<unk>  is the internal<unk>  at which a blood vessel collapses and closes completely. If blood<unk>  falls below<unk> , then the vessels collapse. This happens during the measurement of blood<unk>  with a sphygmomanometer. At resting state the arterial<unk>  is ~ 20 mmHg.<unk>  in arteries is higher than the mean vascular filling<unk>  that develops after death (~7 mmHg). Therefore, arteries collapse after death, then fill up with air once the dissection begins. In severe haemorrhage, blood loss leads to a significant reduction in<unk> . This, combined with activity in the sympathetic autonomic nerves supplying smooth muscle, leads to vasoconstriction to the extent that the vessels may collapse. This occurs at the<unk> ,<unk>  off blood supply to tissues, which can lead to toxic shock.
Critical closing pressure
Vascular resistance
Renal threshold
Flow-mediated dilation
Effective circulating volume
Rate pressure product
Alveolar–arterial gradient
Arterial input function