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PHRM 100 – APPP > APPP 14 and 15: Anatomy and Physiology of the Cardiovascular System (CVS) > Flashcards

APPP 14 and 15: Anatomy and Physiology of the Cardiovascular System (CVS) Flashcards

1
Q

What are the great blood vessels associated with the heart?

A

vessels conveying blood away from the heart

  • pulmonary trunk, which splits into right and left pulmonary arteries
  • ascending aorta

vessels returning blood to the heart

  • superior and inferior venae cavae
  • right and left pulmonary veins
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2
Q

Do arteries or veins have bigger lumens?

A

veins

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3
Q

Do arteries and veins have valves?

A

veins only

  • helps return flow of blood to heart
  • prevents blood from reversing flow
  • use the ‘milking’ action of skeletal muscles to help move blood back to heart
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4
Q

What are capillaries made up of?

A

a single layer of endothelial cells – this allows for exchanges between blood and tissue

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5
Q

What is the pericardium and what is its function?

A
  • double-walled sac that surrounds the heart
  • space between layers of the pericardium are filled with pericardial fluid
  • prevents overfilling of the heart with blood
  • allows heart to work in a relatively friction-free environment
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6
Q

What are the 2 ventricles separated from the atria by?

A

atrioventricular (AV) valves

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7
Q

What holds AV valves in place?

A

chordae tendineae anchor AV vales to papillary muscles

  • when ventricles contract, so do papillary muscles, pulling downward on chordae tendineae – this puts tension on valves
  • AV valves prevent backflow of blood from ventricles to atria when ventricles contract
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8
Q

What is the tricuspid valve?

A

separates right atrium from right ventricle

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9
Q

What is the bicuspid valve?

A

separates left atrium from left ventricle

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10
Q

What valves are open during cardiac relaxation?

A

AV valves are open so venous blood entering the atria continues to flow directly into the ventricles

  • almost 80% of ventricle filling occurs by this means before atrial contraction
  • when atria do contract more, blood is squeezed into the ventricles to complete ventricular filling
  • 20% more filling of the ventricles is possible when atria contract
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11
Q

What are semilunar valves?

A
  • made up of three crescent-shaped cusps or flaps shaped like half-moons
  • prevent backflow of blood from pulmonary trunk and aorta to ventricles
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12
Q

What is the aortic semilunar valve?

A

between left ventricle and aorta

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13
Q

What is the pulmonary semilunar valve?

A

between right ventricle and pulmonary trunk

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14
Q

Describe heart sounds.

A

associated with closing of heart valves

  • first sound (lub) occurs as AV valves (mitral and tricuspid) close, and signifies beginning of systole (contraction)
  • second sound (dub) occurs when semilunar valves (aortic and pulmonary) close at the beginning of ventricular diastole (relaxation)
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15
Q

What are coronary blood vessels (arteries/veins)?

A

forms the heart’s nourishing circulatory system

  • blood in the heart chambers does not nourish the myocardium
  • coronary circulation is the functional blood supply to the heart muscle itself
  • coronary arteries are the first blood vessels to branch from aorta
  • coronary arteries supply blood
  • coronary veins collect blood from heart
  • resting coronary blood flow is roughly about 225 ml/min, which results in 4-5% of total cardiac output
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16
Q

Compare blood circulation on the left and right sides of the heart.

A

both sides pump equal amounts of blood, BUT left side does it against higher resistance and therefore does more work

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17
Q

What is the pulmonary circuit of blood circulation?

A

blood pathway between right side of heart, to lungs, and back to left side of heart

  • delivers blood from right ventricle to lungs, and from lungs to left atrium
  • low pressure, low resistance system
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18
Q

What is the systemic circuit of blood circulation?

A

pathway between left and right sides of the heart

  • delivers blood from left ventricle to rest of the body, and collects blood from the rest of the body (brain, digestive tract, kidneys, muscles, etc.) and delivers to right atrium
  • high pressure, high resistance system
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19
Q

Electrical Activity

What are pacemaker cells?

A

do not contract, but instead initiate and conduct electrical activity (generate their own action potential)

  • make up the SA node, AV node, bundle of His, and Purkinje fibres
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20
Q

Electrical Activity

Compare the pacemaker rates of the SA node, AV node, bundle of His, and Purkinje fibres.

