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Physiology Test 2 > The Heart > Flashcards

The Heart Flashcards

1
Q

what is the function of chordae tendineae?

A

stabilize the cusps during ventricular contractions and hold the cusps in place preventing retrograde flow of blood

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2
Q

what is the serous pericardium?

A

combination of visceral and parietal pericardium

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3
Q

SV = ______

A

EDV - ESV

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4
Q

what is EDV?

A

end diastolic volume. Volume in ventricles and atria at the end of diastole.

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5
Q

what does EDV represent?

A

maximal volume of the chambers of the heart (just before the aortic and pulmonary valves open)

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6
Q

what does ESV represent?

A

minimum amount of blood in chambers of the heart

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7
Q

Does the heart completely empty?

A

NO

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8
Q

define Stroke Volume (SV)

A

amount of blood pumped from ventricle per beat

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9
Q

T/F: the R/L atria are induced to contract simultaneously?

A

TRUE

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10
Q

What is the pathway for electrical activity in the heart?

A
  1. SA node
  2. AV node
  3. bundle of His
  4. Purkinje fibers
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11
Q

why is there a delay at the AV node?

A

allows maximal filling and contraction

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12
Q

what does a P wave represent on a ECG?

A

depolarization of atria in response to SA node triggering

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13
Q

what does the PR interval represent?

A

delay of AV nodes to allow filling of ventricles

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14
Q

what does the QRS complex represent?

A

depolarization of ventricles, triggers main pumping contractions

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15
Q

What does the ST segment represent?

A

beginning of ventricle repolarization, should be flat

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16
Q

What does the T wave represent?

A

ventricular repolarization

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17
Q

T/F: the heart has a refractory period?

A

TRUE

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18
Q

define CO

A

liters of blood pumped per minute

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19
Q

CO = _______

A

SV * HR

20
Q

define preload

A

volume of blood coming back to heart

21
Q

what occurs if preload is compromised?

A
  1. SV to R ventricle is compromised
  2. amt of blood going to lungs is compromised
  3. blood going to left side of heart is compromised
  4. CO to rest of body is decreased
22
Q

SV is regulated by what 3 variables?

A
  1. preload (EDV)
  2. afterload (TPR)
  3. contractility
23
Q

what is TPR?

A

total peripheral resistance

24
Q

define afterload

A

resistance left ventricle must overcome to circulate blood (systolic BP)

25
Q

what happens if afterload is compromised?

A

the heart has to work harder

26
Q

relationship between afterload and SV, CO?

A

increase in afterload = decrease in SV and CO

27
Q

What is the Frank Starling Law?

A

increased EDV stretches cardiac muscle causing an increase in contractility and thus increasing SV

28
Q

what does the Frank Starling Law demonstrate?

A

the role that preload has in defining the SV

29
Q

what is contractility?

A

strength of a contraction. It is a measure of pump function

30
Q

how is contractility assessed?

A

EF (ejection fraction)

31
Q

what does EF tell us?

A

provides insight into delivery of blood to systemic circulation, assess cardiac contractility

32
Q

EF = __________

A

(SV/EDV) * 100

33
Q

what is a normal EF?

A

~50-75%

34
Q

what does venous return influence?

A

EDV

35
Q

what factors influence venous return?

A
  1. blood volume
  2. breathing (neg. intrathoracic pressure)
  3. venous pressure
36
Q

what is the inherent rate of the SA node (in total absence of neural or hormonal input)?

A

100 bpm

37
Q

T/F: Cardiac muscles contract all or nothing?

A

False, cardiac muscle can have graded contractions dependent on the amount of Calcium being released by the SR

38
Q

T/F: cardiac muscle can grade the strength of their contractions?

A

TRUE

39
Q

difference between refractory periods in cardiac and skeletal muscle?

A

skeletal muscle has a shorter refractory period which means contractions can add up and result in tetanus.
The heart has a longer absolute refractory period

40
Q

what is the period called between the aortic valve closing and the AV valve opening?

A

isovolumetric ventricular relaxation

41
Q

when does isovolumetric ventricular relaxation occur?

A

during diastole, prior to the AV valves opening and after the aortic/pulmonary valves close

42
Q

when does atrial contraction occur?

A

at the end of diastole, after most of the ventricular filling has taken place

43
Q

at rest the SA node is more heavily influenced by ________

A

parasympathetic vagus input

44
Q

what are the 3 factors that influence changes in SV?

A
  1. changes in EDV&raquo_space; preload
  2. changes in sympathetic input
  3. afterload
45
Q

SV is directly proportional to _____

A

EDV

46
Q

the relationship between SV and EDV is known as ________

A

the Frank-Starling mechanism

47
Q

how does afterload effect SV?

A

increases in afterload tend to reduce SV

Physiology Test 2 (8 decks)

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