Cardiovascular and Circulatory Systems Flashcards
Describe the conduction system of the heart.
The heart generates its own electrical impulses (autorhythmic) and has its own system devised to spread action potentials through the cardiac muscle.
Describe the role of the Sinoatrial Node.
Pacemaker of the heart and is situated superior to the sulcus terminalis of the RA, next to the opening of the superior vena cava.
Propagates electrical impulses and governs the sinus rhythm from minute to minute.
If this node should fail, the atrioventricular node has the capacity to undertake this role.
Describe the role of the Atrioventricular Node.
Located in the RA; posteroinferior to the interatrial septum and next to the septal cusp of the tricuspid valve.
Picks up and continues the action potentials produced by the SAN.
Its innovative area covers the atria of the heart.
Describe the role of Bundle of His.
Specialised bundle of cardiac muscle fibres seated within the interatrial septum.
These fibres run along the interventricular septum to the apex of the heart, where they branch further as conducting Purkinjie fibres that extend into the myocardium of the ventricles.
Right side has a single bundle that reaches the apex of the heart of the right ventricle before curving around it and travelling back along the right side of the heart.
The left side has an anterior and posterior division. The anterior division cuts across the left ventricle by running through its anterosuperior wall, while the posterior division acts as the right bundle does.
Describe the role of Purkinjie Fibres.
The terminal strands of nervous tissue that are responsible for making sure that every small group of cells is reached by an electrical stimulus, so that the maximum muscular contraction can occur.
Define an anastomoses.
Arteries connect with each other without an intervening capillary network. Provides alternative routes for blood to flow to supply the cells distal to an arterial occlusion (blockage). Each alternative route in any given anastomoses is called a ‘collateral’.
Define an end artery.
The only arterial blood supply to a given area of the body.
Define an infarction.
Irreversible cell death due to hypoxia cause by a loss of arterial blood supply.
Describe 3 ways used to return venous blood to the heart.
Venous valve- provide a unidirectional flow back to the heart against gravity.
Skeletal muscle pump- contraction of skeletal muscles to help push blood through the venous system.
Accompanying veins- small veins can run in pairs to more with an artery in a sheath. Artery pulsation pushes venous blood along.
Name the 2 main venous systems.
Hepatic portal venous system.
Systemic venous system.
Define vasodilation.
Relaxation of the smooth muscle and widening of the lumen to increase blood flow to the organ/tissue supplied.
Define vasoconstriction.
Contraction of smooth muscle and narrowing of the lumen to reduce blood flow to the organ/tissue supplied.
Name the different types of peripheral pulses.
Carotid Pulse.
Brachial Artery Pulse.
Radial Artery Pulse.
Femoral Artery Pulse.
Popliteal Artery Pulse.
Dorsalis Pedis Artery Pusle.