A
  • SA node (60-100 beats/min) and AV node (40-70 beats/min) have fast pacemaker rates
  • bundle of His and Purkinje fibres have slow pacemaker rates (20-40 beats/min)
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21
Q

Electrical Activity

Describe how action potentials occur.

A
  • made up of both depolarizing (more positive/less negative) and repolarizing (bringing current back to resting potential) currents
  • pacemaker cells in SA node sets the tone or rate of the heart – depolarize spontaneously and generate APs that are propagated throughout the cardiac cell
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22
Q

Electrical Activity

What are the different currents (I) of the AP in the SA node? (4)

A
  • pacemaker current (If)
  • transient calcium current (ICa(T))
  • depolarizing current (ICa(L))
  • repolarizing current (IK)
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23
Q

Electrical Activity

What is the pacemaker current (If)?

A

carried by slow Na+ influx responsible for starting the depolarization phase

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24
Q

Electrical Activity

What is the transient calcium current (ICa(T))?

A

open for a short period of time

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25
Q

Electrical Activity

What is the depolarizing current (ICa(L))?

A

carried by slow Ca2+ influx through long-standing Ca2+ channel that remains open for a longer period of time

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26
Q

Electrical Activity

What is the repolarizing current (IK)?

A

carried by K+ efflux

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27
Q

Electrical Activity

What are the special aspects of APs in the ventricular contractile tissue? (4)

A
  • longer duration of action
  • rapid depolarization due to opening of Na+ channels
  • plateau phase due to opening of Ca2+ channels
  • repolarization due to K+ efflux
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28
Q

Muscle Contraction

What does myocardium do in response to AP generation (depolarization or opening of Na+ channels) within cardiac pacemaker cells?

A
  • AP spreads along sarcolemma
  • T-tubules contain voltage-gated Ca2+ channels (L-type) that open upon depolarization
  • this extracellular Ca2+ enters myocadial cell and binds to RyR (ryanodine receptor) Ca2+ release channels on sarcoplasmic reticulum (SR)
  • Ca2+ is released from SR – aka Ca2+ induced Ca2+ release
  • release of Ca2+ from SR causes a Ca2+ spark
  • multiple Ca2+ sparks form a Ca2+ signal – there is an increase in cytosolic Ca2+ (from 50 to 500 nM)
  • increase in Ca2+ activates contractile proteins and muscle contracts
  • note: SR contains more than 99% of intracellular Ca2+ that is bound to calcium-binding proteins (ie. calsequestrin)
  • note: in active muscle, Ca2+ binding to TnC shifts troponin-tropomyosin complex, enabling actin to interact with myosin cross bridges – hydrolysis of myosin-bound ATP enables “rowing” of actin thin filaments toward the
    centre

(excitation-contraction coupling – ‘coupling’ by Ca2+)

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29
Q

Muscle Contraction

What is the force of contraction of the myocardial cell directly related to?

A

concentration of free (unbound) Ca2+

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30
Q

Muscle Contraction

What are the mechanisms of removal of free cytosolic Ca2+? (2)

A
  • sodium-calcium exchanger: reversible exchanges Ca2+ ions for Na+ ions across the cell membrane, causing Ca2+ extrusion from the cell
  • re-uptake of Ca2+ back into SR via SR Ca2+ pump
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31
Q

Muscle Contraction

How does the muscle relax?

A
  • Ca2+ is transported back into SR
  • Ca2+ is transported out of cell via Na+-Ca2+ exchanger (NCX)
  • as intracellular Ca2+ levels drop, interactions between myosin/actin are stopped and muscle relaxes
  • sarcomere lengthens
  • note: in relaxed muscle, troponin C – TnC is not bound to Ca2+ and troponin-tropomyosin prevents actin in thin filament from interacting with myosin cross-bridges
32
Q

Regulators of Heart Function

What is sympathetic stimulation?

A

activated by stress, anxiety, excitement, or exercise

33
Q

Regulators of Heart Function

What is beta-adrenergic stimulation?

A

with norepinephrine

34
Q

What are the regulators of heart function?

