peristalsis

A form of muscular contraction that propogates itself down a body or organ. In humans, it pushes food through the digestive tract by propagating a kind of wave of contraction down the tube. Snakes can also use peristalsis as one of their modes of locomotion.

You can buy a peristaltic pump that uses the principle of peristalsis to move viscous material through a flexible tube.

I find peristalsis interesting, in that can be a highly recursive process; each muscle involved can trigger by reflex the actions of the next one. Want a demonstration? Try swallowing. Then try it again, but try to only use the first two muscles you used before, then stop.

Peristalsis occurs in all parts of the human gastro-intestinal tract between the oesophagus and the anus that are not under voluntary control.

Control of peristalsis is entirely involuntary and is mediated by the enteric nervous system. It works by simultaneously contracting smooth muscle in the area of gut above the bolus of food and relaxing the area just after it. The autonomic nervous system can affect peristalsis, making it slower or faster or even work in reverse (it's called vomiting or emesis).

I seriously wonder about the word peristalsis as used to describe snake movement in bitter engineer's writeup above. Can someone get a definite answer? (I'm not an expert on snake movement)

Alex.tan asks if snakes move by peristalsis. No, they don’t. Some move by lateral undulation; that is they fling their head side to side and the body follows. Some move by rectilinear movement; that is they use their belly scales to push down and move the body forward in a straight line.

Earthworms however, do move by a peristalsis like movement. They have a rhythmic wave of muscle contractions from the head to the tail. Earthworms have 2 types of muscles, circular which contract and longitudinal which extend to make the body longer, then the worm bunches up by contracting the longitudinal muscles and relaxing the the circular muscles. It’s sort of like a slinky being stretched out and brought forward repeatedly, except the slinky doesn't get thinner the way a worm does.

I’ve seen a video of an elephant using a peristaltic wave like movement of the tongue to move a single peanut placed there by its trunk from the anterior tip of the tongue back deep into its mouth. It looked like an ocean wave rising up and rolling back - carrying the peanut back like a surfer in the curl of the wave. I’d love to read more about this phenomenon but have never been able to find anything.

Infants use a peristaltic wave like movement of the tongue to compress the mother’s areola and move milk forward into their mouth. This is very similar to the elephant's tongue movement I’ve described above. The movement of the infant’s tongue has been documented by research ultrasounds and diagnostic video-fluoroscopies. An animated 20-second clip called “Physiology of Nursing” that illustrates the peristaltic movement of the infant’s tongue while breastfeeding can be seen here - under features, and then video clips at this web site:
www.breastfeeding.com

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65535 says "when the peristaltic muscles in your esophagus screw up, you get hiccoughs".

Well, not really. Digestive disturbances can indirectly lead to hiccoughs but they are really a spasm of the diaphragm combined with a forceful closure of the glottis.

Per`i*stal"sis (?), n. [NL. See Peristaltic.] Physiol.

Peristaltic contraction or action.

 

© Webster 1913.