Roos10.txt

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  1. factors regulating arterioles in various regional circulations
  2. Left ventricular coronary flow is highly dependent upon?
    diastolic arterial pressure since little perfusion is possible in the left ventricle during systole
  3. Cerebral Blood Flow
    • relatively independent of MAP & is regulated by local hyperemia and autoregulation
    • however, if MAP is raised higher above this range, or dropped lower, the flow will increase or drop dramatically (respectively)
    • if there is a very sudden rise in MAP, there is the risk of causing hemorrhagic stroke (burst vessel in the brain); local hyperemia & autoregulation work in the range of milliseconds (a slightly slower response
  4. Cerebral Circulation
    • Cerebral neurons require an adequate supply of oxygen and glucose at all times for the human being to remain conscious.
    • Though only 2% of the body mass, the CNS consumes nearly 20% of the O2 at rest and maintains no energy reserve.
    • Cerebral Blood Flow is relatively independent of MAP by local hyperemia and autoregulatory mechanisms.
    • Changes in flow regulation via vascular resistance occur gradually (over minutes) and do not protect the brain from sudden changes in MAP.
  5. Pulpal blood flow
    • electrically stimulating the surface of the tooth causes a huge increase of blood flow in the pulp
    • if you denerve the tooth, there is not this response
    • But sympathetic stimulation of the vessels that supply the pulp reduce their flow.
    • sympathetic stimulation is generally a vasoconstrictor, and a decrease in flow makes sense; but here, we increase the flow-
  6. Antidromic Vasodilation
    • Sensory nerves on gingiva send signals down in the normal direction, then up in the antidromic direction to the pulp to vasodilate
    • Can get the same effect by stimulating the sensory nerve directly.
  7. Pulpal and Gingival Blood Flows
    • Stimulation via the cervical sympathetic chain induces severe vasoconstriction in the vessels supplying the pulp and gingiva.
    • Stimulation of the parasympathetic fibers of the glossopharyngeal nerve (#9) elicit vasodilation of the gingiva, but not the pulp which has not demonstrated a parasympathetic response.
    • Vasodilation in the pulp can be elicited by surface stimulation of the tooth or gingiva by antidromic vasodilation mediated by sensory nerve fibers.
    • Thus irritation of the gingiva during dental procedures might increase blood flow to the teeth!
  8. Saliva and Blood Flow
    • flow of saliva is tightly coupled to blood flow.
    • salivary blood flow is regulated by both sympathetics, but also parasympathetics; if you increase either sympathetic or parasymp stimulation, you will have increased saliva flow (and blood flow), although the composition of the saliva will be different
    • salivary blood flow is regulated by both sympathetics, but also parasympathetics; if you increase either sympathetic or parasymp stimulation, you will have increased saliva flow (and blood flow), although the composition of the saliva will be different
  9. Circulatory Shock
    • Shock exists whenever there is a generalized severe reduction in blood supply to the tissues.
    • There are 4 general categories of shock:
    • Cardiogenic
    • Hypovolemic shock.
    • Anaphylactic & Septic shock.
    • Neurogenic shock.
  10. Cardiogenic shock
    • occurs whenever the cardiac pumping ability is compromised.
    • This can be due to myocardial infarction, valvular disease, heart failure or arrhythmias which reduce the cardiac output.
  11. Hypovolemic shock
    • occurs whenever there is a significant fluid loss.
    • This can be due to hemorrhage, severe burns, chronic diarrhea or prolonged vomiting which lead to fluid loss.
  12. Anaphylactic and Septic shock
    • occur whenever vasodilators are activated.
    • This can be due to severe allergic reactions or from toxins released by infectious agents which lead to decreased venous pressures and vascular resistance.
  13. Neurogenic shock
    • occurs whenever vascular tone is decreased due to a reduction in sympathetic activity.
    • This can be due to severe anesthesia, deep pain or, in a milder form, with strong emotions.
    • Certain emotional events can lead to a “Vasovagal” response
  14. Effect of Anesthesia upon Pressure
    • when anesthesia given, the arterial pressure drops significantly; NE causes a spike in arterial pressure, but prolonged anesthesia will bring pressure down again
  15. Stress
    • factor in heart disease
    • hypothalamus is sensitive to it, releasing corticotropin releasing hormone, which acts on the anterior pituitary, causing it to release adrenocorticotropin hormone, which acts on the adrenal cortex to release cortisol > various effects (see bottom left), with vasoconstriction affecting the heart
    • stress causes sympathetic firing to cause adrenal medulla to release more E and NE (right) > various effects (bottom right)
    • Try to minimize

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Author:
 emm64
ID:
 134876
Filename:
 Roos10.txt
Updated:
2012-02-13 06:03:35
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Roos 10 Systems
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Roos 10 systems
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