Gastric motility

Question 1

Transit time

Answer 1

time taken by food to travel from one location in gut to another

• increased in propulsive motility shortens transit time
• increased in retentive motility increases transit time

Question 2

Functions of GI movements

Answer 2

• to propel ingesta from one location to the next
• to retain ingesta at a given site for digestion, absorption or storage
• to break up food material pysically and mix it with digestive secretions
• to circulate ingesta so that all portions come into contact with absorptive surfaces

Question 3

GI SM cells are _______________ via gap junctions

Answer 3

electrically coupled

-allows transmission of depolarizations from cell to cell

Question 4

GI pace maker cells are called?

Answer 4

interstitial cells of cajal

Question 5

Interstitial cells of cajal are?

Answer 5

intrinsically rhythmic- repeatedly depolarize and then repolarize

Question 6

Slow waves

Answer 6

initiated by ICCs propagate through GI smooth muscle as waves of subthreshold depolarization
-APs do NOT fire and contraction does NOT occue

Question 7

Slow waves determine _________ of contraction._______ determine whether the contraction occurs or not

Answer 7

pattern

neurotransmitters

Question 8

Pacemakers (ICCs) are located in or near SM in?

Answer 8

stomach
duodenum
colon

Question 9

Peristaltic reflex is entirely internal to?

Answer 9

the ENS

Question 10

Motility in the GI tract

Answer 10

mouth, pharynx, larynx
-skeletal muscle
-controlled by CNS
esophagus
-skeletal m (ruminants, dogs) CNS
-mixed (cats, horses): ENS ,ANS
Stomach and intestines
-SM
-mostly controlled by ENS 
-coordination essential for function (gap junctions, intrinsic rhythm)

Question 11

Voluntary and involuntary phase of deglutition (swallowing)

Answer 11

1. voluntary - food is pushed into oropharynx by the tongue

2. involuntary phase: swallowing reflex, controlled by CNS (cranial nerves V, VII, IX, X, XII)

Question 12

Phases of swallowing include

Answer 12

1. oral: tongue forms bolus

2. pharyngeal: propulsion of bolus from base of tongue to larngopharynx ; epiglottis covers tracheal orifice