Motility Flashcards
What are the three muscle layers of the alimentary tract?
submucosal muscle, inner circular muscle, outer longitudinal muscle
What is the submucosal muscle in charge of?
villi movement - shortening and lengthening the vili during digestion
What type of contraction is associated with inner circular muscles?
segmental contractions
What type of contraction is associated with outer longitudinal muscle?
peristaltic contractions
Where is voluntary striated skeletal muscle located in the alimentary tract?
pharynx, proximal esophagus, and anal sphincter
Along with sodium, what else do smooth muscles need to generate an action potential?
calcium
How are myosin binding sites exposed in smooth muscle contraction?
since there is no troponin, calcium binds to calmodulin which will bind to the tropomyosin and expose the binding sites
How do smooth muscle contractions end?
since there is non sarcoplasmic reticulum, they only end when calcium is pumped out of the cell
Is smooth muscle contraction or skeletal muscle contraction quicker?
skeletal muscle contraction
Does smooth muscle contraction or skeletal muscle contraction last longer?
smooth muscle contraction
What is special aboud the stimulation of smooth muscle?
each fiber does not need to be individually stimulated because smooth muscle can function as a syncytium
What is a syncytium?
when large areas of smooth muscle cells contract as a single unit
What is the purpose of gap junctions?
they are low resistance pathways that allow for ion movement and electrical impulses between adjacent cells
How do segmented type contractions work?
areas of circular muscle constriction close the lumen and divide the gut into dilated segments containing ingesta, at periodic intervals the areas of constriction and dilation alternate, exerting a mixing and circulating action on the ingesta
What is the major stimulus for segmented type contractions?
stretch of the gut wall carried out primarily as a local reflex within the ENS
