Physiology

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bbeckers88
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Physiology
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2011-05-13 20:31:05
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Cardiology
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Test 1- Cardiovascular system
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  1. Blood transports:
    • oxygen
    • nutrients
    • warmth
    • water
    • hormones
    • ions
  2. Blood removes:
    • carbon dioxide
    • chemical wastes
    • heat
    • water
    • toxins from liver
  3. blood characteristics
    • red (darker when deoxygenated)
    • pH 7.4
    • 37 degrees C
    • amiable
    • 5 liters
  4. bloods composition after centrifuging
    • plasma (55%)
    • WBCs/platelets (buffy coat)
    • RBCs (45%)
  5. Hematocrit
    • erythrocytes
    • packed with hemoglobin (oxygen transport)
    • 15 grams of Hb per 100 ml blood
    • decreased RBC count = anemia
    • increased RBC count = polycythemia
  6. RBC number is a function of ?
    oxygen content in the blood
  7. Factors effecting red blooc cell synthesis
    • iron and amino acids
    • vitamin B12
    • folic acid
    • oxygen content of blood
  8. how long do RBCs live
    120 days, recycled in the spleen (or liver)
  9. Erythrocyte sedimentation rate
    • the amount of RBCs that settle out of blood in a single hour.
    • elevated during infection, arthritis, and inflammatory diseases
  10. Plasma
    • made of water and plasma proteins
    • made in the liver
    • main function of plasma proteins: plasma colloidal osmotic pressure
  11. Albumin
    • most common plasma protein
    • contributes to plasma colloidal osmotic pressure
    • -prevents excessive fluid filtration
    • carrier function
  12. Alpha globulin
    • carrier proteins
    • clotting factors
    • lipids
    • steroid-binding proteins
    • bilirubin
    • clotting factors
  13. Beta globulin
    • carrier proteins
    • LDLs
    • iron (transferrin)
    • beta 1 and beta 2 subtypes
  14. gamma globulin
    anatibodies
  15. Fibrinogen
    • protein precursor to clot
    • precursor to fibrin which polymerizes to form an insoluble mesh (coagulation)
  16. hemostasis of blood
    ability of blood to maintain its volume
  17. vascular constriction for homeostasis
    • trauma induces vasoconstriction
    • vasoconstrictive factors (endothelin-1) released
    • platelets stimulate vasoconstriction by releasing thronboxane A2 and serotonin
  18. platelet plugs for hemostasis
    • thromboxane and thrombin both promote platelet aggregation causes adherence, aggregation, and secretion
    • adherence promoted by damaged endothelial and exprosed tissue proteins
    • simultaneous aggregation forms platelet plug
    • ongoing secretions of serotonnin promotes vasoconstriction
  19. Clot formation for homeostasis
    • initiation of the conversion of fibrinogen to fibrin
    • -clotting cascade causes amplification
  20. steps in turning fibrinogen into fibrin
    • prothrombin turned into thrombin by prothrombin activator
    • fibrinogen turned into fibrin by thrombin
    • fibrin threads aggregate forming a clot
  21. Intrinsic clotting pathway
    • requires Factor 9
    • requires Factor 8a as a cofactor
    • slower system but greater amplification
    • converts X into Xa (prothrombin activator)
    • once thrombin is produced it works as positive feedback to keep the system going
  22. Extrinsic clotting pathway
    • requires Factors 7 and 3
    • fast pathway with less amplification (weak)
    • converts X into Xa (prothrombin activator)
  23. anti-clotting mechanisms
    • endothelial linings- minimize clotting
    • consumption of clotting factors- alpha-globulin plasma protein called antithrombin 3 binds to thrombin and inactivates it
    • Fibrinolysis- fibrin destruction by plasminogen (protease) --> plasmin (destroys clotting factors)
  24. Vitamin K
    • produced by intestinal bacteria
    • required for the synthesis of several clotting factors
  25. Coumarin
