Heart

What are the ways in which cardiac muscle and skeletal muscle are different?

*Shorter fiber length in general in cardiac muscle and typically one nucleus per cell (fiber) rather than many. **Stimulus for contraction in cardiac muscle is via intrinsic cardiac conducting system rather than brain or spinal cord as in skeletal muscle **Can't be fatigued as skeletal muscles can. **Can't be tetanized as skeletal muscle can **Metabolism is aerobic in cardiac muscle (Require oxygen)--skeletal muscles function anaerobically (for a period of time) **Sources of Calcium for the heart are endoplasmic reticula of cardiac muscle fibers and extracellular fluid. Skeletal muscle uses Calcium that is stored in endoplasmic reticula of muscle fibers.

What are the ways in which cardiac muscle and skeletal muscle are alike?

*The trigger for contraction is Calcium in both cardiac and skeletal muscles.

Describe the path of a red blood cell from the time it enters the heart from the inferior vena cava until it leaves the heart via the aorta, describing in succession every chamber it enters, every valve it crosses every vessel it traverses and any organ, beside the heart, that is in its pathway between inferior vena cava and aorta.

...

Of the following, what happens if the heart rate increases form 75 beats per minute to 150 beats per minute. a) The time spent in diastole decreases b)The time spent in both diastole and systole decreases c)The time spent in diastole decreases more than the decrease in time spent in systole

ALL OF THE ABOVE

Possible outcomes of arterioscleotic coronary artery disease include which of the following? a) Chronic ischemia b) Infarction c) Disturbance of heart rhythm d) Decreased contractility of the myocardium and decreased cardiac reserve, manifested as acute or chronic congestive heart failure. e) Sudden death

ALL OF THE ABOVE

What is the purpose of the 100 millisecond delay in conduction at the AV node?

Allows time for the atria to contract before ventricular contraction begins.

Blood always flows from an area of ______________ pressure to an area of ____________ pressure.

Always from an area of higher pressure to an area of lower pressure.

Ventricular contraction begins where, at the apex or at the base of the heart (recall anatomic orientation of the heart)?

Apex

Define stroke volume. A "normal" SV sould be approximately ______ ml

Approximately 60 ml + / - (about 2 ounces)

The names of the valves sbetween the atria and the ventricles?

Atrioventricular valves R. and L.

What is the technical term for the characteristic of cardiac muscle?

Automaticity or autorhythymicity

From one heart beat to the next which of the following does NOT occur? a) The atria contract (separately from the ventricles) than relax. b)The atria and the ventricles contract simultaneously, than relax. c)The ventricles contract (sparately from the atria), than relax

B

In a cardiac cycle, which of the following is/are true? a) During atrial diastole, thrity percent of the blood in the atria flows into the ventricles. b) During atrial diastolek seventy percent of the blood in the atria flows passively into the ventricles. c) The ventricles do no fill passively, b/c they are filled hby atrila contracion only.

B

What closes the aortic and pulmonic valves after each ventricular contraction?

Back Pressure

What one physiologic principle determines whether blood flows from vena cave to atria or atria to ventricles or ventricles to aorta and pulmary turnk?

Blood always flows from an area of higher pressure to an area of lower pressure.

Do the ventricles fill with blood passively (blood flowing into them from the atria through the AV valves) or as a result of atrial contraction, or both?

Both: filling of the ventricles from the atria is 70% passive, 30% active (via atrial contraction)

Fluid that collects around the outside of the heart but within the (thin but inelastic) pericardial sac can push in on the heart and reduce its ability to fill with blood and thus severely affect its ability to pump blood effectively. This condition is called (two words)?

Cardiac Tamponade

The difference between resting and maximal cardiac output is called the ___________ ________.

Cardiac reserve

You were doing an ECG on a patient. Once the tracing started it showed a normal heart rate and rhythm. All of a sudden, you see a straight line on the ECG. How can you quickly tell whether this indicates absence of a heart beat or a malfunction in the ECG machine?

Check the patients pulse/breathing rate.

The term Chronotropic refers to (rate / force) of cardiac muscle contractionk and the term inotropic refers to (rate / force) of cardiac muscle contraction.

Chronotropic: rate of contraction; Inotropic: force of Contraction

The second heart sound, S2 (the dupp) corresponds to what that is happening mechanically in the heart?

Closure of the aortic and pulmonary valves

The first heart sound, S1 (the lubb) corresponds to what that is happening mechanically in the heart?

Closure of the atrioventricular (AV) valves.

Most of the veins of th eheart drain into what larger venous structure on the posterior aspect of the heart, and into which chamber of the heart does this venous structure drain its blood?

Coronary Sinus; Right Atrium

Define cardiac output and five the units of measurement. Cardiac output is a measure of _____________ _____________ over time.

