The volume of blood ejected by EACH ventricle per UNIT of TIME

Cardiac Output =

HR x SV

= beats/min x mL/beat

=L/min

Cardiac Output at rest

5L/min

Cardiac output to -->

1) the brain

2) the kidneys

3) cardiac muscle

1) 13%

2) 20-25%

3) 4%

Normal HR =

80 beats/min

Normal SV =

70-80 mL/beat

Cardiac output usually refers to which ventricle?

The left! but SV is usually the same for both :)

Stroke Volume is affected by ?

1) venous return 2) peripheral resistance and 3) the ANS

If HR increases to 90 beats/min, the result of CO is?

increased proportionally

If HR increases from 90-140 beats/min, the result of CO is?

CO stays the same, because SV decreases in proportion. This is because the ventricles have LESS TIME to fill during diastole

If HR increases over 140 beats/min, the result of CO is?

CO decreases because the SV decreases faster than the HR is increasing!

Starling's Law of the Heart-

If all other factors remain constant, the stroke volume is determined by the force of the contraction. The heart will automatically eject ALL of the blood that enters it over a BROAD range of volume.

The force of contraction of cardiac and striated muscle is proportional to the ?

degree of stretch

UP TO A LIMIT!!!

The strength of contraction increases in proportion to the  ____ of the ventricle muscle fibers? This implies ___?

length of the fibers, this implies that all the extra blood from an increased venous return is pumped out!

End-Diastolic volume -

The quantity of blood in the ventricles just prior to their contraction. This amount determines the length of the ventricle muscle fibers.

Pre-Load -

The degree of tension of the muscle when it begins to contract. It is determined by the end-diastolic volume.

According to Starling, any change in ____ has a direct effect on the SV and therefore ____.

Any change in the venous return, ultimately the CO is effected.

Increase in the venous return causes?

An increase in the strength of the contraction, which causes an increases the SV, which increases the CO.

Even though the change is indirect, changing BP has similar results as changing ____?

Venous return

Increased blood pressure, increases the ____ Which decreases the ___? This causes an increases in _____ Which _______ the strength of myocardial contraction, which increases the ____.

BP increases the resistance, which decreases  the SV. This increases the end diastolic volume which increases the myocardial contraction strength, which increases the SV.

After the initial adjustment by the starling law what happens?

other factors begin to regulate the strength of the contraction and thus the CO.

The factors that regulate the strength of contraction- (what do they involve and how are they defined)?

Involve the metabolism of the myocardium and DON'T depend on the degree of stretch of the fibers. These are considered homeometric regulation. Once they take over the heart size and degree of muscle stretch is returned to normal.

Blood flow can go in which direction?

ONLY ONE DIRECTION

A-V valves are also known as -

 cuspid valves

The valves between ventricles and the great arteries are known as -

Semi- lunar

Heart sounds are from?

closing of the valves

The first heart sound ____ corresponds to _____?

Lub, closure of the A-V valves

The second heart sound ____ corresponds to ______?

Dup, closure of the semilunar valves

The second heart sound has a _____ frequency compared to the first sound.

  Higher frequency

Sounds of the aortic semilunar valve are heard in the ___ intercostal space at ___ sternal margin.

2nd, right

Sounds of the _______ valve are heard in the ___ intercostal space at left margin.

Pulmonary semilunar valve, in the 2nd space.

Sounds of the mitral valve are heard _____ in the 5th intercostal space in line with _____.

over heart appex. in the 5th intercostal space, in line with middle of clavicle

Sounds of ______ valve are typically heard in right sternal margin of 5th intercostal space. ______ include over the sternum or ______ in 5th intercostal space.

tricuspid valve, variations include over the sternum or over the left sternal margin.

Bicuspid closes before or after tricuspid valve?

slighty before.

This valve is the 1st "lub" of ventricle systole

Mitral/bicuspid valve

Accounts for the "dub" sound

aortic/pulmonary valves in ventricle diastole

Connective tissue covered with endothelial tissue?