    competative inhibitor for vitamin K sites in hepatocytes
  26. Bleeding diseases
    • blood clotting factors are improperly made
    • hemophilia A from a lack of Factor 8
  27. Thromboembolitic conditions
    • abnormal clot that forms in vessel called thrombus
    • -can break away and freely float as an embolism and get stuck in a vessel
  28. Idiopathic thrombocytopenia purpura
    • clotting problem with purple spots (from bruises)
    • decreased platelet numbers
    • prolonged bleeding time, deficient clot retraction, platelet antibodies, anemia
  29. greatest determinant of blood flow thru a vessel
    the radius of the vessel
  30. laminar flow of blood
    • efficient, smooth, quiet
    • faster in the center
  31. turbulent flow
    • occurs when the streamlines are disturbed
    • inefficient, rough, noisy
    • sounds called murmers/bruits
    • due to obstructions and high velocity flow
    • forms eddy currents
  32. reynolds number
    • the point when turbulence happens
    • velocity is usually destabilizing factor
  33. turbulent flows effect on shear forces
    • normally minimal but increases with turbulent flow
    • causes further damage to vessel walls
    • causes clotting, altered endothelial behavior, injury
  34. Compliance
    • blood vessels stretching in proportion to the intravascular pressure put on them
    • give them the ability to absorb more blood
    • a change in volume per a change in pressure
  35. artery vs. vein compliance
    • arteries not compliant
    • veins very compliant
  36. where is most of the blood in the body found
    2/3 of blood is stored in the veins (capacitance vessels)
  37. delayed compliance
    • variably compliant (arteries)
    • initial pressure of blood causes arteries to constrict, will eventually loosen to allow more blood (compliance)
  38. Functional Murmur
    • a sound heard during the eection of blood from a normal heart
    • due to unusually powerful ejections of blood from the left ventricle causing turbulence in the aortic arch
    • usually harmless
  39. control of blood is a function of:
    • the arterial system
    • specifically the arterioles (regulators)
    • smooth muscle forms the tunica media
  40. vasoconstriction vs vasodilation
    • vasoconstriction- decrease in flow, decrease in radius
    • vasodilation- increase in flow, increase in radius
  41. mechanical stimulation for regulation of vascular smooth muscle tone
    • passive streching causes contraction
    • expansion of a vessel causes depolarization
    • autoregulation becuase it stabilizes flow, quick!
    • increase flow causes vasoconstriction
    • decrease flow causes vasodilation
  42. Electrical stimulation for regulation of vascular smooth muscle tone
    voltage-dependent Ca+2 channels
  43. chemical stimulation for regulation of vascular smooth muscle tone
    • main source of regulation
    • contraction by: norepinephrine, angiotensin 2, vasopressin, endothelin-1, serotonin, thromboxane A2
    • relaxation by: nitric oxide, prostacyclin, and local metabolites
    • vascular smooth muscle cells are covered with receptors
  44. adrenergic receptors
    • alpha 1 receptors for norepinephrine from axons of sypathetic fibers causes vasoconstriction
    • beta 2 receptors cause vasodilation
  45. endothelin-1 receptors and angiotensin-2 receptors
    cause vasoconstriction
  46. cholinergic receptors
    • for acetylcholine
    • cause vasodilation
  47. effects of nitric oxide on smooth muscle
    • released by endothelial cells when stimulated by blood-borne agents and shear forces
    • induces intracellular Ca+2 levels to fall
    • causes vasodilation
  48. effects of prostacyclin on vascular smooth muscle cells
    • released by endothelial cells when stimulated by blood-borne agents
    • causes vasodilation
  49. vascular spasm
    • rapid vasoconstriction
    • can not secrete nitric oxide
  50. nirtoglycerin and amyl nitrite
    • induces vasodilation
    • extra sources of nitric oxide
  51. effects of local tissue metabolites
    • production of CO2 as well as other cellular wastes inhibit the ability of vascular smooth muscle to contract
