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Paramedic Curriculum > Chapter 5D - Cardiovascular System > Flashcards

Chapter 5D - Cardiovascular System Flashcards

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0
Q

Describe the pump

A

The left heart pumps blood into the systemic circulation at the maximum pressure called “systolic pressure” varies from 100-140mmHg in healthy people.

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1
Q

Describe the primary function of the cardiovascular system

A

To supply the body with oxygenated blood containing the nutrients needed for metabolism, and to carry away the waste products

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2
Q

Describe the pipes

A

The arteries, arterioles, and capillaries that deliver blood to the body’s cells under pressure (diastolic pressure) varies from 60-90 mmHg

Venules and veins being blood back to the heart at very low pressure

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3
Q

Describe the fluid

A

The blood

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4
Q

Describe the right heart

A

The pulmonary heart

Receives the venous return of deoxygenated blood from the vena cava (preload) and pumps it to the lungs

Pump at lower BP than left heart

<30 mmHg systolic
+_ 10-20mmHg diastolic

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5
Q

Describe left heart

A

Systemic heart

Receives venous return of oxygenated red blood from the lungs and pumps it to the rest of the body.

There is much more resistance in all of the body’s arteries. (Afterload) so it has to work harder

Has greater coronary blood flow

Greater than or equal to 120mmHg systolic
Greater than or equal to 70mmHg diastolic

Gets 75% of all clots in MIs

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6
Q

If right heart is damaged?

A

Not able to deal with all of the venous return (preload) and that will cause this return to “back up” into the veins - overtime result in dependent edema.

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7
Q

If left heart damaged?

A

It will not be able to deal with all of the venous return from the lungs

Will cause a “back up” resulting in pulmonary edema

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8
Q

Explain “the amount of blood in the body occupies 1/5 of the available space “

A

The blood vessels are always fairly tightly constricted. If the “pipes” do not stay tightly constricted. You will go into shock, and/or faint.

If you have 5 quarts of blood, then if all vessels dilated at once it will take 25 quarts to fill them

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9
Q

How much blood does a person have?

A

A person has 1 quart of blood for every 30 pounds of body weight.

5-6 quarts for people weighing 150-180lbs

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10
Q

How much blood loss produces shock?

A

Loss of 15% of blood volume produces moderate shock

30% produces severe shock

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11
Q

Cardiac output

CO = SV x HR

A

Is the cardiac minute volume, the amount of blood pumped by the heart (left ventricle) in one minute. It is the same as the Stroke volume times the heart rate.

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12
Q

Define stroke volume

A

The amount of blood ejected by the left ventricle with each heart beat

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13
Q

Heart rate

A

Number of heartbeats per minute

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14
Q

Define ejection fraction

A

The percentage of blood in the ventricles that is linked out per beat

Usually 60%, but in CHF 20%

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15
Q

Define peripheral vascular resistance PVR

A

Pumping pressure of the arteries and arterioles - is is another way of saying Diastolic pressure. It is largely determined by the diameter of the blood vessels and their muscle tone.

Also called after load because it is the pressure the ventricles must beat against

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16
Q

Define diastolic pressure

A

The lower number in a blood pressure ( PVR)

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17
Q

Systolic pressure

A

Upper number of BP = the pumping pressure of the heart

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18
Q

Pulse pressure

A

Difference between the systolic and diastolic pressures (about 40-50mmHg)

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19
Q

Define Starling’s Law of the Heart

A

Says that within limits, the force of the heart’s contractions is primarily determined by diastolic filling - better the filling, the greater the stretch, the stronger will be the contraction

Based upon preload, the amount of venous return.

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20
Q

Define tachycardia

A

An abnormally rapid pulse rate = greater than or equal to 100 in adults

  • usually indicates insufficient perfusion, so the heart speeds up to compensate.
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21
Q

Define bradycardia

A

An abnormally rapid pulse = less than or equal to 60 in adults

  • may indicate several things, downer drug abuse, poisonings
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22
Q

Define automaticity

A

The characteristic of the heart to generates its own beat. The brain does not tell it when to beat, it does that on its own.

Brain can speed it up using sympathetic nervous system or slow it down using the parasympathetic nervous system via vagus nerve.

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23
Q

Blood pressure is a function of what.

A

Depends on the pumping contractility of the ventricles (reflected by the systolic pressure),

the stroke volume (which in part is a function of preload = the amount of blood returning to the heart [starlings law of the heart], ejection fraction and total body fluid volume),

the heart rate, PVR (how well the arterioles pump, reflected by the diastolic pressure)

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24
Q

RBC - basic function

A

Important in transporting O2 to cells

Contain hemoglobin to carry O2

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25
Q

WBC - basic function

A

Important in fighting infection

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26
Q

Platelets - basic function

A

Important in initiating the blood-clotting cascade

27
Q

Plasma - basic function

A

The liquid portion of blood - acts as a transport medium for blood cells and nutrients, oxygen, ect.