Definition: volume of blood pumped by the heart in one minute, measured in L/min It is measure of ventricular efficiency over time.

The (two-word) name of the tough fibroelastic tissue that surrounds the heart valves and physically (but not electrically) separates the atria from the ventricles?

Fibrous Skeleton

The heart is rotated to the left or to the right on its longitudinal axis?

Left

The heart is located in this central space in the chest (between the lungs)?

Mediastinum

Which part of the brain stem regulates sympathetic and parasympathetic influence on the heart?

Medulla Oblongata

Can cardiac muscle be tetanized?

NO

Do autonomic or hormal stimulation have a role in initating the heart beat?

NO

Which of the following bring about an increase in cardiac output? a) Increase in venous return b) Increase in EDV c) Increase in SV d) decrease in ESV e) Increase in HR f) Increase in contractility g) Increase in afterload

NO FOR AFTER LOAD; YES FOR THE REST

Do the aortic semilunar valve and the pulmonary semilunar valve open as soon as the ventricles begin to contract? Why or Why not?

No. The ventricles ahve to generate enough force to overcome the existing pressures in the systemic and pulmonary circuits (aorta and pulmonary trunk) between ventricular contractions (in other words, the existing pressures in these circuits during diastole).

Blood ejected from the right ventricle traverses which valve, and blood ejected from the loeft ventricle traverses which valve?

Pulmonic Semilunar (pulmonary) valve Aortic Semilunar (aortic) valve

The chambers of the heart are?

R. and L. atria; R. and L. ventricles

The names of the parts of the conducting system of the heart, the physical location of each part and the order of transmission of a conducting impulse, beginning at the sinoatrial node?

Sinotrial (SA) node (R. atrium) internodal pathways (atria) atrioventricular (AV) node (R atrium) atrioventricular bundle or bundle of His (interventricular septum) R. and L. bundle branches (interventricular septum) Purkinje fibers (apex of ventricles and upward in ventricular walls.

Define Bradycardia

Slowness of the heart beat, conventionallya reate less than 60 beats per minute...

The two factors that determine ventricular effciency over time:

Stroke volume and heart rate.

Define infarction

Sudden insufficiency of blood supply that produces an area of necrosis; in the heart this is called myuocardial infarction or in lay terms heart attack...

The right atrium receives blood mainly from these three sources? (It also receives blood from a few anterior cardiac veins)

Superior Vena Cava Inferior Vena Cava Coronary Sinus

Which division of the autonomic nervous system predominates in a person who is frightened and has a hart rate of 110 bpm (beats per minute)?

Sympathetic

The heart pumps blood through these two circuits?

Systemic and Pulmonary

Systole refers to ____________, and diastole refers to __________.

Systole: contraction (of atria or ventricles Diastole: relaxation (of atria or ventricles)

Normally, what keeps the AV node from establishing a heart rate in the range of 40-60/minute?

The faster firing rate of the SA node overrides teh AV node and keeps it from firing (unless the SA node is not functioning normallhy for some reason, in which case the AV node takes over teh rate of firing)

Define Ectopic Pacemaker

The generation of conducting impulses from locations in the heart other than the normal conducting system, whether in the atria or the ventricles. Ectopic stimuli can establish a faster firing rate and/or bypass or override the SA and AV nodes and disrupt the rhythm of the heart. ...

Define end-diastolic volume. How is venous return related to EDV?

The volume of blood in the ventricle at the end of ventricular diastole and just before ventricular systole.

Define en-systolic volume. How is contractility of the heart related to ESV?

The volume of blood remaining in the ventricle immediately after ventricular systole

What is the purpose of the chordae tendineae?

To put tension on the cusps of the atrioventricular valves prior to ventricular contraction in order to prevent prolapse of the valves into their respective atria with resultant reflux of blood from ventricles back into atria.

In spite of teh overall apparent size discrepancy, the R and L ventricles contain equal volujes of blood and eject equal volumes of blood simultaneously with each ventricular contraction, True or False?

True

Can the electrocardiogram show all of the following? a)Heart Rate b) Regularity or irregularity of the heart rhythm c) Ability/inability of myocardial cells to conduct normal action potentials

YES to ALL of the ABOVE

Can on edetermine a person's heart rate by: a)Palpating a pulse at the wrist? b)Listening to the heart beat with stethoscope? c)Counting the R waves on an ECG tracing over a specific timed interval?

YES to all of the above.

A 40 year old man went for his annual physical, which included lab tests, ECG and a chest x-ray. His blood pressure was 120/80, and his heart rate was 82 in the doctor's office. AQ representative segment of LEad II of his ECG is shown below. Is this normal sinus rythm? Tell why are why not.

YES, it is a normal sinus rhythum. Reason: The rate is normal The rhythem is normal Every P wave is followed by a QRS complex The ST segment is isoelectric The duration of the P wave and the QRS complexes are normal The QRS is followed by a normally configured T wave.

