Cardiovascular System

• Cardiovascular System


  Consists of the heart, blood vessels, and blood

  
• Components of the Cardiovascular System

  • Heart
  • Arteries
  • Arterioles
  • Veins
  • Venules
  • Capillaries
  • Blood

  
• Flow of blood through the heart

  1. Right side of the heart

  2. Left side of the heart

  
• Lumen


  Hollow area where blood flows
• Arteries


  • Carry blood from the heart throughout the body
  • Faced with high pressure, more thick, muscular and elastic

  
• Veins


  • Bring blood back to the heart
  • Faced with low pressure, less thick, muscular and elastic

  
• Ageing

  • Vasoconstriction & vasodilation responses are less efficient
  • Regulation of blood flow to the tissues is less well controlled
  • Arterial walls become stiffer and less compliant, which raises blood pressure and increases the work of the left ventricle
  • Blood pressure tends to rise with age, even in the absence of any overt cardiovascular disease

  
• Thrombosis

  Formation of a blood clot (thrombus) inside a blood vessel, interrupting blood supply to the tissues

  
• Embolism


  Blocking of a blood vessel by any mass of material (embolus) traveling in the blood, usually a thrombus or a fragment of a thrombus

  
• Pulmonary embolism


  Blocking of a blood vessel by an embolus in the lungs

  
• Atheroma


  Atheromatous plaques, patchy changes that develop in the endothelium of large and medium-sized arteries

  
• Atheroma complications

  • Thrombosis
  • Ischemia
  • Infarction
  • Hemorrhage
  • Aneurysm

  
• Arteriosclerosis


  Thickening or hardening of the arteries caused by a buildup of plaque in the inner lining

  
• Aneurysm


  Abnormal local dilatations of arteries due to atheroma, hypertension and defective collagen

  
• Varicosed Veins


  When blood flow through veins becomes sluggish, blood pools within them and damages their soft walls, causing the veins to lose elasticity, dilate and become coiled and tortuous

  
• Deep Vein Thrombosis


  Usually affects the lower limb, pelvic or iliac veins but occasionally the upper limb veins

  
• Sinoatrial (SA) node


  Pacemaker of the heart
• Conducting System of the Heart

  1. Sinoatrial (SA) node creates excitation signal

  2. Atria contract

  3. Atrioventricular (AV) node delays signal

  4. Bundle of His carries signal to Purkinje fibers

  5. Purkinje fibers cause ventricles to contract
• Electrocardiogram (ECG)


  Instrument that picks up the electric currents produced by the heart muscle during a cardiac cycle of contraction and relaxation
• Heart Failure


  The heart is unable to circulate sufficient blood to meet the needs of the body
• Stenosis


  Narrowing of a heart valve opening
• Regurgitation


  Failure of a heart valve to close completely
• Ischaemic heart disease


  The heart is not getting enough blood and oxygen
• Myocardial Infarction


  Complete blockage of a coronary artery

  
• Rheumatic heart disease


  Inflammatory illness that sometimes follows streptococcal throat infections, causing the immune system to attack and damage the heart
• Cardiac Arrhythmias

  • Normal sinus rhythm 60-100 bpm
  • Sinus bradycardia = below 60 bpm
  • Sinus tachycardia = above 100 bpm
  • Asystole = no electrical activity in the ventricles
  • Fibrillation = disorderly and uncoordinated contraction of the cardiac muscle fibers
  • Atrial Fibrillation (A-Fib) = ineffective atrial pumping and irregular AV node stimulation
  • Ventricular Fibrillation
  • Heart block = impaired impulse transmission
• Blood Pressure


  The force or pressure that the blood exerts on the wall of the blood vessels

  
• Relationship between pressure, flow and blood vessel diameter

  • Tunica media of large arteries contains elastic tissue to allow expansion and recoil with each heartbeat
  • Tunica media of small arteries and arterioles is rich in smooth muscle to control diameter and blood flow

  
• Systolic blood pressure


  When the left ventricle contracts and pushes blood into the aorta, arterial blood pressure rises sharply

  
• Diastolic blood pressure


  When the heart is resting between beats

  
• Blood pressure falls at rest and during sleep, and increases with age and is usually higher in women than in men
• Hypertension


  High blood pressure that can damage and weaken blood vessel walls

  
• Hypotension


  Low blood pressure that may cause inadequate blood flow through tissue beds

  
• Blood pressure (BP)


  Usually expressed as two readings, the diastolic and systolic

  
• BP = 120 mmHg / 80 mmHg
• Pressure, flow and blood vessel diameter

  Tunica media of large arteries (aorta) contains much elastic tissue to allow them to expand easily with each heartbeat and to minimize the workload of the heart

  
• Pressure, flow and blood vessel diameter

  When the left ventricle ejects blood into the elastic aorta, the vessels expand to accommodate it, and the recoils elastically

  
• Pressure, flow and blood vessel diameter


  This pushes the blood forward into the arterial system and a wave of distension and recoil occurs throughout the large arteries keeping the pressure high and blood moving forwards

  
• Tunica media of the smallest arteries and arterioles


  Rich in smooth muscle and contain more less elastic tissue
• Autonomic nerve fibers


  Supply this smooth muscle and control the vessel diameter, regulating flow and pressure