The Heart and Cardiac Cycle Flashcards

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1
Q

What are the four chambers of the human heart?

A
  • right atrium
  • right ventricle
  • left atrium
  • left ventricle
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2
Q

What is a cardiac cycle?

A

The complete cycle of events in the heart that corresponds to one heartbeat

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3
Q

What is a heartbeat?

A

A heartbeat follows one volume of deoxygenated blood as it enters the heart until it exits as oxygenated blood

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4
Q

Diastole definition

A

period of ventricular relaxation and filling the heart with blood

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5
Q

Systole definition

A

period of contricular contraction and emptying the heart of blood into the arteries

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6
Q

How is the heart regulated?

A

Internally with the heart without the need of the nervous system

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7
Q

What is a myogenic muscle?

A

muscles that can contract and relax without input from an external source

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8
Q

What is a pacemaker:

A

an electrical device that initiates a heartbeat and sets a normal rhythm

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9
Q

What is the sinoatrial node? Where is it? What does it do?

A

It is in the upper wall of the right atrium near the opening to the superior vena cava. It causes the atria to contract

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10
Q

Where is the atrioventricular node? Where is it?

A

It is in the lower part of the right atrium, near the AV valves. It acuses the ventricles to contract

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11
Q

What is the first step in a heartbeat?

A

*SA node initiates an impulse
*Impulse flows over the two upper chambers of the
heart (atria)
* Causes contraction of both atria simultaneously
(systole)
* Blood rushes into the lower chambers (ventricles)
* Tricuspid and bicuspid (AV) valves are open during this
step

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12
Q

What is step 3 in a heartbeat?

A

A bit of delay between contractions as the electrical
impulse travels to the atrioventricular (AV) node

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13
Q

What is step 3 in a heartbeat?

A
  • AV nodes sends impulse:
  • Down the septum
  • Into the left and right bundle branches surrounding the
    ventricles
  • Into Purkinje fibres
  • Causes synchronized contractions of both ventricles
    starting at the bottom, moving upward
  • Pressure opens both pulmonary and aortic semilunar
    valves
  • Blood forced out of the ventricles to arteries (pulmonary
    and aorta)
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14
Q

What is step 4 in a heartbeat?

A
  • All chambers relaxed
  • Blood passively flows into both atria
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15
Q

What is step 5 in a heartbeat?

A
  • All chambers still relaxed
  • AV valves open
  • Blood can now passively flow into atria and ventricles
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16
Q

What is an electrocardiograph? (ECG)

A

a device that measure the electrical signals of the heart

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17
Q

What does an ECG record data on?

A

An electrocardiogram

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18
Q

What are the three parts of an ECG summary?

A

P, Q, R, S, T

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19
Q

What happens on the P wave of an ECG?

A

the SA node sends depolarization signal to atria
- atria depolarize
- the atria contracts (ventricles relax)
- signal travels to AV nodes

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20
Q

What happens on the QRA complex of an ECG?

A
  • AV node sends depolarization signal down septum around ventricles
  • ventricles depolarize
  • the ventricles contract - atria repolarize (atria relaxes)
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21
Q

What happens on the T of an ECG summary?

A
  • recovery period
  • membranes repolarizes
  • ventricles relax
  • atria remains relaxed
22
Q

QRS is both depolarization and repolarization but unable to differentiate signlas because the atria repolarizing is a smaller signal

A
23
Q

What sound does the heart make?

A

a lub-dub osunds as blood flows through the heart and valves close behind it

24
Q

What happens on the lub souds that the heart makes?

A
  • SA node (pacemaker) impulse
  • Right and left atria contract
  • Right and left ventricles relax
  • Blood is pumped to the ventricles
  • Tricuspid and bicuspid AV valves close
25
Q

What happens on the dub sound of the heart

A
  • AV node impulse
  • Left and right ventricles contract
  • Left and right atria relax
  • Blood is pumped to pulmonary artery and aorta
  • Pulmonary and aortic semilunar valves close
26
Q

What are the health measurements of the heart?

A
  • blood pressure
  • heart rate (maximum and resting)
  • stroke volume
  • cardiac output
27
Q

What is blood pressure (BP)

A

a measure of force of blood in arterial wall

28
Q

What are the two types of blood pressure?

A
  • systolic pressure
  • diastolic pressure
29
Q

What is systolic pressure?

A
  • force of blood against arterial walls during contraction of the left ventricle
  • highest pressure
30
Q

What is diastolic pressure?

A

force of blood against arterial walls immediately before the next ventricular contraction

31
Q

How is blood pressure given?

A

sysolic/diastolic pressure

32
Q

What is a normal blood pressure considered?

A

below 120/80

33
Q

pressure is inversely proportional to area

A
34
Q

What is the relationship between blood pressure and distance from the heart?

A

Blood pressure declines with distance from heart

35
Q

Why do arteries have higher bp than veins?

A

they are closer to the heart

36
Q

Which artery has the highest BP?

A

the aorta

37
Q

Capillaries have low BP. Why?

A

many have small circumference but the number of capillaries significantly increase the total area

38
Q

Veins have the lowest BP. Why?

A
  • large circumference
  • further from the heart
39
Q

Which vein has the lowest blood pressure?

A

the vena cavae

40
Q

What are the effects of low blood pressure?

A
  • reduces the capacity to transport blood
  • they are felt when not enough blood is transported the the brain
  • light-headedness
41
Q

What are the effects of high blood pressure?

A

can weaken and rupture the arterial walls

42
Q

What is heart rate?

A
  • frequency of the cardiac cycle
  • contraction of the heart within a given amount of time
43
Q

What is resting heartrate?

A
  • lowest heart rate when a rest
44
Q

what is a normal level for a resting heart rate?

A

60-100 beats/min

45
Q

What is maximum heart rate?

A

hgihest heart rate attainable when exerting maximum physical effort (diminiches with age)

46
Q

What is stroke volume?

A

volume of blood pumped from the heart with each ventricular contraction

47
Q

What is a normal level for stroke colume?

A

70 mL/beat

48
Q

What factors can affect stroke volume?

A

*Distensibility of ventricular wall
* The stretchiness of the heart muscles
* Affects how easily the heart fills with blood
* Strength of ventricular wall
* Affects the strength of each contraction
* Size of ventricles
* Affects the maximum amount of blood that can be held
and thus pumped

49
Q

What is cardiac output (Q)?

A
  • a measure of the volume of blood pumped from each ventricle per unit of time.
  • heart rate and stroke volume affect cardiac output
50
Q

What is a normal cardiac output?

A

5 mL/min

51
Q

What is the cardiac output formula?

A

Q = SV * HR
SV = stroke volume
HR = heart rate