Week 1

Question 0

How is saliva produced?

Answer 0

It is a 2 stage process - initially isotonic containing NaCl, protein and mucus.

It then passes through the salivary duct where K+ and bicarbonate is secreted and salt is era sorted to form a alkaline fluid.

Question 1

What does the soft palate and epiglottis do?

Answer 1

Prevents food going the wrong way, directs it to the oesophagus.

Question 2

What is the neural control for water and mucoid secretion in saliva production?

Answer 2

Water: parasympathetic

Mucoid: sympathetic

Question 3

What are the names of the 3 main salivary glands?

Answer 3

Parotid, submandibular and sublingual.

Question 4

What secretions does the parotid produce and how much of the salivary volume does it release?

Answer 4

The parotid is mainly serous secretion.

Releasing 25% of the salivary volume

Question 5

What enzymes/proteins does the parotid secrete?

Answer 5

Amylase and Proline.

Question 6

What is the innervation of the parotid?

Answer 6

Parasympathetic via CN IX (glossopharyngeal)

Sympathetic via cervical plexuses.

Question 7

What secretions and how much of salivary volume does the submandibular gland secrete?

Answer 7

The submandibular releases a serous and mucous mix.

70% of the salivary volume.

Question 8

What enzymes/proteins does the submandibular release?

Answer 8

The submandibular releases lysozyme and lactopeptidase.

Question 9

What is the innervation of the submandibular and sublingual gland?

Answer 9

Parasympathetic via CN VII

Sympathetic via superior cervical ganglion.

Question 10

What secretions and how much of the salivary volume does the sublingual gland secrete?

Answer 10

Sublingual mainly secretes mucous

Contributing 5% to the salivary volume.

Question 11

What enzyme/protein does the sublingual secrete?

Answer 11

Lingual lipase.

Question 12

At what sites can amylase cut starch and other polysaccharides?

Answer 12

Alpha amylase can only cut at the alpha1-4 sites.

Starch has alpha1-4 sites and alpha1-6 sites.

Question 13

What are the 3 types of tastebuds?

Answer 13

The 3 types are fungiform, filiform and circumvallate.

Question 14

What sensors are salty and sour stimuli detected through?

Answer 14

Salty and sour stimuli are through ion channel based sensors.

Question 15

How are sweet, Unami and bitter stimuli detected?

Answer 15

Sweet, Unami and bitter stimuli are through GPCR based sensors.

Question 16

What does the cardia of the stomach secrete, and why?

Answer 16

The cardia secrets HCO3- to neutralise

Question 17

What does the cardia of the stomach connect with?

Answer 17

The cardia of the stomach connects with the oesophagus.

Question 18

What does the fundus and the body of the stomach secrete?

Answer 18

The fundus and body secrete: H+, intrinsic factor, mucus, HCO3-, pepsinogens and lipase.

Question 19

What is the fundus and body used for?

Answer 19

The fundus and body are the main store area - half a litre to 1 litre.

Question 20

What does the pylorus of the stomach secrete?

Answer 20

The pylorus secretes mucus (lubricant) and HCO3-

The pylorus is also focused on breakdown of foods

Question 21

What is gastric motility?

Answer 21

It is an active process which involves the grinding and churning (antrum) by peristaltic waves to accept and accommodate food.

Emptying at the antrum and pylorus is caused by feedback from duodenum.

Question 22

What is the vaso-Vaal reflex?

Answer 22

The vaso-vagal reflex allows lots of food to be stored in the stomach without a rise in pressure. Stretch receptors signal via the vagus.

A signal then descends to act on enteric nervous system which cause relaxation and dilation of fundus.

Question 23

How is gastric emptying controlled?

Answer 23

Particles less than 1-2mm can only pass through pyloric sphincter.

The duodenum senses acid delivery, amino acids and lipids, so it secretes hormones (CCK, secretin GIP(gastric inhibitory peptide)) which decrease gastric motility and emptying.

Question 24

What do mucous cells secrete?

Answer 24

Mucous cells secrete mucous and HCO3-

Question 25

What do parietal cells (found in funds and body) secrete?

Answer 25

Parietal cells secrete intrinsic factor and HCl

Question 26

What do G cells secrete?

Answer 26

G cells secrete Gastrin

Question 27

What do Chief (peptic) cells secrete?

Answer 27

Chief (peptic) cells secrete pepsinogen.

Question 28

What is Gastrin and where is it secreted from?

Answer 28

Gastrin is a peptide hormone from stomach and intestine.

There are 2 forms: G17, main form secreted from Antrum.
G34 from duodenum. (Homologous with CCK-PZ and can share receptors as 5 amino acids of C terminal of the same)

Question 29

What is gastrin stimulated and inhibited by?

Answer 29

Amino acids and stretch receptors (parasympathetic) stimulate Gastrin.

Gastrin inhibited by H+ (negative feedback)

Question 30

What is somatostatin?

Answer 30

A somatostatin is a peptide hormone –> two forms 14 and 28aa. 28aa in the gut.
Acts on G cells to inhibit Gastrin (as well as CCK and secretin.

It is released from D cells of stomach, duodenum and pancreas. Secreted by paracrine when stimulated by H+.

Question 31

Parietal cells secrete intrinsic factor and HCl. How do they work?

Answer 31

They are stimulate by Gastrin and ACh (acetylcholine) and inhibited by somatostatin. Histamine also stimulates.

Acid is added through use of K+/H+ ATPase.

Question 32

What is pepsin?

Answer 32

Protease secreted from chief cells in response to ACh and H+.

Pepsin is the successor to pepsinogen. It cleaves peptide bonds breaking long polypeptide chains into shorter lengths.