The leaflets of the valves

What is a commissure?

Division between the cusps

What does the Chordae Tendinae anchor and to what??

Anchors ventricular surface of the A-V valves to the ventricular wall.

What is the Chordae Tendinae made up of and what is its function?

Elastic cords that are inserted into the papillary muscles, composed of myocardial tissue. It contracts simultaneously with the ventricles assuring their proper closure during ventricular contraction, preventing blood reflux.  

Chordae tendinae is attached to?

the A-V valves, the tricuspid valve flap and papillary muscles

The cardiac CYCLE is divided into?

Diastole and Systole

Cardiac cycle is defined as -

The cardiac events that occur from the Beginning of one cycle to the beginning of the next!

Each cycle is initiated by ______, in the _____?

spontaneous generation of an action potential, in the sinus node (S-A node).

Describe the path that an action potential of the heart cycle takes -

1) travels through both atria. 2)reaches the A-V node 3) goes to the bundle of his, 4) then bundle branches then 5) purkinjie fibers and finally 6) ALL cardiac fibers

Why is there a delay in the impulse from the atria to the ventricles?

This delay allows the atria to contract a little before the ventricles, contributing to ventricle filling.

What is the conductive system composed of?

Specialized muscle tissue. It function is NOT contraction but IMPULSE GENERATION and TRANSMISSION.

How many components are in the cardiac cycle?

4, they are all typically accomplished in less than 1 second

What passive process determines the opening and closing of the valves?

The pressure gradient across them.

When does the cycle technically begin?

At the end of systole, when all valves are closed and BOTH atria are being filled.

Describe the atria at the start of the cycle.

Both atria are being filled with blood returning to the heart. Pressure within the atria increases until it is higher than in the relaxed ventricles. This leads to the opening of the A-V valves, starting ventricular filling.

What prevents the closing of the A-V valves during ventricular filling?

Atrial contraction that completes emptying of the atria. (helps in better ventricular filling). In this case, the valves stay open even though intraVENTRICULAR pressure is greater than atrial pressure.

How effective is atrial contraction?

Technically the heart can stil function without atrial contraction but it increases ventricular pumping efficiency by 40-50%

What phases does systole consist of?

The contraction phase (I)

and the

Ejection phase (II)

What phase is the contraction phase?

I

What phase is the ejection phase, and what part of the cardiac cycle is it in?

II, systole

What phases are in the diastole phase?

The relaxation phase (III)

and the

Filling phase (IV)

What does P wave represent?

Atrial depolarization. It occurs just before atrial contraction

What does the QRS complex represent?

Ventricular contraction

What does the T wave represent?

Repolarization of the ventricles :)

Where is the impulse generated and what happens?

At the S-A node, atrial excitation begins.

The impulse is delayed where?

At the A-V node.

The impulse passes to the heart apex where, and what happens?

Through the bundle branches, ventricular excitation begins.

Ventricular excitation is complete at the?

Purkinjie fibers

The cardiac cycle can also be described in terms of the _____ of _____?

phases of ventricular pumping, there are 8 phases.

How many phases of ventricular pumping are there in diastole?

5, protodiastole, isometric relaxation, rapid inflow, diastasis, and atrial systole 

Protodiastole is:

The fall in intraventricular pressure and closing of the aortic valve.

Isometric relaxation is:

A phase in ventricular pumping diastole, ventricle is closed, muscle is relaxing but NOT lengthening. Also called isovulmetric relaxation.

Rapid inflow:

A phase in ventricular pumping diastole. Occurs immediately after the opening of the AV valves. (also called rapid filling/ ventricular filling)

Diastasis:

A phase in ventricular pumping diastole. Almost no blood is flowing from the atria. Ventricular filling?

Atrial Systole:

A phase in ventricular pumping diastole. Atrial contraction leads to increase in ventricular filling. Atrial contraction.

