Module 7.6 Stomach Flashcards

1
Q

The ___\_ is a J-shaped chamber

A

The stomach is a J-shaped chamber

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2
Q

The stomach is divided into three parts:

  1. _____,
  2. _____
  3. _____.
A

The stomach is divided into three parts:

  1. fundus,
  2. body
  3. antrum.
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3
Q
  • The entrance to the stomach is sealed by the ___________ sphincter, and
  • the exit from the stomach is sealed by the _____ sphincter.
A
  • The entrance to the stomach is sealed by the lower esophageal (gastroesophageal) sphincter, and
  • the exit from the stomach is sealed by the pyloric sphincter
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4
Q

The stomach folds, called ______ make it possible for the stomach to expand from its empty volume of approximately ___\_mL to its full volume of approximately ____\_ mL.

A

The stomach folds, called rugae make it possible for the stomach to expand from its empty volume of approximately 50 mL to its full volume of approximately 1,000 mL.

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5
Q

Gastric motility involves three stages:

  1. _____,
  2. _____, and
  3. ______
A

Gastric motility involves three stages:

  1. filling,
  2. mixing, and
  3. emptying
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6
Q

The filling of the stomach is mediated by r______\_of the _____________\_ of the stomach wall, which is regulated by ______\_ activity

A

The filling of the stomach is mediated by receptive relaxation of the smooth muscle layers of the stomach wall, which is regulated by vagal nerve activity

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7
Q

The pacemaker cells of the upper fundus generate the ____________\_, which results in weak peristaltic contractions in the fundus

A

The pacemaker cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus

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8
Q

The ______\_ cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus

A

The pacemaker cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus

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9
Q

Peristaltic contractions from the basic electric rhythm (BER) increase in strength as they move toward the __________\_

A

Peristaltic contractions from the basic electric rhythm (BER) increase in strength as they move toward the pyloric sphincter

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10
Q

mixing occurs primarily in the ______\_, whereas the _____\_ of the stomach functions primarily in storage

A

mixing occurs primarily in the antrum, whereas the body of the stomach functions primarily in storage

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11
Q

_______\_ peristaltic contractions force small amounts of chyme through the _______ sphincter in the process of emptying

A

Strong antral peristaltic contractions force small amounts of chyme through the pyloric sphincter in the process of emptying

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12
Q

Outline the steps of Gastric Emptying and Gastric Mixing:

  1. A _____\_contraction originates in the ______ ______and sweeps down toward the pyloric _____\_
  2. The contraction becomes more vigorous as it reaches the thick-muscled _____\_
  3. The ______ ______ peristaltic contraction propels the chyme forward
  4. A small portion of chyme is pushed through the partially open sphincter into the _____\_. The stronger the antral contraction, the more chyme is emptied with each contractile wave
  5. When the peristaltic contraction reaches the _____\_ sphincter, the sphincter is tightly closed and no further emptying takes place
  6. When chyme that was being propelled toward hits the closed sphincter, it is tossed back into the _____\_ with each peristaltic contraction
A
  1. A peristaltic contraction originates in the upper fundus and sweeps down toward the pyloric sphincter
  2. The contraction becomes more vigorous as it reaches the thick-muscled antrum
  3. The strong antral peristaltic contraction propels the chyme forward
  4. A small portion of chyme is pushed through the partially open sphincter into the duodenum. The stronger the antral contraction, the more chyme is emptied with each contractile wave
  5. When the peristaltic contraction reaches the pyloric sphincter, the sphincter is tightly closed and no further emptying takes place
  6. When chyme that was being propelled toward hits the closed sphincter, it is tossed back into the antrum with each peristaltic contraction
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13
Q

Gastric motility is regulated through ______\_, ____\_, and ______\________\__ factors

A

Gastric motility is regulated through cephalic, gastric, and intestinal phase factors

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14
Q

Fill in the table

A
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15
Q

How do the factors within the stomach effect Gastric motility and emptying?

Volume of Chyme:

Fluidity:

A

Volume of Chyme:

  • Direct effect - stretching has effect on excitability
  • Increased volume stimulates motility and emptying

Fluidity:

  • Direct effect: contents must be fluid to be ejected
  • Increased fluidity = faster emptying
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16
Q

How do factors within the duodenum effect Gastric motility and emptying?