A
  • on sympathetic and beta-adrenergic stimulation, cAMP second-messenger system is activated with adenyl cyclase, converting ATP to cAMP (and therefore increasing PKA) – this helps open L-type Ca2+ channels (via phosphorylation), causing increased Ca2+ entry into the cell and eventually into the SR
  • in response to next AP, increased release of intracellular Ca2+ is possible (inotropic response)
  • cAMP also activates hyperpolarization activated-cyclic nucleotide gated channel (HCN channel) in SA node, allowing for an increase in slow Na+ current (pacemaker current), therefore increasing heart rate
  • PKA increases rate of Ca2+ uptake into SR, which enhances rate of cardiac relaxation
  • sympathetic and parasympathetic stimulation
35
Q

How does stimulation of the sympathetic nervous system affect heart function?

A

releases norepinephrine, which increases heart rate and contractility

36
Q

How does stimulation of the parasympathetic nervous system (vagus nerve) affect heart function?

A

releases ACh, which reduces cAMP to decrease heart rate

37
Q

*What are the receptors of the heart and what are their effects?

A
  • beta-1/HCN: heart rate
  • beta-1: increased contractility
38
Q

*What are the receptors of the blood vessels and what are their effects?

A
  • alpha-1: constriction/contraction
  • beta-1: dilation/relaxation

(sum total effect of contraction and relaxation)

39
Q

*What is the optimal blood pressure?

A

120/80

40
Q

*Why reduce high blood pressure?

A

slows progressive organ damage

  • brain (thrombosis)
  • eyes (retinopathy)
  • kidney (nephropathy)
  • heart (hypertrophy)
41
Q

*Why reduce high cholesterol?

A
  • myocardial infarction (heart attack)
  • heart failure
42
Q

*What is an angioplasty?

A

procedure in which a balloon catheter is used to stretch open narrow or blocked coronary arteries

  • restores blood flow to heart muscle without open-heart surgery
43
Q

*What is an arterial stent?

A

short wire mesh tube that acts like a scaffold to help keep artery open

  • inserted with balloon catheter
44
Q

*What is a coronary artery bypass graft (CABG)?

A

procedure that uses your own veins (usually from legs) or arteries (usually from chest or arm) to bypass narrowed areas and restore blood flow to heart muscle

45
Q

*What is atrial fibrillation?

A

irregular heart rhythm (arrhythmia) in which atria beat rapidly and irregularly

46
Q

*What is ventricular fibrillation?

A

irregular heart rhythm (arrhythmia) in which ventricles contract in a very rapid and uncoordinated manner due to disorganized electrical activity, therefore the heart does not pump blood to the rest of the body

47
Q

*What is cardioversion?

A

medical treatment that uses quick, low-energy shocks to restore a regular heart rhythm

  • used to treat some arrhythmias
48
Q

*What is an artificial implantable pacemaker?

A

implanted medical device that generates electrical pulses delivered by electrodes to one or more of chambers of the heart to treat some arrhythmias

  • helps heart beat at a normal rate and rhythm
49
Q

*What is catheter ablation?

A

type of heart ablation procedure used to treat abnormal heart rhythms (arrhythmias)

  • uses radio-frequency energy or other sources to terminate or modify a faulty electrical pathway from sections of the heart
  • strategically destroy abnormal tissue and restore proper heart function
50
Q

What are the characteristics of left ventricular hypertrophy?

A
  • thickening in walls of ventricles
  • hypertensive heart
51
Q

What are the characteristics of right ventricular hypertrophy?

A
  • enlarged right ventricle
  • narrowing of pulmonary artery
52
Q

How do AV valves open and close?

A
  • blood returning to heart fills atria, putting pressure against AV valves which are forced open
  • as ventricles fill, AV valve flaps hang limply into ventricles
  • atria contract, forcing additional blood into ventricles
  • ventricles contract, forcing blood against AV valve cusps
  • AV valves close
  • chordae tendineae tighten, preventing valve flaps from everting into atria
53
Q

How do semilunar valves open and close?

A
  • as ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open
  • as ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close
54
Q

*What is mitral valve prolapse?

A

one or both of the mitral valve leaflets have extra tissue or stretch more than usual

  • mitral valve bows or flops back into left atrium during systole
55
Q

*What are the 3 layers of arteries and veins?

A
  • connective tissue
  • smooth muscle
  • endothelium
56
Q

*How does pressure change in the blood vessels during blood flow?

A

decreases

  • aorta (highest mean systemic blood pressure)
  • arteries
  • arterioles
  • capillaries
  • venules
  • veins
  • venae cavae
57
Q

*Describe the structure of a normal artery.

