Class Notes (811,169)
Canada (494,539)
Brock University (11,942)
Biology (1,613)
BIOL 2P93 (93)

GI Motility

1 Page
Unlock Document

Brock University
Jenny Janke

Outline of Lecture 28 (05-13 B; Ravich) GI Motility - The GI tract can be seen as a series of pumps, conduits, reservoirs, and gates. This allows the tract to perform several functions such as propulsion, grinding, mixing, and compartmentalization. - There are 2 types of enteric smooth muscle contractions. Phasic contractions result from momentary stimulation and are used for pumping. Tonic contractions result in continuous pressure such as in sphincters, and must be relaxed to allow gating. - Neural input for most of the GI tract is mostly autonomic. The parasympathetic side stimulates the GI tract in general, and its nerves enter through the vagus and sacral plexus. The sympathethic side is inhibitory in general, and nerves enter through the sympathetic ganglion. - The myenteric plexus is the intrinsic nervous system of the gut and while it is modulated by the CNS it can operate independently. - Some GI muscle is directly innervated and others are indirectly innervated. - The pattern of contraction determines the result. A smooth contraction wave gives propulsion; a smooth but partial contraction wave gives mixing and propulsion; uncoordinated contractions give mixing and grinding. - Slow waves are rhythmic undulations in the membrane potential of myocytes. Spike potentials, and hence contractions, only occur at the peaks of the slow waves, and this helps control the timing of contractions. - Sphincters act as one-way valves. Hence a proximal distention causes relaxation to allow forward movement of material, but a distal distention causes increased contraction to prevent retrograde flow. - The oropharynx is common to both the GI and respiratory system. In swal
More Less

Related notes for BIOL 2P93

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.