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Medic > Cardiac Anatomy and Physiology > Flashcards

Cardiac Anatomy and Physiology Flashcards

0
Q

Describe the heart valves?

A

AV VALVES separate the atria and ventricles.
The right side is the TRICUSPID VALVE with three leafs
The MITRAL OR BICUSPID VALVES with two leafs

The SEMILUNAR VALVES each with three cusps include the AORTIC AND PULMONARY VALVE located at the exits to the large arteries from the ventricles

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1
Q

Describe the layers of the heart?

A

The covering is a double walled PERICARDIAL SAC. The outer fibrous pericardium anchors the heart to the diaphragm. The visceral pericardium aka EPICARDIUM consists of a serous membrane that provides a small amount of lubricating fluid within the pericardial cavity between the two pericardial membranes to facilitate heart movement. THE MYOCARDIUM is the middle layer of the heart is the real muscle of the heart. The inner layer is the ENDOCARDIUM which also forms the four heart valves that separate the chambers of the heart and ensure one way flow of blood.

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2
Q

What is the cardiac conduction pathway?

A

All cardiac muscle can generate an impulse but it usually starts at theSA node aka the pacemaker located in the right atrium
The sa is set at approx 70 bpm but can be altered by the autonomic nervous system fibers that innervate the sa node
The impulse then spreads throughout the atrial pathways
The impulses then collect at the av node located in the floor of the right atria near the septum
There is a delay at the av node to allow for ventricular filling
Then the impulse travels into the ventricles through the bundle of his (av bundle), the right and left bundle branches, and the purkinje fibers.

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3
Q

What disfunction can be seen on an EKG?

A

Arrhythmia, MI, and electrolyte imbalances.

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4
Q

Where are the heart rate and force of contraction controlled?

A

In the cardiac control center in the medulla of the brain. The baroreceptors in the walls of the aorta and internal carotid arteries alert the cardiac center which then responds through the stimulation of the sympathetic nervous system or parasympathetic nervous system to alter the rate and force of contractions appropriately.

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5
Q

Give an example of how some drugs can work on autonomic receptors in the heart.

A

The sympathetic or beta1 adrenergic receptors are used by beta blockers. Beta blockers fit the receptor sites and prevent normal SNS stimulation to block any increases in rate and force of contractions after the heart has been damaged.

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6
Q

Describe the major blood vessels of the coronary circulation.

A

2major arteries the right and left coronary arteries branching off the aorta immediately above the aortic valve.
The left coronary artery divides into the left descending or interventricular artery which follows the anterior interventricular sulcus or groove downward over the surface of the heart and the left circumflex artery which circles the exterior of the heart in the left atrioventricular sulcus
Similarly the right coronary artery follows the right atrioventricular sulcus on the posterior surface of the hear and branches into the right marginal artery and the posterior interventricular artery, and then descends into the posterior interventricular groove towards the apex of the heart where it comes close to the terminal point of the left anterior descending artery

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7
Q

When is blood flow through the myocardium at its greatest point?

A

Diastole. Systole causes compression of the coronary arteries and decreases blood flow. Thus very rapid or prolonged contraction can interfere with the blood supply to the muscle of the heart.

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8
Q

Why are the sulcus or grooves of the heart important?

A

It permits surgical replacement of obstructed arteries with bypasses- using sections of other veins or arteries.

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9
Q

How does collateral circulation work?

A

It means an alternate source of blood and nutrients.
This is important if an artery has becomes blocked.
When obstruction occurs more capillaries from nearby arteries tend to enlarge or extend into adjacent tissues to meet the metabolic needs.
Regular aerobic exercise contributes to cardiovascular fitness by developing collateral channels.

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10
Q

What do the coronary arteries anatomically supply?

