phsyio exam 3

Describe and draw the circulatory routes

Pulmonary: closed loop of vessels, carrying blood between heart and lungs

Systemic: circuit of vessels, carrying blood between heart and other body systems

Location and cavities of the heart

Ventral, thoracic, mediastinum, pericardial

Coverings of the heart

Visceral pericardium; serous membrane on the heart

Parietal pericardium: serous membrane lining the cavity

What are the layers of the heart?

Endothelium myocardium epicardium

Endothelium

Thin inner tissuw

Epithelial tissue which lines entire circulatory system

Myocardium

Middle layer, composed of cardiac tissue, constitutes bulk of heart wall, does contraction

Epicardium

Thin external layer that covers the exterior of the heart also known as visceral pericardium

What are the four chambers of the heart?

Atria and ventricles

Job of the atria

Upper chambers that receive blood returning to the heart and transfer it to lower chambers

Job of the ventricles

Lower chambers which pump blood from the heart

What is the job of the septums ? interventricular interartial

Continuous muscular partition that prevents mixture of blood from the two sides of the heart

What are the two types of valves?

Atrioventricular and semi lunar

Right and left AV valves are positioned between the ____ on right and left sides

Atrium and ventricle

What is the purpose of the AV valve?

Prevent backflow into atria from ventricles during ventricular contraction

What are the two types of AV valves?

Right AV-tricuspid valve

left AV- bicuspid or Mitral valve

Function of chordae tendinae

Fibrous chords which prevent valves from being averted and inverted during ventricular contraction

Function of papillary muscles

Anchor the cordae tendinae to the muscular ventricular wall

function of semilunar valves

Lie at juncture where major arteries Leave ventricles

prevent backflow of blood into ventricles

What are the two types of semilunar valves?

Aortic valve, which is between the left ventricle and the aorta

Pulmonary valve, which is between the right ventricle and the pulmonary trunk

Arteries definition

Carry blood away from ventricles to tissues

Veins definition

Vessels that return blood from tissues to the atria

Path of blood flow throughout the heart and body

1: Deoxygenated blood enters right atrium from the superior vena cava and inferior vena cava and coronary sinus

2: tricuspid valve

3: right ventricle

4: pulmonary semilunar valve

5: pulmonary trunk → pulmonary arteries → lungs

6: oxygenated blood enters left atrium from pulmonary veins

7: mitral valve

8: left ventricle

9: aortic semilunar valve

10: aorta → body

Definition of autorhythmicity

Heartbeats rhythmically as result of action potential it generates by itself

What are the two types of cardiac muscle fibers?

Contractile cells and pacemaker cells

Describe contractile cells

99% of cardiac muscle cells, do mechanical work of pumping, normally do not initiate on electrical activity

Describe pacemaker cells

Do not contract, specialized for initiating action, potential responsible for contraction of working cells

Draw the cell with calcium sodium and potassium where they are in higher concentration and draw arrows to show where they will diffuse

Draw pacemaker potential and label the changes in permeability of the ions that are responsible for generating the pacemaker potential

list the steps involved in the generation of a pacemaker potential

1. Sodium channels open at -60mV

2. Calcium T type slow leak into threshold (-40)

3. L Type open= depolarize

4. Potassium open to repolarize

5. Start over again with sodium= MP drifts up

Deoxygenated blood enters what chamber of the heart?

RA

What veins deliver oxygenated blood to the heart

Pulmonary veins

What valves do not have chordae tendinae

Semilunar valves: pulmonary and aortic

What valve prevents blood from re-entering the right atrium

Tricuspid valve

What chamber receives blood from the coronary sinus?

Right atrium

What are the first two branches of the aorta?

Right and left coronary arteries

where are the pacemaker cells found in the heart?

SA node

If the SA and AV node do not work, what will be the pacemaker and what will the heart rate be?

Purkinje fibers

20-40

List the steps in the conduction circuit

1. cardiac impulse originates at SA node

2. action potential spreads throughout right and left atria

3. atria contract

4. impulse passes from atria to ventricles through AV node

5. action potential briefly delayed at AV node

6. impulse travels rapidly down interventricular septum by means of bundle of his then to L and R Bundle branches

7. impulse rapidly disperes throughout myocardium by means of Purkinje fibers

8. rest of ventricular cells activated by cell-to-cell spread of impulse through gap junctions

9. ventricles contract

What initiates the cardiac cycle?

Electrical impulses from the sinoatrial (SA) node.

What mechanical event follows SA node activation?

Atrial contraction (atrial systole).

What is the role of the atrioventricular (AV) node in the cardiac cycle?

It delays the impulse to allow the atria to fully contract before the ventricles do.

Through which structures does the impulse travel after the AV node?

The Bundle of His and Purkinje fibers.

What mechanical event is triggered by ventricular depolarization?

Ventricular contraction (ventricular systole).

What happens during ventricular repolarization?

The ventricles relax (diastole), allowing the heart to refill with blood.

Draw and label the ECG.

If the SA node is not firing, what would you see (or not see) on the ECG and what would
the rate be?

absent p waves

What does the P wave on an ECG represent?

Atrial depolarization.

What does the QRS complex on an ECG represent?

Ventricular depolarization.

What does the T wave on an ECG represent?

Ventricular repolarization.

PR segment

AV node delay

ST segment

time during which ventricles are contracting and emptying

TP interval

time during which ventricles are relaxing and filling

How do electrical and mechanical events relate in the cardiac cycle?

Electrical signals trigger muscle contractions, coordinating blood flow through the heart.