Cardiovascular System I: Heart Anatomy and Physiology

Cardiovascular System Defined

Gross Anatomy of the Heart

Operation of Heart Valves

Cardiac Cycle and Heart Sounds

Cardiac Cycle and the EKG (ECG)

Electrical Conduction in the Heart

The Cardiovascular System Defined What it is:

• A closed system of the heart and blood vessels

o The heart pumps blood

o Blood vessels allow blood to circulate to all parts of the body

Function:

• Deliver oxygen and nutrients and to remove carbon dioxide and other waste products

Heart Gross Anatomy• Location: Mediastinum of the

thorax

• Size: As big as your fist

• Serous Membrane Coverings:

1. Epicardium (= visceral pericardium) innermost

2. Parietal pericardium outermost

3. Mediastinal pleura outside that

The Heart Wall: Three Layers

= visceral pericardium

Parietal

Parietal PericardiumVisceral Pericardiu

m (Epicardiu

m)

MyocardiumEndocardium

Exception: In the heart layers, peri- is outside of epi-

Corornal Section of Human Heart

Operation of Heart Valves

HeartValves qt.mov

Stenotic and Regurgitant Valve Conditions

Heart sounds movie online

AV valves

Semilunar valves

Flow of Blood Through the Heart

Coronary Circulation: Blood Feeding the Heart

Blockage of these vescles causes ischemia (lack of O2), causing muscle death (myocardio infarct), and chest pain (angina pectoris)

Posterior View of Real Heart

Auscultation of Heart Sounds

PCG: Phonocardiograph lub dup

“S1” “S2”

Heart sound talk

Auscultation

Sounds 1

Split S1

Split S2

The Heart: Conduction System

Intrinsic conduction system (nodal system)

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

Special tissue sets the pace

1. Sinoatrial node

a. Pacemaker

2. Atrioventricular node

3. Atrioventricular bundle

4. Bundle branches

5. Purkinje fibers

Contraction is initiated by the sinoatrial node

Sequential stimulation occurs at other autorhythmic cells Exterior

conductionPacemaker with electrode in right ventricle

Filling of Heart Chambers – the Cardiac Cycle

Figure 11.6

1. Atria contract simultaneously

2. Atria relax, then ventricles contract

Systole = contraction (can be subdivided into atrial and ventricular contraction but otherwise refers to ventricular systole)

Diastole = relaxation (ventricular)

Cardiac Cycle and Electrocardiography

Cardiac cycle – events of one complete heart beat

• Mid-to-late diastole – blood flows into ventricles

• Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood

• Early diastole – atria finish re-filling, ventricular pressure is low

P Q R S T U

Pressure, ECG, and Heart online

EKG, Heart contractions, conduction online

Note that an ECG does not show actual

contractions but

excitation and

depolarizations

Heart Voltages and the ECG

ArrhythmiasHeart block

Hookups for the ECG