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Flashcards

Circulation

Adrianna Bialecka Physiology Organs University English 122 cards

Circulation

Cards in this deck (122)

  1. 1Why do we have a Circulatory system?-> O2 diffusion in multicellular organisms becomes inefficient beyond distances bigger than 1mm
    -> The vasculature also provides a mechanism for endocrine tissue communication and co-ordination
  2. 2What are the components of the Circulatory system?Cardiovascular (blood) and lymphatic (lymph)
  3. 3What is the cardiovascular system?Heart, blood vessels and blood
  4. 4What is the lymphatic system?Lymphatic vessels/capillaries and lymph
  5. 5What does the human heart act as?dual pump- supplying the systemic and pulmonary circulations at the same time
  6. 6What is the general layout of the cardiovascular system?Deoxygenated blood from around the body going into the right atrium from the vena cava , then right ventricle where it goes to the lungs through the pulmonary artery. Blood gets oxygenated and it returns to the heart through the pulmonary vein. It goes into the left atrium and then left ventricle. Where is gets pumped around the body through the aorta. The typical vessel sequence in an organ is arterioles to capillaries and then venules.
  7. 7What is the pressure and capacitance in veins?Low pressure, high capacitance
  8. 8What is the pressure and capacitance in arteries?High pressure, Low capacitance
    (distribution, Windkessel effect0
  9. 9What is a portal system?All portal systems have two sets of capillaries arranged sequentially (i.e. bypassing the heart)
  10. 10What is an examples of a venous portal circuit?e.g. Liver
    hepatic portal system is responsible for directing blood from parts of the gastrointestinal tract to the liver. The hepatic portal system is the system of veins comprising the hepatic portal vein and its tributaries..
    Capillaries -> veins/venules ->capillaries
  11. 11What is an examples of an arterial portal circuit?e.g. Kidney
    Within the renal portal system, there are two main sets of blood vessels: the afferent arterioles and the efferent arterioles. The afferent arterioles carry oxygenated blood from the renal arteries into the glomerular capillaries, where filtration occurs
    Capillaries ->arterioles ->capillaries
  12. 12Why is blood a colloid?It is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance
  13. 13What does plasma contain?55% of blood is plasma
    -Ions
    -Glucose, amino acids, hormones
    -Proteins: Albumin (60%), globulins, fibrinogen
  14. 14What layer does Leukocytes and platelets form when blood is centrifuged?buffy coat
  15. 15What is the percentage of blodo that consists of erythrocytes?45%
  16. 16What is a hematocrit test?hematocrit test (Hct) is a simple blood test that measures the percentage of red blood cells in your blood
  17. 17What is the total blood volume in an adult 70 kg>8% of body weight, therefore around 5.5 litres
  18. 18What is Hemodynamics?The relationship among blood pressure, flow and vascular resistance across the cardiovascular system
  19. 19What determines local blood flow?pressure and resistance
  20. 20What is Ohm's law?In blood vessels, Ohm's Law is used to relate pressure difference (ΔP) to resistance to flow (R) and blood flow (F)
  21. 21What is the equation given by Ohm's law to explain blood vessels?Q (L/min) = Delta P (mmHg)/ R (mmHg/L/min)
    where
    Q= blood flow
    Delta P = pressure difference
    R = Resistance
  22. 22Diagram showing Ohm's Law appliedDiagram showing Ohm's Law applied
  23. 23What law is used to determine local vascular (arteriolar) Resistance?Hagen Poiseuille law
  24. 24What equations make up the Hagen-Poiseuille law?What equations make up the Hagen-Poiseuille law?
