Dukes' Ch. 42: GI Motility

Question 1

A rabbit is brought to your office. It has wet matted hair and slimy drool around its mouth and on its chest. Its hair coat is in general matted and the rabbit is in a thin condition. It has been eating a high legume/corn mix diet. What are you likely to see on examining the rabbit carefully?

Answer 1

Malocclusion of the molars or incisors

Question 2

During the swallowing reflex, the dorsal soft palate is elevated. Why?

Answer 2

To prevent ingesta from entering the nasopharynx and coming out the nose

Question 3

The premolars of a horse are classified as (A) _____ teeth. Enamel ridges wear more slowly than the ridges composed of (B) _____ and (C) _____ that keep the occlusal surface sharp.

Answer 3

(A) hypsodont, (B) dentin, (C) cementum

Question 4

What kind of receptors does the neurotransmitter released by post-ganglionic fibers of the vagus nerve stimulate?

Answer 4

Muscarinic receptors on target cells

Question 5

A horse consuming red clover hay is drooling several liters of foamy drool per hour.
(A) What is in the clover?
(B) What is it doing/acting on? (Be specific)

Answer 5

(A) Slaframine

(B) Salivary muscarinic receptors

Question 6

_____ exist between muscle cells that form a syncytium. Those structures allow ion fluxes to pass freely from one cell to another within the syncytium.

Answer 6

Gap junctions

Question 7

How does vasoactive intestinal peptide affect the lower esophageal sphincter?

Answer 7

Relaxes it to allow entry of bolus

Question 8

How does gastrin affect the lower esophageal sphincter?

Answer 8

Tightens it closed

Question 9

Arrange the following possible sites of impaction in a horse in order, with 1 being first (most orad) and 6 being last.
(A) Pelvic flexure of colon
(B) Pylorus of stomach
(C) Sternal flexure
(D) Entrance to transverse colon
(E) Cecocolic orifice
(F) Diaphragmatic flexure

Answer 9

B, E, C, A, F, D

Question 10

Arrange the steps (A-G) involved in defecation in oder from first to last.
(A) Conscious decision is made to defecate and signals are sent back down spinal column to somatic motor nerves which reach the external anal sphincter via the pudendal nerve.
(B) Peristalsis in descending colon sends fecal material to rectum
(C) Stretch receptors in vicinity of internal anal sphincter sense presence of matter and send afferent impulses to sacral spinal cord via sacral spinal nerves
(D) Sacral spinal parasympathetic efferent fibers to internal anal sphincter are activated and sphincter relaxes
(E) Pressure on external anal sphincter is sensed by receptors in vicinity of external anal sphincter sending afferent impulses to the higher centers of the brain
(F) External anal sphincter relaxes and with abdominal muscle contraction raising intra-abdominal pressure the fecal matter is passed out
(G) Rectum is normally devoid of feces

Answer 10

G, B, C, D, E, A, F