Flashcards
Cardiovascular Physiology
Cards in this deck (79)
- 1What does the heart do and why?Diffusion ineffective over short distance - long from cell clusters and tissues
Rapid reaction need cells with high metabolic rate
Overcome issue of moving chemicals at high speed - pump allows bulk flow closer to tissue - 2Positive of circulatory systemBigger organisms
Higher metabolic rate
Direct flow of metabolite between organs - 3Cons of circulatory systemCirculatory failure can be fatal
High pressure and flow needed
High pressure strains vessels
Metabolically expensive - 4Other roles of circulationTransport hormones
Thermoregulation
White blood cells - 5hormone transportTo distant target
React with receptor
Adrenal glands on inner medulla and outer cortex in adrenal glands on kidneys
Medulla secretes adrenalin - 6Thermoregulatory control and experiment0.5 rise causes vasodilation.
Rabbit ears on treadmill - sharp rise in temp increases flow to ears
Heat loss calculated from thermal gradient
Cold environment vasoconstriction in peripheries
Persistent lack of O2 can cause tissue death - 7White blood cell transportLymphocyte, phagocyte, monocyte
Fight infection
Platelets cause clotting - 8Open circulatory systemHeart pump fluid through arteries into haemocoel
Fluid bathes organs then returns to heart via veins
No distinction between blood and haemocoel (haemolymph)
Limited to later velocity and distribution
e.g. crayfish
Change in uptake slow and maximal transfer low
Little control, little needed - 9Closed circulatory systemBlood never leaves vessels
Separate from tissue fluid
Relatively high pressure, quick delivery adn high metabolic rates
Squids 3 hearts/ earthworms 5
High control, much needed - 10Evolution of closed systemsVertebrates evolved independently systems closely associated with respiratory system
- 11Fish circulationSingle circulation - flows through heart once each trip
- 12Amphibian, bird, mammalDouble circulation
Heart to lungs (gas exchange) back to heart to be pumped round
Vessels serving rest of body = systemic unit - 13TroutBetween pectoral fins and isthmus- Pericardial cavity
Contail centrical to bulbous arteriosus
No cardiac muscle
Sunus venosus underneath collects venous blood and sends to ventricle via atrium
Blood flow through gills oxygenated - 14Fish heart1 atrium
1 ventricle - 15Amphibians2 atria, 1 ventricle
Oxygen poor blood pumped to lungs/ skin
Oxygen rich to systemic circulation - 16Birds and mammals2 atria, 2 ventricles
One round body, one to lungs
Delivery of blood with maximal oxygen
Warm blooded, large brain, complex behaviour patterns
Rapid sustained movement needs energy - 17Double circulationderived from primitive fish
Fish and embryo gave 6 arches - 18AmphibianStart as fish, 6 arch provides lung
Inefficiency compensated through rich vascular beds beneath moist skin - oxygenate systemic blood which returns to heart already partially oxygenated - 19ReptilesSeptum partially divides ventricle, reduces mixing of oxygenated and deoxygenated blood
More active and no need for moist skin hence new habitats - 20Blood vessels in mammalian circulationArteries- highest pressure
Capillaries - tiny vessels, bridge arteries and veins, oxygen and nutrients out and waste into blood
Veins - wider, low pressure. 2/3 blood. Back to hear via superior and inferior vena cava
Pulmonary artery - only artery carrying deoxygenated blood to lungs - 21William HarveyDiscovered heart involved in blood pumping
- 22Gross structure of heartHeart within pericardial sac, attached to diaphragm so breathing rocks heart
Around collagen skeleton- junction of atria and ventricles, annulus fibrosis holds cardiac valves