28
Q

Early systole - position of cardiac valves

A

As soon as ventricular contraction starts,

AV valves close

Semilunar valves are still closed. Pressure builds

29
Q

Late systole - position of cardiac valves

A

At the point when the pressure inside the ventricles exceed the pressure in the aorta,

semi lunar valves open.

30
Q

Diastole - position of cardiac valves

A

As the ventricles relax and the pressure falls,

Semilunar valves close

When pressure gets low enough, AV’s open.

31
Q

Define atrial kick

A

Describes the way the atria work

They wait during ventricular diastole for the ventricles to almost completely fill

Then the atria contracts, “kicking” in just a little extra blood to help stretch the ventricles

32
Q

Arteries and arterioles - characteristics

A

Carry blood away from the heart at fairly high pressure

Nerve controlled, and can constrict or dilate.

Thick-walled, made up of many layers of smooth muscle.

Carry oxygenated blood (exception is pulmonary artery)

33
Q

Veins and venules - characteristics

A

Carry undersaturated blood back to the heart at fairly low pressure

Thin walled, containing several layers of smooth muscle, but due to thinness do not really pump the blood

Have one way valves to help move blood toward the heart

34
Q

Capillaries - characteristics

A

One cell layer thick, with pores or openings where these cells meet

Allows plasma to flow out carrying oxygen and nutrients to the cells.

While capillaries cannot constrict not dilate, they are supplied with sphincter muscles (pre-capillary sphincters) that open to let blood enter a capillary bed whenever an area of cells runs out of oxygen, or become acidotic

35
Q

Explain the mechanism for returning blood to the heart

A
  1. Gravity - vessels at head, neck, and shoulders
  2. Siphon effect - each time we inhale, the relative vacuum in the thoracic cavity helps draw in blood
  3. Pumped back by skeletal muscles squeezing the veins, this action is assisted with one way valves in the veins. ( most important)
36
Q

Define perfusion

A

To pour through

Refers to the pumping of blood through capillary beds.

The pumping is provided by hydrostatic pressure.

37
Q

Describe the requirements for adequate tissue perfusion (5)

A
  • adequate blood volume
  • adequate cardiac output
  • adequate valves in the heart
  • competent valves in the heart
  • patent blood vessels
38
Q

Explain how the amount of oxygen bound to hemoglobin affect skin color

A

Pink - adequate hemoglobin and adequate O2

Pallor - inadequate hemoglobin, adequate O2 Or, adequate hemoglobin and adequate O2 with vasoconstriction at the skin

Cyanosis - adequate hemoglobin, inadequate oxygen

39
Q

Define anemia

A

Not having enough blood

  • patient has lost blood or has too few red cells
  • patient has enough blood, just with insufficient hemoglobin
  • patient has red cells that are too small
40
Q

Anemia - S/S

A

Pallor
Fatigue
Muscle weakness
Dyspnea on exertion

41
Q

Edema - define

A

Is increased fluid trapped in the interstitial space

  • it occurs when there is an increase in capillary pressure (from gravity) or from fluid backing up in the heart, lungs, or liver, resulting in the inability of venules to get rid of all the blood entering them (CHF)
  • it can occur when there is an increase in capillary permeability as happens with acidosis or hypoxia (allergies cause it due to the actions of histamines)
42
Q

Define venous pooling

A

Results in an increase in the amount of blood staying in the veins, and occurs when:

– there is a decrease in skeletal muscle activity, such as occurs with prolonged sitting – such as a long airplane flights

– there is a drug reaction that causes vasodilation – such as with nitroglycerin, or histamine

43
Q

Baroreceptors - define, location, and function when stimulated

A

Baroreceptors or pressure receptors located in the aortic arch and carotid artery. They detect increases in pressure around them, and provide a feedback signal to the brain stem that helps regulate blood pressure. If they detect an increase in blood pressure, they signal the brain which sends a signal down the Vegas nerve to cause the heart to slow down – the decrease in heart rate will decrease cardiac output and help drop BP

44
Q

Inotropic effect – define

A

Refers to the force of contraction

45
Q

Chronotropic effect – define

A

Refers to the speed of the heart

46
Q

Dromotropic effect - define

A

Refers to the conduction system of the heart

47
Q

Heart rate – how changes alter stroke volume and cardiac output

A
  • As heart rate slows down, cardiac filling time improves, usually resulting in increased stroke volume

– as rate speeds up, Cardiac filling time diminishes, decreasing stroke volume

Increased stroke volume will increase cardiac output and decreased stroke volume will decrease cardiac output

48
Q

Venous return – how changes alter stroke volume and cardiac output

A

Due to starlings law of the heart, stroke volume and cardiac output are very dependent on venous return

– if venous return drops, so does stroke volume and cardiac output

49
Q

Ventricular contractility – how changes alter stroke volume and cardiac output

A

If contractility is reduced due to ischemia, or infarct, or medication, the Myocardium becomes less efficient resulting in decreased stroke volume and less cardiac output

– congestive heart failure is partly due to decreased contractility and a decrease in ejection fraction

50
Q

Atrial kick – how changes alter stroke volume and cardiac output

A

If atrial kick is lost (as in atrial fibrillation), there is a drop in ventricular filling of about 20%. This makes the heartless efficient per beat

51
Q

List the five characteristics of the myocardial tissue

A 
Automaticity 
rhythmicity
Conductivity
Contractility
Irritability
52
Q

Automaticity- define

A

The ability to initiate its own impulses. This is its own internal pacemaker.

