Module 7.6 Stomach Flashcards
The ___\_ is a J-shaped chamber
The stomach is a J-shaped chamber
The stomach is divided into three parts:
- _____,
- _____
- _____.
The stomach is divided into three parts:
- fundus,
- body
- antrum.
- The entrance to the stomach is sealed by the ___________ sphincter, and
- the exit from the stomach is sealed by the _____ sphincter.
- 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
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.
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.
Gastric motility involves three stages:
- _____,
- _____, and
- ______
Gastric motility involves three stages:
- filling,
- mixing, and
- emptying
The filling of the stomach is mediated by r______\_of the _____________\_ of the stomach wall, which is regulated by ______\_ activity
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
The pacemaker cells of the upper fundus generate the ____________\_, which results in weak peristaltic contractions in the fundus
The pacemaker cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus
The ______\_ cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus
The pacemaker cells of the upper fundus generate the gastric basic electric rhythm (BER), which results in weak peristaltic contractions in the fundus
Peristaltic contractions from the basic electric rhythm (BER) increase in strength as they move toward the __________\_
Peristaltic contractions from the basic electric rhythm (BER) increase in strength as they move toward the pyloric sphincter
mixing occurs primarily in the ______\_, whereas the _____\_ of the stomach functions primarily in storage
mixing occurs primarily in the antrum, whereas the body of the stomach functions primarily in storage
_______\_ peristaltic contractions force small amounts of chyme through the _______ sphincter in the process of emptying
Strong antral peristaltic contractions force small amounts of chyme through the pyloric sphincter in the process of emptying
Outline the steps of Gastric Emptying and Gastric Mixing:
- A _____\_contraction originates in the ______ ______and sweeps down toward the pyloric _____\_
- The contraction becomes more vigorous as it reaches the thick-muscled _____\_
- The ______ ______ peristaltic contraction propels the chyme forward
- 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
- When the peristaltic contraction reaches the _____\_ sphincter, the sphincter is tightly closed and no further emptying takes place
- When chyme that was being propelled toward hits the closed sphincter, it is tossed back into the _____\_ with each peristaltic contraction
- A peristaltic contraction originates in the upper fundus and sweeps down toward the pyloric sphincter
- The contraction becomes more vigorous as it reaches the thick-muscled antrum
- The strong antral peristaltic contraction propels the chyme forward
- 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
- When the peristaltic contraction reaches the pyloric sphincter, the sphincter is tightly closed and no further emptying takes place
- When chyme that was being propelled toward hits the closed sphincter, it is tossed back into the antrum with each peristaltic contraction
Gastric motility is regulated through ______\_, ____\_, and ______\________\__ factors
Gastric motility is regulated through cephalic, gastric, and intestinal phase factors
Fill in the table
How do the factors within the stomach effect Gastric motility and emptying?
Volume of Chyme:
Fluidity:
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
How do factors within the duodenum effect Gastric motility and emptying?
- Presence of fat, acid, hypertonicity, or distension
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
How does emotion effect gastric motility and emptying?
- Emotion alters autonomic balance
- Stimulates or inhibits motility and emptying
What effect does intense pain have on gastric motility and emptying?
- Increases sympathetic activity
- Inhibits motility and emptying
Gastric secretions include the digestive juice secreted from the ____\_cells and the gastric hormones secreted from the ______\_ cells
Gastric secretions include the digestive juice secreted from the exocrine cells and the gastric hormones secreted from the endocrine cells
Secretory cells are located in _____ ____\_
Secretory cells are located in gastric pits
Complete the tabe for the secretions from each type of cell
Gastric acid (HCl) secretion is important for maintaining the _________\_of the stomach and for the activation of _______\_
Gastric acid (HCl) secretion is important for maintaining the acidic environment of the stomach and for the activation of pepsinogen
Gastric acid (HCl) is secreted from the ______ ____\_
Gastric acid (HCl) is secreted from the parietal cells
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.
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.
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.
Gastric acidity is important for
- _________\_
- ________\_
- ________\_
- ________\_
Gastric acidity is important for
- molecule breakdown,
- protein denaturation,
- immunoprotection, and
- the activation of pepsinogen
What are two defence mechanisms the stomach has against the acidic luminal environment?
- gastric mucosal barrier
- rapid cell turnover.
Explain the image on defence against stomach acid:
- The luminal membranes of the gastric mucosal cells are ______ to H+ so that ______ ______ ______ into the cells
- The cells are joined by ______ ______ that ______ ______ from ______ between them
- A _____ ______ over the gastric mucosa offers further protection
Explain the image on defence against stomach acid:
- The luminal membranes of the gastric mucosal cells are impermeable to H+ so that HCl cannot penetrate into the cells
- The cells are joined by tight junctions that prevent HCl from penetrating between them
- A mucus coating over the gastric mucosa offers further protection
Pepsinogen is secreted by the ____ ____\_
Pepsinogen is secreted by the chief cells
What is the function of pepsinogen?
functions in the digestion of proteins.
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
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.
Pepsinogen secretion is regulated by:
- ________________
- _______
Pepsinogen secretion is regulated by:
- parasympathetic nervous system activity
- gastrin.
Gastric secretions are regulated by what three factors?
- cephalic,
- gastric, and
- intestinal phase
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.
Cephalic-phase control of gastric secretion
Protein digestion begins in the stomach with the activation of _______\_
Protein digestion begins in the stomach with the activation of pepsinogen
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
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.
Gastric-phase control of gastric secretion
