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(HS) Biology 12 > 10.3 The Human Heart > Flashcards

10.3 The Human Heart Flashcards

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1
Q

What is the heart?

A

a cone-shaped, muscular organ about the size of a fist that is located between the lungs directly behind the sternum and is tilted so that the apex is oriented to the body’s left

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2
Q

What is the myocardium?

A

the major portion of the heart that consists largely of cardiac muscle tissue

the muscle fibres are branched and tightly joined to one another

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3
Q

What is the pericardium?

A

a thick, serous membrane in which the heart lies, that secretes a small quantity of lubricating liquid

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4
Q

What is the inner surface of the heart lined with?

A

endocardium

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5
Q

What is endocardium?

A

a membrane composed of connective tissue with endothelial tissue

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6
Q

What is the septum?

A

an internal wall that separates the heart into a right side and a left side

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7
Q

What are the 4 chambers of the heart?

A

the 2 upper, thin-walled atriums are located above the 2 lower, thick-walled ventricles

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8
Q

What do ventricles do?

A

pump the blood to the lungs and the body

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9
Q

What are the 4 valves of the heart?

A
  • tricuspid valve
  • bicuspid valve
  • pulmonary semilunar valve
  • aortic semilunar valve
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10
Q

What do valves do?

A

direct the flow of blood and prevent its backward movement

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11
Q

What are the atrioventricular valves?

A

the 2 valves that lie between the atriums and the ventricles

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12
Q

What are atrioventricular valves supported by?

A

strong fibrous strings called chordae tendinae

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13
Q

Where are the chordae tendinae?

A

attached to muscular projections of the ventricular walls

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14
Q

What do the chordae tendinae do?

A

support the valves and prevent them from inverting when the heart contracts

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15
Q

What is the tricuspid valve?

A

the atrioventricular valve on the body’s right side

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16
Q

Why is it called the tricuspid valve?

A

it has 3 flaps, or cusps

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17
Q

What is the bicuspid valve?

A

the atrioventricular valve on the body’s left side

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18
Q

Why is it called the bicuspid valve?

A

it has 2 flaps

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19
Q

What are semilunar valves?

A

valves in the heart between the ventricles and their attached vessels, whose flaps resemble half-moons

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20
Q

Where is the pulmonary semilunar valve?

A

lies between the right ventricle and the pulmonary trunk

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21
Q

Where is the aortic semilunar valve?

A

lies between the left ventricle and the aorta

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22
Q

Which side of the heart are the venae cavae and the pulmonary trunk attached to?

A

right side

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23
Q

Which side of the heart are the aorta and the pulmonary veins attached to?

A

left side

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24
Q

Where do the coronary arteries and cardiac veins pass through?

A

cardiac muscle

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25
Q

What do coronary arteries do?

A

bring oxygen and nutrients to cardiac cells, which derive no benefit from blood coursing through the heart

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26
Q

What do cardiac veins do?

A

drain blood into the right atrium

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27
Q

Describe the path of blood through the heart.

A
  • superior vena cava (anterior vena cava) and inferior vena cava (posterior vena cava), which carry oxygen-poor that is relatively high in carbon dioxide, enter the right atrium
  • right atrium sends blood through the tricuspid valve to the right ventricle
  • right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk and through the 2 pulmonary arteries to the lungs
  • 4 pulmonary veins, which carry oxygen-rich blood, enter the left atrium
  • left atrium sends blood through the bicuspid (mitral) valve to the left ventricle
  • left ventricle sends blood through the aortic semilunar valve into the aorta to the rest of the body
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28
Q

Why must blood go through the lungs?

A

in order to pass from the right side to the left side of the heart

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29
Q

Why is the heart a double pump?

A

right ventricle sends blood into the lungs and the left ventricle sends blood into the rest of the body

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30
Q

Why are the walls of the left ventricle thicker than the right?

A

it has the harder job of pumping blood to the entire body, which the right ventricle pumps blood a relatively short distance to the lungs

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31
Q

What is cardiac output?

A

volume of blood that the left ventricle pumps per minute

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32
Q

What is the cardiac output in a person with an average heart rate of 70 beats per minute?

A

5.25 L of blood per minute

this is about equal to the total amount of blood in the body, and adds up to about 750 L of blood per day

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33
Q

How can cardiac output change during heavy exercise?

A

can increase as much as fivefold

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34
Q

What does the pumping of the heart do?

A

sends blood out under pressure into the arteries

35
Q

Where is blood pressure the greatest?

A

in the aorta because the left side of the heart is the stronger pump

36
Q

When does blood pressure decrease?

A

as the cross-sectional area of arteries and then arterioles increase

37
Q

What is a pulse?

A

a wave effect that passes down the walls of arteries when the aorta expands and then recoils with each ventricular contraction

38
Q

What can the arterial pulse be used to determine?

A

the heart rate

39
Q

What may a weak or “thready” pulse indicate?

A

a weak heart or low blood pressure

40
Q

What is a cardiac cycle?

A

each heartbeat; one complete cycle of systole and diastole for all heart chambers

41
Q

How does the heart beat?

A

first, the 2 atria contract at the same time, then the 2 ventricles contract at the same time

then, all the chambers relax

42
Q

What does systole mean?

A

refers to the contraction of heart muscle

43
Q

What does diastole mean?

A

refers to the relaxation of the heart muscle

44
Q

Around how many beats per minute does a heart contract?

A

70

45
Q

How long does each heartbeat last?

