
    • o Norepinephrine – released from sympathetic nerve endings
    • o Epinephrine – released from adrenal glands
    • o Norepinephrine and epinephrine – enhance depolarization rate of SA node by increasing net flow of calcium ions into cells (slope of phase 4 depolarization)
  9. How does the parasympathetic nervous system influence heart rate and force of contraction? (p.6)
    • Parasympathetic nerves – primarily supply atria
    • o Acetylcholine – released from vagus nerve endings of parasympathetic system
    • o Slow HR and decrease force of contraction, especially atria
    • o Acetylcholine – slows HR by increasing membrane permeability to K+ and increasing polarization
    • - (hyperpolarized state)
  10. Where would you find majority of alpha-adrenergic receptors? (p.6-7)
    Located mainly in systemic blood vessels (arterioles) of skin, abdominal viscera, and skeletal muscle
  11. Where would you find majority of beta-adrenergic receptors? (p.6-7)
    • o Lungs (beta-2)
    • o Heart (beta-1); (also beta-2 and alpha-1 in heart)
    • o Skeletal muscles (beta-2)
    • o Blood vessels (arterioles) of these organs (alpha-1, beta 2)
  12. Know general effect of epinephrine on alpha-receptors and beta-receptors.
    • o Excite alpha and beta receptors equally
    • o Beta receptors tend to have lower threshold (increased sensitivity) for epinephrine than alpha receptors
    • - especially on blood vessels in skeletal muscle
  13. Know general effect of norepinephrine on alpha-receptors and beta-receptors.
    • o Excites alpha receptors more than beta receptors
    • o Alpha receptors less sensitive to epinephrine
    • o Little effect on beta-2 receptors, but stimulate beta-1 receptors
  14. If you gave a pharmacologic dose of norepinephrine, what would be the anticipated response of blood vessels?

Card Set Information

Pathophys Test 2
2010-04-01 21:16:57
Cardiovascular Basic

Cardiovascular Basic
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