A

RCA-right side of the heart and the inferior portion of the left ventricle, and the posterior interventricular septum
Left anterior descending artery- anterior walls of the ventricle, the anterior septum, the bundle branches
Circumflex artery- left atrium, lateral And posterior walls of the left ventricle
The supply for the SA depends on the individual. Supplied by the right coronary or the left circumflex.
AV- right coronary artery

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11
Q

What disorders occur via right or left blockages?

A

Right results in disturbance sof the av node-arrythmia

Left coronary artery blockage impairs pumping capability or chf.

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12
Q

What is the course of coronary veins?

A

It generally paralels that of the arteries with the majority of the blood collecting in the coronary sinus and emptying directly into the right atrium.

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13
Q

Describe the flow of blood through the heart?

A

The two atria are relaxed and fill with blood from the inf. and sup. vena caviar into the right atrium, and from the pulmonary veins into the left atrium.
The av valves opens as the pressure increase in the atria and the ventricles relax.
Blood flows into the ventricles almost emptying the atria.
The conduction system causes the atria to contract and force the remaining blood in the ventricles aka atrial kick
The atria relax
The ventricles begin to contract and pressure in the vents increase.
The av valves close.
For a moment all valves are closed the ventricles continue to contract building up the pressure on this isovolumetric phase(no change in volume in the vents).
The pressure opens the semilunar valves. Blood is forced into the aorta and pulmonary artery. The pressure in the left ventricle must be greater then the diastolic pressure in the aorta. Remember it’s not as big a deal for the pulmonary circulation because it is a low pressure system.
At the end the atria have begun to fill and the ventricles relax the aortic and pulmonary valves close to prevent back flow and the cycle repeats.

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14
Q

Which side of the heart has a higher volume of blood?

A

Neither there must be the same volume in both sides of the heart to ensure balance.

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15
Q

What are heart sounds?

A

They are sounds made by the heart valves closing. The av valves cause the Lubb and the semilunar valves cause the dupp.

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16
Q

What is a murmur and what causes it?

A

A murmur is an abnormal heart sound. This can be caused by unusual turbulence in the blood flow caused by defective valves that are leaky or do not completely open. It can also be caused by a hole in the heart septum.

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17
Q

What is an apical pulse and what is the difference between that and a radial pulse?

A

Apical is a pulse taken at the heart itself rather then at an artery such as the radial aka peripheral

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18
Q

What is a pulse deficit?

A

A difference between an apical and a peripheral pulse.

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19
Q

List the ways cardiac function can be measured?

A 
Cardiac output
Stroke volume
Cardiac reserve
Preload
Afterload
Cardiac reserve
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20
Q

What is cardiac output?

A

It is the volume of blood ejected by the heart in one minute.
It is dependent on stroke okie and heart rate. SV X HR=CO or Q

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21
Q

What is stroke volume?

A

The volume pumped by the heart from one ventricle in one contraction.
It varies with sympathetic stimulation and venous return

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22
Q

What is cardiac reserve?

A

The a iLife if the heart to increase output in response to increased demand.

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23
Q

What is preload?

A

Venous return.

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24
Q

What is afterload?

A

It is what the heart has to work against.
It’s is determined by peripheral vascular resistance.
Example, afterload is increased by a high diastolic pressure resulting from excessive vasoconstriction.

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25
Q

What are the two separate circulations in the BODY and describe each?

A

Pulmonary circulation- the right side of the heart, allows the exchange of o2 and co2 in the lungs.
Systemic circulation- the left side of the heart, provides for the exchange of nutrients and wastes between the blood and the cells throughout the body.

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26
Q

What is the difference between arteries and veins?

A

Arteries transport blood away from the heart and veins to the heart.

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27
Q

What are arterioles?

A

Arterioles are smaller branches of arteries that control the amount of blood flowing into the capillaries in specific areas through the degree of contraction of smooth muscle in vessel walls (vasoconstriction or vasodilation)

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28
Q

What are capillaries?

A

Capillaries are very small vessels organized in numerous networks that form The microcirculation
Blood flows very slow through the capillaries
Precapillary sphincters determine the amount of blood flowing from the arterioles into the individual capillaries, depeniding on the metabolic needs of the tissues.

