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