Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI Physiology > Lecture 9 - stomach > Flashcards

Lecture 9 - stomach Flashcards

1
Q

What is responsible for the stomachs gastric mobility?

A

The abundant smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cells of the gastric mucosa secrete gastric juice which include?

A
  • HCl (protein digestion)
  • pepsinogen (pepsin - protein digestion)
  • intrinsic factor (vitB12 absorption in ileum)
  • mucus (protects gastric mucosa from H+: ph1-2)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the cells in the body of the stomach and what do they secrete?

A

parietal cells - secrete HCl and intrinsic factor

Chief cells - secrete pepsinogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the cells in the antrum of the stomach and what do they secrete?

A

G cells - secrete gastrin into the circulation

D cells - secrete somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Function of HCl in the stomach ?

A

Hydrophobic acid which creates a pH of 2 in the stomach. It inhibits bacteria and so proteins lose their shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What id 90 % of stomach is missing?

A

Just take vit b12 pill

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are pits in the stomach?

A

Gastric secretions that come from gastric invaginations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are pits lined with?

A

different secretory cells:

  • Parietal cells (secrete Hal and intrinsic factor)
  • Chief cells (secrete pepsinogen)
  • G cells (secrete gastrin into the circulation)
  • D cells (secrete somatostatin)
  • mucus neck cells (secrete mucus, bicarbonate)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

regional differences occur in the number of cell types that line the gastric pit, what are these differences?

A

Near lower oesophagus and pyloric sphincter - mucus, HCO3-

Rest of stomach - digestive secretions (H+, pensinogen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is at the base of the pits?

A

parietal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is lining the duct of the pits?

A

chief cells, d cells, g cells and at the top the mucous neck cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Function of parietal cell?

A

Secrete acid –> coagulate protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is at the apical membrane of a parietal cell?

A

H+ and K+ ATPase, Cl- channels

H+ is secreted into the lumen of the stomach via primary active transport and Cl- follows H+ into the lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is at the basolateral membrane of a parietal cell?

A

Na+ and K+ ATPase, Cl- and HCO3- exchanger

HCO3- is moved into the interstitial space in exchange for Cl-. Na + goes into the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do the epethial cells contain?

A

contain carbonic anhydrase which catalyses CO2 +O2 into H2CO3 (source of H2CO3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What stimulates H+ secretion?

A

PNS -

  1. ) neurotransmitter ACh
  2. ) secretes into M3 receptor
  3. ) Gq
  4. ) Ca2+ or IP3 (calcium concentration increases)
  5. ) PKA
  6. ) increased ATPase (H+ to K+)

Histamine -

  1. ) released from enterochromaffin like cells in gastric mucosa
  2. ) binds to nearby parietal cells
  3. )binds to histamine H2 receptor
  4. )Gs protein
  5. )cAMP
  6. ) PKA
  7. ) increased ATPase activity

Gastrin -

  1. ) G cells
  2. ) into circulation
  3. ) cholecystokinin B (CCKB) receptor
  4. ) Gs
  5. ) increased calcium concentration (IP3)
  6. ) PKA
  7. ) increased ATPase activity
17
Q

What inhibits potassium hydrogen ATPase?

A

omeprazole

18
Q

Potentiation of the stimulus occurs with ….. between the 3 stimulation

A

cross talk

19
Q

What inhibits H+ secretion?

A 
Somatostatin (produced by D cells):
Direct pathway: 
1.) inhibits parietal cells
2.) binds to receptor 
3.) Gi
4.) reduced cAMP
5.) reduced H+ secretion 
indirect pathway: 
1.) inhibits histamine release from ECL cells 
2.) inhibits gastrin release from G cells
20
Q

Response to a meal, first step ?

A

Vagus nerve innervation:

  1. ) parietal cells directly (ACh) release HCl
  2. ) G cells (GRP, gastrin releasing peptide) releases gastrin into circulation which is carried by bloodstream to parietal cells which releases HCl indirectly.
  3. ) muscarinic blocking agent (atropine) does not fully block HCl secretion
21
Q

Response to meal, step 2 - cephalic phase?

A
  1. ) accounts for 30 % of total HCl secretion
  2. ) stimulates by smell, taste and it is a conditioned reflex. Anticipation of food
  3. ) mechanism - direct and indirect
22
Q

Response to meal, step 2 - gastric phase?

A
  1. ) accounts for 60% of total HCl secreted
  2. ) stimulus - distension of stomach, presence of amino acids and small peptides
  3. ) mechanism - distension direct and indirect vagal stimulation of parietal cells (gastrin). AA and peptides: direct effects on G cells (gastrin)
23
Q

Response to meal, step 3 - intestinal phase?

A
  1. ) accounts for 10 % of total HCl secretion

2. ) stimulus - AA and peptides stimulate G cells to release gastrin then parietal cells release HCl.

GI Physiology (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions