Exam 2 O2 Transport, Blood Flow, Coagulation Flashcards
Blood flow
Volume movement along a pressure gradient w/in vascular bed
Blood Pressure
Blood moves from areas of high (arteries) to low pressure (veins)
Blood resistance
Opposing forces that deter blood flow (as resistance increased flow decreases)
Ohm’s Law of Circulatory Physiology
MAP = CO x TPR (Total Peripheral Resistance)
MAP = DBP + (Pulse pressure / 3)
Flow = _____ / _____
Flow = Pressure/Resistance ( F= P/R)
P = F x R
Pouisuille’s Law Flow =
Resistance = 8LN /πR^4
8 x Length x Viscosity / Pi x Radius to the fourth
Arterioles
Major site of resistance, profound effect on SVR
SVR =
(MAP-CVP) x 80 / CO
Vascular Resistance is regulated _____ by _____ and _____ by ____
Centrally, ANS, locally, tissues
Release of norepinephrine results in ______ via _____ receptors
Vasoconstriction, alpha1
Epinephrine results in ______ via ______ receptors in ______ arteries and _____ muscle vascular beds
Vasodilation, B2 adrenergic, coronary, skeletal
(Epi stimulates a1, a2, B1, B2, B3) The affinity of epinephrine for beta receptors is somewhat greater than its affinity for alpha receptors. When given in low doses, or by slow IV infusion in humans, the beta effects of epinephrine may predominate.
Local blood flow through tissues is regulated through _____ influenced by _____ sensing and release of _____ and _____
Autoregulation, endothelial, nitric oxide, prostacyclin
Steps of vascular smooth muscle contraction
Norepinephrine binds to the __ receptor
A __ protein, ___is activated
__ activates a _____ (“L” type) ____ channel, increasing intracellular ___
Simultaneously, ___ activates_____
____ splits a membrane ____, PIP2, forming two products:_____ and _____
____ releases _____ from intracellular stores in the________, further increasing intracellular ____
Increased intracellular _____ leads to VSM contraction via the ______
A1, G, Gq, voltage-gated, calcium, Ca, Gq, phospholipase C (PLC), PLC, lipid, diacylglycerol (DAG), inositol triphosphate (IP3), IP3, Ca, endoplasmic reticulum, Ca, Ca, myosin light-chain kinase mechanism
Circulating Hormones: Vasoconstriction (2)
Angiotensin II: Tubule glomerular feedback v Na and H2O deliver thereby decreasing MAP). Stimulates renin release.
Vasopressin (ADH): released from posterior pituitary in responses to increased osmolality, acts as vasoconstrictor at V1 receptors through Gq mechanism.
Circulating Hormones: Vasodilation (2)
Kinins (Bradykinin): Endothelial cell beta 2 kinin receptor activation causes cGMP and cAMP mediated vasodilation in adjacent VSM cells.
Natriuretic peptides (ANP/BNP): secreted after atrial/ventricular wall stretch, activated ANP/BNP on VSM receptors = vasodilation
Endothelium: Vasoconstrictors (1)
Endothelial: expressed after shear stress, hypoxia, circulating hormones (angiotensin 2, AVP) IP3 mediated vasoconstriction via endothelin receptors on VSM cells
Endothelium Vasodilators (2)
Prostacyclin (PGI2): Normal endothelium produces PGI2 from arachidonic acid
Nitric Oxide: cGMP mediated relaxation by free diffusion from endothelial to VSM cells. Endothelial NO is a major regulator of local and systemic blood flow!
Transcapillary Exchange of fluids, electrolytes and nutrients
Exchange of gases and nutrients is dependent on pressure gradient between capillary and interstitium.
Starling Law: Transcapillary fluid exchange
Determinants of fluid movement
Fluid movement = P x S (Pcap + πtissue) - (Ptissue + πcap)
Out. In
P = Permeability
S = Surface area
πcap = Plasma oncotic Pressure AKA colloid osmotic pressure (pull into capillary)
Pcap = capillary hydrostatic pressure (push out of capillary)
πtissue = Colloid osmotic (oncotic) pressure
Ptissue = Tissue hydrostatic Pressure
Pressure exerted by impermeable ______ PULL (πcap)
Albumin _____ %
Globulin _____
Fibrinogen ______
Others ______
plasma proteins
51, 17, 4, 28
Pressure exerted by blood on capillary wall function to _____ plasma water and electrolytes ____ of the capillary
(Pcap)
Push, out
Thrombi Development
Stationary blood clot formed w/in a vessel or a chamber of the heart (causes dramatic slowing of blood flow and more turbulent flow)
Emboli Development
Material that forms a clot w/in bloodstream. Traveling clot.
(Can be produced by fat, malignant neoplasm/tumor, collection of bacteria, air)
Vasospasm
Sudden constriction of arterial smooth muscles resulting in obstruction of flow. May be mediated by hormonal changes, food additives or environmental factors.
External compression
May be caused by trauma, tight cast, compartment syndrome
Structural alteration that can causes arterial/venous obstruction (4)
1) Valvular incompetence: superficial = varicose veins, deep = chronic venous insufficiency
2) Atherosclerosis
3) Aneurysms: localized arterial dilutions, bulge outward. (Saccular = one sided balloons out, Fuji form = both sides balloon out, berry = balloon has stem/neck)
4) AV fistula: AVM = most common and serious type, tangled = knot of arteries and veins found most commonly w/in brain
Steps of developing atherosclerotic plaque (4 steps)
1) Initiated by endothelial surface damage to ther arterial intima causing inflammatory response and increase in vessel wall permeability
2) LDL breach intimal layer, leukocytes and endothelial cells oxidize the lipids causing further damage
3) Simultaneously Plt’s aggregate at the site and release platelet-derived growth factor (PDGF); stimulates growth of smooth muscle cells
4) Media smooth muscle cells, normally confined to the other tunica, drawn to the intima and proliferate. (Plaques slowly enlarge, v Orifice of artery and v Perfusion)
Clinical consequences of acute and chronic arterial obstruction
Decreased distal flow and eventually ischemia.
Clinical consequence of superficial and deep vein obstructions
Venous stasis ulcers, pain, and edema
How do plt’s and factors of clotting cascade contribute to hemostasis
After injury endothelin is released and causes vasoconstriction
Platelets bind to exposed collagen via von Willebrand factor and become activated, activated platelets release granules containing mediators (ADP, serotonin, histamine, thromboxane), more platelets are recruited by the ADP that was released, platelet-thrombin coactivation = positive feedback at site of injury.
Fibrin clot: secondary hemostatic plug, intrinsic and extrinsic lead to the common final pathway called coagulation cascade
Clot reaction: antithrombotic counterregulation - fibrinolysis = clot dissolution, occurs as fibrin clot is forming. Factor XII, HMWK, Kallikrein and thrombin release plasminogen activators. These cleave plasminogen to form plasminogen. Plasminogen digests fibrinogen and fibrin and inactivates factor V and VIII
Indications of bleeding disorder
Assessment: pallor, jaundice, hemarthrosis, telangectasisa, petechiae, purport, ecchymosis, hematoma, occult or frank bleeding, hematochezia/melena, hematuria, hematemesis, epistaxis, geophysics, menorrhagia
CBC: to identify anemia, platelet count
PT/INR assess extrinsic pathway of coagulation
aPTT assess intrinsic pathway of coagulation
D-dimer reflects fibrinolysis
Family history of bleeding in both males and females
Von Willebrand disease
Family history of bleeding in males, newly acquired bruising
Hemophilia A or B
Drugs (especially aspirin and NSAIDS, anticoagulant therapy), thrombocytopenia