Cells + Tissues

Question 1

What produces gastric acid?

Answer 1

Parietal cell

Question 2

What do parietal cells secrete?

Answer 2

Gastric acid + intrinsic factor

Question 3

Where are parietal cells

Answer 3

Fundus

Question 4

What prevents excess acid secretion

Answer 4

2 sphincters

• lower oesophageal sphincter (from oesophagus)
• pyloric sphincter (from intestines)

Question 5

Gastric Ulcer

Answer 5

Sore that develops when the lining of the stomach is damaged + underlying tissue is exposed to gastric acid
Bleeding can be caused by blood vessel damage by acid

Question 6

What are peptic ulcers

Answer 6

Duodenal + Gastric (Stomach)

Question 7

What is GORD

Answer 7

Gastro-oesophageal reflux disease

Caused by gastric acid leaking into the oesophagus = tissue damage + pain

Question 8

Cells that make up stomach

Answer 8

Mucous surface cells

Question 9

Mucous cells secrete

Answer 9

Mucus

HCO3- (Bicarbonate)

Question 10

Function of Bicarbonate

Answer 10

Neutralises gastric acid

Question 11

Function of mucus

Answer 11

protects epithelial cells against gastric acid

Question 12

Mucus in the stomach…

Answer 12

Do not easily mix with acid at low pH which protects secreting cells

Question 13

What is mucus composed of?

Answer 13

Mucins (network of rod-like proteins) with sugar moieties attached

Question 14

How many mucins are found in the human body?

Answer 14

20

Question 15

How many mucins make up gastric mucus + what are they?

Answer 15

3
- MUC1 = connected to mucus membrane of the mucus cell
- MUC5AC
- MUC6
Both MUC5AC + MUC6 are secreted + crosslinked together

Question 16

Protective function of gastric acid

Answer 16

Against food-borne bacteria

Question 17

What do chief cells secrete

Answer 17

Pepsinogen

Question 18

Where are chief cells

Answer 18

Fundus

Question 19

What converts pepsinogen

Answer 19

Gastric acid from inactive protease to active form

Question 20

Glycosylation

Answer 20

Post-transitional modification of amino acids with sugar moieties

Question 21

Protective stomach lining can be damaged by

Answer 21

Use of NSAIDs

Helicobacter pylori

Question 22

Where is Gastric proton pump + what does is pump

Answer 22

Apical membrane
It pumps out protons, pumps in potassium ions
maintaining electrochemical gradient

Question 23

What stimulates Gastric acid secretion

Answer 23

Gastrin
Histamine
Acetylcholine

Question 24

Where is Gastrin released

Answer 24

G cells

Question 25

Where is Histamine released

Answer 25

ECL - cells

Question 26

Where is Acetylcholine released

Answer 26

by enteric nervous system

Question 27

What inhibits acid secretion

Answer 27

Somatostatin

Question 28

Where does N-linked glycosylation occur

Answer 28

Endoplasmic reticulum

Question 29

Where does O-linked glycosylation occur

Answer 29

Golgi apparatus

Question 30

N-acetylglucosamine linked to serine is _-glycosylation

Answer 30

O-glycosylation

Question 31

N-acetylglucosamine linked to asparagine is _-glycosylation

Answer 31

N-glycosylation

Question 32

Fibroblasts synthesise...

Answer 32

large proteins and polysaccharide polymers that fill space between cells - providing rigidity + shape to organs

Question 33

How does heartburn + indigestion occur

Answer 33

When excess acid flow up the oesophagus

Question 34

Epithelium found in oesophagus

Answer 34

Stratified squamous epithelium (interspersed with mucus-secreting goblet cells for adequate protection)

Question 35

Stomach / oesophagus? | Which one provides more protection against acid?

Answer 35

Stomach - gastric epithelium

Question 36

What occurs when there is prolonged exposure to acid in oesophagus

Answer 36

Barrett's oesophagus | - when lower part of oesophagus are replaced by mucus-secreting goblet-like cells

Question 37

Epithelium of stomach

Answer 37

Simple columnar epithelium (with mucous cells covering surface)

Question 38

Tight Junctions

Answer 38

Restrict movement of water + ions in the space between the cells

Question 39

Parietal cell in resting state

Answer 39

Proton pumps in tubulovesicles Small surface area Low amount of acid secreted

Question 40

Parietal cell stimulated

Answer 40

Tubulovesicles bind to apical plasma membrane | Large surface area and large no. of proton pumps

Question 41

Where is bicarbonate exchanged + what with

Answer 41

Basolateral membrane + with chloride ions

Question 42

What maintains intracellular chloride ions

Answer 42

Efflux from the cell canaliculus

Question 43

What reduces secretion or neutralises acid

Answer 43

PPIs H2RA Antacid

Question 44

What can restore protective function of stomach

Answer 44

Stop NSAIDs | Antibiotics : eradicate Helicobacter pylori

Question 45

What protects stomach against acid

Answer 45

Mucous surface cells - secrete mucus layer to protect stomach lining - bicarbonate ions to neutralise gastric acid Tight Junctions prevent acid leaking through epithelial layer + causing underlying damage - restricts movement of ions + water between cells

Question 46

Epithelium of oesophagus

Answer 46

Non-keratinised stratified squamous epithelium - Specialised goblet cells secrete mucus - less protection against acid

Question 47

Example of keratinised stratified epithelium

Answer 47

Skin

Question 48

What hydrates CO2 to produce proton + bicarbonate

Answer 48

Carbonic anhydrase