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The jugular venous pulsation has a biphasic waveform. The a wave corresponds to right atrial contraction and ends synchronously with the carotid artery pulse. The peak of the 'a' wave demarcates the end of atrial systole. The x descent follows the 'a' wave and corresponds to atrial relaxation and rapid atrial filling due to low pressure.
Flow-through tests or immunoconcentration assays [1] are a type of diagnostic assay that allows users to test for the presence of a biomarker, usually a specific antibody, in a sample such as blood. They are a type of point of care test, designed to be used by a healthcare provider at patient contact. Point of care tests often allow for rapid ...
Carotid ultrasound is a low-cost, noninvasive, and accurate diagnostic imaging modality used to evaluate diseases of the carotid arteries. [2] It is most often used to diagnose carotid artery stenosis, a form of atherosclerosis, and has the capability to assess plaque morphology and characteristics. [1]
These differ in the amount of estrogen given, and whether they are monophasic (the same dose of estrogen and progestogen during each of the 21 days) or multiphasic (varying doses). The introduction of extended-cycle monophasic pills (i.e. Seasonale) has shown that the withdrawal bleeding intervals can be decreased.
With bi- and tri-phasic pills, skipping the placebo week results in a sudden change in hormone levels, which may cause irregular spotting or flow. (Monophasic pills offer the same dose of estrogen and progestogen whereas multiphasic pills have varying doses from day to day; see formulations for details.) [ citation needed ]
In "retrograde" flow, the flow would reverse (e.g. veins flow away from heart or arteries flow towards the heart). However, "retrograde" flow can be both abnormal or normal. For example, in portal hypertension , there is an abnormal portal venous flow where it flows away from the liver (hepatofugal flow) instead of the normal flow towards liver ...
For example, oxytocin has a half-life of typically about three minutes in the blood when given intravenously. Peripherally administered (e.g. intravenous) peptides like oxytocin cross the blood-brain-barrier very poorly, although very small amounts (< 1%) do appear to enter the central nervous system in humans when given via this route. [31]
For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. [18] There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry. [19]