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anatomy > Ch. 26; The digestive system > Flashcards

Ch. 26; The digestive system Flashcards

1
Q

What are the two categories of organs in the digestive system?

A

Those that belong to the GI tract and the “accessory organs”

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2
Q

Where is food broken down into smaller components in the GI tract

A

within the lumen (inner opening) of the organs for absorption

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3
Q

The organs of the GI tract form a continuous tube lined with a mucous membrane. The organs include: (7)

A
  • oral cavity and pharynx
  • esophagus and stomach
  • small/large intestine and anus
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4
Q

what are the accessory organs and their function (5)

A
  • Salivary glands > saliva production
  • Liver > bile production
  • Teeth and tongue > chewing and swallowing
  • Gallbladder > Concentrates and stores liver secretions
  • Exocrine pancreas > secretes digestive enzymes
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5
Q

what do the accessory organs do 2

A
  • assist in the breakdown of food
  • some produce secretions that empty into the GI tract
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6
Q

What are the 4 tunics of the digestive tract

A

mucosa, submucosa, muscularis, serosa/adventitia

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7
Q
  • parts of the mucosa layer
  • parts of submucosa
  • parts of muscularis layer
A
  • epithelium, lamina propria, muscularis mucosae
  • submucosal nerve plexus
  • inner circular layer, myenteric nerve plexus, outer longitudinal layer
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8
Q

regional specializations of the Ileum

regional specializations of the colon

regional specializations of the esophagus

regional specializations of the stomach

regional specializations of the duodenum

regional specializations of the jejunum

A

Ileum (small intestine): Peyers patch

Colon (large intestine): Myenteric plexus

Esophagus: esophageal submucosal gland

Stomach: Gastric gland

Duodenum: Brunner’s gland, liver and pancreatic secretions,

Jejunum: submucosal plexus

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9
Q
  • what is another word for propulsion?
  • what does it mean
A
  • peristalsis
  • coordinated muscle contraction and relaxation wavelike movements; the bolus moves forward
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10
Q

How does the digestive tract aid in motility (2)

A
  • mostly muscle tissue
  • mixing and moving material through the GI tract
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11
Q

How is mixing motility ? 3

A
  • simultaneous muscle contractions
  • back and forth movements
  • bolus gets mixed with digestive secretions
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12
Q

secretions of the digestive system (2)

A
  • secretions come from glands
  • contains circulatory and lymphatic nerves
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13
Q

connections in the digestive tract (2)

A
  • continuous with the mesenteries
  • contains blood vessels, nerves, and lymphatics
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14
Q

what is mechanical digestion (3)

A
  • begins in the oral cavity (chewing)
  • does NOT break chemical bonds
  • increases surface area for chemical digestion
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15
Q

What is chemical digestion (3)

A
  • begins in the oral cavity but PEAKS in the stomach and small intestine
  • carried out by enzymes
  • breaks chemical bonds to generate small molecules from large molecules
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16
Q

Digestive can be ________ or ____________?

Define digestion

A
  • mechanical or chemical
  • the process of breaking down food molecules
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17
Q

What is absorption (2)

A
  • movement of substance from the lumen to cells
  • highly selective process by specific region
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18
Q

What are the last parts of the major digestive processes

A

secretion and absorption

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19
Q

what is secretion (2)

A
  • movement of substance from cells into the lumen
  • EX secretion of HCl into stomach to start digestion
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20
Q

What layer of the GI tract has specialized glands?

which layer has general glands?

A
  • submucosa
  • mucosa
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21
Q

Which teeth are for cut and tear?

which are for crush and grind?

A
  • incisors and canine
  • premolars and molars
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22
Q

Functions of the oral cavity (4)

A
  • protection against physical and chemical abrasions and pathogens
  • increasing surface area of food
  • coating food with saliva
  • initiation of swallowing to deliver food to the stomach
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23
Q

what are the features of mastication (4)

A
  • mechanically digests food into smaller particles
  • increases surface area
  • mixes food with saliva
  • under control of medulla oblongata
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24
Q

Describe the anatomy of the pharynx (2)

A
  • tube connecting the inner ear, oral cavity, and larynx
  • provides a passageway for food, liquid, and air into the esophagus or trachea
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25
Q

Location of salivary glands in the mouth 3

A

Parotid gland: back of throat

Submandibular gland: under jaw

Sublingual gland: under tongue

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26
Q

Functions of saliva!

pH:

moistening:

carbohydrates:

immunity:

nervous tissue:

