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BIOL 224 Lecture > CH 20 - Cardiovascular System > Flashcards

CH 20 - Cardiovascular System Flashcards

1
Q

What are the 4 functions of the heart?

A

Generate blood pressure
Separate pulmonary/systemic circulations
Ensure one-way blood flow with valves
Regulate blood supply

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2
Q

Where does pulmonary circulation occur?

A

The right side of the heart pumps blood to the lungs, then blood returns to the left side of the heart

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3
Q

Where does systemic circulation occur?

A

The left side of the heart pumps blood to the body, then blood returns to the right side of the heart

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4
Q

How big is the heart?

A

Slightly larger than a closed fist

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5
Q

Where is the heart located?

A

Within the mediastinum of the thoracic cavity, directly behind the sternum

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6
Q

Which intercostal space does the base of the heart sit behind?

A

Second intercostal space

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7
Q

Which intercostal space does the apex of the heart sit behind?

A

Fifth intercostal space

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8
Q

Pericardium

A

Sac-like membrane around the heart, divided into 2 layers

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9
Q

What are the 2 layers of the pericardium?

A

Fibrous pericardium

Serous pericardium

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10
Q

Describe the fibrous pericardium.

A

Outer layer made of dense fibrous tissue that anchors the heart to the sternum and diaphragm, and prevents overdistention

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11
Q

Describe the serous pericardium.

A

Inner layer made of thin, transparent simple squamous epithelium, divided into 2 layers

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12
Q

What are the 2 layers of the serous pericardium?

A 
Parietal pericardium
Visceral pericardium (epicardium)
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13
Q

Describe the parietal pericardium.

A

Outer layer that lines the fibrous pericardium

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14
Q

Describe the visceral pericardium.

A

Inner layer that covers the surface of the heart

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15
Q

Pericardial cavity

A

The space between the parietal and visceral serous layers

Contains 15-50 mL of pericardial fluid secreted by the serous membranes to lubricate heart movements

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16
Q

What are the 3 layers of the heart wall?

Briefly describe them.

A

Pericardium - outer membrane
Myocardium - cardiac muscle
Endocardium - inner membrane

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17
Q

Pectinate muscles

A

Muscular ridges in the auricles and right atrial wall

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18
Q

What separates pectinate muscles and the smooth part of the atrium?

A

Crista terminalis

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19
Q

Trabeculae carneae

A

Muscular ridges and columns on the inside of ventricle walls

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20
Q

Which 3 large veins bring blood to the heart?

A

Superior vena cava
Inferior vena cava
Pulmonary veins

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21
Q

Which 2 large arteries take blood away from the heart?

A

Aorta

Pulmonary trunk

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22
Q

How does blood get to the anterior part of the heart?

A

Anterior interventricular artery

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23
Q

How does blood get to the lateral wall of the left ventricle?

A

Left marginal artery

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24
Q

How does blood get to the posterior wall of the heart?

A

Circumflex artery

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25
Q

How does blood get to the lateral wall of the right ventricle?

A

Right marginal artery

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26
Q

How does blood get to the posterior and inferior aspects of the heart?

A

Posterior interventricular artery

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27
Q

Which vein drains blood from the left side of the heart?

A

Great cardiac vein

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28
Q

Which vein drains blood from the right margin of the heart?

A

Small cardiac vein

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29
Q

Where do veins empty before going to the right atrium?

A

Coronary sinus

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30
Q

What are 2 other names for the bicuspid valve?

A

Left atrioventricular valve

Mitral valve

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31
Q

What is another name for the tricuspid valve?

A

Right atrioventricular valve

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32
Q

How many cusps are within atrioventricular valves?

A

Tricuspid valve - 3 cusps

Bicuspid valve - 2 cusps

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33
Q

What is the function of atrioventricular valves?

A

They prevent blood from flowing back into the atria when moving to the ventricles.

Papillary muscles contract when the ventricles contract and prevent the valve from opening by pulling on the chordae tendineae attached to cusps.

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34
Q

How many cusps are within semilunar valves?

A

Both have 3 cusps

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35
Q

What is the function of semilunar valves?

A

They prevent blood from flowing back into the ventricles when moving to the great vessels.

When blood flows backwards, it fills the cups, causing them to meet in the middle of the vessel and close it.

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36
Q

List the route blood flows through the heart.

A 
Superior & inferior vena cava
Right atrium
Tricuspid valve
Right ventricle
Pulmonary semilunar valve
Pulmonary trunk
Pulmonary arteries
Lungs
Pulmonary veins
Left atrium
Bicuspid valve
Left ventricle
Aortic semilunar valve
Aorta
*Body, back to start
*Coronary arteries, heart, coronary sinus, cardiac veins, right atrium
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37
Q

How does the right atrium receive blood from the body?