3 Phases during systole:

1) Isometric contraction 2) Rapid ejection and 3) Reduced ejection.

Isometric Contraction:

Phase during systole, just after the beginning of ventricular systole BUT before the opening of the semilunar valves. Also known as isovulumetric contraction phase.

 Rapid ejection phase:

A phase in systole. Semi-lunar valves open and blood is pushed into the great artery. Ventricular ejection phase.

Reduced ejeciton phase:

A phase in systole. Ventricles remain contracted but LITTLE blood is pumped out.

Isovulumic contraction: Semi-lunar and AV valves are____?

closed, this is systole

Period of ejection: Semi-lunar and AV valves are____?

Semi-lunar valves are opened

 AV valves are closed

This phase is during systole

Period Isovolumic relaxation: Semi-lunar and AV valves are____?

Closed. This is phase is during diastole

Pressure ventricular filling: Semi-lunar and AV valves are____?

Semi-lunar valves are closed. AV valves are open. This is during diastole.

Active Ventricular Filling: Semi-lunar and AV valves are____?

Semi-lunar vavles closed and AV valves are open. This is during diastole.

Sensors that respond to distention of artery wall as a result of increase in pressure. They send impulses and activates the cardioinhibitor center, which triggers parasympathetic stimulation

Baroreceptors

Baroreceptor stimulation leads to:

Stimulation of the parasympathetic system. HR, cardiac contraction, CO  and BP decreases

If baroreceptors are not stimulated, what is?

If baroreceptors are not stimulated this means BP has decreased, there is no parasympathetic discharge and sympathetic system acts through cardioacclerator center.

There are ___ baroreceptors that are basically nervous endings located in the _____ and _____. These receptors are known as____?

2 baroreceptors: in the AORTA and the CAROTID ARTERIES.  They are known as the aortic sinus and the carotid sinuses.

The aortic sinus is located where and is innervated by what CN?

located in the aortic arch and inervated by the vagus CN.

The carotid sinuses are located _____ and are innverated by the _____.

at the bifurcation of each common carotid innervated by the carotid sinus nerves or nerves of Hering.

Homeostasis for increase in arterial blood pressure:

Homeostasis for decreased arterial blood pressure:

These receptors respond to O2 and CO2 concentrations in the blood and not to variations in pressure

chemoreceptors, they are located NEAR the aortic and carotid and aortic bodies

Chemoreceptors in the PNS respond to:

decrease in O2, increase in CO2 and increase in H+

Chemoreceptors in the CNS respond to:

increase in CO2 and increase in H+ but NOT O2

Carotid bodies are immediately rostral to ____?

The bifurcation of EACH common carotid artery

Aortic Bodies are located:

They are scattered in the tissue BETWEEN the aorta and the pulmonary arteries.

The exact relationship between chemoreceptors and cardiac function is unknown. Hypoxia causes ____ in CO but it is thought to be the result of _______. If hypoxemia is limited to the carotid and aortic bodies the heart action is _____ or ______.

increase, stimulation of the medulla oblongata.

decreased or unchanged.

This value adjusts the CO to the individual person's body size by representing ______ relative to _________ of body surface area. 

= Cardiac index. adjusts CO by representing blood flow relative to a square meter of body surface area.

The normal adult cardiac index range is -

2.5 to 4.2 L/min/m²

Cardiac index =

CO (l/min)

___________

Body surface area m²

Body surface area=

Height (cm) x Weight (kg)

-----------------------------------

3600

Blood flow - (def)

is the amount of blood that passes a given point in the circulation in a given period of time.

Blood flow (Q) =

change in pressure

----------------------------

resistance

Resistance is expressed in:

Peripheral resistance unit

IF change in pressure = 1mmHg AND Q=1 ml/sec THEN PRU = 1

Which factor plays the greatest role when determining the rate of blood flow through a vessel?

