Lecture 7 - Mouth and esophagus

Question 1

What are the 4 major functions of the GI tract?

Answer 1

1. ) Digestion - breakdown to smaller particles both mechanically and chemically
2. ) Secretion
3. ) Absorption
4. ) Motility - mouth to anus usually except vomiting where it is small intestine to mouth

Question 2

How long is GI tract in living vs dead person?

Answer 2

Living - 7-7.5 m bc smooth muscles contracted

dead - 10-11 m because smooth muscles relaxed

Question 3

How much water is ingested and solids a day and how much excreted?

Answer 3

Take in 1200 ml of water and 800g of food. Only 100 ml of water and 50g of food excreted.

Question 4

How much absorbed by small intestine and large intestine?

Answer 4

small intestine - 6700 ml into blood
large intestine - 1400 ml into blood

These come from what we ingest and also secretions:
salivary secretions: 1500 ml 
Gastric secretions: 2000 ml 
pancreatic secretions: 1500 ml
Intestinal secretions: 1500 ml

Question 5

Where does most of the digestion take place?

Answer 5

small intestine

Question 6

Where is the first place of food digestion?

Answer 6

upper esophageal sphincter

Question 7

What does the mouth consist of?

Answer 7

Teeth, tongue, pharynx

Question 8

What is the chewing action?

Answer 8

reflex or voluntary and is mechanical.

Question 9

What does the tongue help to do?

Answer 9

Help shape food into a bolus and push it towards the pharynx

Question 10

What does the pharynx do?

Answer 10

Help crush food and closes nasal opening when swallowing.

Question 11

What is a sphincter?

Answer 11

Thickening of muscle that creates compartmentalisation.

Question 12

What are the major functions of saliva?

Answer 12

1. ) mosten and lubricate food
2. ) Digestion of polysaccharides by amylase
3. ) dissolve food
4. ) Antibacterial actions

Question 13

What are the secretions by the salivary gland?

Answer 13

Serous secretions: enzyme containing, parotid, submandibular, sublingual glands - release salivary amylase (ptyalin) and lingual lipase which requires a neutral pH and breaks down fat.

mucus secretions: Mucin containing - buccal, submandibular and sublingual glands. Lubrication prior to swallowing. Glycoproteins and create specific glycoproteins to trap bacteria.

Question 14

How much saliva produced when not eating?

Answer 14

0.5 ml / min

Question 15

Function of amylase?

Answer 15

breaks down glucose chains

Question 16

Other functions of saliva?

Answer 16

Tooth decay prevention: washing action, mucus coating of mouth and alkaline pH that buffers acidic foods.

Question 17

Where is the carotid salivary gland?

Answer 17

Invagination on the side of the cheek

Question 18

What is the mechanism for salivary excretion?

Answer 18

Initial saliva is produced in acinar cells. Basically, in the salivary ductal cell, proton (H+) is recycled to get pottasium into the saliva and sodium into the interstitial fluid.

Question 19

What are the 4 ions in saliva?

Answer 19

1. ) Na+
2. ) K+
3. ) Cl-
4. ) HCO3-

Question 20

What doesn’t the relationship between the composition of saliva and salivary flow rate not sit well with?

Answer 20

HCO3-

When moving to a higher flow rate, the concentration should also increase and not plateau. This is because there is specific stimulation of bicarbonate by the transporter.

Question 21

What is the regulation of saliva secretion by the autonomic nervous system?

Answer 21

Parasympathetic - through CN VII and IX send to Ach which sends to muscarinic receptor to release IP3 and Ca2+ in acinar or ductal cell.

Sympathetic - Norepinephrine is released and goes to beta receptor which releases cAMP in acinar or ductal cell.