Anatomy & Physiology

Chapter 11The Cardiovascular

SystemWeek 6

Warm-up 04/28Warm-up 04/28Blood starts in the Right Atrium, where to next? Put the following in order:

– Left Ventricle– Capillaries of Lungs– Vena Cava– Right Ventricle– Capillary beds of body

tissue– Pulmonary Veins– Left Atrium– Aorta– Pulmonary Arteries

Correct Order– Right Ventricle– Pulmonary Arteries– Capillaries of Lungs– Pulmonary Veins– Left Atrium– Left Ventricle– Aorta– Capillary beds of body

tissue– Vena Cava

Agenda 04/28Agenda 04/28

• Review of Blood Path

• Heart Diagram Project

Heart ValvesHeart Valves

Atrioventricular ValvesAtrioventricular Valves

Semilunar ValvesSemilunar Valves

Blood Flow Through HeartBlood Flow Through Heart

Heart Diagram ProjectHeart Diagram Project

• Heart Chambers

• Major Vessels

• Valves

• Direction of Blood flow

• pps.171,173,177,178,104, 105, 106

Warm-up 04/29Warm-up 04/29

• Which of the following do you think is a normal heart sound?

–A

–B

–C

A = Pulnomic StenosisB = NormalC = Ventricular Septal Defect

Agenda 04/29Agenda 04/29

• How does the heart pump?– Intrinsic Conduction System

• Listen to your Heart

• What is an ECG (EKG)?

• What is a Cardiac Cycle?

• Finish Heart Project

The Heart: Conduction SystemThe Heart: Conduction System

Intrinsic conduction system (nodal system)

Heart muscle cells contract, without nerve impulses, in a regular, continuous way

The Heart: Conduction SystemThe Heart: Conduction System

Special tissue sets the pace

Sinoatrial node (right atrium)

Pacemaker

Atrioventricular node (junction of r&l atria and ventricles)

Atrioventricular bundle (Bundle of His)

Bundle branches (right and left)

Purkinje fibers

Heart ContractionsHeart Contractions

Clip

Heart SoundsHeart Sounds• Auscultation - listening to sounds made

by body• First heart sound (S1), louder and longer

“lubb”, occurs with closure of AV valves• Second heart sound (S2), softer and

sharper “dupp” occurs with closure of semilunar valves

• S3 - rarely heard in people > 30

Heart SoundsHeart Sounds

Where to listen on chest wall for heart sounds.

Heart ContractionsHeart Contractions

• Listen to your hearts.

• Three formations– P wave: impulse across atria– QRS complex: spread of impulse down septum,

around ventricles in Purkinje fibers– T wave: end of electrical activity in ventricles

Electrocardiograms (EKG/ECG)Electrocardiograms (EKG/ECG)

Electrocardiograms (EKG/ECG) Electrocardiograms (EKG/ECG) ((contcont.).)

Electrocardiogram (ECG)Electrocardiogram (ECG)• Composite of all action potentials of nodal and

myocardial cells detected, amplified and recorded by electrodes on arms, legs and chest

ECGECG• P wave

– SA node fires, atrial depolarization

– atrial systole

• PQ interval– Conduction time from atrial to ventricular excitation

• QRS complex– AV node fires, ventricular depolarization

– ventricular systole

– (atrial repolarization and diastole - signal obscured)

• T wave– ventricular repolarization

Normal Electrocardiogram (ECG)Normal Electrocardiogram (ECG)

1) atrial depolarization begins2) atrial depolarization complete (atria contracted)

3) ventricles begin to depolarize at apex;atria repolarize (atria relaxed)

4) ventricular depolarization complete (ventricles contracted)

5) ventricles begin to repolarize at apex6) ventricular repolarization complete (ventricles

relaxed)

Electrical Activity of MyocardiumElectrical Activity of Myocardium

ECGs, Normal & AbnormalECGs, Normal & Abnormal

No P waves

ECGs, AbnormalECGs, Abnormal

Extrasystole : note the inverted QRS complex, misshapen QRS and T and absence of a P wave preceding this contraction.

ECGs, AbnormalECGs, Abnormal

Arrhythmia: conduction failure at AV node

No pumping action occurs

Pathology of the HeartPathology of the Heart

• Damage to AV node = release of ventricles from control = slower heart beat

• Slower heart beat can lead to fibrillation• Fibrillation = lack of blood flow to the

heart• Tachycardia = more than 100 beats/min• Bradychardia = less than 60 beats/min

The Heart: Cardiac CycleThe Heart: Cardiac Cycle

Atria contract simultaneously

Atria relax, then ventricles contract

Systole = contraction

Diastole = relaxation

Filling of Heart Chambers – Filling of Heart Chambers – the Cardiac Cyclethe Cardiac Cycle