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Vets2011 > Practice questions for Cardio physiology > Flashcards

Practice questions for Cardio physiology Flashcards

1
Q

Briefly describe the components of the circulatory system

A
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2
Q

Briefly describe the cardiovascular system as it relates to its function

A
  • transports nutrients to tissues
  • transports waste products from tissues
  • transport hormones
  • dissipation of heat
  • immune response
  • maintain homeostasis
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3
Q

Briefly describe the coronary circulation

A
  • left + right coronary arteries drain into coronary sinus into right atrium
  • thebesian veins drain ventricular wall which drains into left ventricle
  • have venous admixture which is bypassing pulmonary circulation
  • blood flow through coronary arteries being late systole with 80% occurring during late diastole
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4
Q

Name the 4 phases of the cardiac cycle

A
  1. inflow phase
  2. isovolumetric contraction
  3. outflow phase
  4. isovolumetric relaxation
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5
Q

Indicate what is happening during each phase of the cardiac cycle including which valves are open and closed

A
  1. Av open + SL close, rapid ventricular filling, atrial contraction makes the p wave top up the ventricle, diastole
  2. ventricular contraction causes AV closed = both valves closed, no blood flow, ventricular pressure increasing, when pressure exceeds = aortic valve opens, systole
  3. aortic valve open + blood flow from left ventricle to aorta, ventricular pressure decrease, aortic pressure increase, SL open + AV closed, systole
  4. both valves closed, no blood flow, pressure falls rapidly in left ventricle, diastole
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6
Q

Briefly describe cardiac output, and the 4 main factors that affect it

A

cardiac output = quantity of blood pumped by heart each minute
- factors:
- preload = amount ventricular wall stretch immediately prior to contraction
- afterload = amount of tension that contracting ventricle must produce to open semilunar valves
- heart rate = sinus node controls rate + many conditions affect it
- contractility = myocardial performance independent of pre + afterload
= factors that affect it = ANS, hormones, drugs, ion conc, myocardial disease

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7
Q

What is the frank starling mechanism, and how does it relate to function of the heart

A
  • enables heart to pump automatically amount of blood that returns to right atrium = thus cardiac output rapidly adjusted
  • more cardiac monocytes stretched = greater force of contraction = frank law = enables beat to beat modification of stroke volume
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8
Q

What are the clinical parameters that are used to assess cardiovascular function. Briefly describe their assessment

A
  • heart rate = SA node sets intrinsic HR which changes in response to ANS + extrinsic factors affected by baroreceptors, chemoreceptors, low pressure receptors
  • mucous membranes = oral mucous membrane, conjunctive + vulva/prepuce = pale (vasoconstriction or anaemia) = hyperaemic (vasodilation)
  • capillary refill time = assess time = normal <2 sec, >2 sec decreased perfusion,<1 sec rapid refill + pooling of blood
  • pulse quality = small animals (femoral or dorsal pedal), large animals (submandibular or facial)
  • peripheral temp = temp of extremities vs core temp = assess limp temp = cool (decreased blood flow), warm (increased blood flow)
  • heart rate
  • blood pressure
  • ECG
  • radiograph
  • echo
  • fluid accumulation
  • mentation = consider age + personality
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9
Q

What are primary and secondary cardiac disturbances and give an example of each.

A
  • cardiac disturbances = prevention of cardiac disease
  • primary = congenital disease such as abnormal communication, acquired cardiac disease such as cardiomyopathy
  • secondary = direct effect on heart vasculatureq
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10
Q

Define circulatory shock

A

without oxygen = not energy production in tissues = undergo anaerobic metabolism = less efficient + lactic acidosis develops = damage
- caused by cardiogenic = failure of cardiac pump, hypovolaemia = loss of intravascular volume, obstructive = obstruction of venous return, distributive = maldistribution of blood

