Definition of diastole in US English:

diastole

noun

Physiology
  • The phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood.

    Often contrasted with systole
    • ‘The reflected wave returns to the aorta during systole rather than diastole, increasing systolic work even more and reducing diastolic pressure, on which coronary flow depends.’
    • ‘Coronary blood flow occurs during diastole, and as the heart rate increases diastole shortens.’
    • ‘It relaxes slowly in early diastole and offers greater resistance to filling in late diastole, so that diastolic pressures are elevated.’
    • ‘Systole is that part of the heart's pumping cycle when it contracts and pushes blood out, the pulse if you like, and diastole is when the heart relaxes and fills with blood ready for the next heartbeat.’
    • ‘During diastole, blood fills the veins and moves cephalad with each heartbeat.’

Origin

Late 16th century: via late Latin from Greek, ‘separation, expansion’, from diastellein, from dia ‘apart’ + stellein ‘to place’.

Pronunciation

diastole

/ˌdīˈastlē//ˌdaɪˈæstli/