    • causes vasodilation
  52. intrinsic control of smooth muscle tone
    • cause vasodilation
    • from LOCAL paracrine agents
    • increase metabolism causes increase flow
    • -active hyperemia (produces rubor-blushing)
    • fast/rapid
  53. local tissue wastes affecting intrinsic control
    • carbon dioxide
    • hydrogen ion
    • adenosine
    • potassium ion
    • lactic acid
  54. ischemia
    • depriving tissues of nutrients, especially oxygen
    • tissue turn blue = cyanosis
    • produces pain in tissues
    • extrinsic control used to maintain order
  55. endothelin -1, serotonin, and thromboxane cause:
    vasoconstriction
  56. nitric oxide, bradykinin, histamine, prostacyclin cause:
    vasodilation
  57. reactive hyperemia
    • brief period of ischemia wherein the blood flow is restored in a massive way that nearly matches what would have been delivered during the entire time of ischemia
    • all the accumulated metabolites are washed away
  58. Extrinsic control of vasculature
    • nervous system and endocrine system
    • dependednt on the sensitivity of vascular smooth muscle
    • autonomic nerves
    • -spinal sympathetic chain axons, norepinephrine causes vasoconstriction
    • constant low level vasomotor tone
    • no parasympathetic innervation
  59. suprarenal gland (adrenal medulla)
    • epinephrine and nor epinephrine released becuase of sympathetic innervation
    • lands on alpha-1 adrenergic receptors causing vasoconstriction
    • powerful, slow body wide effect
    • increases blood pressure
  60. kidney (renal cortex)
    • release of renin causes angiotensin 2
    • lands on angiotensin 2 receptors causing endothelin-1 production and vasoconstriction
    • powerful, slow effect
  61. posterior pituitary gland
    • releases vasopressin
    • lands on vasopressin receptors causing production of endothelin-1 causing vasoconstriction
  62. contact dermatitis
    • external agent causes localized inflammation response in the integument
    • -irritant and allergens
    • skin becomes itch, red, and may blister
    • release of histamine promotes arteriolar vasodilation and capillary leaky-ness
  63. cardiac muscle tissue
    striated muscle cells anchored by intercalated disks which have low electrical resistance
  64. functional syncytium
    allowing action potential to move from cell to cell
  65. Phases of an action potential
    • depolarization- influx of Na
    • plateau-cell is resistanct to stimulation- absolute refractory period, release of Ca
    • repolarization- the relative refractory period, influx of K
  66. Digoxin
    inhibits Na/K pump in cardiac muscles, causes stronger heart beat
  67. as a cell is lengthened during relaxation it tends to produce a stronger contraction in the next cycle
  68. flow of action potentials thru the heart
    SA node to atrial muscle to AV node to bundle branches to Perkinje fibers to ventricular muscle
  69. auto-rhythmicity
    • spontaneous action potentials cause contractions
    • membranes of the heart are naturally leaky and dont need nerves to send action potentials and contract
  70. adrenergic receptors on the heart
    • bind norepinephrin and epinephrin
    • primarily beta-1 receptors
    • norephinephrine released from sympathetic fibers
    • increase excitability, strength, and rate of contraction
  71. cholinergic receptors of the heart
    • Ach muscarinic receptors sensetive to Acetylcholine released from parasympathetic fibers
    • causes decreased excitability, strength and rate of contraction
  72. systemic circulation
    to the body, supplied by the left ventricle
  73. pulmonary circulation
    short, to the lungs for oxygenation, supplied by the right ventricle
  74. systole
    contraction and ejection of the blood
  75. diastole
    relaxation and filling of the blood
  76. graphs on the cardiac cycle
    • ventricular pressure
    • aortic pressure
    • ventricular volume
    • electrocardiogram
    • phonocardiogram
    • atrial pressure
  77. most of ventricular filling is active or passive?
