Flashcards in Transport Deck (8)
What is the function of an artery, vein, or capillary?
Artery: pump blood at high pressures
Vein: collect blood at tissues and return it
Capillary: exchange materials
Describe arterial structure.
-Elastic tissue helps propel blood down artery
-Smooth muscle contraction in artery wall determines diameter of the lumen
-Small lumen-> higher pressure
Describe a capillary
-Branch and rejoin repeatedly to form capillary networks which transport blood through almost all the body
-One layer of epithelium cells for rapid diffusion
Describe the structure of a vein.
-Walls less thick. Fewer muscle fibres
Differentiate between systemic and pulmonary circulation.
-Pulmonary is to and from the lungs.
-Systemic is to and from other organs.
Outline one pass through the heart and body.
vena cavae-> right atrium-> right ventricle-> pulmonary artery-> lungs-> pulmonary veins-> left atrium-> left ventricle-> aorta-> rest of body
Outline how the SA node, AV node, and conducting fibres control the heartbeat
-SA node spontaneously initiates action potentials
-Gap junctions allow SA contraction to rapidly travel across entire atrium, causing systole.
-SA nodes reach AV node which spreads signal throughout the heart with purkinje fibres, causing the ventricles to undergo systole. Causes atrioventricular valves to close. Ventricles then empty and the semilunar valves close.
-Ventricles begin diastole, atrioventricular valves open and the ventricles fill with blood. Finally, all four chambers enter diastole and are filling. When they fill, the cycle restarts.