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Physio > Cardiovascular System and Cardiac Action Potential > Flashcards

Cardiovascular System and Cardiac Action Potential Flashcards

1
Q

what is cardiovascular electrophysiology?

A

the study of electrical activity of the heart

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2
Q

what is cardiovascular mechanics?

A

the understanding how the contractile properties of the heart affect its function
(the forces that mediate the work)

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3
Q

what is cardiovascular hemodynamics?

A

the study of blood flow and the factors that control it?

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4
Q

what are the components of the cardiovascular system?

A
  • the heart (left side and right side)
  • arteries
  • veins
  • lungs
  • capillaries
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5
Q

why can we consider the heart to be a dual pump system?

A
  • left side = systemic pump that carries oxygenated blood via arteries throughout the body
  • right side = pulmonary pump that carries the deoxygenated blood to the lungs
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6
Q

what is the significance of the capillaries?

A

they are the site of exchange in the body from blood to tissues back into the blood

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7
Q

what is the order of blood flow throughout the body?

A

right atrium –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary arteries –> lungs –> pulmonary veins –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta –> systemic circulation –> superior/inferior vena cava –> right atrium

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8
Q

describe how the contraction of the left heart work?

A

the mitral valve is controlled by the contraction of the papillary muscles contracting to pull the chordae tendinae which pull the mitral valve open
- coordination of contraction is important for opening and closing

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9
Q

why are valves important?

A

prevent backflow

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10
Q

what is the distribution of cardiac output to the body systems?

A
  • 100% of blood travels through the hear and to the lungs
  • after being released by left side:
  • 15% to brain
  • 5% to coronary
  • 25% to renal
  • 25% to GI
  • 25% to skeletal muscle
  • 5% to skin
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11
Q

how much is the normal cardiac output and venous return?

A

5L/min
- that is how much blood we have in the body

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12
Q

why do the kidneys get so much blood?

A

kidneys are important for chemical balance of the blood and help control blood pressure

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13
Q

how much cardiac output is there during activity?

A

can be as much as 18L/min cycling through the heart –> increased blood flow

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14
Q

where is majority of the blood located and why?

A
  • in the veins
  • because they are larger
  • when you need higher output, the veins are squeezed to release blood into the heart at a faster rate for circulation
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15
Q

what can the heart function be characterized into?

A
  • electrical and mechanical events
  • electrical events generate by the heart trigger AP which triggers the mechanical contraction of the heart to compliment each other
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16
Q

what are the electrical events that occur in the heart?

A
  • cardiac action potential
  • cardiac refractory period
  • conduction of the action potential
  • modulation of electrical activity by the autonomic nervous system (HR)
  • ECG
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17
Q

where are the pacemaker cells located?

A

SA node

18
Q

what properties determine the normal electrical activity of the heart?

A
  • automaticity
  • excitability (responsiveness)
  • conductivity
19
Q

what is automaticity and what cells are related to it?

A
  • the ability of the heart to spontaneously fire action potentials on its own (without stimulus from NS)
  • pacemaker cells (=modified cardiac cells)
20
Q

what is excitability and what is related to it?

A
  • the ability of cardiac cells to respond to electrical activity (under normal conditions) of pacemaker cells
  • refractory period
21
Q

what is conductivity and what is related to it?

A
  • the ability of the heart to conduct action potentials from its site of origin to all cardiac cells
  • cardiac muscle anatomy (functional syncytium)
22
Q

why is the refractory period so important for excitability?

A
  • ensure the heart fully contracts and fully relaxes before another contraction occurs
  • this prevents tetanic contraction form occurring which would keep the heart in a constant state of contraction
23
Q

why is cardiac muscle anatomy so important for conductivity?

A

the cell anatomy is connected and coupled together so the stimulation is passed very easily between cells to contract in unison instead of delayed and unsynchronized

24
Q

what are the ion concentrations and gradients extracellularly and intracelullarly?

A
25
Q

comparison of cardiac muscle cells and their action potentials

A
26
Q

Phases of contractile cell action potential

A
27
Q

Phases of pacemaker cell action potential

A
28
Q

what are “funny” channels?

A
  • non-specific, non-selective cation channels
  • tend to be open all the time
  • drive automaticity and enable immediate regeneration of AP
29
Q

how does the sympathetic nervous system control contraction during exercise?

A

increases calcium entry and increase potassium leaving which therefore increases speed of contraction during exercise

30
Q

what is the functional refractory period? what are the phases? what is the purpose?

A
  • the refractory period after the action potential first fires
  • 2 main parts: effective refractory and supranormal refractory
  • allows time for recovery for ion channels to be activated when the next stimulus is applied
  • prevents tetanic contraction of the cardiac muscle
31
Q

parts of the effective refractory period? what is significant about them?

A
  • absolute = when another AP cannot be triggered no matter what
  • relative = AP can be triggered but low likelihood
32
Q

the supranormal refractory period is important because…

A

= “vulnerable phase” = when another AP can be triggered and is vulnerable to one prior to reaching resting voltage

33
Q

why are intercalated disks important for function?

A
  • they allow cardiac myocytes to operate at a functional syncytium
  • because they have gap junctions and desmosomes to keep cells intact and connect/couple the cells to stimulate neighboring cells
34
Q

what is the importance of gap junctions?

A
  • they are located between cardiac muscle cells
  • allow current to flow from the depolarized cell to a neighboring cell that has not been electrically stimulated yet
  • basically allows it to contract all the cells fast and at the same time
  • allows spread of AP
35
Q

what are the components that make up the pacemakers of the heart?

A
  • SA node
  • AV node
  • purkinje fibers
  • nodes = bundle of pacemaker cells
  • all cells can generate spontaneous action potentials but with different frequencies
36
Q

what is the normal pacemaker of the heart?

A

SA node

37
Q

pacemaker tissues and their rate of action potentials production?

A

SA node = 70-80 AP/min
AV node = 40-60 AP/min
Purkinje Fibers = 20-40 AP/min

38
Q

what is overdrive suppression?

A

it results in the SA node serving as the normal pacemaker

39
Q

what role does the autonomic nervous system have? para? sympa?

A

serves to modulate the rate of firing of cardiac action potentials
- para activation reduces the AP firing rate
- sympa activation increases the AP firing rate
~ antagonistic control

40
Q

antagonistic control of of the heart by NS

A

Physio (15 decks)

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