HA

• Cardiovascular system


  Highly complex, consisting of the heart and a closed system of blood vessels

  
• Heart


  • Hollow, muscular, four-chambered organ
  • Size of a clenched fist
  • Weighs 255 g (9 oz) in women and 310 g (10.9 oz) in men
  • Can be described as an Inverted cone
• Mediastinum


  Middle part of the thoracic cavity between the lungs in the space

  
• Precordium


  Anterior chest area that overlies the heart and great vessels

  
• Right side of the heart


  Pulmonary circulation; pumps blood to the lungs for gas exchange by removing CO2 from blood and replenishing oxygen supply
• Left side of the heart


  Systematic circulation; pumps blood to all other parts of the body. Perfusion occurs when blood flows to tissues and organs promoting the diffusion of oxygen and carbon dioxide
• Great vessels


  • Large veins and arteries leading directly to and away from the heart
• Great vessels


  • Superior and Inferior vena cava
  • Pulmonary artery
  • Pulmonary veins
  • Aorta
• Heart chambers


  • Consists of four chambers, or cavities: two upper chambers (right and left atria) and two lower chambers (right and left ventricles)
  • Septum separates the left and right sides of the heart
  • Thin-walled atria receive blood returning to the heart and pump blood into the ventricles
  • Thicker-walled ventricles pump blood out of the heart
  • Left ventricle is thicker than the right ventricle because the left side of the heart has a greater workload

  
• Atrioventricular (AV) valves


  Allow blood to flow from the atria into the ventricles
• Atrioventricular (AV) valves


  • Two AV valves: the tricuspid valve and the bicuspid (mitral) valve
  • Chordae tendineae anchor the AV valve flaps to papillary muscles within the ventricles
• Bicuspid (Mitral) Valve


  Composed of two cusps and is located between the left atrium and the left ventricle
• Tricuspid Valve


  Composed of three cusps, or flaps, and is located between the right atrium and the right ventricle
• Semilunar valves


  • Located at the exit of each ventricle at the beginning of the great vessels
  • Open during ventricular contraction and close from the pressure of blood when the ventricles relax
  • Blood is thus prevented from flowing backward into the relaxed ventricles
• Pulmonic Valve


  Located at the entrance of the pulmonary artery as it exits the right ventricle
• Aortic Valve


  Located at the beginning of the ascending aorta as it exits the left ventricle
• Heart covering and walls


  • Pericardium - a tough, inextensible, loose-fitting, fibroserous sac that attaches to the great vessels and surrounds the heart
  • Epicardium - same type of serous membrane covers the outer surface of the heart
  • Myocardium - thickest layer of the heart; made up of contractile cardiac muscle cells
  • Endocardium - a thin layer of endothelial tissue that forms the innermost layer of the heart and is continuous with the endothelial lining of blood vessels

  
• Cardiac muscle cells


  Have a unique inherent ability; can spontaneously generate an electrical impulse and conduct it through the heart
• Cardiac Cycle


  Generation and conduction of electrical impulses by specialized sections of the myocardium regulate the events associated with the filling and emptying of the cardiac chambers

  
• Electrical conduction pathways


  • Purkinje fibers - specialized cardiac muscle cells that conduct electrical impulses that allow coordinated contraction of cardiac muscle
  • Bundle of His - elongated segment connecting the AV Node and the left and right bundle branches of the septal crest (with an inherent discharge of 40–60/min)
• Sinoatrial (SA) Node


  • Functions as "Pacemaker of the heart"
  • Located on the posterior wall of the right atrium near the junction of the superior and inferior vena cava
  • Inherent rhythmicity, generates impulses (at a rate of 60–100/min) that are conducted over both atria, causing them to contract simultaneously and send blood into the ventricles
  • Current is initiated by SA node, is conducted across the atria to the AV node located in the lower interatrial septum
  • AV node slightly delays incoming electrical impulses from the atria and then relays the impulse to the AV bundle (bundle of His) in the upper interventricular septum

  
• Electrocardiography (ECG)