A
  • endothelial cells – with tight junctions between
  • intima – contains collagen and proteoglycans
  • internal elastic laminae – in intima
  • media
  • adventitia
58
Q

What is the direction of electrical impulse in the heart?

A
  • SA node
  • AV node
  • AV bundle / left and right bundle branches
  • Purkinje fibres
59
Q

*What is the Bachmann bundle?

A

conducts electricity from right atrium to left atrium

60
Q

*How is electrical activity conducted through the heart?

A
  • SA node activity and atrial activation begin
  • stimulus spreads across the atrial surfaces and reaches AV node
  • there is a 100 ms delay at AV node, then atrial contraction begins
  • impulse travels along interventricular septum within the AV bundle and bundle branches to Purkinje fibres, and also to the papillary muscles of the right ventricle (via the moderator band)
  • impulse is distributed by Purkinje fibres and relayed throughout the ventricular myocardium – atrial contraction is completed, and ventricular contraction begins
61
Q

*Describe the ionic basis for cardiac APs.

A
  • Na+ (depolarizing): extracellular > intracellular
  • K+ (repolarizing): extracellular < intracellular
  • Ca2+ (depolarizing): extracellular > intracellular
62
Q

*What establishes electrical impermeability?

A

AV fibrous tissue

63
Q

*What are the parts/readings on electrocardiograms (ECGs) and what do they represent?

A
  • P wave: atrial depolarization
  • QRS complex: ventricular depolarization
  • T wave: ventricular repolarization
  • PR interval: conduction time from atrium to ventricle
  • QT interval: duration of ventricular AP
64
Q

What pumps are involved in the heart contraction? (2)

A
  • Na+-Ca2+ exchanger
  • Na+-K+ ATPase
65
Q

*What are the two main parts of the cardiac cycle?

A
  • diastole: ventricular relaxation and filling
  • systole: ventricular contraction and ejection
66
Q

*Describe the phases of the cardiac cycle.

A
  • late diastole: both sets of chambers are relaxed and ventricles fill passively
  • atrial systole: atrial contraction forces a small amount of additional blood into ventricles
  • isovolumic ventricular contraction: first phase of ventricular contraction pushes AV valves closed, but does not create enough pressure to open semilunar valves
  • ventricular ejection: as ventricular pressure rises and exceed pressure in arteries, semilunar valves open and blood is ejected
  • isovolumic ventricular relaxation: as ventricles relax, pressure in ventricles fall, and blood flows back into cusps of semilunar valves and snap them closed
67
Q

*What is stroke volume?

A

volume of blood pumped by each ventricle in one contraction

  • end diastolic volume (EDV) - end systolic volume (ESV)
68
Q

*What is end-diastolic volume (EDV)?

A

volume of blood in left or right ventricle at the end of diastole (filling), just before systole (contraction) starts

69
Q

*What is end-systolic volume (ESV)?

A

volume of blood in ventricle at the end of contraction (systole) and beginning of filling (diastole)

70
Q

*What is ejection fraction?

A

percentage of the total amount of blood in the heart that is pumped out with each heartbeat

  • stroke volume (SV) / end-diastolic volume (EDV)
71
Q

*How is blood pressure calculated?

A

cardiac output (CO) x total peripheral resistance (TPR)

72
Q

*What is cardiac output (CO)?

A

amount of blood pumped by each side of the heart in one minute

  • CO = heart rate (HR) x stroke volume (SV)
73
Q

*What are some ways of lowering blood pressure?

A
  • reduce heart rate – beta blockers
  • reduce end-diastolic volume (EDV) – diuretics
  • reduce peripheral vascular resistance – vasodilators
74
Q

*What are baroreceptors?

A

type of mechanoreceptors that allow relaying of information derived from blood pressure within the autonomic nervous system

75
Q

*How does baroreceptor firing affect blood pressure?

A
  • arterial pressure decreases
  • baroreceptor firing decreases
  • increase in sympathetic activity due to firing increases CO and SVR
  • decrease in vagal activity due to firing increases CO
  • increase in CO and SVR results in negative feedback to decrease arterial pressure
76
Q

*What are the receptors of the kidney and what are their effects?

A
  • beta-1: renin release
77
Q

Congestive Heart Failure

A

slide 58

PHRM 100 – APPP (23 decks)

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