AV valves form thin tissue at base of connective ring, connects to chord tendinae. Opposite end tethered to papillary muscle. Stabilise chord. Prevent valve being pushed into atrium - 23Amount of blood pumped200 million litres in lifetime
- 24Valves of heartRight AV = tricuspid, Left AV = bicuspid (mitral)
Semi lunar valves - shape means don't need tendons - 25Gross structure of blood vesselsTunica intima
Tunica media
Tunica adventitia
Venules and veins - 26Tunica intimaEndothelium and elastic connective tissue
- 27Tunica mediaSmooth muscle cells with bands of elastic tissue
Varies in thickness - thick in large arteries so can regulate pressure change
Vessels can temporarily store energy - 28Tunica adventitiaCollagenous extracellular matrix containing fibroblasts, blood vessels and nerves
Adds rigidity - 29CapillariesSingle layer endothelial cells, all cells within 10um of a capillary
- 30Venules and veinsThin walls, valves prevent back flow, large cross sectional area
Little resistance
hold 2/3 blood
Delayed compliance
Over period of tenths od seconds
Pressure in vessel returns following sudden increase or decrease
Result of smooth muscle cells changing length and allows volume in circulatory system to change - 31Why does blood flow?Teleological - oxygen and nutrients to whole body
Mechanism - liquids flow down pressure gradient - 32Darcy's lawQ= change in pressure / resistance
- 33Blood flowPerfusion pressure/ vascular resistance
- 34Cardiac outputblood pressure/ vascular resistance
- 35Blood pressurecardiac output x vascular resistance
- 36cardiac outputheart rate x stroke volume
- 37FlowIn motion stays in motion
Laminar flow - that inside has less friction hence quicker
Turbulent flow chaotic and can indicate plaque - 38Influence on Laminar flowinfluenced by radium, thickness and fluid viscosity
R = vessel length x viscosity / radius^4
Resistance increase with longer length and higher viscosity but decrease with larger radius - 39Capillary bedsrelatively low resistance, despite small radium, as short and connected in parallel hence increases cross sectional area so velocity gives time for diffusion
- 40ViscosityNumber of RBC compared to plasma
Increase in haemocrit at higher altitude, decrease in anaemia - 41Role of radius in resistanceLargest influence
flow increase 16 fold as radius doubles
Creates change in pressure in arterioles as change change diameter via vasomotor - 42Sympathetic vasomotorTotal peripheral vascular resistance regulated by sympathetic
Tonically active vasoconstrictor to maintain pressure and resistance - 43Noradrenaline and vasomotorincrease resistance by vasoconstriction
arterioles much more innervated
increase arteriole constriction increase total peripheral vascular resistance and arterial blood pressure
Constriction of venues allow faster return to heart - 44Adrenalineimportant in vasoactive dilation in skeletal muscle
Constriction in peripheral circulations - 45AcetylcholineLocal factor
stimulates endothelium to produce substance causing dilatation
When endothelium absent, no vasodilation - 46Nitrous Oxidelocal factor
not stored
produced by amino acid argentine by NO synthase
Regulated by intracellular Ca2+-calmodium comlex
causes vasodilatation - 47Blood pressure neededPressure maintained as hypotension decreases perfusion of oxygenated blood to tissues
hypertension could damage circulatory systems - 48Measuring blood pressureSphygmomanometer
when cuff pressure higher than arterial pressure, flow in lower arm stops.
When falls below systolic arterial pressure, blood flows again - korotkoff sound
When sound disappears, diastolic pressure - 49Mean arterial pressurediastolic + 1/3(systolic - diastolic pressure)
- 50Arterial stiffnessageing and cardiovascular disease vessels deposit calcium and collagen - makes more rigid
increases systolic pressure relatively to diastolic pressure.
