Gastrointestinal system 6

Question 1

How many salivary glands are there

Answer 1

3 pairs
Sublingual
Submandibular
parotid

Question 2

How much fluid do the salivary glands produce

Answer 2

1.5L per day
Basal secretion - 0.3 ml/min
Stimulated secretion - 1.5 ml/min

Question 3

What is saliva made up of

Answer 3

Mucus
Dilute solute NaHCO3/NaCl - optimal pH
Digestive enzymes

Question 4

What are the two main digestive enzymes in saliva

Answer 4

Lingual lipase - Fats

alpha-amylase - Starch

Question 5

What does saliva aid

Answer 5

Talking
Chewing and swallowing
Hygiene
(Dissolves food and lubricates)

Question 6

What is xerostomia

Answer 6

‘Dry mouth’ - due to lack of saliva

Can lead to tooth decay

Question 7

How do nerves regulate salivary secretion

Answer 7

Though, smell and sight of food

Presence of food in mouth

Question 8

How does the autonomic nervous system regulate salivary secretion

Answer 8

Parasympathetic - stimulates secretion (copious quantities)

Sympathetic - Small volumes of viscous fluid

Question 9

What volume of gastric secretion produced per day

Answer 9

2-3 L per day
Superimposed on basal rate when eating
Slow between meals

Question 10

What makes up daily gastric secretion

Answer 10

Mucous (mucous cells)
HCL acid - 150 mls per hour (parietal cells)
Intrinsic factor (parietal cells)
Pepsinogen (chief cells)

Question 11

What is he function of gastric mucous

Answer 11

Protection from abrasions and acid

Question 12

What is the function of intrinsic factor

Answer 12

Absorption of Vitamin B in SI

Question 13

What is the function of pepsinogen

Answer 13

Gastric proteolytic enzyme

Converted to active form (pepsin) by acid and starts digestions of proteins

Question 14

What is the function of gastric acid

Answer 14

Dilutes fluid
Denatures proteins
Activates pepsinogen 
Optimum pH for pepsin
Protection (bacteria)

Question 15

What are the thee phases of gastric secretion

Answer 15

Cephalic - head controls
Gastric - stomach controls
Intestinal - intestine controls

Question 16

Describe the cephalic phase

Answer 16

Preparation for arrival of food - stimuli
Chewing action
Parasympathetic NS - via enteric stimulates parietal, chief and goblet cells - stimulates secretion of gastrin into blood

Question 17

What does gastrin do

Answer 17

Stimulates parietal and chief cells

Question 18

Describe the stimuli of the gastric phase

Answer 18

Sufficient secretion to handle ingested food

Stimuli in stomach stretch/distend - elevated pH

Question 19

Describe hormonal and nervous regulation in the gastric phase

Answer 19

Local nervous reflex - ENS
External nervous system - parasympathetic
Stimulate secretion - gastrin - and motility

Question 20

Describe the stimuli of the intestinal phase

Answer 20

Controls delivery to small intestine - stimuli - distention of duodenum - arrival of acid chyme, lipids and carbohydrates

Question 21

Describe the nervous and hormonal regulation of the intestinal phase

Answer 21

Hormones - GIP, CCK, secretin
Nerves - Enterogastric reflex
Both inhibit secretion and motility

Question 22

What volume of secretion does the pancreas produce per day

Answer 22

1 - 1.5 L per day

Question 23

What are the two components of pancreatic secretion

Answer 23

Enzymes (acinar cells) - chemical digestion
Alkaline fluid (duct cells) - bicarbonate - neutralise acid to optimal pH for enzymes

Question 24

What are the four most important pancreatic digestive enzymes

Answer 24

Lipolytic - Pospho/Lipase
Amylytic - amylase
Proteolytic - Trypsin, chymotripsinm carboxypeptidase
Necleolytic - Ribonuclease, deoxyribonuclease

Question 25

How is pancreatic secretion stimulated

Answer 25

Hormone cholecystokinin (CCK) - stimulated by the arrival of lipids and carbohydrates in duodenum

Question 26

What's the difference in secreted enzymes and when they're in the duodenum

Answer 26

Enzymes secreted in inactive precursors and are activated in duodenum

Question 27

What converts trypsin to active state

Answer 27

Enterokinase bound to duodenum wall converts trypsinogen to trypsin

Question 28

What does trypsin do

Answer 28

Converts other enzymes to active form

Question 29

Describe the production of alkaline (HCO3 rich) fluid

Answer 29

Produced in pancreatic duct cells | Stimulated by hormone secretion - stimulated by arrival of acid chyme in duodenum

Question 30

What does alkaline fluid do

Answer 30

Neutralises acid chyme from stomach | Optimal pH for pancreatic and intestinal digestive enzymes (6.7-9.0)

Question 31

What volume of secretion do the biliary organs secrete

Answer 31

0.5 L per day

Question 32

What do the biliary secretions consist of

Answer 32

Bile salts, HCO3- rich fluid (digestion) | Bile pigments - waste products - and cholesterol (excretory products)

Question 33

What is the function of bile salts

Answer 33

Fat digestion

Question 34

What is the function of HCO3- rich fluid

Answer 34

Neutralizes acid

Question 35

What is the function of bile pigments

Answer 35

Excretion

Question 36

Describe hormonal control over bile delivery

Answer 36

CCK (cholecystokinin) - produced in response to products of digestion in duodenum Contracts gallbladder and relaxes hepatopancreatic ampulla

Question 37

What stimulates bile secretion

Answer 37

Hormones mild stimulus of bile in liver | Bile is its own secretion - enterohepatic circulation

Question 38

What is enterohepatic circulation

Answer 38

Bile is transported back to the liver and reabsorbed and secreted

Question 39

Why is enterohepatic circulation important

Answer 39

Bile is expensive to produce - 95% reabsorbed in ileum

Question 40

What volume does the small intestine secrete

Answer 40

1.5 L per day

Question 41

What composes SI secretions

Answer 41

``` Mucus Isosmotic fluid (bicarbonate) Digestive enzymes (shed cells - reabsorbed) ```

Question 42

What does the LI secrete

Answer 42

Mucus