  • Presence of fat, acid, hypertonicity, or distension
A

Presence of fat, acid, hypertonicity, or distension

  • initiates enterogastric reflex or triggers release of enterogastrones
  • Inhibit further gastric motility and emptying until duodenum has coped with factors already present
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17
Q

How does emotion effect gastric motility and emptying?

A
  • Emotion alters autonomic balance
  • Stimulates or inhibits motility and emptying
18
Q

What effect does intense pain have on gastric motility and emptying?

A
  • Increases sympathetic activity
  • Inhibits motility and emptying
19
Q

Gastric secretions include the digestive juice secreted from the ____\_cells and the gastric hormones secreted from the ______\_ cells

A

Gastric secretions include the digestive juice secreted from the exocrine cells and the gastric hormones secreted from the endocrine cells

20
Q

Secretory cells are located in _____ ____\_

A

Secretory cells are located in gastric pits

21
Q

Complete the tabe for the secretions from each type of cell

22
Q

Gastric acid (HCl) secretion is important for maintaining the _________\_of the stomach and for the activation of _______\_

A

Gastric acid (HCl) secretion is important for maintaining the acidic environment of the stomach and for the activation of pepsinogen

23
Q

Gastric acid (HCl) is secreted from the ______ ____\_

A

Gastric acid (HCl) is secreted from the parietal cells

24
Q

Cellular mechanism of gastric acid secretion:

  • Carbon dioxide (CO2) is metabolically produced by the cell or diffuses into the cell from the plasma and combines with water (H2O) and carbonic anhydrase (CA) to produce carbonic acid (H2CO3) which is then broken down into _____\_and _____\_.
  • The H+ moves across the luminal border of the parietal cell by _____\_ pump, a primary active transport protein.
  • K+ is recycled across the luminal border as it moves back from the cell into the lumen by a _____\_
  • HCO3- moves across the _____\_ border of the parietal cell by ______, a secondary active transport protein.
  • In such a way, Cl- is moved into the cell across the _____\_ border and will move down its electrochemical gradient through luminal Cl- channels.
A

Cellular mechanism of gastric acid secretion:

