Cardiovascular System

Heart & Blood Vessels (bv) Transport O2, nutrients,

hormones, cell wastes, etc…

Layers of Cardiac Tissue Pericardium – encloses

heart Pericardial cavity Heart Wall:

Epicardium – surface of heart

Myocardium – cardiac muscle

Endocardium – lines heart chambers

Valves

Atrioventricular (AV valves) – located between the atrial and ventricular chambers on each side Prevent backflow into the atria when

ventricles contract Bicuspid (Mitral) valve – left AV

valve Tricuspid valve – right AV valve

Semilunar valves – guard 2 large arteries leaving the ventricular chambers

Pulmonary Aortic

AV valves open during heart relaxation and closed during ventricle contraction

Semilunar valves closed during heart relaxation and open during ventricle contraction

Circulation

Systemic circulation – from left side of the heart through the body tissues and back to the right side of the heart

Pulmonary circulation – from right side of the heart to the lungs and back to the left side of the heart

Setting the Rhythm of Heart

Heart pumps about 6,000 quarts of blood per day! Setting the Rhythm Can contract spontaneously and

independently Atrial cells 60 times/min Ventricular cells 20-40 times/min ANS nerves can accelerate or decelerate Nodal system – special tissue

Depolarizes in atria-ventricle direction Causes heart to beat as coordinated

unit Sinoatrial (SA) Node – “pacemaker”

found in right atrium Impulse spreads from SA to

Atrioventricullar (AV) node and then the atria contract to Purkinje fibers causing ventricles to contract to eject blood from heart into arteries

Electrocardiogram (ECG) Maps electrical activity of heart 3 waves

P wave – signals depolarization of atria prior to contraction

QRS Complex Q – prior to vent. contrct. R – ventricular contraction S

T wave – repolarization of the ventricles

Tachycardia – rapid heart rate (>100bpm)

Bradycardia – slow heart rate (<60bpm)

Ischemia – lack of blood supply Fibrillation – uncoordinated heart

muscles Myocardial Infarct – dead cardiac cells

Cardiac Cycle

Cardiac cycle – events of 1 heartbeat 0.8sec Atria contract simultaneously as they relax,

ventricles contract Systole – contraction of ventricles Diastole – relaxation of ventricles

Heart Sounds “lub-dup” pause “lub” – closing of AV valves (long & loud) “dup” – closing of semi-lunar valves (short & sharp) Murmurs – abnormal heart sounds

Vital Signs

Pulse Expansion & recoil of artery Normal 70-76 bpm @ rest

Blood Pressure Force blood exerts against inner walls of bv and keeps

blood flowing continuously 2 measurements (mmHg)

Systolic – pressure in arteries @ peak of ventricular contractions (110 – 140)

Diastolic – pressure when ventricles are relaxing (75 – 80)

Blood Vessels Blood Vessels – closed

transport system Aorta – blood leaves heart Arteries – thick walls, red

O2 rich Arterioles – branch off of

arteries Capillary beds – found in

tissues, 1 cell layer for easy gas exchange

Venules – drain capillary beds

Veins – drain venules, low pressure, thin walls Have valves to prevent

backflow Vena cava – enters heart

Capillary Exchange

Substances move to/from body cells according to their conc. gradient

Pulmonary gas exchange (see pic)

Systemic gas exchange…

Major Systemic

Arteries

Major Systemic Veins