Cardiovascular System

Flashcards related to the cardiovascular system lecture.

Right ventricle

Propels blood to the pulmonary circulation.

Left ventricle

Propels blood to the systemic circulation.

Tricuspid valve

Located between the right atrium and right ventricle.

Mitral valve (bicuspid)

Located between the left atrium and left ventricle.

Pulmonary valve

Located between the right ventricle and pulmonary artery.

Aortic valve

Located between the left ventricle and the aorta.

Heart: 2 pumps in series

Volume output LHS = RHS; Pressure generated LHS ~ 4x RHS; ~ 5 litres/min or ~ 70 ml/beat; ~120 vs 30 mmHg.

Cardiac Output Equation

CO = Heart rate X Stroke volume (litres / min) = (beats/min) X (ml/beat)

Venous return (exercise)

Rises because of compression of veins by contracting skeletal muscle which increases Cardiac Output.

SNS activity (exercise)

Increased by higher brain centres which initiate exercise and in part by receptors in exercising muscles. Increases heart rate, which leads to increased CO.

PNS activity (exercise)

Inhibited during exercise which increases heart rate.

Cardiac hypertrophy

Develops with prolonged training where the left ventricle enlarges, raising stroke volume.

Aorta & large arteries Function

Distribution (conduit), handles high pressure reservoir, forward propulsion.

Aorta & large arteries Structure

Thick walled, highly elastic.

Arterioles Function

Tissue distribution of flow, variable resistance

Arterioles Structure

Thick walled, muscular, highly innervated

Capillaries Function

Exchange

Capillaries Structure

Thin walled (single cell), lacking elastic tissue and smooth muscle

Venules and veins Function

Reservoir (capacitance); at rest approximately 60% blood volume

Venules and veins Structure

Thin walled, some muscle and innervation, valves (unidirectional)

Individual vessel diameters

Aorta > Arteries > Arterioles > Capillaries and Capillaries < Venules < Veins

Blood stream velocity

Dependant on cross-sectional area

Blood Flow (Q)

Refers to the volume of fluid that passes a given cross-section of the vessel per unit time.

Fluid Velocity

Velocity is inversely proportional to cross-sectional area.

Velocity vs area

The larger the area, the lower the velocity

Pressure (Poiseuille’s Law)

Flow is proportional to the difference between inflow and outflow pressure.

Length (Poiseuille’s Law)

Flow is inversely proportional to length of the vessel.

Radius (Poiseuille’s Law)

Flow is proportional to radius of the vessel to the fourth power.

Viscosity (Poiseuille’s Law)

Flow is inversely proportional to viscosity of the blood.

Resistance equation

Pressure difference/Flow

Arterioles

Greatest capacity to change their radius and therefore influence resistance.