A

Superior vena cava
Inferior vena cava
Coronary sinus

38
Q

How does the left atrium receive blood from the lungs?

A

Pulmonary veins (4)

39
Q

What does the right ventricle open to?

A

Pulmonary trunk

40
Q

What does the left ventricle open to?

A

Aorta

41
Q

How many nuclei are in a cardiac muscle cell?

A

1-2 centrally located nuclei

42
Q

Where are T tubules of cardiac muscle found?

Why are they here?

A

Near the Z disk of sarcomeres

Calcium must diffuse a greater distance from SR in order to experience longer contractions to build pressure within the heart

43
Q

What is the function of intercalated disks?

A

Speed communication between cells

44
Q

What is the function of gap junctions in cardiac muscle?

A

They allow cytoplasm to flow, resulting in low electrical resistance between cells.
This allows AP’s to pass quickly among cells so that the heart depolarizes as a single unit (in sync)

45
Q

Why are mitochondria and myoglobin abundant in heart muscle?

A

The heart is almost fully dependent on aerobic metabolism

46
Q

What is the plateau phase?

A

Voltage-gated calcium channels remain open for a longer period of time, slowing repolarization.

This causes longer contractions, allowing pressure to build within the heart.

47
Q

Conducting system

A

A network of specialized cardiac muscle cells (pacemaker and conducting cells) that initiate and distribute a stimulus to contract

48
Q

What are the 5 components of a conducting system?

A 
Sinoatrial (SA) node
Internodal pathways
Atrioventricular (AV) node
AV bundle and bundle branches
Purkinje fibers
49
Q

Describe the sinoatrial (SA) node.

A

Pacemaker cells located in the posterior wall of the right atria, near the superior vena cava

A spontaneous AP is generated here to create a heartbeat, and spreads to conducting cells

50
Q

Describe internodal pathways.

A

Conducting cells that distribute signals through both atria

51
Q

Describe the atrioventricular (AV) node.

A

Backup pacemaker cells located between atria and ventricles that activate when SA node fails

Slower pacing than SA node

52
Q

Describe the AV bundle.

A

Conducting cells that transmit signals from the AV node through a hole in the cardiac skeleton to get to the interventricular septum.

The only electrical connection between the atria and ventricles.

53
Q

Describe bundle branches.

A

Conducting cells that transmit signals to the apex, then spread out into ventricular walls

They extend beneath endocardium to apex

Left bundle branch is larger

54
Q

Describe purkinje fibers.

A

Thick conducting cells with few myofibrils that radiate up through ventricular walls

Propagate AP’s as fast as myelinated neurons (many gap junctions)

Stimulate ventricular myocardium and trigger a contraction

55
Q

List the steps of the conducting system.

A

SA node creates AP that travels across atria walls to AV node

AP passes through AV node along AV bundle into the interventricular septum

AV bundle divides into bundle branches, allowing AP to travel to apex of each ventricle

Purkinje fibers carry AP to ventricular walls and papillary muscles

56
Q

Autorhythmicity

A

Cardiac muscle’s ability to contract at its own pace, independent of neural/hormonal stimulation

57
Q

Pacemaker potential

A

Spontaneously developing local potential due to movement of sodium, potassium, and calcium

58
Q

What type of activity do electrocardiograms record?

A

Electrical heart activity

Summation of all APs in a given time period

59
Q

What does the P wave represent?

A

Atrial depolarization

Signals onset of atrial contraction

60
Q

What does the QRS complex represent?

A

Ventricular depolarization

Signals onset of ventricular contraction, and simultaneous repolarization of atria

*Larger wave due to larger ventricular muscle mass

61
Q

What does the T wave represent?

A

Ventricle repolarization

Precedes ventricular relaxation

62
Q

What does the PQ (or PR) interval represent?

A

Period from start of atrial depolarization to start of ventricular depolarization

Atria contracts and begins to relax

Ventricles begin to contract

63
Q

What does the QT interval represent?

A

Time for ventricles to undergo a single cycle

Ventricles contract and begin to relax

64
Q

What event is not seen on an electrocardiogram?

A

Atrial repolarization - hidden in QRS complex

65
Q

Cardiac cycle

A

Repetitive pumping process that begins with onset of contraction and ends with beginning of next contraction

66
Q

Systole

A

Contraction of a chamber (blood leaves)

Time between first and second heart sounds

67
Q

Diastole

A

Relaxation of a chamber (chamber refills)

Time between second heart sound and next first heart sound

68
Q

List the 5 steps of the cardiac cycle.

