Cardio Lecture 5 (ch17)

  1. Local Control of Blood Flow
    each tissue controls its own blood flow in proportion to its needs

    • tissue needs:
    • 1. delivery of O2 to tissues
    • 2. delilvery of nutrients such as glucose, amino acids, ect
    • 3. removals of CO2 , H and other metabolites from the tissues
    • 4. Transport various hormones and other substances to different tissues
  2. increase in tissue metabolism leads to
    increase in blood flow
  3. decrease is oxygen availability to tissue...
    increases tissue blood flow
  4. Flow (Q) through a blood vessel is determined by
    • 1. the pressure difference (ΔP) between 2 ends of the vessel
    • 2. resistance (R) of the vessel
  5. equation for blood flow
    Image Upload 1
  6. autoregulation
    ability of a tissue to maintain blood flow relatively constant over a wide range of arterial pressure
  7. Metabolic Theory of Blood Flow Autoregulation
    as arterial pressure is decrease, Oor nutrient delivery is decreased resulting in a release of a vasodilator
  8. Myogenic Theory of Blood Flow Autoregulation
    as arterial pressure falls the arterioles have an intrinsic property to dilate in response to decreases in wall tensions
  9. Laplace's Law of Myogenic Mechanism
    Tension = Pressure x radius
  10. Long-term Local Blood Flow Regulation
    • occurs by changing the degree of vascularity of tissues (size and number of vessels)
    • oxygen is an important stimulus for regulating tissue vascularity
  11. Angiogenesis
    • the growth of new blood vessels
    • occurs in response to angiogenic factors
  12. Anigogenic factors are released from:
    • 1. ischemic tissues
    • 2. rapidly growing tissue (embryology)
    • 3. tissue with high metabolic rates (ovary, cancer)
    • most are small peptides 
    • VEGF: vascular endothelial cell growth factors
    • FGF: fibroblast growth factor
    • angiogen
  13. Vasoconstrictors
    • NE and EPI
    • angiotensin
    • vasopressin
    • endothelin
  14. Vasodilator
    • bradykinin
    • serotonin
    • histamine
    • prostaglandins
    • nitric oxide
  15. NE and EPI vasoconstrictors
    • Catecholamine, non-peptide NT, that are secreted by the adrenal medulla
    • bind to α and β GPCR andwork through   second messengers  (Gs- cAMP) affecting K and Ca
  16. Angiotensin (II)
    • important in kidney control of BP
    • peptide hormone more potent then NE/ Epi
    • mainly acts on the arterioles to increase total peripheral resistance
    • AT1 and AT2 receptors
    • activate PLC IP/ DAG
  17. function of renin
    cleaves angiotensiogen into angiotensin I
  18. ACE
    • angiotensin converting enzyme
    • converts Angiotensin I to II
  19. Effects of Angiotensin II
    • vasoconstrictor 
    • Acts on Adrenal Cortex, Pituitary, Cardiac and Vascular hypertrophy, systemic vasoconstriction
    • increased blood volume 
    • renal sodium and fluid retention
  20. Vasopressin
    • vasocontrictor 
    • ADH: anti-diuretic hormone
    • formed from nerve cells of hypothalamus 
    • secreted by posterior pituitary gland into blood
    • increases water reabsorption in the kidneys
  21. serotonin
    • vasodilator
    • 5HT2
    • important in localized vasoconstriction
    • dilated cardiac blood vessels
    • secreted by platelets
    • Increases PLC, increase IP3, and increases intracellular calcium
    • involved in wound healing
  22. histamine
    • vasodilator
    • occurs in every tissue
    • released by immune cells in respinse to damage, allergy, and inflammation
    • Gs
  23. Nitric oxide (NO)
    • vasodilator
    • released from healthy, endothelial cells
    • acts locally on vascular SM cells
    • cGTP converted to cGMP by guanylate cyclase enzyme to cause local SM relaxation
Card Set
Cardio Lecture 5 (ch17)