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11
Q

Briefly describe the compensation of circulatory shock

A

= body attempts to restore core tissue perfusion + oxygnation
- activation of sympathetic nervous system + release catecholamines
= peripheral vasoconstriction
= tachycardia
= increased contractility
-activate RASS

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12
Q

Describe the anatomy and function of cardiac muscle

A
  • has actin + myosin filaments and gap junctions which allow for rapid diffusion of ions
  • pacemaker triggers AP which propagates throughout cardiac myocytes + when its threshold is reached = fast sodium channels open triggering AP
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13
Q

Compare and contrast cardiac muscle to skeletal muscle

A
  • cardiac muscle have actin and myosin filaments
    • they are connected by intercalated discs which forms 2 syncytial ( atria + ventricle)
    • have gap junctions for rapid diffusion of ions
  • action potentials are longer for skeletal muscle due to activation of slow sodium channels + inactivition of potassium channels preventing rapid depolarisation
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14
Q

Briefly describe what is occurring during the phases of the cardiac muscle action potential

A
  • phase 0 = depolarisation. = fast sodium channels open
  • phase 1 = initial repolarisation = fast sodium channels close + fast potassium channels open
  • phase 2 = plateau = calcium channels open + fast potassium channels close
  • phase 3 = rapid repolarisation = calcium channels close + slow potassium channels open
  • phase 4 = restoration of resting membrane potential
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15
Q

What is the refractory period

A
  • absolute refractory period
    • period of time where cardiac muscle is refractory to restimulation
  • relative refractory period
    • additional period of time after AP whistle cardiac muscle is more difficult to excite
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16
Q

Briefly describe cardiac conduction

A
  • atria contract abut 1/6 of a second ahead of ventricles = allow for ventricular filling
  • ventricular conduction must be coordinated
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17
Q

Why is the sinus node the pacemaker and describe its activation and automaticity

A
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18
Q

Briefly describe the sympathetic and parasympathetic activation of the heart

A

Sympathetic:

  • adrenaline/noradrenaline
  • beta adrenergic receptors in heart:
    • increase calcium and sodium permeability = increase contraction + sinus node discharge = fast HR
    • more potassium channels open = reduce refractory period
  • alpha adrenergic receptors in blood vessels = vasoconstriction

Parasympathetic

  • acetylocholine
  • cholinergic receptors
    • increase potassium ion permeability = hyper polarisation = less excitable membrane
    • decrease sinus node = slow HR
    • decrease AV nodal conduction
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19
Q

Identify the different components of the normal ECG

A
  • measures electrical conductivity from skin surface
  • P wave = atrial depolarisation
  • QRS wave = ventricular depolarisation
  • T wave = ventricular repolarisation
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20
Q

What are the standard and augmented limb leads of the ECG

A
  • neg + pos electrodes placed on skin
  • standard leads mostly used in animals attached to limbs
  • appearance of ECG trace dependent for each lead
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21
Q

What is the mean electrical axis and why?

A
  • lead 2 = closest to mean electrical axis
    = mean electrical axis = 59 degrees C and lead 2 = 60 degrees C
    = highest magnitude of electrical activity from base to apex
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22
Q

Briefly describe the base apex lead system used in large animals

A
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23
Q

Briefly describe the steps of rhythm analysis and apply these to interpret an ECG trace

A
  1. calculate heart rate = count no. of QRS complexes in 6 secs + multiple by 10 to give no of QRS complexes in 60 sec
  2. is rhythm regular? = r-r intervals equidistant = regular
  3. P wave for every QRS? = do P waves occur at regular rate + for every QRS
  4. are waves of normal shape + consistence? = p waves - are they all similar in appearances, is appearance normal, QRS - are all same shape + polarity, is shape, duration + polarity appropriate for this lead + species, T waves - is wave appropriate size
  5. are segments + intervals normal = is PR of appropriate duration, is ST depressed or elevated, is T wave appropriate size
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24
Q

What are common causes of sinus bradycardia and sinus tachycardia?

