THE CARDIOVASCULAR SYSTEM

EMERITA C. MENDOZA, R.N., M.D.

LOCATION OF THE HEART

• Hollow, muscular organ

• PMI is at the 5th left MCL

• Weighs 1 lb.

FUNCTIONS

• Transports O2 from the lungs to

tissues of the body• Delivers nutrients from the GIT to all systems• Carries wastes from tissues to the excretory

system• Serves as a route for hormones, enzymes,

and other chemicals to reach target tissues

LAYERS OF THE HEART

3 layers within a sac: • Endocardium

(Inner)

• Myocardium (Middle)

• Epicardium or visceral pericardium

(Outer)• surrounded by

parietal pericardium

• Myocardium is the thickest layer

• Unique because of the presence of INTERCALATED DISCS allows a single stimulation to cause all cardiac muscle fibers to contract.

MUSCLES WITHIN THE CHAMBERS

• PAPILLARY MUSCLES - found within the chamber walls

• Extend into CHORDAE TENDINAE attached to valves

BLOOD FLOW THROUGH THE HEART

• Left LUNGS LA mitral valve opens LV mitral valve closes LV muscles contract AV opens aorta distribution

• Right BODY RA tricuspid valve opens RV tricuspid valve closes RV muscles contract pulmonary valves open lungs

HEART SOUNDS

• Aortic valve: second ICS(intercostal space) R

PSL(parasternal line)

• Pulmonic valve: second ICS L PSL

• Tricuspid valve: fourth ICS L PSL

• Mitral valve: fifth ICS L MCL(midclavicular line)

HEART SOUNDS

• S1 : closure of mitral and tricuspid; “lub” sound

• S2: closure of aortic and pulmonic; “dub” sound

• S3: ventricular gallop

• S4: atrial gallop

CONDUCTION SYSTEM

• Sympathetic ( increase in CR,

norepinephrine or epinephrine is increased)

• Parasympathetic ( decrease in CR)• Creates an electrical impulse/activity

ELECTROCARDIOGRAM

• Measures the electrical activity of the heart

• 3 major limb leads: AVR, AVL, AVF (right & left wrists, left foot); V1 to V6 (precordial leads)

• Normal cycle: NSR(normal sinus rhythm)

• P wave (atrial contraction), QRS complex (ventricular contraction)

When the heart contractsWhen the heart relaxes

Cardiac Rate and Pulse Rate

• CR obtained via auscultation; PR is palpated.

• Most common pulses:

- Radial pulse - Carotid pulse - Femoral pulse - Dorsalis pedis

BLOOD PRESSURE

• Pressure when the heartbeat can be heard (Systolic = contraction pressure)

• Pressure when the heartbeat disappears (Diastolic = relaxation pressure)

• BP is expressed as systole/ diastole

•

JNC VII (Joint National Committee on the Prevention,

Detection, Evaluation & Treatment of High BP)

CATEGORY SYSTOLIC

DIASTOLIC

NORMAL <120 <80

PREHYPERTENSION

120-139

80-89

STAGE I 140-159

90-99

STAGE II >/= 160 >/= 100

STARLING’S LAW OF THE HEART

• All venous return is accommodated by contractility of the cardiac muscle fibers.

• May be called EJECTION FRACTION (EF) percentage of blood pumped into the aorta from the left ventricle

• Cardiac output= stroke volume x cardiac rate

PULSE RATE

• Place the tips of digits 2 and 3 (index and middle fingers) over the surface where the artery is found

• Feel the pulse and count per minute

• Normal adult PR: 60-100 bpm (beats per minute)

• < 60 = Bradycardia• > 100 = Tachycardia

THE VASCULAR CIRCULATIONS

• Blood flow through the body is the Systemic circulation

• Blood flow through the lungs is the Pulmonary circulation

• The Hepatoportal circuit is a subdivision of the systemic that serves the liver

• The Circle of Willis is the systemic circuit at the base of the brain

• FetalFetal circulation differs from an adult circulation differs from an adult

General Plan of the

Systemic & Pulmonary

Circulations