  25. 25When would n, dynamic viscosity change?If dehydrated - blood is goopy
  26. 26What is Resistance proportional to?1/r^4
  27. 27What is flow proportional to?r^4
  28. 28What happens if radius decreases by 16%?resistance doubles, Flow halves
  29. 29What happens if radius increases by 19%?Resistance halves and flow doubles
  30. 30What happens if the radius is cut by half?Resistance increases by 16-fold and flow decreases by 94%
  31. 31What happens if the radius is doubled?Resistance decreases by 94% and flow increases by 16-fold
  32. 32So how does resistance and flow relate to radius?Resistance increases, whilst flow decreases to the fourth power of vascular radius r
  33. 33What is the cardiovascular system?a transport system
    (aka plumbing driven by a pump)
  34. 34What do blood vessels do?Contribute to perfusion and homeostasis according to structure, location and functional changes due to vasoactive molecules and the local microenvironment
    (e.g. pH, CO2, O2, cytokines, etc)
  35. 35What do arteries do?Two types (Elastic = 1-2 cm, and Muscular = 0.-1 cm)
    -function in blood distribution at high pressure
  36. 36What do Arterioles do?<100 micrometres
    -function in flow and resistance regulation
  37. 37What do capillaries do?(4-30 micrometres)
    -function in exchange of O2, nutrients, CO2 and fluids
  38. 38What do venules do?(50-200 micrometres)
    -capacitance vessels
  39. 39What do veins do?(200 micrometres- 3cm)
    -capacitance vessels
  40. 40What are the structural differences between arteries and veins?What are the structural differences between arteries and veins?
  41. 41What is the histology of Tunica IntimaEndothelium: single layer of polygonal, flattened epithelial cells elongated in the direction of blood flow
    Basement Membrane
    Sub-Endothelium: contains loose connective tissue and fibroblast    What is the histology of Tunica Intima
  42. 42What are the functions of the endothelium in the Tunica Intima?-Selective permeability barrier
    -Leukocyte adhesion
    -Cytokine and growth factor secretion
    -Modulation of vascular tone upon smooth muscle cells (release of NO and prostacyclin = vasodilators, or endothelins =vasoconstrictors)
    -Hemostasis (von Willebrand factor, NO, prostacyclin - anticoagulant role when endothelial barrier is intact)
  43. 43What is the histology of the Tunica Media?Vascular smooth muscle cells: Concentric layers, helical arrangement
    Elastin fibers: fenestrated sheets
    Collagen fibers:    What is the histology of the Tunica Media?
  44. 44Which blood vessels lack internal and external elastic lamina?Veins lack internal and external elastic lamina
  45. 45What is the histology of the Tunica Adentitia?Collagen and elastin fibers: longitudinal arrangement
    Autonomic Innervation
    Lymphatic vessels
    Vasa vasorum (vessels of the vessel) -provide O2 and nutrients to the cells in the vessel wall -more frequent in larger vessels than in arteries    What is the histology of the Tunica Adentitia?
  46. 46What do elastic arteries look like?Media contains alternating layers of smooth muscle cells and elastic laminae (elastic staining =black)What do elastic arteries look like?
  47. 47What do muscular arteries look like?Media contains layers of smooth muscle and some elastic fibers
    -Prominent internal elastic lamina and less accentuated external elastic lamina
  48. 48What do arterioles look like?-Media contains 1-2 layers of smooth muscle cells
    -elastic fibers limited to the internal elastic lamina
    -no external elastic lamina
    -Transition from large to small arterioles is indicated by the loss of Internal elastic lamina
    -Tunica adventitia is very thin
  49. 49What do venules look like?>Capillaries drain into postcapillary venules, similar in structure to capillaries: bearing endothelium and pericytes (large diameter = 15-20 micrometres)
    >Postcapillary venules drain into collecting venules: larger diameter with an increase in pericyte density
    >Collecting venules drain into muscular venules: media layer with 2-3 layers of smooth muscle cells
  50. 50What do small and medium veins look like?Tunica media contains a few layers of smooth muscle cells
    -Tunica adventitia contains some elastin and collagen fibers arranged longitudinally
    -No elastic laminae
    -Flattened shape of vessel    What do small and medium veins look like?
  51. 51What do large veins look like?Tunica media contains a few layers of smooth muscle cells
    Tunica adventitia contains some elastin and collagen fibers, arranged longitudinally
    -No elastic laminae
    -Adventitia contains vasa vasorum    What do large veins look like?
