Cardiovascular System Heart & Blood Vessels (bv) Transport O 2, 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 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 rest Blood Pressure  Force blood exerts against inner walls of bv and keeps blood flowing continuously  2 measurements (mmHg) Systolic – pressure in 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 O 2 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