    • 75% passive
    • 25% by the atria
  78. sub phases of ventricular diastole
    • isovolumetric relaxation- no filling but continued relaxation of ventricular muscles
    • rapid inflow- 1/3 of the time, filling of ventricles (passive)
    • diastasis- 1/3 of the time, minimal filling (passive)
    • atrial systole- 1/3 of the time, filling via atrial contraction (active)
  79. sub phases of ventricular systole
    • isovolumetric contraction- contraction with valves closed
    • ejection- releasing of blood
  80. end-diastolic volume
    130 ml
  81. end-systolic volume
    60 ml (always some blood in the ventricles)
  82. Stroke volume
    end-diastolic volume - end-systolic volume = 70 ml
  83. ejection fraction
    • indicator of performace
    • Stroke volume/end-diastolic volume
    • should be greater than 50%
  84. Systolic blood pressure
    highest point of aortic pressure
  85. diastolic blood pressure
    lowest point of aortic pressure
  86. S1 sound
    • "lub"
    • closure of the AV valves
  87. S2 sound
    • "dup"
    • closure of the semilunar valves
  88. Aortic stenosis
    • difficulty pushing blood thru the aortic valve
    • loud murmur heard thru systole
    • "thrill" of chest
  89. aortic insufficiency
    • valve fails to prevent backflow
    • "blowing" murmur during diastole
  90. mitral stenosis
    • difficulty pushing blood thru mitral valve
    • murmur during second half of diastole
  91. mitral insufficiency
    • valve allows blood back up into the left atrium
    • murmur during systole
  92. Cardiac output
    • stroke volume X heart rate
    • normal 5000 ml/min
  93. intrinsic autoregulation of cardiac output
    • Frank-Starling Mechanism- increase diastolic filling causes increased EDV causes increased strength of contraction causing decreased ESV causing increased stroke volume
    • increase venous return = increase cardiac output (no nerves needed!!)
    • tops out at 15 l/min
  94. Blood pressure
    • doesnt affect cardiac output
    • AFTERLOAD- pressure at aortic valve at end-systolic volume
  95. reflex control of cardiac output
    • mediated by nerves
    • anticipatory
    • max 30 l/min
    • sympathetic nerves: stress response, mostly to ventricles, from sympathetic chain
    • parasympathetic nerves: restorative resoponse, from the X nerves to nodal tissues
  96. nerves modifying excitability of cardiac muscles
    • conduction speed = dromotropic effect
    • rate of contraction = chronotropic effect
    • strength of contraction = inotropic effect
  97. Sympathetics on the heart
    • cause positive dromotropism, chronotropism, and inotropism
    • increases heart rate and stroke volume
    • occurs during exercise
    • maximum efficiency 140-160 bpm
    • can reduce CO if inhibited
  98. tachycardia
    heart rate greater than 100 bpm
  99. beta blockade
    competitively inhibits the receptors, governors heart rate
  100. parsympathetics
    • present on SA and AV nodal cells
    • creates negative dromotropism, chronotropism, and inotropism
    • decreases heart rate down to 30 bpm and stroke volume to 25%
  101. congestive heart failure
    • heart fails to adequately pump blood
    • presents with dyspnea, peripheral edema, and fatigue
    • abnormal electrocardiogram, enlarged heart
    • abnormal echocardiogram, low ejection fraction
    • from a decompensated heart
    • heart has coronary artery disease, valvular problems, high resistance in vessels
  102. which area of heart tissue has the fastest intrinsic firing range?
    • SA nodal tissue
    • it is the pacemaker of the heart
    • produces a sinus rhythm
  103. the impulse of the heart is held up for up to 1/10th of a second at the AV node
    gives the atria time to contract before the ventricles do
  104. electrocardiography
    monitors the electrical behavior of the heart
  105. P wave
    atrial depolarization
  106. QRS complex
    ventricular depolarization
  107. T wave
    ventricular repolarization
  108. PR segment
    • due to AV nodal slowdown
    • elongation is bad, shows that there is AV heart block
  109. ST segment
    • due to absolute refractory period
    • when segment is longer shows that the ventricles are bad
  110. mean QRS vector
    • summation of the QRS voltages shows the direction of electrical current flow
    • normal is -10 to 100 degrees
  111. arrhythmia
    asynchronous contractions of the heart
  112. 4 causes of arrhythmias
    • abnormal rhythmicity of the pacemaker
    • blocks in the conducting system
    • abnormal impulse pathways
    • spontaneous generation of impulses
  113. bradycardai
    • low heart rate
    • can be normal in athletes
    • abnormal when caused by excessive parasympathetic stimulation
  114. sinus arrhythmia
    when the heart rate changes with breathing changes
  115. Atrioventricular block
