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A & P1 for PCP > Lecture 10 - Cardiovascular 3 The Heart > Flashcards

Lecture 10 - Cardiovascular 3 The Heart Flashcards

1
Q

Where is heart located

A

In mediastinum

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2
Q

How does heart sit in chest

A

2/3rds to the left

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3
Q

What is approximately size of heart

A

Vary with body size
About 310g male and 225g female
About two fist clench together

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4
Q

What is a survivable birth defect re: location of heart

A

Right sided heart - 1 per 200 rats

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5
Q

Where is Apex of heart

A

Bottom left side

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6
Q

What are 2 types of pericardium

A

Fibrous and serous

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7
Q

What is structure is fibrous pericardium

A

Tough, loose fitting inextensible sac

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8
Q

What is structure of serous pericardium

A
  • Parietal layer lies inside the fibrous pericardium
  • visceral layer (epicardium) adheres to the outside of the heart
  • pericardial space with pericardial fluid separates the two
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9
Q

What to heart covering protect against

A

Friction

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10
Q

What are the three layer distinct layers that make up wall of the heart

A

Epicardium
Myocardium
Endocardium

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11
Q

What is epicardium

A

Outer layer of heart

Visceral layer of serous pericardium

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12
Q

What is myocardium

A

Thick, contractile middle layer of heart wall

- compresses the heart cavities and the blood within them with great force

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13
Q

What is endocardium

A

Delicate inner layer of endothelial tissue

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14
Q

How is heart divided into right and left

A

By the septum ( ventricles separated by inter ventricular septum)

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15
Q

How many chambers are there

A

4

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16
Q

What are receiving chambers

A

Atria because they receive blood from veins

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17
Q

Where are atria

A

Top of heart superior to the ventricles

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18
Q

How to stir receive and push blood

A

Relax to receive and contract to push

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19
Q

Is myocardial wall of atria thick and why

A

No because they dont have to move blood far ; just sending into ventricles

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20
Q

What is article of heart

A

Earlike flap protruding from each atrium

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21
Q

What are the pumping chambers

A

Two lower chambers which are the ventricles that push blood into larger networks of vessels

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22
Q

Describe ventricle myocardium

A

It is thicker than atria’s because great force must be generated to pump blood a large distance;
- myocardium of left ventricle thicker than right as must pump blood much farther

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23
Q

What are the valves of the heart

A

Mechanical devices that permit the flow of blood in one direction only

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24
Q

What do atrioventricular (AV) valves do

A
  • prevent blood from flowing back into the atrium from the ventricles when the ventricle contract
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25
Q

What is tricuspid valve

A

Its is atrioventricular valve of R side of the heart

- has 3 flaps of endocardium that are attached to papillary muscles by chordae tendineae

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26
Q

What is bicuspid valve

A

Also called mitral valve

  • L side of heart
  • only two flaps that attach to papillary muscles by chordae tendineae
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27
Q

What are semi lunar valves

A

Half moon shaped flaps growing out from lining of the pulmonary artery and aorta
- prevent blood from flowing back into ventricles from aorta or pulmonary artery

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28
Q

What is pulmonary valve

A

The pulmonary semi lunar valve at entrance of pulmonary artery

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29
Q

What is aortic valve

A

Valve at entrance of the aorta

- aortic semi lunar valve

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30
Q

What is skeletal structure of heart

A

Set of connecting rings that serve as a semi rigid support for the heart valves and the attachment of cardiac muscle of myocardium
- serves as electrical barrier between myocardium of the atrium and that of ventricles

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31
Q

What is coronary circulation

A

The blood flow to supply the cardiac tissue of the heart with nutrients and remove waste

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32
Q

Where do ventricles receive blood from

A

From left LCA and right RCA coronary arteries

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33
Q

Where do atria receive blood from

A

Small branch of coronary artery

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34
Q

Where does majority of coronary blood flow go

A

To left ventricle

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35
Q

What % of people have a dominant RCA, LCA or neither

A

RBC 50%
LCA 20%
NEITHER 30%

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36
Q

What are anastomosis

A

They are extra branches arteries make so they can bypass blocks if needed to keep blood flowing

