Test 2 Cardiac System Flashcards by Mary Braxton

ventricular contraction

systole

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ventricular relaxation

diastole

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explain the 4 stages of the cardiac cycle

1: ventricular filling (isotonic-no contraction occurring-no pressure)
2: ventricular contraction (isometric; tension being developed but no change in circumference) – pre-ejection
3: ventricular contraction (isotonic) – ejection; change is occurring
4: ventricular relaxation (isometric)

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All cardiac valves are designed to only allow _____ of blood between chambers, dependent on ______

one-way flowpressure differential

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What are the 4 valves in the heart? what is their purpose?

aortic, pulmonic, mitral, and tricuspid

one way blood flow in the heart( 2 way blood flow is a disorder)

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When a valve is _____ it only allows one way blood flow, i.e., easy flow in the proper direction

“competent”- working the way it should be

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Backward flow of blood through a one-way valve is called ______

“regurgitation”- can cause a murmur

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Resistance to the normal direction of blood flow through a valve is usually caused by valve _______.

“stenosis” (means narrowing or constriction of a passage)

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What are the semilunar valves of the heart?

aortic and pulmonic valves

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Name 3 characteristics of the aortic and pulmonic valves.

Firm, thick valves between ventricles and pulmonary artery and aorta
Three valve leaflets (tricuspid)
Prevent back flow (“regurgitation”) into ventricles

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Name the atrioventricular or AV valves of the heart and how many leaflets each has.

Tricuspid-3 leaflets and mitral valves-2 leaflets

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What is the lub dub sound?

the semilunar valves opening and closing

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a think cartilage band that hold valves tightly together to avoid leaking when the heart is pumping

the valve annulus

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Which valves are thick, flexible valves between atria and ventricles? Floppy like a parachute

tricuspid and mitral valves

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which valves are stabilized with chordae tendinea attached to papillary muscles (1 muscle and chord bundle for each leaflet)?

tricuspid and mitral

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dense connective tissue cords connecting valves to papillary muscles

Cordae tendinea

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_____ contract during ventricular systole and maintain tension throughout systole

Papillary muscles

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Heart and blood flow competency depends on coordinated what 4 things?

function of the annulus, valve leaflets, papillary muscles, and ventricular walls

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: when ventricles contract (opens semilunar valves and closes AV valves)

Ventricular systole

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when the ventricles relax and blood flows into them from the atria (results in closing of the semilunar valves due to artery back pressure)

Ventricular diastole

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when atria contract (opens the AV valves)

Atrial systole

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when the atria relax and blood flows into them from the vena cava (R) and the pulmonary vein (L)

Atrial diastole:

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True or False: there is no electrical connection btw the upper and lower parts of the heart

true

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Which valve is the only bicuspid valve?

mitral valve

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narrowed valve opening due to thickening, calcification, or non-separation of leaflets

Stenosis

What can result from malfunction?

disease

backwards blood flow due to stretching, stenosis, papillary muscle or cordae tendinae disruption

Regurgitation

the absence of valve formation in utero/the incomplete formation

"atresia" | *Most commonly occurs with the pulmonic valve

Heart (and vascular) sounds are caused by _____

vibration

describe the two normal sounds heard from the heart

First is a low "lub" (S1) as the AV valves close at the start of ventricular systole Second is a high-pitched "dup" (S2) as the semilunar valves close after ventricular systole

High rate of blood flow into chambers (e.g., 3rd and 4th heart sounds) could mean what for a patient?

heart failure

______ are abnormal sounds heard in various parts of the vascular system

Murmurs and bruits

Murmurs are sounds caused by _______, most commonly around valves

blood turbulence in the heart | *(late aortic stenosis)

Bruits (pronounced “brew-ee”) are sounds caused by _______

blood turbulence in blood vessels | *(carotid bruit)

Know the blood flow throughout the heart

veins carry oxygenated blood | arteries carry deoxygenated blood

What are the 3 major epicardial arteries (outside heart)?

Left common coronary artery divides into: -Left anterior descending (LAD) artery: Supplies the apex, left anterior wall, anterior septum _Left circumflex artery: Supplies the lateral left Right coronary artery: Supplies the right wall, posterior wall, posterior septum

What is the second sound we hear that is associated with pulse?

S2-closure of semilunar valves

What is the first sound we hear that is not associated with pulse?

S1- closure of av valves

Smaller branches extend from the coronary arteries, penetrating into and perfusing the myocardium

intramural arteries

When the left ventricle contracts, the aortic valve opens. The valve cusps prevent what?

filling of the coronary arteries

When the left ventricle relaxes, aortic pressure closes the aortic valve, allowing what?

the coronary arteries to fill

only time the heart is receiving blood flow

diastole

From most superficial to deep, how is the heart blood vessels arranged?

coronary arteries-->intramural arteries-->capillaries | gets smaller and smaller

Blood from heart muscle is drained by what into what?, then into what?

cardiac veins; coronary sinus; right atrium

true or false: coronary veins generally run parallel to coronary arteries

true

_____ are electrically conductive cells which discharge rhythmically and continuously, starting an electrical impulse which normally travels through conductive pathways (specialized cardiomyocytes)

Pacemakers

How many pacemakers in the heart?

2;Sinoatrial node (SA node; “pacemaker”) and Atrioventricular node (AV node)

What is the normal pacemaker of the heart?

Sinoatrial node (SA node; “pacemaker”)

what is the gate keeper between the atrium and ventricles?

Atrioventricular node (AV node)

what are present in the atria, ventricles or conductive tissue and can take over when the SA and AV nodes aren’t functioning or conduction is blocked?

“Latent pacemakers"

what connects the electrical discharge through the atriums?

