HEART PHYSIOLOGY & CONDUCTION SYSTEM

Ana RibićMentor: A. Žmegač Horvat

PHYSIOLOGY

phase 1 - A-V Valves Open, Semilunar Valves Closed

p wave of ECG atrial depolarization →

atrial contraction → pressure increases → pressure gradient across the AV valves

blood flow across the open atrioventricular (AV) valves

"a-wave" ventricular end-diastolic

volume (EDV) ventricular preload

phase 2 - All Valves Closed

QRS complex → ventricular depolarization

first heart sound (S1) ventricular pressure

rises - "isovolumetric" contraction

phase 3 - Aortic and Pulmonic Valves Open; AV Valves Remain Closed initial and rapid ejection

of blood into the aorta and pulmonary arteries from the left and right ventricles

total energy of blood ventricular maximal

outflow pressure blood continues to flow

into atria

phase 4 - Aortic and Pulmonic Valves Open; AV Valves Remain Closed

after the QRS ventricular

repolarization T-wave ventricular pressure

falls slightly left atrial and right

atrial pressures gradually rise

phase 5 - All Valves Closed

aortic and pulmonic valves abruptly close

second heart sound (S2)

isovolumetric relaxation

dicrotic wave end-systolic volume LAP continues to rise

http://www.google.hr/imgres?imgurl=http://www.stethographics.com/heart/images/s123.jpg&imgrefurl=http://www.stethographics.com/main/physiology_hs_introduction.html&h=312&w=545&sz=55&tbnid=_Rg21HUd1Y5qXM:&tbnh=76&tbnw=133&prev=/images%3Fq%3Dheart%2Bsound&hl=hr&usg=__K4rsx1G_XCRY8TFdItVW4Fi9rBw=&ei=dYSeS8m_A4ee_gb0_qn7CQ&sa=X&oi=image_result&resnum=5&ct=image&ved=0CBkQ9QEwBA

phase 6 - A-V Valves Open

intraventricular pressures fall below their respective atrial pressures

ventricular filling third heart sound

(S3)

phase 7 - A-V Valves Open

ventricles continue to fill with blood and expand → intraventricular pressures rise

aortic pressure and pulmonary arterial pressures continue to fall

CONDUCTION SYSTEM

1. Sinoatrial node (SA node) -sends the electrical impulse that triggers each heartbeat

- upper area of the right atrium

2. Atrioventricular node (AV node) - sends an impulse through the nerve network to the ventricles

3. Common AV bundle4. Right & left bundle branches -

nerve fibers that send impulses that cause the cardiac muscle tissue to contract

ELECTROCARDIOGRAM

e-lek-tro-KAR-de-o-gram - EKG/ECG painless test that records the heart's

electrical activity signal causes the heart to contract and

pump blood and creates an electrical current that can be seen on a graph called an electrocardiogram

signal causes the heartbeat each heartbeat has two basic parts:

diastole and atrial and ventricular systole

P wave - represents the wave of depolarization that spreads from the SA node throughout the atria

P-R interval -represents the time between the onset of atrial depolarization and the onset of ventricular depolarization

QRS complex - ventricular depolarization

ST segment - time at which the ventricle is depolarized and corresponds to the plateau phase of the ventricular action potential

T wave - represents ventricular repolarization and is longer in duration than depolarization

Q-T interval - represents the time of both ventricular depolarization and repolarization

An EKG shows: how fast your heart

is beating whether the rhythm

of your heartbeat is steady or irregular

the strength and timing of electrical signals as they pass through each part of your heart

This test is used to detect and evaluate many heart problems, such as heart attack, arrhythmia and heart failure

http://video.google.com/videoplay?docid=5701496219687599581&ei=NG-eS_T5C4rk2gLfoeH0DA&q=heart+conduction+system&hl=hr#

http://www.cvphysiology.com http://www.nhlbi.nih.gov http://www.wisegeek.com metacafe.com