53
Q

Rhythmicity- define

A

The ability or tendency to set a predictable pattern.

54
Q

Conductivity - define

A

The ability to transfer electrical impulses from one cell to another

55
Q

Irritability- define

A

The ability to respond to an impulse or stimulus.

56
Q

Explain the “all or none phenomena”

A

The characteristic of the heart to contract as a unit, with all muscle cells contracting together. Your biceps on the other hand can selectively contract only 30% or 50% of its muscle fibers to lift a given object

57
Q

Describe the normal pathway of an electrical stimulus through the heart

A
  • The sinoatrial node spontaneously fires

– the signal spreads throughout the atria causing them to contract (the impulse also travels through the intra-atrial fibers)

– the atrioventricular node receives impulses, pauses to aid in ventricular filling, and then fires the signal down the bundle of His

– the bundle of his carries the impulse to the bundle branches

– the bundle branches carry the impulse to the purkinje fibers

– the purkinje fibers for the ventricles from the bottom up

58
Q

Intrinsic rate of depolarization of the heart

A 
SA Node - 72
AV node - 60
Bundle of his - 54
Bundle branches - 46
Purkinje fibers - 40
59
Q

Intrinsic range of depolarization of the heart

A 
SA Node - 60-100
AV Node - 40-60
Bundle of his - 40-60
Bundle branches - none
Purkinje fibers - 20-40
60
Q

Explain the significance of these intrinsic rates

A

With the stimulation by the autonomic nervous system, the heart would be led by the SA node to beat a roughly 72 bpm.

In the event of an infarct damage in SA node, the AV node would take over as a back up pacer, but it would be at about 60 bpm

61
Q

Describe why increases in heart rate affect myocardial perfusion through the coronary arteries

A

The openings of the coronary arteries are behind the aortic valve leaves.

Due to being partially covered during systole, and as arteries are compressed during systole, the only time the heart is resupplied with blood is during diastole.

As the heart speeds up, systole remains at almost the same duration (blood is thick and takes a certain amount of time to move).

It is diastole that shortens most when the heart speeds up. Therefore, during tachycardia, the heart works harder, But receives less blood per heartbeat.

62
Q

Describe when it is important to auscultate the apical pulse

A

– To determine death under policy #814

– when the patient is in pulseless electrical activity

– pediatrics when pulses are difficult to obtain

63
Q

Hemodynamic response – describe

A

Is the patients signs/symptoms in response to a particular level of perfusion.

As with PEA do not treat the monitor evaluate the patient’s hemodynamic response

64
Q

Pulses paradoxes – define/describe

A

An anomaly of blood pressure that is tied to starlings law of the heart – in that during inhalation, momentarily there is a drop of intrathoracic pressure and that may cause a Drop in systolic blood pressure during that breath. This is found in severe obstructive pulmonary disease, severe respiratory distress or constrictive pericardial disease.

An example would be that you hear the first sound at 136 and it thumbs until it reaches, say 130, at which time the patient inhaled forcefully and you note that the sound disappears for several beats, only returning when he exhales again. If it is then steady at 120 regardless of breathing, than the fact that the period of silence was greater than 10 mmHg makes this a positive pulses paradoxes

65
Q

Pulses alternans – define/describe

A

Alternating normal pulses followed by a much weaker one. This is found in severe left ventricular failure. This is more often heard it and then fell.

An example would be, given a regular pulse of 60 bpm, you hear the first sound at say 130 mmHg, then you hit 120, the pulse rate doubles to 120 bpm. Then what happened was that originally you were only hearing the stronger beats, not the weaker ones. If the patient is on an ECG at the same time this would be obvious. at the beginning of the monitor would show a pulse of 120, but when taking a BP you would only, initially hear a sound every second 60 bpm until the cuff pressure gets low enough

66
Q

Auscultatory gap - define/describe

A

Something similar to pulses paradoxes except that it does not occur during inhalation. This is found in some patients with hypertension.

An example would be that you hear the first sound say at 200 mmHg and continues until 180 at which time it vanishes, only to reappear again at 130, with a diastolic at say 100 if this is not recognize, it would result in an incorrect BP being recorded as 130/100 (having miss the upper sounds) an indication that this is not likely is that the pulse pressure is too narrow in this range.

The blood pressure should be recorded as 200/100 within auscultatory gap from 180 to 130

Paramedic Curriculum (22 decks)

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