The diameter of blood vessel

Poiseuille's law:

This law demonstrates that the rate of blood flow is directly proportional to the 4TH power of the radius of the vessel

The heart has a specialized system for:

1) generating rhythmical impulses to trigger contraction of the heart muscle

2) conducting these impulses quickly throughout the heart

When working properly, the atria contract how long before ventricle contractions?

1/6 th of a second

The heart also has a system that allows all portions of the ______ to contract ALMOST simultaneously.

ventricles

Cardiac fibers have the capacity to ____. This can cause _______ and _____. This is especially ture for these fibers____?

self-excitation, this can cause automatic rhytmical discharge and contraction. This is especially true for the SA node fibers of the conduction system.

The potential of the SA fibers between discharges = 

This is because??

-55-60, because they are naturally leaky to Na+

Potential for the ventricles muscle fibers

-85-90 mv

SA fibers conduct potentials _____ than ventricular muscle fibers.

There are ____ types of membrane ion channels that play an important role in causing the voltage changes of the action potential.

3,  fast sodium channels, slow calcium-sodium AND potassium channels

What membrane ion channel is responsible for the spike-line onset of the action potential in the ventricular muscle

The fast Na+ channels, because of the rapid influx of Na+ to the interior of the fiber

The plateau of the ventricular action potential is due to:

The slower opening of the slow Ca2+/ Na+ channels

What happens to the K+ channels and what is the result?

They have increased opening that allows for large amounts of diffusion of K+ out of the fiber, This returns the membrane potential to its resting level

At resting level describe the Na+ and Na+/Ca+ channels-

The Na+ are permanently closed and only the slow Na+/Ca+ channels can open.

Because [Na+] outside is high AND because of the _____ inside, there is a tendency for Na+ to leak inside. The ____ fibers have a moderate # of channels open to Na+. This influx in Na+ causes a rise in membrane potential. The threshold for these fibers is ______. Once threshold is met ______ is activated.

1) negative charge inside. 2) SA fibers 3) -40 mv

 4) Ca+/Na+ channels are activated and the sudden entrance of Ca2+ and Na+ causes an action potential :)

The natural leakiness of SA fibers to Na+ causes their self-excitation. But they are not depolarized all of the time because ______?

Because the Ca2+/Na+ channels close within 100-150 miliseconds AFTER opening, almost immediately and to the same time that the K+ channels are opening!

Hyperpolarization is due to ___ and it signals the ____?

1) the K+ channels remaining open for a little more time forcing more K+ out and a more negative (hyperpolarized) charge inside.  It signals a -55 -(-60) mV, 2) The end of action potential.

Hyperpolarization doesn't last because ____?

The K+ channels are closing while Na+ is still leaking in. (slowly climbing to the -40 mV threshold)

Rhytmicity is possible because?

It is never negative enough in the cell to keep all of the channels closed.

Standard limb leads =

I, II, and III

Positive and negative input for I lead?

left arm and right arm

Positive and negative input for II lead?

Left Leg, Right Arm

Positive and negative input for III lead?

Left leg, left arm

Augmented limb leads?

aVR, aVL, aVF

Positive and negative input for aVR?

right arm, left arm +left leg

Positive and negative input for aVL?

Left arm, right arm plus left leg

Positive and negative input for aVF?

left leg, left arm + left arm? :P

Precordial leads =

V1- V9, wilson central terminal is the negative input for all.

Positive input for V1?

right sternal margin, 4th intercostal space

Positive input for V2?

Left sternal margin, 4th intercostal space

Positive input for V3?

midway between v2 and v4

Positive input for V4?

left midclavicular line, 5th intercostal space

Positive input for V5?

left anterior axillary line

Positive input for V6?

left midaxillary line

Positive input for V7?

posterior axillary line

Positive input for V8?

Posterior scapular line

Positive input for V9?

