Control of UGF

Question 1

Sympathetic neurotransmitter

Answer 1

Noradrenaline

Question 2

Sympathetic receptors

Answer 2

Adrenoceptors (alpha + beta)

Question 3

Parasympathetic neurotransmitter

Answer 3

Acetylcholine

Question 4

Parasympathetic receptors

Answer 4

Muscarinic

Question 5

In the sympathetic nervous system, what does Acetylcholine act on?

Answer 5

Nicotinic receptor

Question 6

Sympathetic agonist

Answer 6

Noradrenaline @ alpha + beta-adrenoceptors

Question 7

Sympathetic antagonist

Answer 7

Atenolol @ Beta-adrenoceptors

Question 8

Parasympathetic agonist

Answer 8

Acetylcholine @ muscarinic receptors

Question 9

Parasympathetic antagonist

Answer 9

Atropine @ muscarinic receptors

Question 10

Salivation + benefits

Answer 10

Glandular production of saliva

• aids speech
• promotes dental hygiene
• allows mastication (chewing)
• adds fluid
• starts digestion of starches (amylase)

Question 11

Production of saliva is under _________ control

Answer 11

Autonomic control - parasympathetic (acetylcholine at muscarinic receptors)

Question 12

Stomach secretes __ litres per day

Answer 12

2

Question 13

What pH is the Stomach + benefit

Answer 13

Low = 1 - 1.5 = acidic

• acidity sterilises food to prevent food poisoning
• optimal pH for enzyme

Question 14

Chief cells of gastric mucosa secrete

Answer 14

Pepsinogens

Question 15

What does the acid environment activate

Answer 15

pepsinogens to form pepsins

Question 16

What is pepsins

Answer 16

Endopeptidase - proteolysis of (breaks down) proteins to polypeptides

Question 17

Cephalic phase

Answer 17

prepares stomach for food arrival - begins prior to food entry

Question 18

What nervous system is stimulated by cephalic phase

Answer 18

Parasympathetic

Question 19

Cephalic phase is stimulated by…

Answer 19

Sight, smell, taste

Question 20

(Cephalic phase) What does parasympathetic system stimulate

Answer 20

Acid release

Gastrin release into blood

Question 21

What releases gastrin

Answer 21

G cells

Question 22

Gastric phase

Answer 22

Occurs while food is in the stomach

• Stretch receptors detect distension of stomach
• Release of ACh, histamine + gastrin

Question 23

What is secreted in gastric phase

Answer 23

Acid, pepsinogen, mucus

Question 24

What releases histamine

Answer 24

Mast cells

Question 25

(Gastric phase) What stimulates g cells to secrete gastrin)

Answer 25

Prescence of peptides (food)

Question 26

Intestinal phase

Answer 26

occurs when chyme enters small intestine | - presence of chyme in duodenum opens pyloric sphincter

Question 27

(Intestinal phase) What inhibits secretion

Answer 27

CCK inhibits acid

Question 28

What do acinar cells secrete

Answer 28

amylase + electrolytes with similar tonicity to plasma

Question 29

What modifies secretion of saliva

Answer 29

Striated + excitatory ducts

Question 30

What reduces saliva production + flow

Answer 30

``` Muscarinic antagonist (antimuscarinic, parasympathetic) e.g. old tricylic antidepressants ```

Question 31

Effect of old tricylic antidepressants

Answer 31

Dry mouth, urinary retention, constipation + blurred vision

Question 32

What will enhance/cause salivation

Answer 32

Muscarinic agonist (inhibitors of acetylcholinesterase)

Question 33

What increases acid secretion

Answer 33

Histamine (H2 receptors) Gastrin Acetylcholine (M-receptors = M3 on parietal cells)

Question 34

Decreases acid secretion

Answer 34

Prostaglandins (E2 + I2) | cytoprotective via bicarbonate + mucus release (from superficial epithelial cells)

Question 35

What is histamine + what is it responsible for

Answer 35

Endogenous mediator | Responsible for skin rashes + gastric acid secretion

Question 36

What are Histamine H1 receptors responsible for

Answer 36

Allergies | - antihistamines bind e.g. loratadine

Question 37

What are H2 receptors ressponsible for

Answer 37

Gastric acid secretion | - H2RA e.g.ranitidine to treat dyspepsia

Question 38

What is gastrin

Answer 38

Peptide hormone | Agonist at CCK

Question 39

What releases gastrin

Answer 39

Antral cells to mediate gastric phase

Question 40

where is arachidonic acid

Answer 40

Cell membranes

Question 41

What releases arachidonic acid

Answer 41

Phospholipase A2

Question 42

2 pathways for arachidonic acid metabolism

Answer 42

- Cyclooxygenase (COX): prostanoids | - Lipoxygenase: leukotrienes

Question 43

Examples of NSAIDs

Answer 43

Ibuprofen, aspirin, diclofenac

Question 44

What do NSAIDs inhibit

Answer 44

NSAIDs

Question 45

Mastication

Answer 45

chewing and addition of saliva

Question 46

Salivary amylase

Answer 46

(stimulated by parasympathetic) Enzyme to start hydrolysis of starch

Question 47

pH of duodenum

Answer 47

5-6

Question 48

Duodenum secretes...

Answer 48

Pancreatic enzymes - lipase - amylases - proteolytic enzyme Bile (secreted by gallbladder) into duodenum to emulsify fats

Question 49

Function of Intrinsic factor

Answer 49

Secreted by parietal cells to help absorb Vit B12

Question 50

Stomach cancer

Answer 50

``` Poor prognosis (18% - 5 year survival) Present with dyspepsia - bleeding - weight loss - > 55 years - abdominal masses ```

Question 51

Prostanoids/prostaglandins

Answer 51

Family of AA metabolites - PGs = inhibit acid secretion - PGI2 = inhibits platelet aggregation (vasodialtion) - TXA2 = stimulate platelet aggregation (vasoconstriction) Also cause: - pain - inflammation - temperature - asthma - uterine contractions - miscarriage

Question 52

Production of cyclic AMP

Answer 52

``` Hormone (1st messenger) binds to receptor receptor activates G protein G protein activates adenylate cyclase Adenylate cyclase converts ATP to cAMP (2nd messenger) ```

Question 53

Function of cAMP

Answer 53

Stimulate acid secretion

Question 54

PGE2 PGI2

Answer 54

Inhibit increase in cAMP suppress proton pump activity | Cytoprotection: release mucus + bicarbonate

Question 55

Proton pump activated

Answer 55

Activated by phosphorylation + calcium | Dynamic: produced in cell + cycles to membrane

Question 56

Gastrin cause Ca-dep or cAMP

Answer 56

Ca-dep

Question 57

ACh cause Ca-dep or cAMP

Answer 57

Ca-dep

Question 58

Histamine cause Ca-dep or cAMP

Answer 58

cAMP