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29
Q

What are venules?

A

Small veins that conduct blood from the capillary beds toward the heart.

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30
Q

What is a vein?

A

Veins take blood to the heart.
They collect blood draining from the venules.
Normally70% of the blood is contained in the veins at any time.
Valves In the larger veins of the arms and legs keep blood flowing toward the heart.

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31
Q

Describe the flow of blood through the circulatory system.

A

Heart>Arteries>arterioles>capillaries>venules>veins>heart

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32
Q

What are the layers and function that make up a vein and an artery?

A

Tunics intima the inner layer (endothelial), tunica media smooth muscle that controls the diameter of the vessel in the middle, tunica adventitia or externa the outer connective tissue that contains elastic and collagen fibers.

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33
Q

What is the vasa vasorum?

A

Tiny blood vessels that supply blood to the tissues of the vessel wall itself.

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34
Q

What is the physical difference of arteries and veins?

A

Veins have thinner walls and less smooth muscle.

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35
Q

What controls LOCAL vasodilation or vasoconstriction in arterioles?

A

It is controlled by autoregulation a reflex adjustment in a small area of tissue or an organ, depending on the needs of the cells in the area.
Example- decrease inPH, increase in co2, or decrease in o2 leads to local vasodilation. Release of chemical mediators like histamines or an increase in temperature will cause vasodilation.
These local changes do not affect the systemic bp

36
Q

What causes increased systemic vasoconstriction?

A

Epi and norepinephrine
By stimulating alpha1 adrenergic receptors I. Arteriolar walls.
Angiotensin
Another powerful systemic vasoconstrictor

37
Q

When is your sympathetic nervous system active?

A

A all times even at rest making small changes to systemic vasomotor tone.

38
Q

What are capillary walls made of?

A

A single endothelial layer to fascilitate the exchange of fluid,o2, co2, electrolytes, glucose, and other nutrients and wastes between the blood and interstitial fluid.

39
Q

What is blood pressure?

A

The pressure against the arterial walls.

40
Q

What is pulse pressure?

A

The difference between systolic and diastolic pressures.

41
Q

What is bp dependent on?

A

CO X PR=BP

cardiac output and peripheral resistance.

42
Q

What can cause increase in peripheral resistance?

A

Systemic vasoconstriction caused by SNS stimulation, or obstruction of blood vessels.

43
Q

What causes decrease in peripheral resistance?

A

Systemic vasodilation from reduced SNS stimulation( there is no parasympathetic nervous system innervation in the blood vessels)
Local vaso dilation or constricion does not effect bp.

44
Q

What are the two ways the SNS elevates the bp?

A

The SNS and epinephrine act at the beta1 adrenergic receptors in the heart to increase both rate and contractility.
SNS, Eli and norepinephrine, increase vasoconstriction by stimulating the alpha1 adrenergic receptors in the arterioles of the skin and viscera. This reduces the capacity of the system and increases venous return

45
Q

List hormones that contribute to bp control?

A 
Epi
Norepinephrine
Antidiuretic hormone
Aldosterone
The renin-angiotensin-aldosterone system.
46
Q

What does antidiuretic hormone do?

A

Increases water reabsorption through the kidneys, the increasing blood volume. ADH is also known as vasopressin for its vasoconstrictive action.

47
Q

What does aldosterone do?

A

I crease blood volume by increasing reabsorption of sodium ions and water. Increase blood volume means increased blood pressure.

48
Q

What does the renin-angiotensin-aldosterone system do?

A

Located in the kidneys that is initiated when a decrease in renal blood flow stimulates the release of renin, which in turn activates angiotensin (vasoconstrictor) and stimulates aldosterone secretion. Angiotensin II is a powerful vasoconstrictor.

49
Q

How is the heart positioned in the chest?

A

The upper heart border (the base) is at the2nd intercostal space
The lower heart border(the apex) in a blunt point at the fifth intercostal space. Left midclavicular
About 2/3s of the heart lies left of the body’s midline.

