Gastrointestinal: Swallowing and Mastication

Question 1

List the three salivary glands and where they secrete.

Answer 1

Parotid- upper 2nd molar
Submandibular- under lower edge of the mandible
Sublingual- floor of the mouth

Question 2

What are the functions of saliva?

Answer 2

Lubrication
Solvent
Antibacterial 
Carbohydrate digestion
Neutralises acid
Sucking in infancy

Question 3

What cells are respinsible for the primary secretion of saliva?

Answer 3

Acinur cells

Question 4

What is secondary secretion and what cells carry it out?

Answer 4

Cells modify secretion by removing sodium and chlorine and adding carbonate and potassium- DUCT CELLS

Question 5

When is the level of bicarbonate in the saliva highest?

Answer 5

During high flow rates

Question 6

Describe the unconditioned production of saliva/

Answer 6

Chemo/oressure receptors detect food bolus
Visceral afferents to salivary centre in medulla
Autonomic nerve impulses
Salivary gland increase production

Question 7

Describe conditioned production of saliva.

Answer 7

See/hear/think about food
Cerebral cortex
Salivary centre of medulla
Autonomic nerves
Saliva production

Question 8

What parasympathetic nerves are responsible for saliva production

Answer 8

Glossopharyngeal

Facial

Question 9

What effect does parasympathetic stimulation have on saliva?

Answer 9

Increase production

Watery and enzyme rich

Question 10

What affect does sympathetic stimulation have on salivat production

Answer 10

Small volume
Thick
MUcus rich

Question 11

Describe peristalsis in the oesophagus.

Answer 11

Circular fibres behing bolus squeeze

Longitudinal fibres in front shorten

Question 12

What controls peristalsis in the oesophagus?

Answer 12

Enteric nervous system

Question 13

What happens to the lower oesophageal sphincter in swallowing?

Answer 13

Opens within response to swallowing and closes after passage of bolus to prevent reflux

Question 14

What is the function of the stomach

Answer 14

Mixes food with gastric secretions to produce chyme

Stores food before passing it into the small intestine for digestion and absorption

Question 15

What controls gastric motility?

Answer 15

Pacemaker cells

in the fundus

Question 16

What do the pacemaker cells do

Answer 16

Establish a basal electrical rhythm

Question 17

How does the electrical rhtythm spread?

Answer 17

From fundus to pyloric schincter

Question 18

What gastric factors determine the rate of stomach emptying?

Answer 18

Distention- increases motility due to stretch of smooth muscel which stimulates increased vagus nerve activity and gastrin increase
Constituency of chyme- finely divided, thick liquid chyme speeds up emptying

Question 19

What duodenal factors determine the rate of gastric emptying?

Answer 19

Neuronal- enterogastric reflex- decreases peristalsis through signals fromt he intrinsic nerve plexus and the autonomic nervous system
Hormonal- enterogastrone release inhibits stomach contraction

Question 20

Name two entergastrones

Answer 20

Secretin

CCK

Question 21

How does fat affect gastic emptying?

Answer 21

Fats take a long time to digest- slows it down

Question 22

How does acid affect gastic empyting?

Answer 22

If duodenum detects acid- will inhibit stomach peristalsis due to the fact it need to wait for alkaline solutions from the pancreas

Question 23

How does hypertonicity affect gastric emptying

Answer 23

– products of carbohydrate and protein digestion are osmotically active and draw water into the small intestine – danger of reduced plasma volume and circulatory disturbances
Slows down emptying

Question 24

How does distention affect gastic emptying?

Answer 24

distention in the duodenum slows down gastic emptying