GI: Salivary & Gastric Secretion

Question 1

Secretion

Answer 1

Addition of fluids, enzymes and mucus to the lumen of the GI tract

For digestion and absorption

Question 2

Salivary secretion

Answer 2

• Produced by the salivary gland

Question 3

Gastric secretion

Answer 3

Produced by cells of the gastric mucosa

Question 4

Pancreatic secretion

Answer 4

Produced by exocrine cells of the pancreas

Question 5

Bile (secretion)

Answer 5

Produced by the liver

Question 6

Enzymatic secretion

Answer 6

Produced by intestinal epithelial cells

Question 7

Synthesis and secretion are well controlled by:

Answer 7

Neurohormonal activity

Question 8

Major Salivary Glands (3):

Answer 8

• Parotid glands
• Mandibular glands
• Sublingual glands

** Also minor glands present in the mucosa**

Question 9

Parotid glands secrete:

Answer 9

Watery or serous saliva

Question 10

Mandibular glands secrete:

Answer 10

Mixed serous and mucous secretion

Question 11

Sublingual glands secrete:

Answer 11

Predominantly secrete mucus

Question 12

Minor glands in the mucosa secrete:

Answer 12

Highly mucous saliva

Question 13

Major functions of saliva:

Answer 13

• Lubricate and solubilize ingested food
• Digestion
• Protection

Question 14

Lubrication as a function of saliva:

Answer 14

• Solubilize the ingested food
• Bolus formed for swallowing and tasting
• Mucins help with improving solubility

Question 15

Digestion as a function of saliva:

Answer 15

Omnivorous animals (rats, pigs):

• Secrete salivary amylase to digest starch

Young Animals:

• Secrete lingual lipase for lipid digestion

Question 16

Protection as a function of saliva:

Answer 16

• Antibacterial activity
• Antibody secretion and lysozyme secretion

Question 17

Composition of Saliva in Ruminants

vs.

Saliva in Monogastric Animals

Answer 17

Ruminant Saliva:

• Alkalizing quality
• High [HCO3-]
• High [PO4 2-]
• Makes the pH high to help neutralize the acid produced by fermentation in the rumen
• Bicarbonate-phosphate buffer secreted in large quanities (100-200 L/day)

Monogastric animals:

• Much lower electrolyte concentration than the serum
• Hypotonic saliva

Question 18

Complications with blockage of the esophagus in Ruminants:

Answer 18

• Rapid dehydration due to inability to recycle saliva
• Acidosis
• Flow of saliva is diverted from the GI tract
• Inability to reabsorb saliva and recirculate it

Question 19

Structure of the Salivary Gland (Acinar Gland)

Answer 19

• Saliva is initially secreted by the acinar cells
• Then it is modified as it passes through intercalated ducts (collecting ducts)
• Moditification of acinar secretions by duct epithelia is common among several types of glands

Question 20

What do acinar cells secrete?

Answer 20

Acinar cells secrete: water, electrolytes, enzymes and mucus

Acinus: singular, grape-like structure

Acini: small sac-like cavity in a gland, surrounded by secretory cells

Question 21

Acini:

Answer 21

Cellular evaginations that together compose collecting ducts of the acinar gland

Question 22

Saliva is intially secreted into:

Answer 22

The lumen of the acini