A
  • 6.5-7.5
  • moistens epithelia and liquefies food
  • 5% of polysaccharide breakdown (salivary amylase)
  • immunity due to anti-microbial lysozymes and IgA
  • secretion stimulated by facial and glossopharyngeal nerves in response to varied stimuli
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27
Q

what are the components of saliva (9)

A

water

  • electrolytes
  • mucous
  • leukocytes
  • epithelial cells
  • glycoproteins
  • enzymes
  • IgA
  • lysozymes
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28
Q

Describe the pharyngeal phase of swallowing (5)

A
  • food contacts sensors
  • info is sent to the medulla oblongata
  • motor information travels back to the soft palate and pharynx
  • soft palate elevation
  • the nasopharynx and oropharynx passage ways are closed
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29
Q

saliva moistens ingested food to help it become?

what does salivary amylase do?

taste receptors become stimulated by?

A
  • bolus
  • initiates chemical breakdown of starch
  • food molecules being dissolved
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30
Q

what cleanses the oral cavity structures?

lysozymes and IgA do what?

A
  • saliva
  • they are antibacterial substances that inhibit bacterial growth
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31
Q

During swallowing, the ______ moves to the _______.

Swallowing connects the _____ _____ to the ________

A
  • The bolus moves to the pharynx
  • The oral cavity connects to the stomach
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32
Q

What are the parts of the pharynx

A

nasopharynx, oropharynx, laryngopharynx

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33
Q

describe the esophageal phase (4)

A
  • passageway for food and water from the pharynx to stomach
  • food bolus moves by peristalsis
  • upper esophagus: voluntarily controlled
  • lower esophagus: involuntarily controlled
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34
Q

describe the epiglottis bends (3)

A
  • epiglottis cartilage covers the opening to the larynx
  • upper esophageal sphincter relaxes (involuntary)
  • food moves safely into esophagus
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35
Q

What things aid the esophagus in swallowing?

A

Gravity and peristaltic waves.

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36
Q

how is the esophagus stimulated?

A

stretch receptors signals the enteric nerve plexus to smooth muscle, which stimulates contraction; efferent neurons stimulate more contraction

37
Q

functions of the stomach (4)

A
  • short-term storage (2-6 hours)
  • mix and grind contents with HCl and pepsin
  • continue chemcial and mechanical digestion (especially for proteins and fats)
  • move contents (chyme) into small intestine for further processing
38
Q

how does food enter the stomach

A

As food approaches the stomach, the lower esophageal sphincter relaxes to allow food bolus in

39
Q

Chyme enters the stomach through the ____
It exits the stomach through the ______

A

lower esophageal sphincter
pyloric sphincter

40
Q

The stomach contains _______ folds

where is rugae found?

what does rugae do?

T/F the stomach returns to normal size when empty?

A
  • gastric AKA rugae
  • found on the internal stomach lining when it’s empty
  • allows the stomach to expand greatly when it fills with food to allow more surface area for chyme to contact digestive juices
  • TRUE
41
Q

what are gastric pits

A

openings on rugae for secretions into the stomach

42
Q

cells of gastric pits (5)

A
  • parietal cells
  • chief cells
  • G cells (gastrin)
  • D cells (somatostatin)
  • Enterochromaffin cells
43
Q

Features of SURFACE mucus cells in the stomach (4)

A
  • line stomach lumen and extend into gastric pits
  • continuously secrete alkaline products containing mucin
  • mucous layer helps to prevent ulceration of the stomach lining
  • protects from gastric enzymes and high acidity
44
Q

Features of mucus neck cells in the stomach

A
  • immediately deep to the base of gastric pits
  • produce acidic mucin
  • help maintain acidic conditions
45
Q

which mucus cell of the stomach protects it from abrasion and injury

A

BOTH surface mucus cells and mucus neck cells

46
Q

Unique digestive secretions of G cells (3)

A
  • Secretes gastrin in RESPONSE TO FOOD in lumen and stomach distension
  • Stimulates parietal cells to release HCl
  • stimulates pepsin (chief cells) and histamine (ECL cells) secretion
47
Q

Unique digestive secretions of chief cells (3)

A
  • secrete pepsinogen, the precursor to pepsin
  • CHl stimulates conversion of pepsinogen to pepsin
  • secretes gastric lipase for fat digestion
48
Q

Unique digestive secretions of enterochromaffin (ECL) cells (2)

A
  • secretes histamine
  • binds H2 receptors on parietal cells to stimulate their HCl secretion
49
Q

what unique epithelial cell types line the small intestine, what are the functions (4)

A

Columnar cells: extensive microvili; produce digestive enzymes

Goblet cells: produce protective mucus

Granular cells: immune protection

Endocrine cells: produce hormones

50
Q

Unique digestive secretions of parietal cells (3)