Left border of spine

question slide:

The right sided precordial leads V3R to V6R are taken in mirror image positions on the right side of the chest

leads v5 to v9 are taken in the same horizontal plane as....?

q is ______ negative

R is always _____

S is _____ ______

P and T________

1) ALWAYS

2) POSITIVE

3) ALWAYS NEGATIVE

4) may be + or -

When no R wave is present......

one large negative QS wave exists.

How much voltage does 1 mm box represent?

0.1 mV, 5 boxes carries 0.5 mV

Normal Sinus Rhythm:

Description-

Treatment-

Questions-

Next steps-

1) 60-100 bpm

each complex is complete

no wide, bizzare, ectopic, early or late complexes

2)monitor vital signs, check bp

3)ampler?

4)monitor pts. condition

Arrhythmias originating in the sinus node?

1) sinus tachycardia

2) sinus bradycardia

3)sinus arrhythmia

4) sinus arrest

 5) sinus exit block

6) SA reentry

These arrhythmias (in the SA node) are physioogical or pathological

Physiological sinus node arrhythmias

these arrhythmias are the responses to fevers and sympathetic stimulation

Pathological sinus node arrhythmias

are associated with sinus nodal disease

Sinus arrhythmia

Name-

Description-

Treatment-

Question-

Next Step-

1) sinus arrhythmia (normal variation)

2)60-100 beats per min

all intervals except R-R are within normal limits

3)monitor vital signs

4)AMPLER?

5)monitor this. however, this is a natural variation caused by normal breathing!

Sinus Tachycardia-

Name-

Description-

Treatmet-

Question-

Next Step-

1) sinus tachycardia (normal fast)

2) 100 -160 bpm

p waves may be buried in the previous t wave and all intervals except rate are within normal limits

3) AMPLER do you take digoxin?

4) monitor and treat underlying condition

Sinus bradycardia

Name-

Description-

Treatment-

1)sinus bradycardia (normal slow)

2) less than 60 bpm, everything but rate is normal

3)treatment - monitor, check bp, normal in young healthy pts if normal bp. if pt is hypotensive,cool clammy, shocky, chest pain or change in mental status  consider Atropine. IF ecotopic activity is present consider atropine b4 lidocaine.

Premature Atrial contractions -

Name-

Description-

1) premature atrial contractions (early ectopic atrial activity)

2) usually 60-100 bpm but varies on atrial beats created

premature atrial contractions are ectopic beats that occur in the context of other rhythms

P waves look different, may be smaller or peaked vs. normal p waves.

Atrial tachycardia -

160 - 250 bpm

the SA node is no longer the dominant pacemaker

characterized by rapid rate and regular rhythm, sudden in onset and often terminates abruptly. May be followed by a pause.

the p waves in this case are different from sinus p waves because atrial pacemaker is ectopic?

Atrial Flutter -

Name -

Description -

1) F waves, very rapid atrial rate, think of atrial fluuuuutttter!

 this is a rapid, remarkable form of  atrial tachycardia, it is usually paroxysmal, lasting for periods varying from seconds to hours and maybe even days.

2) fast, constant, firing of an ectopic focus, 240-360 bpm, has f waves instead of p waves,

the ventricular rate depends on the conduction raio

complexes are incomplete

upside down resembles a saw tooth pattern

Atrial fibrilation -

Name -

Description-

1) atrial fibrilation (f waves) (uncoordinated, fast atrial activity)

2) atrial rate appears at a baseline 350 -600 beats per minute may be coarse and easy to count or fine and hard.

no p waves but f waves

rate is 100-160 bpm

R-R interval is always irregular because of chaotic stimulation from atria

atrial fibrilation is the disorganized ______ of the atria resulting in irregular heartbeat, hemodynamic compromise, risk of ______, and an increased mortality. It may be acute (onset) within 24-48 hours, rapid heart rate. Subacute _______ rate or chronic (paroxysmal, persistent, or permanent)

Treatment involves -

1) electrical activity

2) thromboembolism

3) (controlled heart rate)

treatment involves - antithrombotic therapy, ventricular rate control, attempts to convert to normal sinus rhythm.