50
Q

What is the point of maximal impulse?

A

The spot were the heart can be palpated during ventricular contraction at the fifth intercostal space left midclavicular.

51
Q

what are the hearts two main unique properties?

A

It can withstand continual activity without fatigue.

And it’s capable of generating electrical impulses that stimulates the heart to beat.

52
Q

Name the heart surfaces.

A

Anterior- front
Posterior-back
Inferior-bottom
Lateral-side

53
Q

List the layers of the heart.

A 
Fibrous pericardium
Serous pericardium (parietal layer)
Pericardial cavity
Serous pericardium (visceral layer)
Myocardium
Endocardium
54
Q

Describe the pericardium?

A

A sac like structure that invades the heart.
Consisting of:
An outer tough, inelastic, fibrous sac - fibrous pericardium
An inner thin, two layered, fluid secreting membrane- the serous pericardium

55
Q

How is the heart attached to the body?

A

The fibrous pericardium is attached to the center of the diaphragm inferiorly, to the sternum anteriorly, and t the esophagus, trachea, and main bronchi posteriorly.

This anchors the heart to the body

56
Q

Describe the serous pericardium.

A

The moist serous pericardium is a continuous membrane that double back on itself to form two layers.

The PARIETAL LAYER, which lines the inside of the fibrous pericardium

The VISCERAL LAYER aka epicardium, which lines the outer surface of the myocardium.

Between these two layers is the pericardial cavity filled with10-30 cc of thin, clear, serous fluid secreted by the serous layer. Preventing friction while the heart beats.

57
Q

Describe the myocardium.

A

The thick middle muscular layer that makes up the bulk of the heart wall. This layer is responsible for the hearts ability to contract.

58
Q

Why is heart thickness important?

A

It is related to the amount of resistance the heart must overcome to pump blood out the chamber.

59
Q

Describe the endocardium.

A

A smooth thin layer of tissue that lines the chambers and Valves of the heart. The smooth inner surface allows blood to flow more easily through the heart.

60
Q

What is the coronary sinus function?

A

Returns venous blood from the coronary veins.

61
Q

Where does the right atrium receive blood from?

A

Superior and inferior vena cava and the coronary sinus.

62
Q

What are the two basic cardiac cell groups?

A

The pacemaker cells and the myocardial cells.

63
Q

What are the four primary characteristics of cardiac cells?

A

Automaticity-the ability of the pacemaker cells to generate their own impulses spontaneously, this is specific to the pacemaker cells.
Excitability- the ability of the cardiac cells to respond to an impulse
Conductivity- the ability of cardiac cells to receive an impulse and transmit it to other cells
Contractility- ability to shorten and cause muscle contraction, specific to myocardial cells.

64
Q

What is an electrolyte?

A

A substance whose molecules dissociate into charged particles (ions) when placed in water, producing positively and negatively charged ions.

65
Q

What is a cation?

A

A positively charged ion.

66
Q

What is an anion?

A

An ion with a negative charge.

67
Q

What are the primary intracellular and extracellular ion?

A

Potassium k+ intracellular

Sodium Na+ extacellular

68
Q

What is depolarization?

A

Periods of electrical stimulation in the heart.

69
Q

What is repolarization?

A

Periods of rest in the heart.

70
Q

What is the basic concept of depolarization and repolarization?

A

Pacemaker cells are able to generate and conduct electrical impulses that result in stimulation of the cardiac cell. These electrical impulses are the result of the brief but rapid flow of ions(primarily sodium and potassium) back and forth across the semipermeable cardiac cell membrane. Once a cell is stimulated, the membrane permeability changes, allowing an inward diffusion of sodium into the cell. Muscle contraction follows depolarization. When depolarization is complete, the influx of sodium into the cell stops and there is an outward diffusion of potassium signaling early repolarization. Toward the end of repolarization there is an excess of sodium inside the cell and an excess of potassium outside the cell. The sodium potassium pump is activated to actively transport sodium out and potassium in, causing the cell to become more negative(cell is repolarized).