A
  • Secretes HCl into the stomach lumen
  • Maintains an acidic pH of 0.8 in the stomach; denatures proteins, kills most microorganisms
  • Secrete intrinsic factor (required for vitamin B12 absorption)
51
Q

what are the two primary functions of stomach motility

A
  • mixing the bolus to form chyme
  • emptying chyme form the stomach to the small intestine
52
Q

Unique digestive secretions of D cells (2)

A
  • Secrete somatostatin
  • Inhibits gastrin and histamine secretion
53
Q

describe gastric mixing (3)

A
  • form of mechanical digestion
  • changes semi-digested bolus into chyme
  • churned and mixed molecules leads to the reduction of swallowed particle size
54
Q

define retropulsion

A

the reverse flow of some contents back toward the stomach

55
Q

What are the 5 detailed steps of gastric emptying in the stomach

A
  1. contractions of smooth muscle in the stomach wall mix bolus with gastric secretions to form chyme
  2. peristaltic waves result in pressure gradients that move stomach contents toward the pyloric region
  3. pressure gradient increases force in pylorus against pyloric sphincter
  4. sphincter opens, small amount of chyme enters
  5. sphincter closes with retropulsion
56
Q

what is the small intestine responsible for

A

90% of digestion. It is a major site of absorption.

57
Q

what is secretin (4)

A
  • hormone released from the small intestine in response to increased chyme acidity
  • causes the release of alkaline solution containing HCO3- from the liver and ducts of the pancreas
  • helps neutralize acidic chyme
  • inhibits gastric secretions and motility
58
Q

where does nutrient digestion and absorption occur?
Describe the folds of the small intestine
These modifications increase?

A
  • Brush borders
  • Plicae > Villi > Microvilli (columnar cells with brush borders)
  • they increase the small intestine surface area by 600-FOLD
59
Q

describe motility in the small intestine (3)

A
  • both segmentation and peristalsis
  • slow chyme movement allows time for digestion
  • at the ileocecal sphincter, chyme moves into the large intestine
60
Q

Functions of the small intestine (5)

A
  • mix liver and pancreatic secretions with chyme
  • continue digesting carbohydrates, proteins, and initiate fat digestion
  • absorb nutrients
  • move chyme toward large intestine
  • produce regulatory hormones and immune cells in large numbers
61
Q

what is Cholecystokinin (CCK) (4)

A
  • hormone released from the small intestine in response to fatty chyme
  • stimulates the gallbladder to strongly contract and release bile
  • relaxes smooth muscle within the hepatopancreatic ampulla which allows the entry of bile and pancreatic juice into the small intestine
  • inhibits motility and release of gastric secretions
62
Q

describe the secretion from the small intestine into the lumen (3)

A
  • contains mucous, electrolytes, and water
  • disaccharidases, peptidases, and nucleases are attached to microvilli
  • CCK and secretin are released into the bloodstream
63
Q

what do Peyer’s patches do

A

contribute to immune surveillance in the Ileum (3rd layer) of the small intestine

64
Q

describe the secretion from the accessory organs into the small intestine (2)

A
  • pancreas supplies digestive enzymes and alkaline broth to neutralize acid from the stomach
  • liver and gallbladder supply bile salts for lipid digestion
65
Q

what is the last organ of the digestive system

A

the large intestine

66
Q

The defecation reflex involves?

A

relaxation of both the internal and external anal sphincters

67
Q

functions of the large intestine (4)

A
  • absorption of water from remaining chyme, converting it to feces
  • secretion of protective mucus and movement of remaining non-digested food
  • site of bacterial colonization for specific nutrient digestion
  • site of immune cell production
68
Q

anatomy of the large intestine

A

Cecum > ascending colon > transverse colon > descending colon > Sigmoid colon

69
Q

The large intestine has a ___________ appearance

feces is eliminated by ________

how much of chyme is reabsorbed in the cecum?

A

> segmented

> defecation

> more than 90% each day

70
Q

describe the involuntary control of the defecation reflex

A

INTERNAL ANAL SPHINCTER: A stool in the rectum is sensed by the nervous system and causes parasympathetic relaxation

71
Q

how does the large intestine display motility; what initiates defecation

A
  • mass movements move chyme in the transverse and descending colon
  • rectal wall distension and CNS reflexes
72
Q

What is the voluntary control of the defecation reflex?

A

EXTERNAL ANAL SPHINCTER: “pushing”/”bearing down” to expel the feces

73
Q

how does the large intestine display secretions (2)

A
  • predominantly mucous with little digestive activity
  • feces that leaves the GI tract consists of water, mucous, undigested food, microorganisms, and sloughed-off epithelial cells
74
Q

what are acini?

what are islet of langerhans?

what do ducts do in the exocrine pancreas?

