Summary Lecture notes Unit 1 - Lifestyle, Transport, Genes and Health Salters-Nuffield AS/A level Biology Student Book 1 + ActiveBook

the cardiac cycle

capillary
valve present along the vessel :(
wall consists of a single layer of cells :)
endothelial cells present :)

veins
valves present along the vessel :)
wall consist of single layer of cells :(
endothelial cells present :)

three phases of cardiac cycle
atrial systole
ventricular systole
cardiac diastole

atrial systole
blood returns to the heart under low pressure to
the atria..as the atria fills, pressure increases
against the atrioventricular valve until they are
pushed open and blood begins to leak into the
ventricles
atria walls contract forcing more blood into the
ventricles

ventricular systole
ventricular systole follows atrial systole
ventricles contract from the base upwards,
increasing the pressure in the ventricles
the increased pressure forces the semilunar
valves open and pushes blood up and out
through the aorta and pulmonary arteries
the pressure of blood against the
atrioventricular valves closes them