A

brachycardia = slow HT
tachycardia = fast HR
- normal response to decreased output
- stress, anxiety, fever

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25
Q

Briefly describe the effect of high potassium on the membrane potential, threshold potential and the resulting clinical findings with each of these electrolyte disturbances.

A

= hyperkalaemia

  • decrease resting membrane potential = partially depolarise membrane with less sodium channels open
  • causes bradycardia, atrial arrest and even death
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26
Q

Briefly describe the effect of low calcium on the membrane potential, threshold potential and the resulting clinical findings with each of these electrolyte disturbances

A

= low calcium

  • decrease membrane potential
  • most common = tremors, seizures, behaviour changes + cardiovascular changes ( less common) = hypotension + decreased cardiac contractility
27
Q

What is the difference between a physiologic and pathologic arrhythmia?

A 
physiological = disturbances in normals minus rhythm caused by canes in sympathetic tone
pathologic = defect in cardiac system
28
Q

common arrhythmias

A

-

29
Q

supraventricular -vs- ventricular

A

This is a pathological arrhythmia which has caused a third degree AV block

  • supra ventricular is atrial in origin
    • atrial premature depolarisation
    • atrial filling
  • ventricular in origin
    • ventricular premature depolarisation
    • ventricular tachycardia
    • ventricular fibrillation
30
Q

sinus arrhythmia

A

= changes in vagal tone during respiration

  • inspiration = blood sucked into lungs, decreased vagal tone, increased heat rate
  • expiration = blood squeezed from lungs, increased vagal tone, decreased heart rate
31
Q

AV block

A

AV block = variable conduction from atria to ventricle

  • classified as 1st, 2nd or 3rd degree
  • 1st = characterised by prolonged P-R interval
  • 2nd = p wave not followed by QRS + high parasympathetic tone
  • 3rd = no conduction through AV node + supra or ventricular in origin
32
Q

atrial fibrillation

A

= multiple re=entrant pathways causing rapid + disorganised depolarisation without atrial contraction

  • depolarises continuously bombard AV junction
  • results from atrial enlargement
  • irregular irregular rhythm
  • no p waves
33
Q

APDs and VPDs

A 
APD = atrial premature depolarisation = P wave early + different on appearance from sinus P wave + P wave may be buried in T wave of previous beat
VPD = ventricular premature depolarisation = QRS occurs early + wide and bizarre in appearance, QRS not associated with P wave, T wave opposite polarity
34
Q

ventricular tachycardia

A

= lots of VPC joined together + rapid regular rhythm

  • QRS wide + bizarre + not associated with P
  • high heart rate = reduced cardiac output
35
Q

Ventricular fibrillation

A

impulse propagates into area of non-refractory muscle;

  • slow conduction velocity
  • long circuit
  • short refractory period
  • terminal arrhythmias = form of cardiac arrest
36
Q

Briefly describe the abnormalities that may be identified during auscultation?

A

diagnose abnormal heart sounds/arrhythmia

  • murmurs
  • arrhythmias
  • bradycardia
  • tachycardia
  • muffled heart sounds
    • pericardial/pleural space disease
37
Q

What are the normal heart sounds that are heard during auscultation in small animals, and when do they occur?

A
  • S1 = Av valve closure
  • S2 = semi-lunar valve closure
  • S3 = rapid diastolic filling of ventricle
  • S4 = atrial contraction
  • S1 + S2 = high frequency normal heart sounds = caused by vibrations within ventricles
  • S3 + S4 = gallop rhythms = abnormal in dogs + rarely heard in normal cats + can be heard in larger animals
38
Q

What are the abnormal heart sounds that may be heard during auscultation and when do they occur?

A
39
Q

What is a gallop rhythm?

A

s3 +s4

40
Q

What is a heart murmur?