A
  • grapelike clusters of exocrine cells that secrete digestive enzymes
  • secrete insulin, glucagon, and somatostatin
  • fuse and drain into the duodenum
75
Q

What is bile?

What does bile emulsify?

Bile aids in?

Bile flows?

Where is Bile stored?

A
  • a complex fluid containing water, electrolytes, and organic molecules
  • fat particles in the small intestine
  • digestion of fat soluble vitamins and neutralization of acidic chyme
  • through the biliary tract and the sphincter of Oddi into the small intestine
  • in the gall bladder and released upon stimulation by CCK
76
Q

Liver (2) and gallbladder (1) functions

A
  • detoxify a wide range of chemicals brought into the body through digestion (liver)
  • metabolize nutrients into other forms for storage or use by other tissues (liver)
  • store bile until it is needed for fat digestion (gall bladder)
77
Q

Exocrine pancreas function (2)

A
  • acinar cells produce enzymes that aid in chemical digestion in the small intestine
  • duct cells produce a watery secretion rich in HCO3-
78
Q

which digestive enzyme is responsible for bulk digestion of proteins

A

Endopeptidases like trypsin and chymotrypsin

79
Q
  • which digestive enzyme works with liver bile salts to digest fats
  • what does pancreatic amylase do?
A
  • lipases
  • digests starch
80
Q

What is Cirrhosis of the liver?

Caused by? (5)

Causes?

Symptoms (7 total)

A

> when hepatocytes are replaced by fibrous scar tissue and compress blood vessels

> chronic injury to hepatocytes, alcoholism, liver disease, drugs/toxins, viral infections from hepatitis B or C

> Hepatic portal hypertension, compresses bile ducts in the liver

> Fatigue, weight loss, nausea, pain in the upper right quadrant. IF ADVANCED: Jaundice, edema, toxin accumulation

81
Q

which digestive enzyme is responsible for cleaving peptides into single amino acids

A

exopeptidases like carboxypeptidase

82
Q

Digestion of carbohydrates: (3)

A
  • Ingested carbohydrates include polysaccharides, disaccharides, monosaccharides, glycogen, and starch
  • Amylase breaks down polysaccharides
  • Brush border enzymes digest disaccharides and monosaccharides
83
Q

What are the implications of chronic acid reflux (4)

A
  • erodes esophageal tissue
  • Built-up scar tissue leads to narrowed lumen
  • Barrett’s esophagus: stratified squamous epithelium changes to columnar secretory
  • increases risk of cancerous growth
84
Q

What is GERD

causes

effects

how is it diagnosed

A

> gastroesophageal reflux disease: backflow of acid stomach contents into the esophagus

> lower esophageal sphincter doesn’t close properly

> heartburn

> X-ray shows barium contrast moving back into the esophagus. Endoscopic image shows narrowing of esophagus near the stomach junction

85
Q

Describe the digestion of lipids (3)

A
  • Emulsification increases the surface area for lipid digestion
  • Lipases (primarily from the pancreas) produce free fatty acids, diglycerides, monoglycerides, and glycerol
  • These components then form micelles which combine with bile salts
86
Q

describe the digestion of proteins (2)

A
  • Digestion begins in the stomach and continues in the small intestine
  • Only peptides smaller than 3 amino acids are absorbed
87
Q

Who are Barry Marshall and Robin Warren?

A
  • Australian doctors that discovered H. pylori could lead to peptic (stomach and duodenal) ulcers
  • Barry Marshal infected himself to test his theory
88
Q

What is a gastric ulcer?

Causes?

risk factors?

symptoms? (6)

treatments? (5)

A
  • a break in normal tissue lining the stomach or small intestine
  • caused by an imbalance between acid/pepsin secretions and mucosal lining defenses
  • bacterial infection with H. pylori; chronic inflammation; use of NSAIDs
  • abdominal pain, nausea, indigestion, vomiting blood, blood in stool, weight loss
  • antacids, antibiotics, dietary changes, H2 receptor antagonists, proton pump inhibitors
89
Q

What is appendicitis?

other causes? (7)

If left untreated:

effects:

Treatment:

A
  • inflammation of the appendix due to fecal matter obstructing it
  • lymphoid tissue, parasites, gallstones, tumors, appendix swells, blood supply compromised, bacterial growth
  • it could burst causing peritonitis, a dangerous infectionwith pain localized to right lower quadrant
  • nausea, vomiting, abdominal tenderness, and fever
  • surgical removal (appendectomy)

anatomy (17 decks)

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