G.I.T Motility

All of the following are correct regarding GI smooth muscles EXCEPT :

Correct! Wrong!

Smooth muscle is an involuntary non-striated muscle. It is divided into two subgroups; the single-unit (unitary) and multiunit smooth muscle. Within single-unit cells, the whole bundle or sheet contracts as a syncytium.


They are arranged in bundles

Which of the following is example of Electromechanical Coupling?

Correct! Wrong!

Pharmacomechanical Coupling
Binding of a ligand to its receptor on the muscle membrane leads to opening of Ca++ channels


Mechanomechanical Coupling
Stretch-sensitive calcium channel

Basic Electrical Rhythm is present in all parts of GIT EXCEPT:

Correct! Wrong!

The slow waves, which oscillate significantly are called basal electrical rhythm (BER) that occurs due to wide variation in the RMP of GI smooth muscles.


The BER is present in all parts of GIT except in the esophagus.

Slow waves are generated by :

Correct! Wrong!

Slow waves are generated by the interstitial cells of Cajal located between the longitudinal and circular muscle layers

The frequency of slow waves is highest for which place?

Correct! Wrong!

The frequency of slow waves is :
- 3/min in stomach,
- colon - 6 to 10/min
- jejunum and ileum -15/min in
- duodenum - 18/min

Which of the following is CORRECT regarding amplitude of slow waves?
1. Sympathetic stimulation increases the amplitude of slow waves
2. Parasympathetic stimulation increases the amplitude of slow waves
3. Sympathetic stimulation decreases the amplitude of slow waves 4. Parasympathetic stimulation decreases the amplitude of slow waves

Correct! Wrong!

Which is TRUE for electrical coupling of Smooth muscle cells of the GIT?

Correct! Wrong!

Electrical coupling between circular cells is better than the longitudinal cells

Electrical coupling between circular cells is better than the longitudinal cells because :

Correct! Wrong!

Electrical coupling between circular cells is better than the longitudinal cells because the circular cells have more gap junctions.

Which of the following is one of Major excitatory neurotransmitters in GIT Motility?

Correct! Wrong!

Major excitatory neurotransmitters - acetylcholine and substance P,


inhibitory neurotransmitters - Catecholamines, ATP, VIP, and NO.

Which of the following is a excitatory neurotransmitters in GIT Motility?

Correct! Wrong!

Major excitatory neurotransmitters - acetylcholine and substance P,


inhibitory neurotransmitters - Catecholamines, ATP, VIP, and NO.

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