  52. 52What about veins structures allows large fluid capacitance-Thin wall and wide lumen = easily collapsed and expanded
    -facilitates function as capacitance (storage) vessels
    -70% of blood is in veins
  53. 53What are arteries characterised by?-A narrower lumen
    -A thicker wall and media layer
    -Greater wall-to-lumen and media-to-lumen ratios
  54. 54Why is there a greater elastin content of the arterial medial layer?-especially in elastic arteries (windkessel effect)
    -dampens pulse pressure
  55. 55What do veins contain that arteries dont?Valves (intimal projections) that prevent backflow, thus facilitating venous return
  56. 56What are capillaries?A single layer of endothelial cells located upon a basement membrane
    -diameter 4-10 micrometres
    -Three forms of capillary classified according to the nature of the endothelium
    ->continuous
    ->fenestrated
    ->discontinuous (sinusoids)
  57. 57What do continuous capillaries look like?What do continuous capillaries look like?
  58. 58What do Fenestrated capillaries look like?What do Fenestrated capillaries look like?
  59. 59What do Sinusoids look like?Large intracellular gaps
    -Large Fenestrations (no diaphragms)
    -discontinuous basement membrane
    -diameter = 30-40 micrometres: liver, bone marrow, spleen -places where there is exchange of cells    What do Sinusoids look like?
  60. 60Coronal section - cardiac anatomyCoronal section - cardiac anatomy
  61. 61What are the four cardiac valves?Aortic valve (between the left ventricle and the aorta)
    Mitral valve (Bicuspid) (between the left atrium and the left ventricle)
    Pulmonary valve (between the right ventricle and the pulmonary artery)
    Tricuspid valve (between the right atrium and the right ventricle)
  62. 62What is triggered by electrical activity within the cardiac pacemakers?any mechanical activity (contraction of atrial and/or ventricular muscle is preceded and thus triggered, it then flows through the cardiac excito-conductor system
  63. 63How does blood flow?in favour of the presssure gradient (from regions of high to low pressure)
  64. 64What does systole (atrial or ventricular contraction) do?increases pressure
  65. 65When do atrioventricular valves open and close?Open when atrial > ventricular pressure
    Close when gradient is reversed
  66. 66When do semilunar valves open and close?Open when ventricular > aortic/pulmonary pressures
    Close when gradient is reversed
  67. 67What are all valves...?Unidirectional -prevent backflow from the arteries and ventricles towards the atria and veins
  68. 68Diagram showing showing origins of electrical activity?Diagram showing showing origins of electrical activity?
  69. 69What is the normal pacemaker in the heart?Sinoatrial (SA) node
  70. 70What is the Atrioventricular (AV) node?secondary pacemaker (intrinsic frequency = 40 min-1)
  71. 71What do pacemakers do?Set the rhythm of cardiac contraction
  72. 72What does it mean when pacemakers are described as automatic?spontaneously generate rhythmic action potentials (autorhythmic cells)
  73. 73What is the cardiac cycle?Sequence of mechanical (contractile) events triggered in a coordinated manner by the cardiac conduction system, as they relate to changes in volumes, pressures and valve opening/closure in the heart and major vessels
    -Broadly divided according to the stata of ventricles
    (contracting =systole or relaxing = diastole)
    -At a heart rate of 75 min-1 (bpm), with a beat-to-beat interval (RR= 800 ms or 0.8 s), systole lasts for 1/3 of the cycle 267 ms or = 0.3 s), wheras diastole occupies the remaining 2/3 (533ms or = 0.5s)
  74. 74What is the ventricular output per minute?Blood volume pumped by each ventricle in one minute (LV=RV)
    -Volume in average 70kg adult is = 7% of body weight = 5 liters
  75. 75What is the cardiac output?SV X HR
    = Stroke volume x Heart rate
    =75ml/beat x 75 beat/min = 5,626 ml/min = 5.63 liters/min
  76. 76What are the two cardiac systole phases?What are the two cardiac systole phases?
  77. 77What are the three cardiac diastole phases?What are the three cardiac diastole phases?
  78. 78What is LV pressure?9-120 mmHg
  79. 79What is Aortic pressure?80-120 mmHg
  80. 80When does ejection occur?LV pressure > aortic pressure
  81. 81What is stroke volume?volume of blood ejected by the LV onto the Aorta (systole)
  82. 82What are the normal values for SV and EF?SV = 130 - 50 = 80 ml
    EF = 80/130 X100 = 62%    What are the normal values for SV and EF?
