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Pharm 2 > Cardiovascular physiology > Flashcards

Cardiovascular physiology Flashcards

1
Q

What is the very general pathway of blood in the heart?

A

-deox blood enters right atrium -> pushed into right ventricle -> pumped up to semilunar valve -> out to lungs to get oxygenated -> ox blood comes back to heart -> enters left atrium -> left ventricle -> up into aorta -> out to three places

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2
Q

What does the thickness of the ventricles have to do with their function?

A

-right ventricle has thin muscle because only has to pump to pulmonary valve
-left ventricle has thick muscle because has to pump to brain and rest of body = more important

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3
Q

The aorta has three branches, where do they go?

A

-upper body
-lower body
-supply for the heart itself

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4
Q

What is the number one priority of the heart?

A

-pump blood to the brain

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5
Q

What is flow velocity?

A

rate/C-S area of vessel

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6
Q

What three things affect resistance of flow?

A

-vessel diameter
-blood viscocity
-tube length

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7
Q

Does flow depend on absolute pressure?

A

-no, depends on pressure difference

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8
Q

Which factor of resistance can be changed through drugs and influence blood flow?

A

-vessel diameter
-viscocity??

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9
Q

What are the two main factors of blood flow?

A

-Pressure gradient
-Resistance

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10
Q

What are the two muscle types in the heart?

A

-skeletal = striated
-cardiac muscle

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11
Q

What are the characteristics of skeletal heart muscle?

A

-striations of fibers are parallel
-stimulated by somatic NS
-can only contract in one direction
-voluntary

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12
Q

What are some characteristics of cardiac muscle?

A

-fibers are branched
-pumps blood to heart
-stimulated by autonomic NS
-involuntary

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13
Q

What are the two types of muscle cells?

A

-myocardial autorhythmic cells
-myocardial contractile cells

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14
Q

What are myocardial autorhythmic cells?

A

-“pacemakers”
-generates electricity
-doesn’t contract
-never rest

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15
Q

What are myocardial contractile cells?

A

-contracts
-only 1% are self-excitable
-gap junctions = faster signals = heart contracts as one unit
-long refractory period = 250ms

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16
Q

What are the general features of cardiac cells?

A

-intercalated discs = branching
-gap junctions = fast signal relay
-many mito
-large T tubes

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17
Q

What is the intrinsic cardiac conduction system?

A

-network of noncontractile cells (autorhythmic) that initiate and distribute impulses to coordinate depolarization and contractions

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18
Q

What does the potential of an autorhythmic cell look like?

A

Pacemaker potential = slowly opening Na+ channels = unstable resting potential -> at threshold -> Ca2+ channels open -> Ca2+ influx = rising phase of AP = depolarization -> Ca2+ channels inactivated and K+ channels open -> repolarization -> charge falls

-never a flat line because it never rests

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19
Q

What is the charge of the cell naturally?

A

-70 mV

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20
Q

What is the threshold for action potential?

A

-40 mV

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21
Q

What is the pathway for the action potential of contractile cells?

A

depolarization opens Na+ channels in sarcolemma -> -90mV to +30mV -> depolarization in T tubules -> SR release Ca2+ -> also opens Ca2+ channels in sarcolemma -> Ca2+ surge = long depolarization = plateau -> repolarization from inactivating Ca2+ channels and opening K+ channels -> back to resting potential

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22
Q

What does the action potential for cardiac contractile muscle look like from a cellular view?

A

action potential enters -> voltage gates Ca2+ channels open -> Ca2+ enters cell -> Ca induced Ca release at ryanodine receptor -> Ca released from SR -> calcium spark -> Ca signal -> Ca binds to troponin -> contraction -> Ca unbinds -> relaxation -> Ca pumped into SR to store -> Ca exchange with Na -> Na gradient mediated by Na-K ATPase

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23
Q

What is Frank-Stirling Law?

A

-increase in end-diastolic ventricular volume produces increase in stroke volume
-force of heart muscle varies with wall fiber tension, which is function of length

-basically = more dilation of the left ventricle = increased ejection
-more SA of actin covering myosin = more contraction

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24
Q

pathway for regulation of monocyte action through adrenergic system

A
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25
Q

What signals control contraction?

A

-norepinephrine
-epinephrine

26
Q

What is the relationship between contractions and crossbridges?

A

-graded contraction is proportional to crossbridges formed
-more Ca = crossbridges = more force/speed

27
Q

What nerve connects to the SA and AV node?

A

-The vagus nerves

28
Q

Where on the heart do the sympathetic nerve chain connect?

A

-only connects to contractile cells
-doesn’t connect to AV and SA node

29
Q

What factors affect arterial blood pressure?

A

-cardiac output
-heart rate
- contractility
-filling pressure
- blood volume
venous tone

-peripheral resistance
-arteriolar tone

30
Q

When you stand up from lying down, what is the pathway for maintaining blood pressure?

A

lying down -> stand up -> decrease in venous return -> decrease in end-diastolic volume -> decrease stroke volume -> decrease cardiac output -> decrease BP (stimuli) -> baroreceptors -> sensory neurons -> medulla obl. -> increase sympathetic and decrease parasympathetic = vasoconstriction, increase HR, increase peripheral resistance -> increase in blood pressure (-ve feedback response)

31
Q

What are the Purkinje fibers?

A

-branch of cells in the ventricles
-allow the heart to have synchronized contractions

32
Q

What is the bundle of His?