A

= sounds created by turbulent blood flow

  • high velocity
  • obstruction to flow
  • low viscosity
41
Q

What is the different between a physiologic and a pathologic heart murmur and give an example of each?

A

Physiological

  • low intensity, high frequency, early systolic murmurs
  • turbulent flow in aorta or pulmonary artery
  • e.g anaemia

Pathological

  • most due to high velocity flow through narrow orifice
  • insufficiency (regurgitation)
    • leaky valve
  • stenosis
    • narrowing of valve
42
Q

Identify when murmurs are heard with regurgitant -vs- stenotic heart valves

A
  • murmurs of valvular regurgitation occur when valve is suppose to be closed
  • blood flows at high speed through defect in valve because pressure different between ventricle + atrium during systole
  • murmurs of stenosis occur when valve is suppose to be open
  • some blood goes into ventricle down normal pressure gradient
  • blood pushed by atria through stenotic valve
43
Q

Discuss how blood flow changes from the large arteries down to the capillaries

A
44
Q

What are the main determinants of blood flow through a vessel?

A

dependent on pressure gradient along vessel

45
Q

What are the main differences between veins and arteries?

A 
arterties = thick walled + move blood to tissues
veins = carry blood to heart + thinner walls
46
Q

What vessels provide the largest contribution to total peripheral resistance?

A
47
Q

What effect does vasoconstriction and vasodilation have on total peripheral resistance?

A

vasoconstriction
- increases blood pressure + therefore increases TPR

  • vasodilation
    • decreased blood pressure + therefore TPR
48
Q

What factor has the most significant factor on laminar blood flow?

A

describes flow of fluid through laminar tube is dependent on:

  • change in pressure along tube
  • radius of tube
  • viscosity of fluid
  • length of tube
  • BUT diameter of vessel plays greatest role in determining
49
Q

What are the main factors that determine blood pressure?

A

determined by:

  • cardiac output (SVxHR)
  • resistance from vessels
50
Q

Define mean arterial pressure?

A

average pressure within arteries

51
Q

What determines the pulse pressure?

A

pulse pressure = SBP - DB

52
Q

Briefly describe the vasomotor centre and its regulation of arterial blood pressure

A

located in medulla + pons

  • vasoconstrictor area
  • vasodilator area
53
Q

Briefly describe the short-term neural mechanisms present for the rapid control of blood pressure, including the baroreceptor reflex

A

SNS can cause rapid changes in arterial pressure by:

    1. Vasoconstriction = control of TPR + distribution of blood flow
    1. Constriction of veins = increase preload + therefore CO
    1. Increased contractility + HR = increased by SV + therefore CO

negative feedback loop
- increased mean arterial pressure
- stretch of barorecpetors
-> vagus+ glossopharyngeal nerves
-> nucleus tractus solitaries of medulla
-> inhibition of vasoconstrictor centre
-> decreased sympathetic nervous system activation
-> vasodilation
-> bradycardia
-> decreased contractility
= thus decreased TPR + CO = thus decreased BP

54
Q

Briefly describe the humoral (longer term) mechanisms of blood pressure control

A
  • pressure diuresis = increased urine production
  • activation of RAAS
    • vasoconstriction
    • retention of Na + water
  • thirst
  • ADH secretion by hypothalamus
  • ANP released from atrial myocytes = natiuresis
55
Q

Briefly describe the Bainbridge reflex

A
  • stretch of atrium causes increase in heart rate
    • ANS control of sinus node
  • thus effect of increased intravascular volume is net effect of baroreceptor reflex which reduces HR + Bainbridge reflex which increases HR
  • when blood volume increase above normal Bainbridge reflex usually prevails whereas low blood volume barorecpetors reflex prevails
56
Q

Briefly describe the production and mechanism of action of atrial natriuretic peptide

A
57
Q

Briefly describe how the arterioles work to regulate the local control of blood flow to individual tissues (including the vasodilator and oxygen demand theories).