71
Q

List the factors that determine the distribution of ions on either side of the membrane.

A

Membrane channels(pores)
Concentration gradient
Electrical gradient
Sodium-potassium pump

72
Q

What is active transport?

A

The movement of solute using carrier and energy from low concentration to high concentration

73
Q

Describe the membrane channels or pores of the myocardial cell.

A

The cell membrane has openings through which ions pass back and forth between extra cellular and intracellular space. Some channels are always open, some can be opened or closed and some can be selective on what they let in. Membrane channels open to a stimulus(electrical, mechanical, or chemical)

74
Q

Describe the concentration gradient of the myocardial cells.

A

Particles in solution move, or diffuse, from areas of higher concentration to areas of lower concentration. In the case of uncharged particles, movement proceeds until the particles are uniformly distributed within the solution.

75
Q

Describe the electrical gradient of myocardial cells.

A

Charged particles also diffuse, but the diffusion of charged particles is influenced not only by the concentration gradient but also by an electrical gradient. Like charges repel; opposite charges attract. Therefore positively charged particles tend to flow toward negatively charged particles; and negatives to positives.

76
Q

Describe the sodium-potassium pump of the myocardial cells.

A

The sodium-potassium pump is a mechanism that actively transports ions across the cell membrane against its electrochemical gradient.

77
Q

Describe the cardiac conduction pathway.

A

Sinoatrial node
The interatrial tract (Bachmann’s bundle) that goes from the sa node and terminates in the left atria
The internodal tracts which go from the SA node to the av node.
The atrioventricular node
Bundle of His
The right and left bundle branches
The purkinje fibers

78
Q

What is the SA nodes intrinsic rate?

A

60-100 bpm

79
Q

What are the backup pacemakers and what is their rate?

A

Secondary is The av nodes fires at 40-60 bpm

And there are others in the ventricles which fire at 30-40 bpm or less.

80
Q

What are the functions of the av node?

A

To slow conduction of the impulse which is the pr segment.
To serve as a backup pacemaker.
To block some of the impulses from being conducted when the atrial rate is rapid thus protecting the ventricles from dangerously fast rates.

81
Q

What is the bundle of His?

A

It is the pathway just before it splits into the right and left bundle branches.

82
Q

What do the right and left bundle branch do?

A

The rig conducts the impulse to the right ventricle.
The left splits into the anterior fascicles and the posterior fascicles. The anterior supplying the impulse to the anterior left ventricles and the posterior to the posterior left ventricles.

83
Q

What does the term His-purkinje system refer to?

A

The bundle of His, the bundle branches and the purkinje fibers.

84
Q

What does the term refractory mean?

A

The period of time in the cardiac cycle during which the cell is unable to respond to a stimulus. Aka is refractory to a stimulus

85
Q

What are the three phases of refractoriness?

A

Absolute refractory period, relative refractory period, and supernormal period.

86
Q

What is the absolute refractory period?

A

In this period the cells absolutely can not respond to a stimulus. This period extends from the onset of the QRS and the peak of the T wave. Because the cells have not depolarized to their threshold potential(aka the level at which a cell must be repolarized before it can depolarize again) they can not be stimulated to depolarize.

87
Q

What is the relative refractory period?

A

In this period the cells have repolarized sufficiently enough to respond to a strong stimulus. This period begins at the peak of the t wave and ends with the end of the t wave. This is aka the vulnerable refractory period of repolarization. A strong stimulus occurring in this period may usurp the primary pacemaker, the SA node. An example is PVC that falls during this period and takes over control of the heart and causes a V-tach.

88
Q

What is the supernormal period?

A

During this period the heart will respond to a weaker then normal stimulus. This occurs just at the end of the t wave, just before the cells have completely repolarized.

Medic (8 decks)

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