Control of Blood Vessel Function

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Control of Blood Vessel Function
2015-03-29 12:27:45
Blood vessel function physiology

Vet Med - Module 10
Show Answers:

  1. What are the chief resistance vessels of the systemic circulation?
  2. What is basal tone?
    The natural degree of tone arterioles (and some larger vessels) have in their vascular smooth muscle
  3. What is the symbol for blood flow?
  4. What two major categories influence basal tone?
    Local factors and extrinsic factors
  5. What type of factors (local or extrinsic) dominate over a) critical organs eg brain b) non-critcal organs e.g. kidney
    • a) local 
    • b) extrinsic
  6. What organ are both local and extrinsic factors important in?
  7. List the 5 local control factors and mechanisms
    • Temperature
    • Compression
    • Myogenic response
    • Local metabolites
    • Autocoids
  8. What effect does heating/cooling have on cutaneous arterioles?
    • Heating - vasodilation
    • Cooling - vasoconstriction
  9. What effect does mechanical compression have on blood flow?
    It stops blood flow
  10. What is the myogenic response?
    A rise in internal pressure distends blood volume but most arterioles react by contracting
  11. Many byproducts of normal tissue metabolism cause vascular relaxation or contraction?  Why?
    Relaxation - this increases blood flow and increases local tissue perfusion to organs with a higher metabolic rate
  12. Give examples of local metabolites that cause vascular relaxation
    Acidosis, ATP breakdown and K+ released by muscle
  13. What are autocoids?  Give an example of an autocoid
    • Vasoactive chemicals produced, released and acting locally
    • Histamine, serotonin, bradykinin, prostoglandin, nitrous oxide
  14. Where is adrenaline and noradrenaline secreted from?
    The adrenal medulla
  15. What are situations adrenaline and noradrenaline secreted in response to?
    Fight, flight, fear, exercise, hypotension and hypoglycaemia
  16. Where are baroreceptors located?
    In the aortic arch and carotid sinus
  17. Afferent fibres from which cranial nerves are in the carotid sinus and aortic arch?
    IX (glossopharyngeal) and X (vagus)
  18. What do baroreceptors do?
    They detect and respond to changes in blood pressure
  19. What type of receptors are baroreceptors?
  20. Increased pressure in the artery causes distention - what effect does this have on baroreceptors?
    This excites the receptors
  21. What effect does the following have on the heart? a) increased sympathetic activity b) decreased parasympathetic activity
    • a) increased HR and contractility 
    • b) increased HR
  22. What effect does increased sympathetic activity have on blood vessels?
    Arteriole vasoconstriction
  23. Why can baroreceptors not regulate blood pressure in the long term?
    As baroreceptors adapt to the prevailing level of arterial pressure e.g. in animals that are hypertensive long term the baroreceptors come to accept this as normal and regulate pressure at the elevated level
  24. What are the three other ways the baroreceptor reflex tries to increase blood volume by?
    • Increasing the sensation of thirst
    • Increasing ADH which decreases urine flow from the kidneys 
    • Increases renin which acts to produce aldosterone which decreases Na excretion