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68 Cards in this Set
- Front
- Back
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The term used to describe the ability of an organ to maintain normal or near normal blood flow in the face of changes in arterial pressure.
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Autoregulation
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If blood flow exceeds the autoregulatory range the blood will become ?
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pressure-passive
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When pressure exceeds the autoregulatory range of blood flow, ? will decrease due to the pressure that forces the vessel to dilate.
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Vascular Resistance decrease
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If pressure drops below the autoregulatory range, vessels are fully dilated and ? cannot drop any further
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Resistance
(it cant drop any further) |
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True or False
Autoregulation is a LOCAL control phenomenon and is DEPENDENT of nerve activity |
FALSE
autoregulation is a LOCAL control phenomenon and is INDEPENDENT of nerve activity |
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Autoregulation appears to be related to what types of control mechanisms?
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metabolic control
myogenic control Increased release of NO |
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Name the metabolic factors that can result in vasodilation. (6)
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increase Adenosine
increase CO2 increase H+ increase K+ increase Lactic Acid increase Osmolarity |
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Define as a period of higher than normal blood flow that occurs transiently
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reactive hyperemia
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Removal of flow restriction will lead to ?
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Reactive Hyperemia
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The term used to describe the ability of an organ to maintain normal or near normal blood flow in the face of changes in arterial pressure.
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Autoregulation
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If blood flow exceeds the autoregulatory range the blood will become ?
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pressure-passive
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When pressure exceeds the autoregulatory range of blood flow, ? will decrease due to the pressure that forces the vessel to dilate.
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Vascular Resistance decrease
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If pressure drops below the autoregulatory range, vessels are fully dilated and ? cannot drop any further
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Resistance
(it cant drop any further) |
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True or False
Autoregulation is a LOCAL control phenomenon and is DEPENDENT of nerve activity |
FALSE
autoregulation is a LOCAL control phenomenon and is INDEPENDENT of nerve activity |
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Autoregulation appears to be related to what types of control mechanisms?
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metabolic control
myogenic control Increased release of NO |
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Name the metabolic factors that can result in vasodilation. (6)
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increase Adenosine
increase CO2 increase H+ increase K+ increase Lactic Acid increase Osmolarity |
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Define as a period of higher than normal blood flow that occurs transiently
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reactive hyperemia
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Removal of flow restriction will lead to ?
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Reactive Hyperemia
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Acute increase in blood flow will increase ? which induces NO induced vasodilation.
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Shear Stress
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Describe Flow Dependent Vasodilation
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acute increase in blood flow
=> increase shear stress => NO induced vasodilation |
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Biosynthesis of NO is principally performed by ?
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Calcium-dependent endothelial isoform of endothelial nitric oxide synthase (eNOS)
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What molecular chaperone is used during vasodilation of Flow Dependent vasodilation.
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HSP90
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What amino acid is used to synthesize NO?
What is the byproduct of this reaction (besides NO)? |
L-Arginine
L-citrulline |
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? is the catalyst that converts L-Arg into NO.
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eNOS
(endothelial nitric oxide synthase) |
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NO diffuses into smooth muscle cells where it activates its effect enzyme ?
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Guanylate Cyclase (GC)
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Guanylate Cyclase converts GTP to cGMP which then activates ?
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Protein Kinase G
(PKG) |
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What does activation of Protein Kinase G (PKG) do?
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modulation of MLCK --causing smooth muscle relaxation.
Causes I(k) channels to open --causing hyperpolarization and then relaxation |
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Name 2 methods of stimulating NO production.
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Shear Stress
Agonist binding BOTH cause Ca2+ release |
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What does eNOS require in order to function?
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Ca2+ is required for eNOS to function
(Ca2+-dependent endothelial isoform of eNOS) |
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Describe how FLOW MEDIATED VASODILATION in exercising muscle works.
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increase ATP utilization/breakdown
=> increase [Adenosine] => binds to ADENOSINE-2 RECEPTORS (A2) => causes vasodilation =>decrease resisitance flow => increase blood flow to skeletal muscle arterioles => increase shear stress => release of nitric oxide |
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REMEMBER
increased BLOOD FLOW => causes increase SHEAR STRESS =>NO induced vasodilation FLOW DEPENDENT VASODILATION |
REMEMBER
increased BLOOD FLOW => causes increase SHEAR STRESS =>NO induced vasodilation FLOW DEPENDENT VASODILATION |
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Describe the Myogenic Mechanism?
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Increase Blood flow and Perfusion Pressure
=> Vascular Smooth Muscle "stretch" =>opens sensitive Cation Channels =>Cations enter =>membrane depolarizes => voltage gated Ca2+ channels open => Ca2+ enters --causes contraction =>Vasoconstriction => blood flow / perfusion REDUCED |
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True or False
Endothelium are required for the MYOGENIC STRETCH RESPONSE to function correctly. |
FALSE
Myogenic response is INDEPENDENT of endothelium |
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Extrinsic control of local blood flow is mediated by what nervous system?
