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pathophysiology > gi objectives 1-5 - Sheet1 > Flashcards

gi objectives 1-5 - Sheet1 Flashcards

1
Q

What are the primary components of saliva?

A

Water, mucus, sodium, bicarbonate (normal pH 7.4), chloride, potassium, salivary alpha-amylase, and immunoglobulin A.

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2
Q

Which glands produce saliva?

A

Submandibular, sublingual, and parotid glands.

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3
Q

What controls salivation?

A

Sympathetic and parasympathetic branches of the autonomic nervous system (ANS).

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4
Q

Which systems stimulate saliva secretion?

A

Cholinergic parasympathetic activation and beta-adrenergic stimulation from the sympathetic nervous system (SNS).

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5
Q

What stimulates gastric secretion?

A

Eating.

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6
Q

What are the main components of gastric secretions?

A

Mucus, acid, enzymes, hormones, intrinsic factor (for Vitamin B12 absorption), gastroferrin (for iron absorption), and potassium.

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7
Q

What are the consequences of vomiting or suctioning on electrolyte balance?

A

Depletion of potassium and sodium stores.

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8
Q

What does the liver secrete, and what is its function?

A

Bile, which contains conjugated salts for fat emulsification and absorption, cholesterol, bilirubin, electrolytes, and water.

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9
Q

How are bile salts recycled?

A

They are absorbed in the terminal ileum and returned to the liver via the portal circulation.

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10
Q

What does the pancreas secrete, and why?

A

The pancreas secretes enzymes (e.g., alpha-amylase, lipase) and alkaline fluids for digestion.

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11
Q

What is the role of alpha-amylase?

A

Digests carbohydrates.

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12
Q

What is the role of lipase?

A

Digests fats.

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13
Q

What other substances does the pancreas produce?

A

Insulin, glucagon (promotes glycogen breakdown to glucose), somatostatin (inhibits growth hormone in the GI tract), and bicarbonate.

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14
Q

What is the function of the upper esophageal sphincter?

A

Prevents air from entering the esophagus during respiration.

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15
Q

What is the function of the lower esophageal (cardial) sphincter?

A

Prevents regurgitation of stomach contents.

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16
Q

How does the lower esophageal sphincter function during swallowing?

A

It relaxes just before food arrives and tightens immediately after.

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17
Q

What is the function of the pyloric sphincter?

A

Prevents reflux of food from the small intestine into the stomach.

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18
Q

What are the functional areas of the stomach?

A

Fundus (upper), body (middle), and antrum (lower).

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19
Q

How does the smooth muscle layer of the stomach vary by region?

A

The smooth layers become progressively thicker in the body and antrum.

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20
Q

What is peristalsis, and how is it controlled in the esophagus?

A

Peristalsis is the coordinated sequential contraction and relaxation of esophageal muscles. It is controlled by afferent fibers sending signals to the brainstem about wall tension.

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21
Q

What are the two phases of esophageal activity?

A

Oropharyngeal (voluntary) and esophageal (involuntary).

22
Q

What are the main functions of the stomach?

A

Food storage, secretion of digestive juices, mixing food with juices, and propelling partially digested food (chyme) forward.

23
Q

What happens to the stomach fundus during swallowing?

A

The fundus relaxes.

24
Q

What causes peristalsis in the stomach?

A

Neural and hormonal activity.

25
Q

What is the role of gastrin in peristalsis?

A

Gastrin secretion (triggered by partially digested protein) stimulates gastric glands to secrete HCl and pepsinogen and promotes growth of the gastric mucosa.

26
Q

How does motilin influence gastrointestinal motility?

A

Motilin secretion (triggered by the presence of acid and fat in the duodenum) increases gastrointestinal motility.

27
Q

What nerve activation is associated with peristalsis?

A

The vagus nerve.

28
Q

What inhibits peristalsis?

A

Sympathetic nervous system activity and secretin secretion in the intestine.

29
Q

How does peristalsis assist with food breakdown?

A

Peristaltic waves move food forward and backward in the stomach, breaking it up and mixing it with gastric acid.

30
Q

What factors influence the rate of gastric emptying?

A

Volume, osmotic pressure, chemical composition of gastric contents, and blood glucose levels.

31
Q

How does food volume affect gastric emptying?

A

Large food volumes increase stomach pressure, which increases peristalsis and gastric emptying.

32
Q

What delays gastric emptying?

A

Solids, fats, and hypertonic or hypotonic solutions.

33
Q

What happens when fat enters the duodenum?

A

The liver secretes bile, and the pancreas secretes pancreatic enzymes to aid in fat digestion.

34
Q

What role does cholecystokinin play in gastric emptying?

A

Cholecystokinin is secreted in response to fat digestion and inhibits gastric motility and emptying to ensure fats do not enter the duodenum faster than bile and pancreatic enzymes can process them.

35
Q

What do osmoreceptors in the duodenum detect?

A

They are sensitive to the osmotic pressure of duodenal contents.

36
Q

How do hypertonic or hypotonic stomach contents affect gastric emptying?

A

They activate osmoreceptors, signaling to delay gastric emptying to allow for acid neutralization and the creation of a more isotonic environment.

37
Q

What is the effect of low blood glucose levels on gastric activity?

A

Low blood glucose stimulates the vagus nerve and gastric smooth muscles, increasing peristalsis without increasing gastric emptying (hunger pains).

38
Q

Where does digestion begin, and what enzymes are involved?

A

Digestion starts in the stomach with the breakdown of food by hydrochloric acid (HCl) and pepsin.

39
Q

Where does digestion continue, and what processes occur?

A

Digestion continues in the small intestine with pancreatic enzymes (amylase and lipase), intestinal enzymes, and bile salts breaking food into nutrients.

40
Q

What are carbohydrates broken down into during digestion?

A

Monosaccharides and disaccharides.

41
Q

What are proteins broken down into during digestion?

A

Amino acids.

42
Q

What are fats broken down into during digestion?

A

Fatty acids and monoglycerides.

43
Q

How are nutrients, water, vitamins, and electrolytes absorbed in the intestine?

A

They are absorbed across the intestinal mucosa into the blood through active transport, diffusion, or facilitated diffusion.

44
Q

Where do broken-down nutrients go after absorption?

A

They travel through the blood to the liver for processing.

45
Q

What percentage of water in the GI tract is reabsorbed into the bloodstream?

A

85-90%.

46
Q

What happens to water that is not reabsorbed in the small intestine?

A

It travels to the large intestine.

47
Q

How are most electrolytes processed in the intestine?

A

Most are reabsorbed into the bloodstream, with some renally excreted and others reabsorbed or excreted by the colon.

48
Q

What inhibits bacterial growth in the stomach?

A

The acidic environment of the stomach kills ingested pathogens and inhibits bacterial growth.

49
Q

What three factors inhibit bacterial growth in the duodenum?

A

Bile acid secretion, intestinal motility, and antibody production.

50
Q

What is the bacterial concentration in the duodenum and jejunum?

A

There is a low concentration of aerobic bacteria (e.g., streptococci, lactobacilli, staphylococci) and no anaerobes.

51
Q

What percentage of bacteria in the large intestine are anaerobes, and what is their role?

A

Anaerobes account for 95% of large intestine bacteria and contribute to the bulk of feces.

52
Q

What is the bacterial state of the intestines at birth?

A

The intestines are sterile at birth but become colonized within a few hours.

pathophysiology (56 decks)

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