    • due to ischemia of the AV node or bundle branches
    • 1st degree: minor lengthening of PR interval
    • 2nd degree: serious lengthening of PR interval, occasional dropped beat in ventricles
    • 3rd degree: complete, ventricular escape
  116. interventricular block
    problem in the purkinje system causing abnormal QRS interval
  117. ectopic foci
    electrical event out of sequence
  118. Premature contraction
    • if in the atria it is harmless
    • in the ventricle can be deadly
    • caused by hyper-excitablility of myocardial tissue
    • -over use of stimulants
    • -local ischemia
    • may cause fibrillation
  119. Fibrillation
    • electrical chaos of impulses
    • tolerable in atrias
    • deadly in ventricles in minutes
    • due to myocardial ischemia
    • from circus entry - impuse rentry
  120. Defibrillation
    • shocking the heart
    • stops it, allows it to reset, and hopefully restarts on its own
  121. AV heart block
    • arrhythmia due to blockage in electrical conduction system
    • different degrees
    • caused by: coronary artery disease, inflammation of nodal tissue
    • treatment: medication or pacemaker
  122. blood pressure
    • the force excerted on the container
    • BP = cardiac output X peripheral resistance
  123. Blood pressure is a function of:
    • blood
    • vascular tree
    • heart
  124. pulse pressure
    systolic BP - diastolic BP
  125. purpose of the atrial system in regards to blood pressure
    • distributes blood
    • absorbs shock
  126. augmentation
    summation of pulse wave-forms
  127. there is no pulse pressure beyond?
    arterioles
  128. venous pump
    • combination of valves and skeletal muscles
    • the "second pump" of the systemic system
  129. hydrostatic forces
    • gravity effects atrial and venous pressures
    • venous pressure rises to 90 mmHg in the feet while standing, lower while walking due to musculature
  130. measurment of blood pressure
    sphygmomanometry-blood pressure cuff and stethoscope
  131. peripheral resistance in vessels due to:
    • blood volume
    • blood viscosity
    • size of vascular container
  132. systemic arterial BP
    averages 100mmHg
  133. Arterial Baroreceptor reflex
    • nervous control system using aortic and carotid baroreceptors
    • alters BP thru efferent innervation to the heart and vasculature
    • fast acting, high gain, not long-term
    • used for changes in body position
  134. Arterial Chemoreceptor reflex
    • nervous system control using aortic and carotid chemoreceptors (in aortic and carotid bodies)
    • fast acting, high bain, lasts a few hours
    • involved in control of respiration
  135. Atrial stretch reflex
    • nervous system control using atrial stretch receptors
    • fast acting, unknown gain
    • can increase heart rate
    • "Bainbridge reflex"
    • activates baroreceptors
    • competition minimizes venous damming of blood
    • hormonal effect from atrial natriuretic factor
    • -increases atrial pressure
    • -decreases blood volume
  136. CNS ischemic response
    • nervous system control using neurons of the cardiovascular control center
    • fast acting, high gain, lasts for an hour
    • rare reflex
  137. cardiovascular center pressor region
    • evokes vasoconstriction, cardiac acceleration, enhanced myocardial contractility
    • vasoconstrictor sub-areas are tonically active
  138. cardiovascular center depressor region
    evokes inhibition of teh pressor area causing decreased sympathetic outflow and increased parasympathetic activity
  139. epinephrine system
    • humoral control using hormones from the adrenal medulla
    • -epinephrine and norepinephrine
    • land on alpha and beta adrenergic receptors
    • cause vasoconstriction and increased cardiac output
    • release caused by sympathetic innervation
    • fast acting, unknown gain, long lasting
  140. Stress-relaxation behavior
    • delayed compliance
    • slow-acting, low gain,
  141. capillary fluid shift
    • changing pressure of the capillary walls will change filtration of the blood
    • slow acting, low gain
  142. renin-angiotensis system
    • humoral system using hormones from the kidney and blood
    • -renin and angiotensin 2
    • slow acting, low gain
  143. effects of angiotensin in the body
    • cardiac myocyte hypertrophy
    • thirst
    • direct stimulation of nephron to retain Na and H2O
    • efferent arteriolar vasoconstriction
    • increased glomerular filtration
    • stimulate the release of ADH from pituitary
  144. ACE inhibitor
    • blocks angiotensin converting enzyme
    • used for management of hypertension/heart failure
  145. Aldosterone system
    • humoral control using hormones from the adrenal cortex
    • -aldosterone
    • slow acting, low gain
  146. vasopressin system
    • humoral control using osmotically sensitive neuons in the hypothalamus to produce a hormone in the posterior pituitary