  • Carbon dioxide (CO2) is metabolically produced by the cell or diffuses into the cell from the plasma and combines with water (H2O) and carbonic anhydrase (CA) to produce carbonic acid (H2CO3) which is then broken down into hydrogen ions (H+) and bicarbonate ion (HCO3-).
  • The H+ moves across the luminal border of the parietal cell by H+/K+ ATPase pump, a primary active transport protein.
  • K+ is recycled across the luminal border as it moves back from the cell into the lumen by a K+ channel.
  • HCO3- moves across the basolateral border of the parietal cell by HCO3-/Cl- exchange protein, a secondary active transport protein.
  • In such a way, Cl- is moved into the cell across the basolateral border and will move down its electrochemical gradient through luminal Cl- channels.
25
Gastric acid secretion is **stimulated** by * _\_\_\_\_\_\_ ______ \_\_\_\_\_\_ \_\_\_\_\_\_\_,_ * _\_\_\_\_\_\_\_, and_ * _\_\_\_\_\_\_\_\__ And is **inhibited** by * _\_\_\_\_\_\_\__.
Gastric acid secretion is **stimulated** by * _parasympathetic nervous system activity,_ * _gastrin, and_ * _histamine_ And is **inhibited** by * _somatostatin_.
26
Gastric acidity is important for * _\_\_\_\_\_\_\_\_\_\__ * _\_\_\_\_\_\_\_\_\__ * _\_\_\_\_\_\_\_\_\__ * _\_\_\_\_\_\_\_\_\__
Gastric acidity is important for * _molecule breakdown,_ * _protein denaturation,_ * _immunoprotection, and_ * _the activation of pepsinogen_
27
What are two defence mechanisms the stomach has against the acidic luminal environment?
1. gastric mucosal barrier 2. rapid cell turnover.
28
Explain the image on defence against stomach acid: 1. The luminal membranes of the gastric mucosal cells are ______ to H+ so that ______ \_\_\_\_\_\_ ______ into the cells 2. The cells are joined by ______ \_\_\_\_\_\_ that ______ \_\_\_\_\_\_ from ______ between them 3. A _____ \_\_\_\_\_\_ over the gastric mucosa offers further protection
Explain the image on defence against stomach acid: 1. The luminal membranes of the gastric mucosal cells are _impermeable_ to H+ so that _HCl cannot penetrate into_ the cells 2. The cells are joined by _tight junctions_ that _prevent HCl from penetrating_ between them 3. A _mucus coating_ over the gastric mucosa offers further protection
29
Pepsinogen is secreted by the _\_\_\_\_ \_\_\_\_\__
Pepsinogen is secreted by the _chief cells_
30
What is the function of pepsinogen?
functions in the digestion of proteins.
31
**Pepsinogen** is produced and secreted in its inactive form as a _\_\_\_\_\__(the inactive form of an enzyme) and must be activated by _\_\_\_\__ before _\_\_\_\__ digestion can occur
Pepsinogen is produced and secreted in its inactive form as a _zymogen_ (the inactive form of an enzyme) and must be activated by _HCl_ before _protein_ digestion can occur
32
Activation of pepsinogen in the gastric lumen: * **Pepsinogen** is secreted in an *inactive* form and is activated to its *active:* _\_\_\_\_\_\_\_\__, in the gastric lumen by _\_\_\_\_\_\_\_\_\_\_\_\_\__. * Pepsin begins digestion of _\_\_\_\_\_\__and _\_\_\_\_\_\_\_\_\__ activates more _\_\_\_\_\_\_\__.
Activation of pepsinogen in the gastric lumen: * **Pepsinogen** is secreted in an inactive form and is activated to its active form, _pepsin_, in the gastric lumen by _hydrochloric acid (HCl)_. * Pepsin begins digestion of _protein_ and _autocatalytically_ activates more _pepsinogen_.
33
Pepsinogen secretion is regulated by: * \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ * \_\_\_\_\_\_\_
Pepsinogen secretion is regulated by: * parasympathetic nervous system activity * gastrin.
34
Gastric secretions are regulated by what three factors?
1. cephalic, 2. gastric, and 3. intestinal phase
35
**Intestinal phase** regulation is an _\_\_\_\_\_\__mechanism in which increased _\_\_\_\_\_\__, increased concentrations of _\_\_\_\_\_\__and _\_\_\_\_\_\__, and increased _\_\_\_\_\_\__in the small intestine stimulate _\_\_\_\_\_\_ \_\_\_\_\_\__ and _\_\_\_\_\_\_ \_\_\_\_\_\__pathways that result in the secretion of _\_\_\_\_\_\__, _\_\_\_\_\_\__, and _\_\_\_\_\_\__.
**Intestinal phase** regulation is an _inhibitory_ mechanism in which increased _osmolarity_, increased concentrations of _fats_ and _acids_, and increased _distension_ in the small intestine stimulate _short reflex_ and _long reflex_ pathways that result in the secretion of _cholecystokinin (CCK)_, _secretin_, and _GIP_.
36
Cephalic-phase control of gastric secretion
37
**Protein** digestion begins in the stomach with the activation of _\_\_\_\_\_\_\_\__
**Protein** digestion begins in the stomach with the activation of _pepsinogen_
38
Although *salivary amylase* is _\_\_\_\_\_\__by HCl, some **carbohydrate** digestion still continues in the stomach by this mechanism _\_\_\_\_\__ the _\_\_\_\_\_ \_\_\_\_\__
Although *salivary amylase* is _inactivated_ by HCl, some **carbohydrate** digestion still continues in the stomach by this mechanism _inside_ the _unmixed bolus_
39
In general, there is no _\_\_\_\_\_\_\__ of food, water, or electrolytes in the stomach. However, two exceptions to this are _\_\_\_\_\__and _\_\_\_\_\_\_\_\__, both of which are absorbed through the _\_\_\_\_\_\_\_._
In general, there is no _absorption_ of food, water, or electrolytes in the stomach. However, two exceptions to this are _alcohol_ and _acetylsalicylic acid (aspirin)_, both of which are absorbed through the _gastric epithelium._
40
Gastric-phase control of gastric secretion