Internodal atrial pathways

Where does the bundle of his separate to?

RBB and LBB

The fastest pacemaker always sets the pace: __ > __ > _____

SA (60-100 per min)> AV > inherent ventricular pacemakers | *if something is higher than SA it could be tachycardia

purkinje system

the smallest fibers of the bundle branches

Why do pacemakers never enter resting potential?

they’re always preparing for or participating in an AP

Explain the 1st stage of pacemaker action potential.

``` 1st phase (4 on figure): Slow passive Na+ inward movement (if – red) At ~ -50 mV, Ca2+ T (transient) channels open, slow inward movement (green) ```

Explain the 2nd phase of pacemaker action potential

``` 2nd phase (0 on figure): At threshold (~ -40 mV), Ca2+ L (long) channels open, faster inward movement go ions (blue) ```

Explain the 3rd phase of pacemaker action potential

At ~ 0 mV the Ca2+ L channels close and K+ channels open (orange), fast K+ outflow to return potential to ~ -60 mV

What normally sets the pace in cardiac conduction?

SA node | *But fastest pacemaker ultimately controls heart rate

What conduct to the AV node in cardiac conduction?

Internodal pathways | *Atrial myocytes depolarize following internodal pathway depolarization

What delays transmission to the bundle of His in cardiac conduction? (delays conduction from upper to lower part of the heart)

AV node | *Facilitates coordination of atrial and ventricular contraction

What is the path from the bundle of His in cardiac conduction?

Bundle of His to bundle branches to Purkinje fibers to ventricular myocytes – very rapid

What is a measure of electrical activity in the heart?

The electrocardiogram (ECG, previously called the EKG)

What are branched and conduct depolarizations through intercalated disks?

Cardiomyocytes

What do atrial myocytes secrete?

atrial natriuretic peptide (ANP) with atrial distension (stretch)

What does ANP cause?

vasodilation, diuresis (increased water excretion into urine) and Na+ excretion

What do ventricular myocytes produce?

produce B-type natriuetic peptide (BNP) with ventricular distention (similar effects to ANP)

What is qrs associated with?

depolarization of ventricles

Why do we measure blood BNP concentration?

an indicator of ventricular stretch, e.g., with heart failure

What is the average BPM for most people?

70 BPM

What is the normal sinus rhythm?

means HR coming from SA node

If you have a slower or junctional rate about 40-59 BPM where is that coming from?

AV node

If you have a very slow rate under 40 BPM aka ventricular rate, where is that coming from?

Purkinje fibers and myocardial cells

If there is no P wave on an ECG, what does that mean?

something wrong with SA node

Myocytes in the heart (cardiomyocytes) release 2 hormones. What are they?

ANP and BNP (BNP is primary lab test that tests if someone has heart failure but there is stretch on the heart)

What provide strong union between fibers via desmosomes and provides low-resistance bridges for the spread of excitation from one cell to another via gap junction channels?

intercalated disks

Describe cardiomyocyte action potential.

- -Rapid depolarization (phase 0) due to Na+ influx through rapidly opening Na+ channels (the Na+ current, INa) - -Initial rapid repolarization (phase 1) due to inactivation of Na+ channels and activation of repolarization process (phase 3) due to net K+ efflux through K+ channels - -Plateau (phase 2) due to Ca2+ influx through more slowly opening Ca2+ L(long or slow channels) channels (the Ca2+ current, ICa) - -Rapid repolarization process (phase 3) due to closure of Ca2+ channels with continued K+ efflux through K+ channels - -Return to the resting membrane potential (phase 4)

What provides all parasympathetic control?

vagus nerve

What are the stimulation effects of the parasympathetic system on the heart?

- Decrease HR by decreasing SA and AV node pacing rate | - Does not affect myocardial contractility (force)

What nerves are responsible for the sympathetic nervous system?

spinal T2-T4 segments (thoracic vertebra) | **Pass into the cardiac plexus to the SA node (right) and AV node (left)

What are the stimulation effects of the sympathetic nervous system?

- Increase HR via increasing SA and AV node pacing rate | - Increase in myocardial contractility (force, therefore cardiac output)

The pressure developed in the ventricle is proportional to the ventricular end-diastolic volume, i.e., increased stretch of myofibrils results in increased contractile force, resulting in increased stroke volume

Frank-Starling Law

What are three things the heart has in reference to oxygen?

- -An abundant blood supply providing O2 and nutrients - -High myoglobin content (muscle O2 “storage” protein) - -Many mitochondria (fat metabolism, requires more O2)

Myocytes derive most of their energy from aerobic metabolism. Does this require continuous supply of O2?

yes

What are the sources myocytes receive energy from?

Glucose (35%) Ketones and amino acids (5%) Fat (60%)

Pericardium is a fibrous sack which _____ and _____ it from thoracic viscera

encloses the heart; separates

What are the two layers of the pericardium?

1. Visceral: thin inner layer, directly attached to the myocardium 2. Parietal: tough, fibrous out layer

Space between the visceral and parietal pericardium (the pericardial sac) contains 5 to 30 mL of clear ______. Lubricates to minimize what?

pericardial fluid; | friction

The heart is fully developed by pregnancy week ____.

7 or 8

In utero function of ductus arteriosis and foramen ovale is to _____.

reduce blood flow to lungs

Within a few days after birth the ductus arterioles closes off completely and forms what?

ligimentum arteriosum | *Sometimes remains open (“patent ductus arteriosis”)

_____ (between atria) closes at birth and gradually fuses together over several weeks or months.

Foramen ovale | *Sometimes remains open (“patent foramen ovale”)

Rate x stroke volume = ____

total cardiac output

Test 2 Cardiac System Flashcards

(93 cards)