  83. 83What are the three phases during diastole that cause ventricular filling?What are the three phases during diastole that cause ventricular filling?
  84. 84What do the chordae tendineae do?prevent valve eversion: mechanical stability
  85. 85What factors influence atrial pressures?-Atrial systole and diastole
    -Ventricular systole and diastole
    -Atrio-ventriuclar (AV) valves
    -Cardiac contractile (pump) function
    -Valves are absent between the atria and their respective veins
    -Venous pressure and atrial pressure are similar and assessment of jugular vein pressure provides insight into right atrial pressure
  86. 86How is the Central venous pressure (CVP) estimated from jugular pulse?-In reclined position, the jugular pulse is visible higher up in the neck
    -Jugular venous pressure (JVP, as estimate of CVP) is measured in cm of H2O, not mmHg
    -CVP = A + B
    (9 cm blood = 7 mmHg)    How is the Central venous pressure (CVP) estimated from jugular pulse?
  87. 87What does MSJ stand for?manubriosternal junction (angle of Louis)
  88. 88What is the atrial pressure wave components (central venous pulse)?-There are no valves between large veins and atria
    -Jugular vein pressure waves can be used to estimate right atrial pressure and function    What is the atrial pressure wave components (central venous pulse)?
  89. 89What is the physiology of the heart sound?-Opening of heart valves is silent in healthy subjects
    -Closure of heart valves casues vibration and turbulence which can be heard using a stethoscope or a microphone
    -Two heart sounds S1 (lub) and S2 (dub) are normally heard:
    S1: Closure of AV valves
    S2: closure of semilunar valves (aortic and pulmonary)
    S2 can be split during inspiration due to early aortic valve closure, followed by the pulmonary valve closure
    (physiological split is common in young individuals)
  90. 90What are S3 and S4 sounds?-Can be normal or pathological
    -lower pitched as compared to S1 and S2; both diastolic
    -S3 is early diastole: turbulent flow into the ventricles (volume overload) -usually heard in people who are athletic -usually not pathological
    -S4 is late diastole: atrial systole (hypertension, AV valve dysfunction) -ventricles are overloaded -usually pathological
  91. 91What does an ecg look like for the heart sounds?What does an ecg look like for the heart sounds?
  92. 92What are the surface projections for auscultation (listening to heartbeat)?What are the surface projections for auscultation (listening to heartbeat)?
  93. 93What are two reasons for valvular heart disease?Stenosis (narrowing) or regurgitation/incompetence (insufficiency)
  94. 94What is stenosis?opening of the valve is insufficient, increasing the force required for either AV flow or ventricular ejection (VALVE IS TOO TIGHT)
  95. 95What is regurgitation/incompetence?Valve does not close completely, allowing backflow
  96. 96What is an example of a congential or acquired cause for valvular disease?rheumatic fever-Beta-haemolytic bacterial infection uncommon nowadays, endocarditis, autoimmune diseases, among others)
  97. 97What are some things that cause physiological murmurs?Pregnancy, strenuous exercise, young patients- usually systolic: benign or innocent murmurs
  98. 98What is Aortic stenosis?systolic in waves or crescendo/decrescendo
  99. 99What is Aortic regurgitation/incompetence?both systolic and diastolic
  100. 100What is mitral regurgitation?systolic murmur with constant intensity (pansystolic) - consider valve geometry
  101. 101What causes flow murmur?A flow murmur is often due to increased blood flow.
  102. 102What do the heart sounds look like for pathological murmurs?What do the heart sounds look like for pathological murmurs?
  103. 103What is the structure of a capillary?-Single endothelial cell layer laid upon a basement membrane (diameter range= 4-10 micrometres)
    -Three types according to inter-endothelial cell distance: continuous, fenestrated and discontinuous    What is the structure of a capillary?
  104. 104How is capillary fluid exchange governed?Starling PrincipleHow is capillary fluid exchange governed?