A

Atrial systole, active ventricular filling
Ventricular systole, period of isovolumetric contraction
Ventricular systole, period of ejection
Ventricular diastole, period of isovolumetric relaxation
Ventricular diastole, passive ventricular filling

69
Q

What is the state of the heart at the beginning of the cardiac cycle?

A

Atria and ventricles relaxed
AV valves open
Semilunar valves closed

70
Q

What happens during atrial systole, active ventricular filling?

A

Depolarization of SA node creates APs that spread over atria (P wave)

Atria contracts and fills ventricles, beginning cardiac cycle

Atrial diastole until next cycle

71
Q

What happens during ventricular systole, period of isovolumetric contraction?

A

Pressure builds in the ventricles, causing AV valves to close (all valves now closed)

End diastolic volume - 120mL of blood left in ventricles from last diastole

Begins at completion of QRS complex

72
Q

What happens during ventricular systole, period of ejection?

A

Pressure in ventricles > pressure in pulmonary trunk/aorta, so semilunar valves open and blood is ejected

Left ventricle pressure is much higher than right

End systolic volume - 60mL of blood left in ventricles

73
Q

What happens during ventricular diastole, period of isovolumetric relaxation?

A

Completion of T wave results in ventricular repolarization and relaxation

Pulmonary trunk/aorta pressure > ventricular pressure

Semilunar valves close (AV valves also closed) which begins ventricular diastole

74
Q

What happens during ventricular diastole, passive ventricular filling?

A

While ventricles were in systole, atria were filling with blood

Atrial pressure > ventricular pressure, AV valves open

Blood flows into relaxed ventricles

75
Q

Cardiac output

A

The amount of blood pumped by the heart per minute

Stroke volume x heart rate = cardiac output

76
Q

Stroke volume

A

The amount of blood pumped during each heart beat

77
Q

Heart rate

A

The number of times the heart beats per minute

78
Q

Peripheral resistance

A

The total resistance against which blood must be pumped

79
Q

Venous return

A

The amount of blood returning to the heart from systemic circulation

80
Q

What does the first heart sound “lubb” represent?

A

Closure of atrioventricular valves and surrounding fluid vibrations at beginning of ventricular systole

81
Q

What does the second heart sound “dupp” represent?

A

Closure of semilunar valves at beginning of ventricular diastole (lasts longer)

82
Q

What is intrinsic regulation controlled by?

A

Normal heart function

83
Q

Preload

A

The amount of stretch of the ventricular walls

The greater the stretch, the greater the force of the contraction

*AKA Starling’s law of the heart

84
Q

Afterload

A

The pressure that the contracting walls must produce to overcome the pressure in the aorta to get blood to aorta

*Heart is more sensitive to preload

85
Q

What is extrinsic regulation controlled by?

A

Neural and hormonal control

86
Q

Describe parasympathetic stimulation within extrinsic regulation of the heart.

A

Supplied by the vagus nerve

Brainstem - heart wall - SA node - AV node - coronary blood vessels - atrial myocardium

Little effect on stroke volume, but can increase since more blood is filling

ACh hyperpolarizes heart, causing longer contractions and a decreased HR

87
Q

Describe sympathetic stimulation within extrinsic regulation of the heart.

A

Thoracic spinal cord - cervical sympathetic chain ganglia - SA and AV nodes - coronary blood vessels - atrial/ventricular myocardia

Increases HR, cardiac output, force of contraction, stroke volume

Norepinephrine increases rate of depolarization, AP frequency

88
Q

What are the effects of blood pressure?

A

Baroreceptors in the walls of the internal carotids and aorta monitor blood pressure

Sensory info goes to cardioregulatory center in medulla oblongata to increase or decrease heart rate

89
Q

What are the effects of pH, CO2, and O2?

A

Chemoreceptors for pH/CO2 are found in the hypothalamus

Chemoreceptors for O2 are found in the internal carotids and aorta

Low O2 increases HR, which increases blood pressure to deliver more O2

Chemoreceptor reflexes regulate heart activity to maintain pH and blood gas values

90
Q

What are the effects of extracellular ion concentration?

A

Increase or decrease in EC K+ decreases HR

Heart block can result, which is the loss of AP conduction through the heart

91
Q

What are the effects of body temperature?

A

Body temperature increases cause HR increases and vice versa

BIOL 224 Lecture (3 decks)

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