Is it ture that in the absence of neural or hormonal stimulation, cardiac muscle will contract on its own?

Yes

Is it ture that at some point in the cardiac cycle the atria and the ventricles are in diastole simultaneously?

Yes.

Conducting cells of the heart have a distinguishing characteristic that is the basis of automatically, or autorhythmicity--the abilityof the heart to beat on its own. State this characteristic by completing in five words the folling sentence: The conducting cells of the heart can not maintain........

a stable resting membrane potential.

THe range of the inherent firing rate of: a) the sinoatrial (SA) node b) the atrioventriculoar (AV) node c) the purkinje fibers

a) 80-100/minute b) 40-60/minute c) 20-40/minute

Regarding the blood supply of the heart: a) The arteries that supply it orginate where (from what large artery?) b)How many main arteries are their names?

a) Aorta b) Two; Right and Left Coronary Arteries

By definition: a) A heart rate that is greater than 100 beats per minute is called? b) A heart rate that is less than 60 beats per minute is called?

a) Tachycardia b) Bradycardia

Define Dysrhythmia

defective or abnomal rhythm...

Define ischemia

insufficient blood supple to a region of the body. In the heart, insufficient blood supply to the myocardium mainly due to arterial narrowing and/or vasospasm...

Define arrhythmia

loss or absence of rhythm...

Define Fibrillation

rapid, uncoordinated contraction or twitching of individual muscle cells that impairs or prevents normal function that may occur in atria or ventricles. ...

The normal/natural pacemake of the heart is the?

sinoatrial node

Define angina pectoris

sudden onset of spasm of severe pressure and constricing pain in the cheast due to myocardial ischemia; may readiate to one or bothshoulder upper limbs, neck, jaw, or back, or epigastrium; can be precipitated by increased work load on the heart as in physical exertion by emotional excitement and by exposure to cold. ...

The heart is positioned erect (as shown in textboods and manuals for clarity of demonstration of its features) or tilted posteiority?

tilted posteriority

Do the ventricles normally contract at the same time or at different times?

Same time.

The SA node fires: a) just before the atrial contract b)simultaneously with atrial contraction c)after atrial contraction

A

The heart is positioned between which rib about and which rib interspace below?

2nd & 5th

The normal cardiac output in an average-sized adult male is somewhere in the range of ______ L/min

5-6

If the span of time from the beginning of one heart beat to the beginning of the next is 800 milliseconds, what is the heart rate (number of heart beats in the space of one minute)?

75 beats per minute. Remeber: divide the length of the cardiac cycle INTO 60; you want to now how many cardiac cycle are occurring in one minute. 800 millisaeconds = 0.8 second 1 beat / 0.8 second x 60 seconds/ minute = 75 beats per minute.

The heart rest on the __________?

Diaphragm

What is an ectopic pacemaker? Can an ectopic pacemaker: a) establish a faster firing rate than the SA node would normally establish and/or b) bypass or override the inherent firing rate of the SA and AV nodes?

Ectopic Pacemaker: abnormal pacemaker, not in the typical conducting system location/sequence a) Yes b) Yes

The electrocardiogram (ECG) is a graphical recording of?

Electrical events occurring at different location in the heart.

Preload is directly proportional to which -- end-diastolic volume or end-systolic volume

End-Diastolic volume (EDV)

Name the layers of the heart wall from outside to inside.

Epicardium (also called visceral pericardium) Myocardium Endocardium

The left ventricle pumps more blood per contraction than the righ bentricle b/c the systemic circuit is larger than the pulmonary circuit. True or False?

FALSE

An increase in venous return to the right atrium triggers stretch receptors in the right atrium. Does this lead to an increase in the heart rate or a decreases in the heart rate?

Increase

In a person with hypertension, say 180/120, is afterload increased or decreased?

Increased

On an ECG tracing: The P-wave The QRS complex and The T-wave all represent what?

P-wave: atrial depolarization QRS complex: ventricular depolarization T-wave: ventricular repolarization

When you are asleep, the natural rythm of the SA node is inhibited by autonomic input via __________________ nerves?

Parasympathetic (via cardiac branches of the vagus nerves.)

The heart is surrounded by a specific thin-walled structure call the?

Pericardium/pericardial sac

Define a cardiac cycle (in simplest terms)

Period of time measured from the beginning of one heart beat to the beginnin of the next.

Define Tachycardia

Rapid beating of the heart, conventionally applied to rates over 100 beats per min

What is happening, in what parts of the heart, righ after the QRS complex of the ECG?

Ventricular contraction.

Is it ture that in a normal heart each QRS complex should be followed by a palpable peripheral pulse?

YES

Whithin the limits of effcient contractility of cardiac musle cells, is it correct to say that as EDV increases, SV increases and thus CO increases?

YES