5

Question 1

Vomiting reflex outward expulsion of gastric contents
through the esophagus & mouth. It is often preceded by:

Answer 1

• Nausea. - salivation & sweating.

Question 2

Types & causes: of Vomiting

Answer 2

Reflex vomiting
Central vomiting:

Question 3

Reflex vomiting

Answer 3

Conditioned reflexes due to sickening scenes or
nauseating smells.

Unconditioned reflexes: GIT
1. Intrinsic reflexes - From inside GIT e.g. * due to irritation of the posterior part of the tongue, oropharynx & gastric mucosa.
* Cases of Gastro-
* Impulses stimulate the
enteritis & vomiting centre.
appendicitis.

2. Extrinsic reflexes - From outside GIT e.g. Renal colic, myocardial infarction & motion sickness.

• Impulses stimulate the vomiting centre

Question 4

Central vomiting:

Answer 4

Central vomiting:
(A) Chemical:
- Drugs: as morphine, apomorphine and digitalis.
- Hypoxia, toxemia & uremia.
- Stimulate chemoreceptors (chemoreceptor trigger
zone; CTZ) in medulla oblongata which stimulates
vomiting center.
(B) Mechanical:
- Intracranial tension (ICT) & meningitis.
- Projectile vomiting (sudden, strong & not preceded
by nausea).

Question 5

Effects of excessive vomiting

Answer 5

1 . Dehydration (loss of water).
2. Hypokalaemia (loss of K+).
3. Metabolic alkalosis (loss of Hcl).
- In prolonged vomiting, metabolic acidosis due to
dehydration & ketosis result from starvation.

Question 6

Vomiting is the means by which the …………rids itself of its
contents when almost any part becomes

Answer 6

upper GIT, duodenum

excessively irritated, overdistended, or even over-excitable.

Question 7

Receptors: The sensory signals that initiate vomiting originate mainly from the……………,………..,……. ,……………

Afferent: The nerve impulses are transmitted by both …………….,…………… afferent nerve fibers to multiple distributed nuclei in the brain stem (center) that all together are called the
“vomiting center.”

Answer 7

Receptors: The sensory signals that initiate vomiting originate
mainly from the pharynx, esophagus, stomach, and upper
portions of the small intestines.

Afferent: The nerve impulses are transmitted by both vagal and
sympathetic afferent nerve fibers to multiple distributed nuclei
in the brain stem (center) that all together are called the
“vomiting center.”

Question 8

Efferent: The motor impulses that cause the actual vomiting are transmitted from the vomiting center by way of the …..,….,….,…,…cranial nerves to the ………. GIT,
through upper………..,……. nerves to the ………. GIT,
and through ………to the……………..,………..

Answer 8

Efferent: The motor impulses that cause the actual vomiting are
transmitted from the vomiting center by way of the 5th, 7th, 9th,
10th, and 12th cranial nerves to the upper GIT, through vagal and
sympathetic nerves to the lower GIT, and through spinal nerves to
the diaphragm and abdominal muscles.

Question 9

Antiperistalsis, the Prelude to Vomiting
- In the early stages

Answer 9

excessive GI irritation or overdistention, antiperistalsis begins to occur often many minutes before vomiting
appears.

Question 10

At the onset of vomiting,

Answer 10

strong intrinsic contractions occur in both
the duodenum and the stomach, along with partial relaxation of the
esophageogastric sphincter, thus allowing vomitus to move from the
stomach into the esophagus.

Question 11

Vomiting Act
Once the vomiting center is stimulated, the first effects are:

Answer 11

(1) a deep breath
(2) raising of the hyoid bone and larynx to pull the upper
esophageal sphincter open
(3) closing of the glottis to prevent vomitus flow into the lungs
(4) lifting of the soft palate to close the posterior nares.
(5) Next, a strong downward contraction of the diaphragm along
with simultaneous contraction of all the abdominal wall eat
stomach
muscles occur. This squeezes the stomach between the diaphragm and the abdominal muscles, increasing the intra- gastric pressure to a high level.

6) Finally, the lower esophageal sphincter relaxes completely,
allowing expulsion of the gastric contents upward through
the esophagus.