    • -vasopressin
    • slow acting, unknown gain
  147. renal-blood fluid system
    • fluid and humoral system that uses the kidney
    • -uses the nephron and renin-angiotensin system
    • slow acting, high gain
    • the ultimate mechanism
    • adjusts the amount of fluid in the vascular compartment
    • relies on diuresis (formation of urine)
  148. 2 primary determinants of long-term arterial pressure
    • level of water and salt intake
    • behavior of kidneys as represented in the acute renal output curve
  149. chronic renal output curve
    • salt levels directly related to extracellular fluid volume
    • angiotensin acts directly on kidneys to retain salt and water
    • angiotensin acts on adrenal glands to increase aldosterone secretion causing increased water and salt retention in kidneys
  150. Hypertension
    • resting SBP above 140 or DBP above 90
    • usually due to kidneys not secreting enough salt and water
  151. diuretic
    causes kidneys to make more urine
  152. Short term vs long term regulatory systems
    • short term alter cardiac output and peripheral resistance
    • long term alter blood volume
  153. renal artery stenosis
    • vascular stenosis to the kidneys- atherosclerosis
    • renal vascular hypertension
    • ischemic nephropathy
    • cant regulate long-term blood pressure
  154. highest amounts of blood flow occur where?
    kidneys, GI tract
  155. control of flow thru coronary arteries
    • sympathetic fibers cause vasodilation (beta 2 receptors)
    • local metabolic factors from cardiac myocytes cause vasodilation
    • -release of CO2 and H, some adenosine
  156. myocardial ischemia
    intense pain from obstruction of coronary artery
  157. angina pectoris
    • chest pain from myocardial ischemia
    • not a heart attack
  158. myocardial infarction
    • progression of myocardial ischemia
    • death of cardiac muscle tissue
    • compromises cardiac output
  159. heart attack
    coronary artery blockage and death of myocardial tissue
  160. skeletal muscle circulation
    • 4 ml/min/100g of tissue at reast
    • up to 80 ml/min/100g of tissue during exercise
  161. control of skeletal muscle flow
    • sympathetic fibers cause vasoconstriction or vasodilation
    • local metabolites cause vasodilation (main mechanism)
  162. mass sympathetic discharge
    • increase cardiac output and vasoconstriction = better delivery of blood
    • thinking about exercise can cause increase heart rate
  163. Cerebral circulation
    • area given the highest priority
    • 700 ml/minute
    • least tolerant area for ischemia
  164. cerebral stroke
    • due to blockage of a cerebral blood vessel
    • preceded by a transient ischemic attack
  165. control of cerebral circulation
    • local metabolic factors from neurons cause vasodilation
    • release of CO2 and H
  166. Cerebrospinal fluid
    • ultrafiltrate
    • plasma: increased Na, decreased glucose and K
  167. Splanchnic circulation
    given the lowest priority
  168. control of flow of splanchnic circulation
    • local metabolic factors form GI tissues cause vasodilation
    • sympathetic fivers cause vasoconstriction
    • -parasympathetic stimulation promotes glandular activity which causes vasodilation
  169. abdominal cramps
    maifestation of ischemia due to lack of priority
  170. peritoneal compartment
    • fluid derived form GI vasculauture
    • excessive fluid can cause ascites
  171. Liver circulation
    • 75% of blood from the hepatic portal vein
    • 25% of blood from hepatic artery

    flow determined by local intestinal factors
  172. Spleen circulation
    • red pulp can store up to 50 ml of concentrated RBCs
    • cleanse blood of old cells
  173. Kidney circulation
    • huge supply of cardiac output to maintain filtration rate
    • sympathetic innervation produces vasoconstriction and a drop in flow
  174. skin circulation
    • priority for temperature regulation
    • many arteriovenous anastomoses (cold areas)
    • controls core body temperature
    • -increase core temp = vasodilation and sweating
    • -decrease core temp = vasoconstriction
  175. control of flow for skin regulation
    • sympathetic fibers cause vasoconstriction
    • parasympathetic fibers cause vasodilation
    • cholinergic sympathetic fibers innervate sweat glands

    when cold gets into dermis arterioles beome paralized causing vasodilation
  176. "exposure"
    • vasodilation of arterioles in extremely cold weather
    • leads to frostbite
    • -tissues freeze
  177. intermittent claudication
    • due to atherosclerosis affecting arteries of the leg
    • causes ischemic pain due to loss of circulation and drainage
    • -intermittent becuase gets worse during exercise when muscles call for oxygen
  178. what is cardiac output set by?
