Lab 6 - Digestion Flashcards

1
Q

What substances taste salty?

A

Neutral salts of strong acids and bases

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2
Q

Histamine acts on which receptors?

A

H2 receptors

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3
Q

What effect has verapamil?

A

Ca2+ channel inhibitor

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4
Q

Effects of acetylcholine is mediated by which type of receptors?

A

Muscarine Ach receptors

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5
Q

Which effect has acetylcholine on gastric SM?

A

Stimulating

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6
Q

Which gastric juice producing cells are influenced by Acetycholine?

A

Parietal Cells

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7
Q

What enzyme initiates SM contraction?

A

MLCK = Myosin Light Chain Kinase

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8
Q

What pathway does muscarinic Ach receptors activate?

A

G-protein phosphlipase C pathway

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9
Q

ED50?

A

Active ingredient concentration needed for half maximal muscle contraction

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10
Q

Examples of bitter taste?

A

Several alkaloids: strychnine, quinine, several glycosides, ethers, some Mg2+ and Ca2+ salts, ammonium compound and sulphates

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11
Q

Examples of sour taste?

A

Hydrogen ion dissociating molecules – buffers of saliva alters sensation

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12
Q

What dissociates the actomyosin complex?

A

Myosin phosphatase (MP) enzyme

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13
Q

How to measure the basal HCl consentration?

A

By titratin 0.01 M NaOH, after adding phenophtalein

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14
Q

Where can you find the food eaten last?

A

in the cardia

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15
Q

Which cells does gastrin have effect on?

A

Parietal cells

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16
Q

In which way does verapamil inhibit muscle contraction?

A

Ca2+ channel inhibition

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17
Q

What substance act on pariental cells?

A

Acetylcholine, Histamine and Gastrin

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18
Q

Where in gastrointestinal tract does ptyalin act?

A

In the stomach

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19
Q

Mixture of stomach content is called?

A

Chymus

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20
Q

The mixture of food structure resembles what?

A

onion

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21
Q

The taste pathway?

A

fascial (VII), glossopharyngeal (IX) and vagus (X) are involved

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22
Q

Feed taken up first is at ?

A

At the curvature major

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23
Q

What does the next part of the feed thats not in contact with the gastric wall do?

A

Allowis the ptyalin enzyme from the saliva to function further.

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24
Q

What finally mixes the different layers?

A

Gastric peristalsis, and the saliva enzymes are inactivated.

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25
Q

Gastric juice is secreted by?

A

The chief (peptic) and parietal cells in the fundus region of the gastric mucosa.

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26
Q

What does Parietal cells produce?

A

HCl, while chief cells produce pepsinogen.

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27
Q

What does cheif cells produce?

A

Pepsinogen.

28
Q

HCl secretion of the parietal cells is regulated by ?

A

Neuronal and endocrine mechanisms.

29
Q

What activates the Parietal cells?

A

Acetylcholine (neurotransmitter), histamine (paracrin mediator), and gastrin (hormone)

30
Q

What does the The central nervous system have an effect on?

A

The central nervous system has an effect on gastric juice secretion through the vagus nerve

31
Q

What does Acetylcholine released from cholinergic postganglionic do?

A

Directly stimulates the parietal and ECL (enterochromaffin-like) cells.

32
Q

What does Acetylcholine indirectly do?

A

indirectly stimulates the G cells as well.

33
Q

Histamine is produced by?

A

ECL (enterochromaffin-like) cells

34
Q

What does Histamine do?

A

It diffuses to the parietal cells and acts on H2 receptors.

35
Q

What is Histamine production primarily regulated by?

A

Gastrin and the vagus nerve.

36
Q

What is Gastrin secreted by?

A

Gastrin is secreted by G cells in the antrum region

37
Q

What is the effect of gastrin secretion?

A

It increases HCl secretion by stimulating the parietal cells and the H cells as well.

38
Q

What regulates the function of a G cell?