A

-the AV bundle
-sends electrical impulses from AV node to Purkinje fibers

33
Q

In what order of structures does the electrical current flow?

A

-SA node -> pumps atria -> AV node -> AV bundle -> purkinje fibres -> pump ventricles

34
Q

what is the cardiac cycle?

A

-coordinates sequence of events as blood enters atria, leaves ventricles and starts over
-synchronizing via Intrinsic electrical conduction system
-rate influenced by symp and parasymp division of ANS

35
Q

What are the 6 stages of the cardiac cycle?

A
  1. Late diastole: full of blood
  2. atrial systole: makes sure all blood is in heart; top contraction
  3. isometric ventricular contraction (lub): no movement; pressure built; no backflow; atria go to diastole
  4. Ventricular ejection: ventricles contract; semilunar valves open
  5. isometric ventricular relaxation (dub): last bit of blood leaves ventricles; no more contraction; AV valves still closed
  6. diastole: heart fills with blood from atria to ventricles; due to low pressure
36
Q

What is the electrical conduction pathway of the heart?

A

-SA node initiates -> depol spreads through atria via gap junctions and internodal paths -> to AV node ->fibrous tissue slows formation of APs -> AP travel down Bundle of His -> split to L and R atrioventricular bundles -> into purkinje cells

37
Q

What is systole?

A

period of contraction

38
Q

What is diastole?

A

period of relaxation

39
Q

Why does increased pressure in the ventricles cause the AV valves to close?

A

**

40
Q

What is the sympathetic nervous system activated by?

A

-emotional or physical stressors
-ex. norepinphrine = more rapid pacemaker

41
Q

What is the vagal tone?

A

-the heart at rest
-parasympathetic

42
Q

Which NS system does parasympathetic oppose?

A

-sympathetic
-involves acetylcholine

43
Q

What is the Bainbridge?

A

-aka atrial reflex
-sympathetic reflex initiated by increased venous return
-SA node stim by stretch of atrial walls
-same law as Frank Sterling but for atria

44
Q

What are the two main chemical regulations of heart rate?

A

1: hormones
-epinephrine = increased HR and contractility
-thyroxine = increases HR and effects of epinephrine

2: intra/extracellular ion [ ] maintenance

45
Q

What are other factors of heart rate?

A

-age
-gender
-exercise
-body temperature

46
Q

What occurs with age that can increase the effects on the heart?

A

-sclerosis and thickening of valve flaps
-decline in cardiac reserve
-fibrosis of cardiac muscle
-atherosclerosis

47
Q

What are three possible congenital heart defects?

A
  1. ventricular septal defect: no septum separating ventricles = blood mixes; more blood in right
  2. coarctation of the aorta: narrow aorta = increases workload of left ventricle
  3. tetralogy of Fallot: four defects = narrow pulmonary trunk; hypertrophied R ventricle; ventricular septal defect; aorta opens from both ventricles
48
Q

What is an arrhythmia?

A

-most common disorder
-includes atrial fibrillation and flutter
-related to age and or heart disease

49
Q

What are the symptoms of arrhythmias?

A

-palpitation or fluttering sensation
-racing heart
-dyspnea
-syncope (fainting)
-fatigue
-chest pain
-cardiac arrest

50
Q

What can cause arrhythmias?

A

-coronary artery disease (ischemia or infarction)
-altered impulse conduction
-changes in cardiac structure from heart failure
-drugs
-electrolyte distrubances

51
Q

Why is coronary artery disease a common cause of arrhythmia?

A

-because it causes ischemia or infarction
-if cardiac cells lack O2, they depolarize = altered impulse formation and conduction
-this causes changes in automaticity

52
Q

What are Ectopic Foci?

A

-ectopic foci = abnormal pacemaker sites outside of SA node with automaticity
-occur in atria or ventricles
-create additional beats
-can lead to tachycardia and bradycardia
-can occur after reentry too

53
Q

What is Wolfe Parkinson White Syndrome? (on exam)

A

-cause of supraventricular tachycardia in children
-extra conducting tissue = accessory pathway
-sometimes can conduct electricity and establish a circuit with AV node

54
Q

What is an AV block?

A
  • conduction block within the AV node or bundle of His
    -impairs impulse conductions from atria to ventricles
55
Q

What are 5 types of supraventricular arrhythmias?

A

-Sinus tachycardia
-atrial tachycardia
-paroxysmal atrial tachycardia
-atrial flutter
-atrial fibrillation

56
Q

What is sinus tachycardia?

A

-high sinus rate
-100-180 beats/min
-during exercise or from conditions that lead to increased SA nodal firing rate

57
Q

What is atrial tachycardia?

A

-series of 3+ consecutive atrial premature beats at over 100/min

58
Q

What is paroxysmal atrial tachycardia?

A

-tachycardia begins and ends in acute manner

59
Q

What is atrial flutter?

A

sinus rate of 250-350 bpm

60
Q

What is atrial fibrillation?

A

-uncoordinated atrial depolarizations

61
Q

What are 4 ventricular arrhythmias?

A

-ventricular premature beats: from ectopic ventricular foci
-ventricular tachycardia: from abnormality or reentry; 100-200 bpm; life threatenening
-ventricular flutter: over 200 depol/min
-ventricular fibrillation: uncoordinated depol

62
Q

When do the two heart sounds occur?

A

isometric ventricular contraction = lub
isometric ventricular relaxation = dub

Pharm 2 (11 decks)

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