The Cardiovascular System Flashcards
What are the functions of the cardiovascular system?
Bulk flow system - O2, CO2, nutrients, metabolites, hormones, heat.
Reliable.
Flexible - pump can vary output; vessels can redirect and store blood.
Why are the heart pumps in series?
Ensures equal output on both sides.
Blood would accumulate otherwise.
Why are the vascular beds in parallel?
All tissues get oxygenated blood.
Allows regional redirection of blood.
What is the structure of the blood supply in the liver and gut?
Liver - portal system.
The gut and liver are in series.
Nutrients are absorbed in the gut and then sent to the liver for metabolism.
What is Darcy’s Law?
Flow = Pressure difference / Resistance.
Pressure difference = MAP - CVP.
Resistance - controlled by radius^4.
Controlled by arteriole contraction and dilation.
What is capacitance?
The ability to store blood.
Veins and venules can contain up to two thirds of the total blood volume.
What is the fractional distribution of blood?
The constriction and dilation of veins and venules to expel some of the spare capacitance of blood they contain, towards the heart.
How are organs related to cardiac output and oxygen consumption?
Similar = brain, skeletal muscle, abdominal organs.
CO > O2 - skin (thermoregulation); kidney (filtration).
CO < O2 - heart.
What is the structure and function of the aorta?
Thick and elastic walls.
Wide lumen.
Damps pressure variations.
What is the structure and function of the arteries and arterioles?
Arteries - thick and muscular walls, wide lumen, low resistance conduit.
Arterioles - thick and contractile walls, narrow lumen, controls resistance and flow.
What is the structure and function of the capillaries?
Thin walls.
Narrow lumen.
For exchange.
What is the structure and function of the venules and veins?
Thin and distensible walls.
Wide lumen.
Low resistance conduit and reservoir.
What are the valves used for?
Pulmonary and aortic - open when blood is squeezed out of the ventricles; closed when the heart fills with blood.
Mitral and tricuspid - prevents regurgitation of blood from the ventricle back into the atrium.
What are the functions of the chordae tendineae and papillary muscles?
CT - prevents valves from inverting. Lengthens when the heart contracts to take tension off the valves.
PM - attached to the CT. Contracts at the same time as the ventricles and maintains tension on the CT, preventing valve inversion.
What is the journey of blood?
(Start with the pulmonary trunk.)
Lung - pulmonary vein - LA - mitral valve - LV - aortic valve - aorta - arteriole - capillary - venule - vein - vena cava - RA - tricuspid valve - RV.