A

Vagus nerve and gastric pH.

39
Q

Where do you find the stomach?

A

In the left side of the body, covered by the guts and the liver.

40
Q

Pharmacological effect and Effect on smooth muscles in the GI tract of Acetylcholine?

A

parasympathicomymetic

stimulation

41
Q

Pharmacological effect and Effect on smooth muscles in the GI tract of atropine?

A

parasympathicolytic

inhibition

42
Q

Pharmacological effect and Effect on smooth muscles in the GI tract of norepinephrine?

A

sympathicomymetic

sphincter: constriction, elsewhere: relaxation

43
Q

Pharmacological effect and Effect on smooth muscles in the GI tract of Verapamil?

A

Ca2+ channel inhibition

inhibition

44
Q

What kind of contraction are the contractions of the GI tract?

A

Rhythmic.

45
Q

What are the “slow waves”?

A

The frequency is determined by the so-called slow waves:

the continuous change in the membrane potential of smooth muscle cells

46
Q

When will spike potentials appare?

A

When the slow waves reach the threshold potential due to membrane depolarizing effects

47
Q

What is spike potentials?

A

Action potentials in the smooth muscle cells caused by a calcium influx that elicits muscle contraction.

48
Q

What initiates the muscle contractions?

A

MLCK (myosin light chain kinase) enzyme after intracellular Ca2+ has reached a certain level.

49
Q

What dissociates the actomyosin complex?

A

Phosphatase (MP) enzyme.

50
Q

In smooth muscles, what is the efect of acetylcholine (parasympathetic neurotransmitter)?

A

Mediated by type M(3) muscarinic Ach receptors.

51
Q

What does the M(3) muscarinic Ach receptors do?

A

Activate the G-protein – phospholipase C pathway,

52
Q

What is caused by the activation of the G protein?

A

Increase in the intracellular calcium level thus activating the MLCK (myosin light chain

53
Q

What is the overall effect of the acetylcholine?

A

An increase in the contraction rate and spontaneous activity of GI smooth muscles.

54
Q

What can inhibit the effect of different transmitters?

A

With specific receptor antagonistic drugs.

55
Q

What happens in case of competitive antagonism?

A

The transmitter (agonist) and the antagonist compete for the same binding sites.

56
Q

What happens in case of reversible competitive antagonism?

A

The binding of the antagonist can be eliminated by increasing the concentration of the agonist.

57
Q

What inhibits the muscarinic Ach receptors?

A

Atropine

58
Q

What is the competitive antagonist of acetylcholine?

A

Atropine

59
Q

Is it posible to block non-spesific block the smooth muscle function in another way than by using drugs acting on different receptors?

A

Yes, by administering calcium channel blockers.

60
Q

What blocks calcium channels thus the activation of MLCK enzyme?

A

Verapamil

61
Q

What happens when verapamil blocks the calcium chanels?

A

Muscle contraction is hindered.

62
Q

What is the substance that compleetly blocks the effect of ED50 acetylcholine on the smooth muscle sample?

A

Varapamil

63
Q

Where is the location of taste sensation?

A

On the surface of the tounge

64
Q

Name some of the multiple physiological roles of the sensation of taste.

A

Food checking,
inducing saliva and gastric juice production
(cephalic phase), etc

65
Q

What is the receptor cells of taste sensation are organized into?

A

Taste buds

66
Q

What does the taste sensation pathway include, and what does they do?

A

Facial (VII), glossopharingeal (IX), and vagus (X) nerves and projects sensation to the solitary tract

67
Q

What are the 4 basic tastes?

A
  • Sweet (sugars e.g.: saccharine, saccharose)
  • Salty (neutral salts of strong acids and bases)
  • Sour (hydrogen ion dissociating molecules – buffers of saliva alters sensation)
  • Bitter (several alkaloids e.g.: strychnine, quinine, several glycosides, ether, some Mg2+ and Ca2+ salts, ammonium compounds, sulphates)