Deglutition

Voluntary Phase

• Food (bolus) voluntarily squeezed to the back of oral cavity into oropharynx by movement of tongue upward and backward against palate

Pharyngeal Phase

• Bolus stimulate the receptor in oropharynx
• Impulses send to deglutition center in medulla oblongata.
• This causing the uvula and soft palate to move upward & close the nasopharynx which prevent swallowed foods and liquids entering the nasal cavity
• Epiglottis closes off the opening to larynx which prevent the bolus from entering the respiratory tract
• Once upper esophageal sphincter relaxed, bolus moved into esophagus

Esophageal Phase

• It begins once bolus enter the esophagus
• Peristalsis action pushes the bolus onward
• Circular muscles on the superior of the bolus contract and squeeze the bolus toward stomach
• Longitudinal muscles on the inferior to bolus contract and pushes the wall outward so it can receive the bolus
• As the bolus approaches the end of esophagus, Lowe Esophageal Sphincter (LES) relaxes and bolus moves into stomach

Vomiting

• Vomiting or emesis is the forceful expulsion of gastric contents out through the mouth and generally perceived as being caused by abnormal gastric motility.

• Stomach, esophagus and associated sphincter relaxes during vomiting.

• The major force of expulsion comes from contraction of respiratory muscles (diaphragm and abdominal muscles which aid during active expiration)

• Vomiting is coordinated by Vomiting Center in medulla.

• It begins with a deep inspiration and closure of glottis to prevent vomited material enter respiratory passage and uvula is elevated to close the nasal cavity.

• The contracting diaphragm descends down on stomach and contraction of abdominal muscles compresses the abdominal cavity, increasing the intra-abdominal pressure and forcing the abdominal viscera upward.

• This would cause the gastric contents forced upward through the relaxed sphincter and esophagus and out through mouth

• Vomiting is usually preceded by profuse salivation, sweating, rapid heart beat, and sensation of nausea.

• Causes of Vomiting:
• • Tactile (touch) stimulation of the back of the throat
  • Irritation or distention of stomach
  • Elevated intracranial pressure from cerebral hemorrhage
  • Rotation or acceleration of head
  • Chemical Agents
  • Emotional factors
  
  
• Effect of Vomiting

- Body experience large losses of secreted fluids and acids that normally would be reabsorbed.
- Reduction of plasma volume can lead to dehydration and circulatory and loss of acid would lead to metabolic alkalosis
- Vomiting also beneficial in removing noxious material in stomach (emetics given in the case of accidental
ingestion of poison)

Inguinal Canal

Location

• Inguinal Canal is an oblique passage through the lower part of the abdominal wall.
• It is formed by aponeurosis of External Oblique Muscle and extended from anterior superior iliac spine (ASIS) to pubic tubercle
• In male, it allows structure to pass to and from testis to the abdomen.
• In female, it allows the round ligament of the uterus to pass from the uterus to the labium majus

Walls

• Anterior - external oblique aponeurosis, lateral 2/3 of internal oblique muscle
• Posterior - fascia transversalis on lateral part, medial 1/3 of conjoint tendon on medial part.
• Superior - arching fibers of internal oblique muscle & transversus abdominis muscle
• Inferior – Lower edge of inguinal ligament and lacunar ligament on medial end.

Content

• Spermatic Cord
• Ilio-inguinal nerve
• Genital branch of genitor-femoral nerve

Extend

• The canal extends from the deep inguinal ring, a hole in the fascia transversalis, downward and medially to the external oblique muscle.
• It lies parallel and immediately above the inguinal ligament.

Major Gastrointestinal Hormones

· Gastrin – secreted by G cell of antrum of stomach.

· Cholecytokinin – secreted by I cell of duodenum and jejunum. It strongly contracting gallbladder, expelling bile into small intestine where bile in turn plays important play important role in emulsifying fatty substances. It also inhibit stomach contraction moderately

· Secretin – secreted by S cell in response to acidic gastric juice emptying into duodenum. It has mild effect on motility of GIT and act to promote pancreatic secretion of bicarbonate

· Gastric Inhibitory Peptide – in response in fatty acid and amino acid. It has mild effect in decreasing motor activity of stomach and therefore slows emptying of gastric contents into duodenum

· Motilin – Increase gastrointestinal motility

· Somatostin – Inhibition of secretion of gastrin, VIP, GIP, secretin and motilin.

HCl Secretion by Parietal Cell of Gastric Mucosa

· Acid is secreted when the parietal cells of the stomach are stimulated

· The pH of the acid is about 0.8

· The Hydrochloric Acid (HCl) is formed at the vilus-like projection inside the canaliculi of the parietal cells

· Proton pumps powered by H⁺/K⁺ ATPases actively transport H+ into the lumen while bringing potassium ion (K⁺) into the cell

· At the same time, Chloride ion (Cl^-) and K+ diffuse out into the lumen through the Cl^- and K⁺ channel.

· Carbonic Anhydrase catalyze the formation of carbonic acid from water and carbon dioxide. Carbonic acid dissociates into H⁺ and bicarbonate ion.

· As bicarbonate ion builds up in the cytosol, it diffuse out from the parietal cell into the ECF in exchange to the movement of Cl^- from ECF to the parietal cell

· Bicarbonate ion diffuses into nearby capillary

· Water passes into the canaliculus by osmosis. Thus, the final secretion contain water, hydrochloric acid, potassium chloride and sodium chloride

Differences Between Small & Large Intestine

Small Intestine	Large Intestine
Present of villi	No villi
Less Crypts of Lieberkuhn	More Crypts of Lieberkuhn
Less number of Goblet Cells	More Goblet cells
Present of Brunner’s gland in Submucosa of Duodenum	Brunner’s glands is absent
Taenia Coli is absent	Taenia Coli present at Muscularis Externa
Small intestine (except duodenum) is mobile	Ascending and descending parts of colon is fixed
Caliber of Small intestine is smaller	Caliber of Large intestine is larger
Present of mesentery that passes downward across midline into right iliac fossa	Absent of mesentry
The longitudinal muscle forms continuous layer around the gut	The longitudinal muscle is collected into three bands (taenia coli)
No fatty tags attach to the wall	Fatty tags (appendices epiploicae) attach to the wall
Wall of small intestine is smooth	Wall of large intestine is sacculated
Plicae circularis is permanent	Absent of Plicae circularis
Peyer patches found in mucous membrane	Peyer Patches is absent in mucous membrane
Mucous membrane contain villi	Absent of villi in mucous membrane