The Digestive System Part 2 EXTRA Flashcards
The colon has four major parts to it, list them
the ascending colon, the transverse colon, the descending colon and the sigmoid
what is the taeniae coli
the teniae coli are three separate longitudinal bands of smooth muscle on the outside of the four colons
what is the function of the taeniae coli
the teniae coli contract lengthwise to produce the haustra - the bulges in the colon
the large intestine has a absorptive and storage function, what does it absorb and what does it store
absorbs water and electrolytes, stores faeces
the large intestine is motile, what type of movements take place
mixing and propulsive movements
mixing occurs in the large intestine, what type of contraction allows this to occur
haustral contractions
what are the two types of mixing movements that the haustral contractions bring about
primary motility, slow back-forth mixing movement
what does the mixing movement allow
the exposure to absorptive surfaces
what does propulsion allow
mass movements to take place
large segments of ascending and transverse colon contract simulateneously roughly how many times a day
3/4 times a day
where do the propulsive movements propel the contents to
to the anus obvs
what is the rectum
the straight portion of the large intestine which stores faeces
the rectum opens to the exterior via which structure
the anal canal
what are the two sphincters called
the internal and external sphincters
the sphincters are in a ____ state of contraction
tonic
what is a tonic contraction
Tonic contractions are those contractions that are maintained from several minutes up to hours at a time. These occur in the sphincters of the tract, as well as in the anterior stomach.
what type of muscle makes up the internal anal sphincter
smooth muscle
under what control is the internal anal sphincter
involuntary
what type of muscle makes up the external anal sphincter
skeletal muscle
under what control is the external anal sphincter
voluntary
what do faeces in the rectum stimulate
the stretch receptors > desire to defecate
what happens to the internal anal sphincter when the stretch receptors are stimulated
the internal anal sphincter relaxes
when does the rectum and sigmoid colon contract more vigorously
once the internal anal sphicnter relaxes as a result of the stretch receptors being stimulated
the defecation reflex may be voluntarily inhibited by what
the external sphincter
