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A&P 1 > Chapter 20: The Heart > Flashcards

Chapter 20: The Heart Flashcards

1
Q

The 4 chambers of the heart

A

-left and right atrium
-left and right ventricles

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2
Q

What do the heart chambers do?

A

Chambers contract in unison to deliver equal volumes of blood through the pulmonary and systemic circuits

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3
Q

What are the differences in ventricles?

A

-RV is pouch shaped, LV is round
-RV has thin walls, LV is very thick
-RV produces less pressure (lungs are close)
-LV requires 4-6X the pressure to push systemic circulation

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4
Q

Pericardium

A

sac-like network of collagen fibers
-visceral pericardium (epicardium)
-parietal pericardium

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5
Q

Flow of blood through the heart

A
  1. superior/inferior vena cava
  2. right atrium
  3. tricuspid valve
  4. right ventricle
  5. pulmonary arteries
  6. lungs
  7. pulmonary veins
  8. left atrium
  9. biscupid (mitral) valve
  10. left ventricle
  11. aortic valve
  12. aorta
  13. body
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6
Q

Coronary circulation

A

-heart pumps continuously
-needs a reliable supply of O2 and nutrients

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7
Q

What vessels have the highest blood pressure?

A

left and right coronary arteries

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8
Q

Conducting system

A

generates and distributes electrical impulses necessary to push blood through the systemic and pulmonary systems

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9
Q

Components of conducting system

A

-sinoatrial node (SA node)
-atrioventricular node (AV node)
-conducting cells of internodal pathways
-AV bundle and bundle branches
-Purkinje fibers

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10
Q

Sinoatrial (SA) node

A

-embedded in posterior wall of RA near entrance of superior vena cava
-depolarizes first
-established heart rate
-80-100 action potentials/ min
-connected to AV node

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11
Q

Atrioventricular (AV) node

A

conducts normal electrical impulse from the atria to the ventricles.

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12
Q

Purkinje fibers

A

distribute impulse to ventricular myocardium

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13
Q

Pacemaker action potential

A

-resting embrane potential = 60 mV
-threshold potential = 40 mV

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14
Q

Cardiac muscle potential

A
  1. Rapid depolarization
  2. Plateau
  3. Repolarization
  4. Refractory period
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15
Q

Rapid depolarization

A

sodium channels open and close quickly allowing a lot of Na+ into the cell

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16
Q

Plateau

A

sodium channels close and slow calcium channels open

17
Q

Repolarization

A

slow calcium channels close, slow potassium channels open and K+ efflux returns cell to resting potential

18
Q

Refractory period

A

when muscle cannot respond to AP

19
Q

Cardiac cycle

A

beginning of one heartbeat to the beginning of the next
-800 msec; 75 bpm,
-includes both contraction and relaxation

20
Q

Systole

A

contraction; blood pressure rises

21
Q

Diastole

A

relaxation; blood pressure falls

22
Q

Atrial systole

A

atrial contraction begins
-AV valves open
-semilunar valves close
-atria eject blood into ventricles
-ends with closed AV valves

23
Q

Atrial diastole

A

atrial relaxation begins
-av valves are closed
-semilunar valves closed
-ventricles contain maximum blood volume (End-Diastolic Volume EDV)

24
Q

Ventricular systole

A

ventricles contract (isovolumetric contraction) and pressure builds with AV valves
-ventricular pressure exceeds atrial pressure
-isotonic contraction opens semilunar valves and ventricular ejection

25
Q

Stroke Volume (SV)

A

amount of blood pumped out of the ventricles in a single beat

26
Q

End systolic volume (ESV)

A

blood remaining in ventricles

27
Q

ventricular diastole

A

`ventricular pressure drops
-all heart valves closed
-ventricles relax via isovolumetric relaxation
-blood flows into relaxed atria

28
Q

Cardiac cycle steps

A
  1. atrial contraction begins
  2. atria eject blood into ventricles
  3. atrial systole ends; AV valves close
  4. isovolumetric ventricular contraction
  5. ventricular ejection occurs
  6. semilunar valves open
  7. isovolumetric relaxation occurs
  8. AV valves open; passive ventricular filling occurs
29
Q

SV =

A

EDV-ESV

30
Q

Ejection fraction =

A

EDV/SV

31
Q

Cardiac output (CO)

A

amount of blood pumped out of the left ventricle in one minute
-represents blood flow through systemic circuit
-measure of ventricular efficiency over time

32
Q

CO =

A

HR x SV

33
Q

If HR increases,

A

SV must decrease

34
Q

What affects HR?

A

autonomic nervous system or hormones

35
Q

What affects SV?

A

changes in EDV, ESV, or both

36
Q

Cardiac centers of the medulla oblongata that regulate autonomic inputs

A

cardioaccelatory center and cardioinhibitory center

37
Q

Cardioaccelatory center

A

controls sympathetic neurons
-increases heart rate

38
Q

Cardioinhibitory center

A

controls parasympathetic neurons
-slows heart rate

A&P 1 (6 decks)

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