Cardiovascular system

• Cardiovascular system function:

  →delivery of oxygen & nutrients

  → Removal of carbon dioxide & metabolic waste

  → Transport of hormones from glands to target receptors

  → Maintenance of body temperature
• Pulmonary Cycle:

  → Right side of heart recieves venous blood

  →sends deoxygenated blood to the lungs
• systemic cycle:

  → left side of heart recieves oxygenated blood from lungs

  →sends it out again to supply the body tissues
• Frank-starling law of the heart:

  → stroke volume is regulated by end-diastolic volume,average aortic pressure& strength of ventricular contraction

  →End-diastolic volume:preload or the stretch placed on the heart muscle

  →The critical factor effecting SV is preload

  → Most important factor stretching cardiac muscles is the volume of blood returning to heart called the venus return
• Cardiac Output: Volume of blood pumped out of the left ventricle per minute
• Stroke volume: volume of blood pumped out of the left ventricle per beat
• Training Effect:

  → Endurance training increases plasma volume & venous return

  →Increasing Preload

  → overtime LV hypertrophies increasing SV
• Wall thickness:

  → RA, RV, LA =5mm

  → LV=8-12mm
• Tunica Intima:

  → Innermost layer

  → Contain endothelium cells

  → Endothelium cells fit closely together forming a smooth surface to minimise friction
• Tunica Media:

  → Middle layer

  → Contains smooth muscle cells & sheets of elastin

  →activity of muscle regulated by a sympathetic vasomotor nerve fibres and the ANS

  →Bulkiest layers in arteries & are responsible for maintaining blood pressure
• Tunica Externa:

  → outermost layer

  → Composed of loosely woven collagen fibres then protect & reinforce the vessels

  → Infiltrated with nerve fibres & veins have a network of elastin fibres
• Sino-Atrial Node:

  → located in the right atria wall

  → generates impulses about 75x a minute

  → sets pace of the heart

  → No other region depolarises as quickly

  → causes atria to contract & ventricles fill up
• Atrioventricular Node:

  →from SAN the depolarisation waves spreads through both to the AVN via inter-nodal pathways

  → Impulse is delayed for about 0.12 seconds

  → once through AVN speeds through the rest of the system
• Purkinje fibres:

  → completes the pathway through septum

  → Network more elaborate in left ventricle

  → both ventricles contract at same time