  Measure and record the electrical activity
• Phases of the electrocardiogram

  • P wave: Atrial depolarization; conduction of the impulse throughout the atria
  • PR interval: Time from the beginning of the atrial depolarization to the beginning of ventricular depolarization, that is, from the beginning of the P wave to the beginning of the QRS complex
  • QRS complex: Ventricular depolarization (also atrial repolarization); conduction of the impulse throughout the ventricles, which then triggers contraction of the ventricles; measured from the beginning of the Q wave to the end of the S wave
  • ST segment: Period between ventricular depolarization and the beginning of ventricular repolarization
  • T wave: Ventricular repolarization; the ventricles return to a resting state
  • QT interval: Total time for ventricular depolarization and repolarization, that is, from the beginning of the Q wave to the end of the T wave; the QT interval varies with heart rate (HR)
  • U wave: May or may not be present; if present, it follows the T wave and represents the final phase of ventricular repolarization

  
• Cardiac Cycle


  • Refers to the filling and emptying of the heart's chambers
  • Two phases: Diastole (Filling; relaxation of the ventricles) and Systole (Emptying; contraction of the ventricles)
  • Diastole endures for approximately two thirds of the cardiac cycle and systole is the remaining one third
  • Heart sounds S2, S3, and S4 are associated with diastole, whereas S1 is associated with systole

  
• Heart sounds


  • Produced by valve closure
  • Opening of valves is silent
  • "Lub-dub" (S1 and S2)
• Normal heart sounds


  • S1 (Lub) - First heart sound; result of closure of the AV valves: the mitral and tricuspid valves
  • S2 (Dub) - results from closure of the semilunar valves (aortic and pulmonic) and correlates with the beginning of diastole

  
• Extra heart sounds (S3 & S4)


  • Referred to as diastolic filling sounds
  • Result from ventricular vibration secondary to rapid ventricular filling
  • S3 - can be heard early in diastole, after S2 (termed ventricular gallop)
  • S4 - results from ventricular vibration but vibration is secondary to ventricular resistance (noncompliance) during atrial contraction (termed atrial gallop)

  
• Arteries


  • Blood vessels that carry oxygenated, nutrient-rich blood from the heart to the capillaries
  • Arterial network is a high-pressure system
  • Contain elastic fibers
  • Arterial pulse can be felt only by lightly compressing a superficial artery against an underlying bone

  
• Major arteries accessible to examination


  • Temporal
  • Peripheral
  • Carotid
  • Aorta
• Major arteries of the arm


  • Brachial artery - major artery that supplies the arm
  • Radial artery - extending down the thumb side of the arm
  • Ulnar artery - extending down the little finger side of the arm
• Brachial pulse


  Can be palpated medial to the biceps tendon in and above the bend of the elbow
• Radial pulse


  Can be palpated on the lateral aspect of the wrist
• Ulnar pulse


  Located on the medial aspect of the wrist, is a deeper pulse and may not be easily palpated
• Palmar arches


  Provide extra protection against arterial occlusion to the hands and fingers
• Major arteries of the leg


  • Femoral artery - major supplier of blood to the legs; palpated just under the inguinal ligament
  • Popliteal artery - travels down the front of the thigh then crosses to the back of the thigh
  • Dorsalis pedis artery - anterior branch descends down the top of the foot; great toe side of the top of the foot
  • Posterior tibial artery - posterior branch; palpated behind the medial malleolus of the ankle

  
• Dorsal arch


  Formed by dorsalis pedis artery and posterior tibial artery; Superficial and deep palmar arches of the hands, provides the feet and toes with extra protection from arterial occlusion
• Popliteal pulse


  Can be palpated behind the knee
• Pulse strength


  • 0 - Absent
  • 1+ - Weak, diminished (easy to obliterate)
  • 2+ - Normal (obliterate with moderate pressure)
  • 3+ - Strong (obliterate with firm pressure)
  • 4+ - Bounding (unable to obliterate)
• Veins


  • Blood vessels that carry deoxygenated, nutrient-depleted, waste-laden blood from the tissues back to the heart
  • Contain nearly 70% of the body's blood volume
  • Because blood in the veins is carried under much lower pressure than in the arteries, the vein walls are much thinner

  
• Types of veins


  • Deep veins
  • Superficial veins
  • Perforator veins