a large ratio indicates resistance - 51Change in cardiac output and ventilationCaused by whole body exercise
Release adrenalin increases both - 52Blood flow in exerciseLocal vasodilation shunts to exercising muscles
Blood flow of resting skeletal muscles low - contract compresses vessels if develops more than 10% max tension
When more than 70%, flow stops
Between contractions, flow enhances 30 fold - 53Local MetabolitesCause vasodilation
Blood flow doesn't return immediately after exercise due to clearance of local metabolites
Oxygen demand balanced by increased oxygen supply generated by local metabolites - 54Positive feedbackMore oxygen, more metabolites, more dilatations
- 55Diffusion distanceSome muscle capillary have no blood flow - pre capillary sphincters constricted and closed
increased flow opens dormant capillaries, shortening diffusion distance
Capillary recruitment increase SA - 56Cardiac cycleAtrial systole
isovolumetric contraction
Ventricular ejection
Isovolumetric relaxation
Late diastole - 57Atrial systolemost flood enters in diastole. last 20% by atrial systole
Heart rate increase, significant role in ventricle filling
When contract, small amount forced backwards into vena cava
Seen as pulse in jugular vein if in specific position - 58Isovolumetric contractionContraction with no volume change
Begins at spiral base and contract to squeeze blood up, increasing pressure
AV and semilunar closed - 59Ventricular ejectioncontraction generates pressure to open SL valves
blood into arteries, pressure drives flow
Ventricular blood enters aorta quicker than can leave atrial tree
arteries distended and engorged with blood - 60Isovolumetric relaxationrapid fall in ventricular pressure, below aortic pressure hence closing valve
Brief rise in arterial pressure - dicrotic notch
Final 1/3 ventricular blood flows away from heart due to kinetic energy
Overall change in ventricular volume = stroke volume - 61Late diastoleboth chambers relax and passively fill with blood
- 62PhonocardiogramListed to audible events with stethoscope. 1st round - closure AV values
2nd sound - closure SL valves
3rd sound, murmurs due to incomplete valve, clicking from abnormal valve movement - 63ECGSmall changed in potential detected between different location on skin - reflect underlying activity of the heart.
Waves appear as deflections above and below baseline
Segments sections between 2 waves, 3 waves on normal ECG - 64P-waveatrial depolarisation
- 65QRS complexVentricular depolarisation
Complex masks atrial repolarisation - 66T waveventricular depolarisation
- 67R-R intervalAccurate measure of heart rate
- 68Long Q-T signalmutation in myocardial Na+ and K+ channels or drug side effect (Seldane antihistamine)
- 69Cardiac pressure volume loopWidth of loop = stroke volume
Area within loop = ventricular stroke work - 70Aortic stenosisleft ventricular emptying impaired
high outflow resistance as small valve area
Large pressure gradient over aortic valve in ejection - peak systolic pressure much higher
increase ESC and decease stroke volume
Enlarged heart and increased risk of failure - 71Heart conduction systemMycoytes electrically connected via gap junctions- syncytium. Contract only when stimulated
Pacemaker cells depolarise and contract spontaneously and regularly. SAN highest intrinsic rate, but AV can take over
Bundle of his conducting cells connect atria and ventricles
Terminate on purkinje fibres - excite vesicles - 72Autonomic influenceInnervated by parasympathetic and sympathetic from cardiac centre in medulla oblongata
Accelerator nerves to SA, AVN and most portion of myocardium
Release noradrenalin - binds to beta adrenergic receptors on fibres - 73Pacemaker potentialSlope determines heart rate
Sympathetic positive chronotropic effect increases hr
Noradrenaline increases force - positive inotropic effect - 74ParasympatheticReach by vagus Xth nerve
Acetylcholine in muscarinic receptors at SAN
Parasympathetic negative chronotropic effect
No force impact - 75Carotid baroreceptorsWalls of carotid arteries and aorta
When stimulated, send afferent information to brainstem via carotid sinus nerve to IXth cranial nerve
Arotic send information to aortic nerve to Xth cranial nerve - 76Need for baroreceptorsMaintain blood pressure after change - hypotension decrease perfusion of oxygenated blood, hypertension damage fragile system
- 77Importance of carotidMaintain pressure in brain circulation, aortic goers systemic arterial blood pressure homeostasis
Tonically active - 78Arterial blood pressure increaseStretches walls or aorta and carotid sinus, stimulating baroreceptors
Increase frequency of AP to CV centre, inhibit accusatory centre decreasing heart rate and force of contraction - 79Cardiac baroreflexPotentiated by vasomotor baroreflex
Peripheral vasodilation reduced blood pressure further
Fall in arterial blood pressure
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- Physiology of Organisms (Cardiovascular Physiology) Flashcards on Cardiovascular Physiology, created by Alice Hathaway on 08/01/2019.
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- Alice Hathaway
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