Alimentary Canal Anatomy (first half)

Question 1

Mouth and pharynx (oropharynx and laryngopharynx)

Answer 1

• allows passage of food, fluid, and air
• lined by mucous membrane bearing stratified squamous epithelium (preventing cuts from tongue)
• larynx lined with skeletal muscles
• has vestibule: space between teeth and gums
• has tonsils: palatine (posterior end) and lingual (base of tongue)

Question 2

Pharynx

Answer 2

• passageway for food, fluid, and air
• food is propelled to the esophagus by two smooth muscle layers (longitudinal outer layer and circular inner layer)
• alternating contractions of muscle layers propels food down (peristalsis)

Question 3

Esophagus

Answer 3

• 25 cm
• collapsed when not in use
• first organ in the canal to have all four alimentary canal layers (mucosa, submucosa, mucsularis, and adventitia)

Question 4

Mucosa

Answer 4

• moist membrane

- composed of epithelial, connective, and muscular layer

Question 5

Epithelial layer of the mucosa

Answer 5

• simple columnar except in the esophagus, where it’s stratified squamous
• included goblet cells (that makes mucus) and enteroendocrine cells (that make hormones
• had direct contact with food
• cells only last a few days

Question 6

Connective Tissue later of the mucosa

Answer 6

• lamina propria: areolar

- lymphatic Tissue: mucosa associated lymphoid Tissue (MALT)

Question 7

Muscular Tissue of the mucosa

Answer 7

• muscularis mucosae

- thin layer of smooth muscle-causes mucosa to fold up and allows gland secretion

Question 8

Submucosa

Answer 8

• areolar tissue containing:
• blood vessels
• MALT & lymphatic Vessels
• nerve fibres that innervate surrounding tissue (submucosal nerve plexus)
• elastic fibres to maintain shape

Question 9

Muscularis externa

Answer 9

• two layers of smooth muscle (inner circular, outer longitudinal)
• thickening of circular layers that form sphincters ( controls passage of food from one portion to the next)
• allows segmentation and peristalsis
• nerve Tissue (myenteric nerve plexus) lies between the two layers

Question 10

Serosa

Answer 10

• outermost later
• contains fluid-producing cells
• in the abdominopelvic cavity, it is the visceral peritoneum (areolar connective Tissue covered by simple squamous epithelium)
• in the esophagus, serosa is replaced by adventitia

Question 11

Enteric nervous System

Answer 11

• alimentary canal has its own NS (has more neurons than the spinal cord)
• largely consists of two networks of neurons (submucosal and myenteric nerve plexus)
• linked to the CNS by sensory neurons from the sympathetic and parasympathetic neurons
• regulates mobility and secretory activity of the GI tract