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37
Q

Do coronary arteries anastomose

A

Yes

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38
Q

Where do coronary veins drain into

A

Coronary sinus into right atrium

Veins follow arteries side by side

39
Q

Structure of cardiac muscle

A

Striated muscle cells, ratified, involuntary contractions

40
Q

What links cardiac muscle cells

A

Intercalated discs which have:
Desmosomes (link cells together
Gap junctions ( permit muscle action potential or electrical signal to pass from 1 myocyte to another inside the motor unit)

41
Q

Why are cardiac myocytes and skeletal myocytes similar

A

They have same mechanism of contraction

- actin and myosin

42
Q

Function of cardiac muscles

A

Intercalsted discs form a solid connection so that contraction generated acts as if it came from a single source
- called functional syncytium

43
Q

How are units electrically isolated

A

Through CT

44
Q

What are main components of the conduction system of the heart (5)

A
  1. Sinoatrial (SA) node
  2. Atrioventricular (AV) node
  3. Atrioventricular (AV) bundle (bundle of His)
  4. R & L Bundle branches
  5. Subendocardial branches (Purkinje fibres)
45
Q

What is special about conduction system structures

A

More highly specialized then ordinary cardiac muscle tissue and permit only rapid conduction of an action potential through the heart

46
Q

Another name for SA node

A

Pacemaker

47
Q

What is function of SA node

A

Initiates each heart beat and sets its pace

48
Q

How does SA node work

A

Specialized pacemaker cells in the node possess an intrinsic rhythm
- after being generated by the SA node, each impulse travels through the muscle fibers of both atria, which begin to contract

49
Q

What happens after atria begin to contract

A
  • as action potential enters the AV node from the right atrium its conduction slows to allow complete contraction of both atrial chambers before the impulses reach the ventricles
50
Q

Where do the impulses go after the AV node

A

Conduction velocity increases as the impulse is relayed through the AV bundle into the ventricles

51
Q

Where do impulses go after AV bundle

A

Right and left branches of the bundle fibers and subendocardial branches (purkinje fibers) conduct the impulses throughout the muscles of both ventricles, stimulating them to contract almost simultaneously

52
Q

What is autonomic nervous system influence on conduction system of the heart

A

Composed of modified cardiac muscle, it generates and distributes the heart’s own rhythmic contractions
- can be regulated by afferent nerves

53
Q

What is autonomic nervous system influence on cardiac plexuses

A

Located near the arch of the aorta
composed of sympathetic and parasympathetic fibers
- fibers from cardiac plexus accompany R and L coronary arteries to enter the heart
- most fibers end in SA node but some in AV node and atrial myocardium (the nodes are hearts pacemaker)

54
Q

What is autonomic nervous system influence on sympathetic nerves

A

Accelerator nerves

55
Q

What is autonomic nervous system influence on vagus fibers

A

Inhibitory, or depressor nerves

56
Q

What does autonomic nervous system do

A

Innervates the heart, modifies activites

57
Q

Where can sympathetic nervous system impulses come from

A

Medulla (cardioacceleration)

Sympathetic neurons

58
Q

What is sympathetic nervous system hormonal mechanism to increase cardiac frequency

A

The release of noradrenaline

59
Q

Where can parasympathetic nervous system send impulses from

A

Medulla (cardioihibitory neurons )

Vagus nerve

60
Q

What is parasympathetic nervous system hormonal mechanism to decrease cardiac frequency

A

Release acetylcholine

61
Q

What is autorhythm

A

Heart beats at 75 beats / min in an autonomic fashion without any nerve impulses

62
Q

What is action potential

A

Essentially a nerve impulse or electrical signal traveling through a cell

63
Q

Why do cells need to receive action potential do contract

A

As it causes them to depolorize

64
Q

What is resting membrane potential for most cells

A

-70mV

65
Q

What happens when get a signal from nerve

A

Protein “gates” on cell membrane open allowing ions into cell
- effectively change electrical charge inside and outside the cell (depolarization)

66
Q

What is repolarization phase of action potential

A

After all Na+ ions from outside go into cell the K+ ions that were in cell go out
- charge will rebalance = repolarization

67
Q

Do cells always overshoot action potential repolarization

A

Yes but balance back out

68
Q

Depolarization

A

Contraction

  • influx of Na+ ions
  • rapidly increasing membrane potential
  • cell has been depolarized and the nerve impulse is propagated forward
69
Q

Repolarization

A

Relaxation

  • movement of K+ ions out of the cell
  • rapidly decreasing membrane potential
  • cell has been repolarized and the nerve impulse finished
70
Q