A
  • stop cocks of circulation
    • regulate flow through capillaries
      • constriction
      • dilation
    • offer greater résistance to flow
    • maintenance of vascular tone
  • vasodilator theory
    • vasodilator substances
    • released in response to decreased O2 conc
    • adenosine reasoned from heart msucle cells when coronary blood flow is reduced
  • oxygen demand theory
    • smooth muscle surrounding pre-capillary sphincters + met-arterioles constrict in presence of oxygen
    • high flow delivering high oxygen -> precapillary constricts reducing blood flow
    • decreased oxygen -> relaxation of smooth muscle -> vasodilation -> increased blood flow
58
Q

What is autoregulation and why is it important?

A
  • maintaining local blood flow during changes in arterial blood pressure
  • increase in blood pressure immediately increases blood flow, auto regulation returns blood flow to normal
  • particularly precise in brain + heart
    • maintains normal blood flow
59
Q

Briefly describe the metabolic and myogenic mechanisms by which autoregulation is thought to occur

A

Metabolic theory

  • arterial pressure increases
    • increased delivery of oxygen + other nutrients
    • increased blood flow also washes out local vasodilators
      • vasoconstriction

Myogenic mechanism

  1. Increased BP -> increase blood flow
  2. Blood flow increase -> stretch of vascular smooth muscle
  3. Muscle starts responding to stimulus by contracting
  4. Contraction narrows lumen -> increased resistance to flow
  5. Greater stretch = greater contraction
    - low pressure = less stretch = vasodilation
60
Q

Briefly describe the functional anatomy of the capillary bed, and how it differs in different tissues

A
  • at their organ a smooth muscle fibre completely encircles capillary = pre-capillary sphincter
  • unicellular layer of endothelial cells surrounded by thin basement membrane
  • intercellular spaces (clefts) through which water-soluble substances diffuse
  • brain
    • tight junctions that only allow water + gases to permeate
  • liver
    • are wide open to allow passage of all molecules including proteins
  • kidney
    • glomerular capillaries are fenestrated + allow tremendous amount of small molecular + ionic substances
61
Q

Describe the fluid compartments of the body

A
  • extracellular compartment = 1/3
    • interstitial space = 3/4
    • intravascular space = 1/4
  • intracellular compartment = 2/3
62
Q

Briefly describe the movement of fluid and particles across the capillary wall, what factors can affect this movement

A

hydrostatic forces push fluid through capillary pores into interstitium

  • osmotic forces (colloid on optic pressure) within capillary lumen act to keep fluid within vessel
  • lymphatics return excess fluid + proteins to circulation (some proteins leak through)
  • diffusion
    • most important means of substance transfer between IVS + interstitium
    • H2O + particles move back + forth through capillary wall
      • lipid soluble = cell membrane = extremely fast/easy movement
      • H2O soluble = intercellular clefts = still very fast flow
  • net rate of disunion of substance through any membrane is proportional to conc different of substance between two sides of membrane
    • O2 flows from capillary into tissue
    • CO2 flow from tissues into capillaries
63
Q

What are starlings forces?

A

components of startling forces

  • hydrostatic pressure
  • osmotic pressure - colloid osmotic pressure
  • endothelial (blood vessel wall) permeability
64
Q

Briefly describe the lymphatics system and its function?

A
  • small amount of net filtration that occurs within capillaries result in slight excess of fluid within interstitium
  • this fluid is returned to circulation via lymphatic system
  • network of channels/ducts that drain excess interstitial fluids
  • accessory route from interstitium to intravascular space
    • lymph vessels drain to thoracic duct + right lymph duct before draining into venous system
  • in addition to excess fluid = also carries proteins + large molecules that cant be removed by absorption into capillaries
  • lymphatic endothelial cells overlap so edge is free to fold inward forming a one way flap that opens to allow passage of large suspended particles
    • these flaps are present on all lymphatic vessels

Vets2011 (13 decks)

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