  105. 105How is Net filtration pressure determined?-Traditionally, capillaries at the venous side have been considered as the only site where fluid absorption occurs
    -However, more recent measurement techniques show that filtration occurs along the entire length of capillaries (whilst excess filtrate is drained by lymphatics) this is true as long as hydrostatic capillary pressure is sufficient to keep NFP at a positive value
    -Overall, low Pc favours fluid absorption as it occurs in the intestinal mucosa and peritubular renal capillaries    How is Net filtration pressure determined?
  106. 106What is the arterial NFP and venous NFP when standing?-Most sites wherein net flow does not equal net outflow leave a residual amount of fluid in the interstitium
    -Lymphatic vessels converge into lymph nodes, involved in filtering and immune surveillance, thus recovering "spillover" flow from the capillary network
    -The excess filtrate is then returned into the circulation via lympathic vessel absorption and drainage onto the thoracic veins    What is the arterial NFP and venous NFP when standing?
  107. 107What is the overall organisation of the lymphatic system?-Lymphatic system is an asymmetrical system = more vessels on the right side
    -Lymphatic capillaries contain a single layer of lymphatic endothelial cells (LECs), bearing large intercellular spaces and a discontinuous basement membrane
    -They drain onto collecting vessels endowed with smooth muscle, unidirectional valves and LECs
    -Lymph is propelled towards the thoracic duct and veins through intermittent compression (skeletal muscle activity, intrathoracic and intra-abdominal pressure change)    What is the overall organisation of the lymphatic system?
  108. 108What does lymphatic capillary's permeability allow?allows the passage of fluid, macromolecules and cells
    e.g.    What does lymphatic capillary's permeability allow?
  109. 109What happens when there is interstitial accumulation of fluid:Oedema
    -caused by malnutrition
    -Hypertension (increases Pc)
    -Venous obstruction or lower venous return (increases Pc)
    -Leakage of plasma proteins onto the interstitium (increases πIF)
    -Decreased plasma protein concentration (e.g. hypoalbuminemia = decreased πc and increased πIF)
    -Increased capillary permeability (e.g. by inflammation or local trauma)
    -Lymphatic vessel blockade
  110. 110What does the permeability of a given molecule depend on?lipid solubility (hydrophobicity) and size (molecular weight)
    -"the more lipophilic and small a molecule is, the higher its permeability will be"
  111. 111What are the three categories that solutes fall into?1. Lipid soluble
    2. Small hydrophilic
    3. Large hydrophilic
  112. 112How does Transcapillary solute exchange occur mostly?via diffusion in favour of concentration gradients
  113. 113How does solute exchange occur in the brain?-continuous, impermeable capillaries utilize transporter-mediated facilitated diffusion (especially for glucose) : blood-brain barrier
  114. 114How do lipid soluble molecules diffuse?through the endothelial cell membrane
  115. 115How do lipid insoluble molecules diffuse?require water-filled channels to allow transcapillary diffusion
  116. 116How do small hydrophilic molecules diffuse?Through aqueous channels and convective transport (solvent drag)
  117. 117How do large hydrophilic molecules diffuse?through vesicles and caveolar transcellular transport
  118. 118What is the total capillary length in an adult human?can reach 40,000 km (4x10^7m)
  119. 119How does hydrophilic transcapillary transport via vesicles look like?How does hydrophilic transcapillary transport via vesicles look like?
  120. 120How does hydrophilic transcapillary transport via caveolae look like?How does hydrophilic transcapillary transport via caveolae look like?
  121. 121What is the problem with aqueous transcytotic channels?too large to explain transcapillary permeability properties - too big to provide selective barrier
  122. 122What is the fiber matrix hypothesis?glycocalyx reduces the effective width of junctions and fenestrations
    -Glycocalyx is a macromolecular meshwork of membrane glycolipids and glycoproteins
    -Effective pore size is determined by steric hindrance, electrostatic interactions and interfiber spacing
    -Charges are influence by sugar added    What is the fiber matrix hypothesis?

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University Physiology Organs (Cardiovascular) Flashcards on Circulation, created by Adrianna Bialecka on 21/01/2025.
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