CARDIOVASCULAR SYSTEM
HEART
General
Closed System- Blood Remains in Blood Vessels & Heart
Double System- Four Chambers (Separation of Oxygenated
& Deoxygenated Blood)- Each Side Supplies Different Circuit:
* Pulmonary Circuit (R. Heart Lungs Heart)
* Systemic Circuit (L. Heart Body Tissues Heart)
Heart – Size & Location
Size: Adult Clenched FistPosition: Mediastinum, 2/3 to Left of
MidlineRelationships to Other Organs:
- Deep to Sternum- Superior to Diaphragm- Medial to Lungs- Anterior to Esophagus, Descending Aorta
Heart – Surface Anatomy
Sulci- Grooves, Indicate Boundaries of Chambers- Coronary Sulcus (Between Atria &
Ventricles)- Interventricular Sulci (Between Ventricles)
Apex (Inferior, Pointed Tip)Base (Posterior surface; formed by atria,
mostly left)
Heart - Chambers
Atria (2)- Superior Receiving Chambers (From Veins)- Auricles (ear-like flaps)- Right Atrium:
* O2 Poor Blood From Venae Cavae & Coronary Sinus
- Left Atrium:* O2 Rich Blood From Pulmonary Veins of Lungs
Heart – Chambers continued
Ventricles (2)- Inferior Pumping Chambers (to Arteries)- Receive from Atria- Right Ventricle:
* O2 Poor Blood from Rt Atrium to Pulmonary Arteries (Pulmonary Circ.)
- Left Ventricle:* O2 Rich Blood from Left Atrium to Aorta
(Systemic Circ.)
Heart - Septa
Internal WallsSeparate Chambers2 Septa:
- Interatrial Septum - (Between the Atria)- Interventricular Septum - (Between the Ventricles)
Heart - Valves
One-Way, Direct Blood FlowPassive; blood pushes them open & closed2 Pairs:
- Atrioventricular (Cuspid) Valves
*Between Atria & Ventricles
*Prevent blood flowing back into atriaTricuspid (Right)Bicuspid (Left)
Atrioventricular Valves cont.
* AV Valves are anchored to structures in the ventricles: Chordae Tendineae
Strong, Fibrous StringsPrevent Cusp Eversion
Papillary MuscleConical Extensions of Myocardium
in VentriclesContract & pull on chordae
tendineae
Heart - Valves
- Semilunar Valves
*Between Ventricles & Arteries
*Prevent blood from back flow into ventriclesPulmonary Semilunar Valve
(Right)Aortic Semilunar Valve (Left)
Heart - Wall
3 Layers:- Endocardium (Inner)
* Endothelium* Lines Chambers, Valves, Septa, Blood
Vessels- Myocardium (Middle)
* Thickest Layer (Esp. in Left Ventricle!)* Cardiac Muscle Tissue* Inherent Rhythmicity
Heart Wall
Heart – Wall continued
- Epicardium (Outer)* Visceral Pericardium* Serous Membrane* Thin, Fibrous, Transparent
Fibrous SkeletonBetween atria & ventriclesDense regular C.T.Encircle valves & great
arteriesAttachment for cardiac
muscleElectrical insulation
between atria & ventriclesStabilizes valves
Heart – Pericardial Sac
Encloses Heart & Bases of Great VesselsComposed of 2 layers:
- Parietal Pericardium
*Inner serous coat of sac
*Secretes lubricating pericardial fluid into
*Pericardial cavity (space between serous layers)
Heart – Pericardial Sac continued
- Fibrous Pericardium
*Outer, fibrous coat of sac
*Tough, protective
*Reinforces serous coat
CARDIAC CYCLE
Events of one heartbeat:
- Systole*Atria Contract, Ventricles Fill*Ventricles Contract, Blood Forced
into Aorta and Pulmonary Trunk
- Diastole*Atria Relax & Fill*Ventricles Passively Receive Blood
from the Atria
Cardiac Output
Stroke Volume (SV)- Volume of blood pumped out by ventricle
each heartbeat - 70ml/beat
Cardiac Output (CO)- Volume pumped out by ventricle in 1 minute- CO = Heart Rate x Stroke Volume- 75 b/min x 70 ml/beat = over 5,000 ml/min
Factors Influencing Cardiac Output
Venous Return directly effects Stroke Volume (& CO)
Heart Rate (& CO) is effected by drugs, hormones & ions
BLOOD PRESSURE
BP = pressure blood exerts on inner blood vessel walls
BP rises & falls in response to heart contraction & relaxation
BP keeps blood moving between heart contractions
BLOOD PRESSURE
Systole (contraction of the heart)- Contraction of ventricles causes arterial
pressure to rise- Systolic pressure (SBP) is the maximum
pressure during contraction
BLOOD PRESSURE CONTINUED
Diastole- Relaxation and refilling of ventricles while
semilunar valves are closed- Arterial pressure drops as blood flows
“downstream”- Diastolic pressure (DBP) is the minimum
pressure just before the next systole
Average BP = less than 120/80
Arterial surge in pressure = Pulse
Pulse rate usually = heart rate
Average adult pulse = 60-80 BPM
CONDUCTION SYSTEM OF THE HEART
Specialized Cardiac Muscle TissueCapable of Generating & Conducting
Action Potentials Stimulates Contraction of Myocardial
TissueSets basic rhythm of the heart
CONDUCTION SYSTEM OF THE HEART continued
5 Components:- Sinoatrial Node (Pacemaker)
* Right Atrium* Spontaneously Depolarizes* Activates Atrial Contraction* Origin of Heart Beat* Action Potential Spreads to Atrial
Myocardium &:
CONDUCTION SYSTEM OF THE HEART continued
- Atrioventricular (AV) Node* Rt. atrium (interatrial septum) * Action potential spreads to:
- Atrioventricular Bundle (Bundle of His)* Only electrical pathway between atria &
ventricles (C.T. Block)* Carries action potential through
interventricular septum to:
CONDUCTION SYSTEM OF THE HEART continued
- Bundle Branches (Left & Right )
* Interventricular septum* Carries action potential toward
respective ventricles- Purkinje Fibers
* Myocardium of ventricles* Conduct action potentials to ventricular
myocardium
C. T. Blocks Action Potentials Between Atria & Ventricles
Moderator Band(Septomarginal Trabecula)
ELECTROCARDIOGRAM (ECG/EKG)
Record of Electrical Changes in Heart MuscleElectrical Changes due to Depolarization &
Repolarization of Cardiac Muscle FibersMetal Electrodes Applied to Skin, Attached to
Physiograph, Pick-up Electrical ActivityNormal Cardiac Cycle Gives Rise to
Characteristic “Waves”
ELECTROCARIDOGRAM (ECG/EKG) continued
P Wave- SA Node Stimulates Atrial Depolarization
- Occurs Prior to Atrial Contraction
QRS Complex- Ventricular Depolarization
- More Tissue, More Electrical Activity, Larger Wave
- Occurs Prior to Ventricular Contraction
T Wave- Ventricular Repolarization
HEART SOUNDS
Caused by Closing of Heart ValvesAV Valves
- prevent blood from flowing backwards into atria
- “Lubb”Semilunar Valves
- prevent blood from flowing backwards into ventricles
- “Dupp”
HEART MURMURS
Abnormal soundOften indicates valve disorderCauses:
- Congenital defects- Scarring- Insufficiency/Backflow