    metabolizing tissues of the body
  179. 2 outputs in the cardiovascular system
    • cardiac output: from the left ventricle
    • tissue output: from the body, coupled with the venous pump
  180. vascular return is determined by?
    the size of the vascular compartment
  181. what happens if a given area vasodilates?
    • total pressure could fall decreasing total flow
    • blood flow is reduced to non-essential areas to keep up pressure
  182. pulmonary circulation
    • must pump the same amount of blood as systemic circulation/unit of time
    • 22 SBP/8 DBP, creates negative intrapleural pressure
    • not compliant
  183. control of pulmonary circulation
    • decreased O2 causes vasoconstriction
    • venous return to R ventricle sets pulmonary flow
    • -increased metabolism in tissue cause vasodilation allowing more blood back to the right atrium/ventricle causing an increase in pulmonary flow
  184. circulatory shock
    • inadequate blood flow causing tissue damage
    • 3 origins
    • 1. decrease blood volume= hypovolemic shock
    • 2. decrease peripheral resistance= low-resistance shock
    • 3. decrease cardiac output= Cardiogenic shock
    • problem of systemic circulation
  185. capillary circulation
    • diffusion extremely important
    • fluid diffuses out of capillaries into the interstitium, becomes lymph
  186. fluid/molecular movement thru capillaries is a function of?
    • colubility
    • size
    • capillary permeability
    • concentration
    • pressure
  187. 3 types of capillaries
    • 1. small molecule/lipid soluble movememnt. most common
    • 2. lots of leakage, filter is a function of pressure
    • 3. wholesale leakage
  188. 4 types of pressure determining net fluid exvhange b/t blood and interstitium
    • capillary pressure- outward pushing force (fluctuates)
    • interstitial free fluid pressure- inward pushing force
    • plasma colloidal osmotic pressure- inward pulling
    • interstitial fluid colloidal osmotic pressure- outward pulling
  189. net driving force
    • summation of all forces acting on a capillary
    • total is 28 in and 28 out = 0
  190. difference in capillary pressure across a capillary
    • net out at the arteriole end
    • net in at the venule end
  191. Starling equilibirum
    midpoint in the capillary where net force is 0
  192. slight net outward filtration pressure in capillaries causes:
    flux from plasma to interstitium causing systemic vascular filtered plasma loss of approx 2-3 ml/min
  193. lymphatic pump
    skeletal muscle contracts, lymph fluid flows
  194. increased interstitial free fluid pressure causes increased lymphatic fluid flow
    • interstitial free fluid pressure is stable due to natural tension of tissues
    • fluids leave capillaries and promptly enter the lymphatic system
  195. safty factor of the lymphatic system
    nromal pressure has a range, if it reaches 0 mmHg thats BAD!
  196. edema
    fluid accumulation in tissues
  197. incrased capillary permeability
    from damaged endothelia
  198. high capillary pressure
    • from altered BP/flow dynamics
    • caused from venous obstruction, acute arteriolar dilation or cardiac failure
  199. decreased plasma protein
    • changed in blood
    • from nephrosis, starvation, burns
  200. lymphatic obstruction
    • from parasite, surgery
    • causes lymphodemea
    • blockage of the drainage from the lymphatic system
  201. lymphedema
    • accumulation of lymphatic fluid causing swelling
    • severity variable depending upon fluid accumulation
    • disease of capillary dynamics and lymphatic circulation

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