A

about .85 s

46
Q

Describe the heartbeat times.

A

Time Atria Ventricles

  1. 15 s Systole Diastole
  2. 30 s Diastole Systole
  3. 40 s Diastole Diastole
47
Q

What is a stethoscope?

A

an instrument used to isolate and amplify the body’s internal sounds

48
Q

What sound does a heart beat make?

A

“lub-dub”

49
Q

What is the longer lower-pitched “lub” sound caused by?

A

vibrations occurring when the atrioventricular valves close due to ventricular contraction

50
Q

What is the shorter and sharper “dub” sound caused by?

A

when semilunar valves close due to back pressure of blood in the arteries

51
Q

What is the heart murmur (slight whooshing sound) after the “lub” most commonly caused by?

A

blood flowing back through an ineffective mitral valve

52
Q

What does the intrinsic (internal) conduction system of the heart cause?

A

the rhythmic contraction of the atria and ventricles

53
Q

What makes the intrinsic conduction system possible?

A

the presence of nodal tissue (a unique type of cardiac tissue)

54
Q

What are the 2 types of nodal tissue?

A

sinoatrial node, and atrioventricular node

55
Q

Where is the SA node located?

A

in the upper dorsal wall of the right atrium

56
Q

Where is the AV node located?

A

in the base of the right atrium very near the septum

57
Q

What does the SA node do?

A

initiates the heart beat and sends out an excitation impulse every 0.85 seconds, which causes the atria to contract

58
Q

What happens when the SA node impulses reaches the AV node?

A

a slight delay allows the atria to finish contraction before the ventricles begin to contract

59
Q

Where does the signal for ventricles to contract travel?

A

from the AV node through specialized cardiac muscle fibres called the AV bundle before reaching Purkinje fibres

60
Q

Why is the SA node called a pacemaker?

A

it usually keeps the heartbeat regular

61
Q

What happens if the SA node fails to work properly?

A

the heart still beats due to impulses generated by the AV node, but the beat is slower

62
Q

What can be done to correct the failure of the SA node?

A

an artificial pacemaker may be implanted that gives an electrical stimulus to the heart every 0.85 seconds

63
Q

Describe the intrinsic control of the heartbeat.

A

the SA node sends out a stimulus, which causes the atria to contract

when this stimulus reaches the AV node, it signals the ventricles to contract

impulses pass down the 2 branches of the AV bundle to the Purkinje fibres, and thereafter the ventricles contract

64
Q

What is the medulla oblongata?

A

a portion of the brain that controls internal organs

65
Q

What does the cardiac control centre in the medulla oblongata do?

A

can alter the beat of the heart by way of the autonomic system

66
Q

What is the autonomic system?

A

a portion of the nervous system

67
Q

What are the 2 subdivisions of the autonomic system?

A

parasympathetic and sympathetic

68
Q

What does the parasympathetic subdivision of the autonomic system do?

A

promotes functions of a resting state

decreases SA and AV nodal activity when we are inactive

69
Q

What does the sympathetic subdivision of the autonomic system do?

A

brings about responses to increased activity or stress

increases SA and AV node activity when we are active or excited

70
Q

What is epinephrine and norepinephrine?

A

hormones released by the adrenal medulla that stimulate the heart

71
Q

What is the adrenal medulla?

A

the inner portion of the adrenal gland

72
Q

What happens when we are frightened?

A

the heart pumps faster and stronger due to sympathetic stimulation because of the release of epinephrine and norepinephrine

73
Q

What is an electrocardiogram?

A

a recording of the electrical changes that occur in the myocardium during a cardiac cycle

74
Q

What do ions in body fluids do?

A

conduct electrical currents

75
Q

Why can electrical changes in the myocardium be detected on the skin’s surface?

A

because the ions in body fluids conduct electrical currents

76
Q

What are electrodes placed on or near the chest connected by?

A

connected by wires to an instrument that detects and records the myocardium’s electrical changes

77
Q

What does a normal ECG usually indicate?

A

the heart is functioning properly

78
Q

Describe the cycle that the ECG records.

A

when SA node triggers an impulse, atrial fibres produce an electrical change called the P wave

the P wave indicates that the atria are about to contract

QRS complex signals that the ventricles are about to contract

electrical changes that occur as the ventricular muscle fibres recover, produce the T wave

79
Q

What are arrhythmias?

A

various types of abnormalities that can be detected by an electrocardiogram

80
Q

What is atrial fibrillation (AF)?

A

most common type of arrhythmias

instead of the heart generating regular single impulses from the AV node, multiple chaotic impulses are generated, resulting in a fast irregular heartbeat

sometimes occurs infrequently and resolves on its own, sometimes requires medication

81
Q

What are the symptoms of AF?

A
  • palpitations: fluttering sensation of the heart
  • dizziness
  • weakness
  • chest pain
82
Q

What is ventricular fibrillation (VF)?

A

a more serious medical emergency

an uncoordinated contraction of the ventricles, commonly followed after a heart attack, but also caused by an injury or drug overdose

83
Q

What must you do to treat VF?

A

because a heart in VF is not pumping blood, it must be defibrillated by applying a strong electrical current for a short period of time

then, the SA node may be able to reestablish a coordinated beat

84
Q

What are AED’s?

A

automatic external defibrillator

small devices that can be used to determine whether a person is suffering from VF, and if so, administer an appropriate electrical shock to the chest

(HS) Biology 12 (46 decks)

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