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