Hyperpolarization

A
  • overshoot during the movement of K+ out and Na+ back in using sodium potassium pump
71
Q

What is ECG /EKG

A

Electrocardiograms

  • recording of the electric current during the cardiac cycle
  • does not record function of heart just the electrical impulses in heart
72
Q

How is ECG done

A

Use electrodes placed at various sites: legs, arms, chest

73
Q

What is 4 lead

A

Limb leads

- used to gather basic info regarding electrical conduction as it travels through the heart

74
Q

What is 12 lead

A
  • used to assist with identification of myocardial infarctions and their possible location within the heart
75
Q

What are the 3 distinguishable waves of ECG

A

P- wave
QRS complex
T-wave

76
Q

What occurs in P wave

A

Lasts about 0.08s

  • atrial depolarization that goes from the sinoatrial node and throughout the atria
  • 0.1s after the beginning of P wave the atria contracts
77
Q

What happens in P-R interval

A

Lasts about 0.16s

  • delay between the start of the atrial contractions and the start of ventricular contractions
  • measures time necessary for the action potential to go throughout the atrioventricular node, atrioventricular bundle and the rest of the conduction system
78
Q

What happens in QRS complex

A

Lasts about 0.08s

  • ventricular depolarization that goes throughout the ventricles
  • then ventricles start to contract at the beginning of the QRS complex
79
Q

What is the T wave

A

Lasts about 0.16s

  • ventricular repolarization; produced immediately before the ventricular fibers relax
  • it is possible to perceive the repolarization of the atria but it is ordinarily INVISIBLE because of the superimposed QRS complex
80
Q

What is S-T segment

A

End of s wave and the start of T wave

- period where the fibers of the ventricles are depolarized

81
Q

What is Q-T interval

A

Lasts about 0.38s

-period from ventricular depolarization up to ventricular repolarization

82
Q

When does arterial pressure vary

A

As ventricle is contracting or relaxing

83
Q

Is the arterial pressure in left and right ventricles and atria the same

A

No

- right ventricle has the lowest pressure because it has thinnest walls (even though right atrium is smaller)

84
Q

What is systole

A

Phase of contraction

85
Q

What is diastole

A

Phase of relaxation

86
Q

There is both a _______ and a ______ for the atria and ventricles

A

Systole and diastole

87
Q

How long is cardiac cycle normally and how many bpm approx

A

0.8s or 75bpm

88
Q

Breakdown the 0.8s of cardiac cycle

A

Contraction
• atrial systole 0.1s
• ventricular systole 0.3s

Relaxation
• atrial systole 0.3s
• ventricular diastole 0.1s

89
Q

What is isovolumetric diastole

A

Early diastole

  • short phase following T wave
  • ventricles relaxes; decrease in ventricular pressure
  • blood of aorta and pulmonary trunk backflow towards the ventricles closing their semilunar valves
  • ventricles are entirely closed (all 4 valves closed)
90
Q

What is phase of ventricular filling

A

Mid to late diastole

  • low pressure in atria and ventricles, then increases in atria
  • circulating blood passively flows into atria and ventricles through open atrioventricular valves
  • aortic and pulmonary valves are closed during the relaxation period
  • when ventricles about 70% full cusps of atrioventricular valves begin to close
  • depolarization (systole) of atria (p-wave) results in contraction and blood is compressed
  • pressure in atria increases and residual blood (30% left over) is ejected into the ventricles
91
Q

What is ventricular systole

A
  • atria relaxes (atrial diastole)& ventricles depolarize (systole) ( QRS complex)
  • pressure in ventricles increases leading to AV closure
  • phase of isovolumetric contraction: during a fraction of a second, all valves are closed and the blood volume is constant
  • pressure in the ventricles continues to increase until it exceeds the pressure of the large arteries of ventricles
  • aortic and pulmonary valves open; the blood is exposed: ventricular ejection phase
92
Q

What produces heart sounds

A

Principally produced by the closure of valves

93
Q

What are the 2 normal heart sounds

A

1st Lub is loud and long
- from closure of AV valves and is start of ventricular systole
2nd dup is sharp and short
- from closure of aortic and pulmonary valves and is start of ventricular diastole

94
Q

What is refractory period

A

It is the PAUSE after the last sound
Making fundamental rhythm
Lub-dub, pause, lub-dub, pause

A & P1 for PCP (19 decks)

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