physio

Question 1

what are slow waves?

Answer 1

intrinsic electrical activity: oscillating membrane potentials, occur spontaneously, no Ca+2 entrance but Na+ entry increases. aren’t action potentials but they create partial depol. (5-15mV) rhythmical.

Question 2

what are spikes?

Answer 2

depol.s that create APs

Question 3

cajal cells

Answer 3

are the pacemakers of smooth muscle cells, they express mechanosensitive Na+ conductance that regulates slow wave freq. Slow waves’ purpose is to depol. smooth muscle cells sufficiently to activate Ca+2 influx.

Question 4

what are phasic contractions

Answer 4

brief periods of both relaxation and contraction - mix the chyme - phasic smooth muscle contracts in bursts triggered by APs that causes increased Ca+2 levels

Question 5

what are tonic contr?

Answer 5

continuous, may take up to several hours - tonic smooth m. partially contracted at all times - contraction level depends on cytosolic Ca+2 levels

Question 6

where do phasic contr occur

Answer 6

posterior stomach and small intestine

Question 7

where do tonic contr occur

Answer 7

splinchters and ant stomach