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sympathetic nervous system
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α-1 adrenergic receptors are activated by ?
What does it cause? Where are α-1 adrenergic receptors found? |
NOREPINEPHRINE
(sympathetic activation) VASOCONSTRICTION Vascular Smooth Muscle Plasma Membrane |
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Describe the α-1 Adrenergic receptor activation pathway.
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PIP2 =>> IP3 and DAG
IP3 binds to SR membrane SR Ca2+ channels open [Ca2+]i increases VASOCONSTRICTION |
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? vasoconstriction will dominate in organs that require no increase in blood flow.
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α-1 mediated
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β2 Receptors are activated by ?
What does it cause? Where are these receptors found? |
EPINEPHRINE
(sympathetic activation) VASODILATION vascular smooth muscle cells found in skeletal muscle ARTERIOLES |
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Describe the β2 receptor activation pathway
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G(s) Protein
=> activates AC (adenyl cyclase) => cAMP increase => activates PKA (protein kinase A) => phosphorylates MLCK (inhibition --causes decrease actin/myosin interaction) =>PKA phosphorylates K(ca) channels causing hyperpolarization =>PKA activates SERCA VASODILATION |
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True or False
Blood vessels DO NOT receive innervation from the Parasympathetic Division. |
TRUE
however, there are 2 exceptions -external genitalia ACh -vasodilation -salivary glands, pancrease, gastric mucosa |
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? are the inflow valves that control the rate of capillary/nutritive blood flow.
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Arterioles
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? regulates the distribution of available blood between Peripheral venous Compartment and the Central Venous Compartment
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Veins
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True or False
Metabolites that accumulate in the interstitial space have NO EFFECT on veins. |
True
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When a person is lying down, all venous valves will be (open?close) and venous blood flow toward the heart continuously.
Will they be (open?close) in a person who is standing? |
All valves will be OPEN when lying down.
All valves will be Opening and CLOSING in a person who is standing |
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Where is pressure the greatest when a person is standing (venous blood system)?
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venous pressure in the foot RISES as blood pools due to gravity
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Upon walking, the pumping action of the leg muscles on leg veins facilitate venous return causing VENOUS PRESSURE to ?
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Decrease
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The microcirculation is defined as blood vessels from the ? to the network of capillaries to the ?
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First order arteriole
First order venule |
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Flow of blood in the capillaries is called?
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vasomotion
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True or False
Blood does not flow continuously in capillaries but flows intermittently turning on and off. |
True
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Vasomotion is due to the intermittent contraction of ? and ?
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arterioles
precapillary sphincters |
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What is the MOST important factor that regulates the opening and closing of arterioles is ?
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Concentration of Oxygen
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Extraction ratio for oxygen equation
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EO2 = [O2]A - [O2]V / [O2]A
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Fick's law describes ?
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flux of substance
move across capillary membrane per unit time |
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Fick's law equation
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J = P * S (Co - Ci)
P * S = capillary surface area Co = concentration outside capillary Ci = concentration inside capillary |
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The quantity of substance that diffuses across the capillary membrane per unit time (J) is directly proportional to ?
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surface area
concentration gradient of the substance across the membrane |
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The random movement of particles can be limited by blood flow
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Flow limited exchange
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the random movement of particles can be limited by capillary wall
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diffusion-limited exchange
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Gas Exchange in the lungs is a classic example of what type of exchange?
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Flow Limited
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Go over page 11
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go over page 11
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Starling hypothesis is..
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filtration and reabsorption across capillaries
determined by... hydrostatic colloid osmotic pressure capillary filtration coefficient |
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Starling hypothesis equation
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Qf = K [(Pc - Pi) - (πc - πi) ]
Qf = net filtration rate k= filtration constant Pc = capillary hydrostatic/blood pressure Pi= interstitial fluid hydrostatic /blood pressure πc= capillary colloid osmotic pressure πi= interstitial fluid colloid osmotic pressure |
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A positive number equals ?
A negative number equals ? |
filtration
reabsorption |
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How do plasma proteins in the interstitial space reenter the circulating blood?
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Lympathics
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lymphatics are absent from what tissue?
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myocardium
brain |
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Angiotensin II causes (vasodilation?vasoconstriction)
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Vasoconstriction
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Endothelial product that is a vital component of the clotting cascade
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von Willebrand factor
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What is colloid osmotic pressure?
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osmotic pressure from plasma proteins in the capillaries
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What is the key factor that PREVENTS fluid loss from the capillaries?
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Oncotic pressure
(colloid osmotic pressure) |
