Peristalsis ( PERR-ih-STAL-siss, US also  -⁠STAWL-) is a radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which is preceded by a simultaneous contraction of the longitudinal muscle and relaxation of the circular muscle in the lining of the gut.In much of a digestive tract such as the human gastrointestinal tract, smooth muscle tissue contracts in sequence to produce a peristaltic wave, which propels a ball of food (called a bolus before being transformed into chyme in the stomach) along the tract. The peristaltic movement comprises relaxation of circular smooth muscles, then their contraction behind the chewed material to keep it from moving backward, then longitudinal contraction to push it forward. Earthworms use a similar mechanism to drive their locomotion, and some modern machinery imitate this design. The word comes from New Latin and is derived from the Greek peristellein, "to wrap around," from peri-, "around" + stellein, "draw in, bring together; set in order". Human physiology
Peristalsis is generally directed caudal, that is, towards the anus. This sense of direction might be attributable to the polarisation of the myenteric plexus. Because of the reliance of the peristaltic reflex on the myenteric plexus, it is also referred to as the myenteric reflex. Mechanism of the peristaltic reflex
The food bolus causes a stretch of the gut smooth muscle that causes serotonin to be secreted to sensory neurons, which then get activated.
In medicine, aortoiliac occlusive disease is a form of central artery disease involving the blockage of the abdominal aorta as it transitions into the common iliac arteries. Signs and symptoms
Classically, it is described in male patients as a triad of the following signs and symptoms:
claudication of the buttocks and thighs
absent or decreased femoral pulses
erectile dysfunctionThis combination is known as Leriche syndrome. However, any number of symptoms may present, depending on the distribution and severity of the disease, such as muscle atrophy, slow wound healing in the legs, and critical limb ischemia. Diagnosis
The physical examination usually shows weakened femoral pulses and a reduced ankle-brachial index. The diagnosis can be verified by color duplex scanning, which reveals either a peak systolic velocity ratio ≥2.5 at the site of stenosis and/or a monophasic waveform. MRA and multidetector CTA are often used to determine the extent and type of obstruction. Another technique is digital subtraction angiography which allows verification of the diagnosis and endovascular treatment in a single session. Angiography provides important information regarding the perfusion and patency of distal arteries (e.g. femoral artery). The presence of collateral arteries in the pelvic and groin area is important in maintaining crucial blood flow and lower limb viability. However, angiography should only be used if symptoms warrant surgical intervention. Treatment
Treatment involves revascularization typically using either angioplasty or a type of vascular bypass
Kissing balloon angioplasty +/- stent, so named because the two common iliac stents touch each other in the distal aorta.