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A&P Final Part 2 > Chapter 24 - The Digestive System - Part 2 > Flashcards

Chapter 24 - The Digestive System - Part 2 Flashcards

1
Q

the pharynx is a passageway between the __ and the ____

A

between the oral cavity and the esophagus

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2
Q

the pharynx is a passageway for both __ and ___

A

food/liquid and air

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3
Q

Food normally passes through the ___pharynx and ____pharynx on the way to the esophagus

A

oropharynx and laryngeal pharynx

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4
Q

the pharynx is a ___ shaped tube lined with a ___ membrane

A

funnel shaped tube lined with a mucous membrane

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5
Q

the muscles or the pharynx work together with the muscles of which 2 other structures to start swallowing??

A

the muscles of the oral cavity and the esophagus

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6
Q

Describe the structure and function of the pharynx

A

the pharynx is an anatomical space that receives a food bolus or liquids and passes them to the esophagus as part of the swallowing process

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7
Q

The esophagus is a hollow, muscular tube that conveys food and liquids to…..

A

the stomach

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8
Q

the esophagus lies ___ to the trachea and connects the ___ to the ____

A

POSTERIOR to the trachea and connects the pharynx to the stomach

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9
Q

what is another word for swallowing

A

Deglutition

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10
Q

is swallowing voluntary or involuntary? explain

A

swallowing is initiated voluntarily but proceeds automatically once it begins

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11
Q

Name the structure connecting the pharynx to the stomach

A

the esophagus

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12
Q

Compared to the other segments of the digestive tract, what is unusual about the muscularis externa of the esophagus?

A
  • it contains skeletal muscle cells along most of the length of the esophagus
    -it is surrounded by adventitia rather than a serosa
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13
Q

What is occuring when the soft palate and larynx elevate and the glottis closes?

A

swallowing (deglutition) is occurring

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14
Q

what is the term for the hollow interior of an organ

A

the lumen

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15
Q

What prevents air from entering the esophagus and prevents backflow of materials from the stomach?

A

resting muscle tone in the circular muscle layer of the esophagus

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16
Q

The wall of the esophagus has __ layers

A

3

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17
Q

Name the 3 layers of the wall of the esophagus

A

Mucosa
Submucosa
Muscular Layer

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18
Q

What anchors the esophagus to the body wall?

A

adventitia

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19
Q

What are the 4 phases of swallowing?

A

-buccal phase
-pharyngeal phase
-esophageal phase
-bolus enters stomach

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20
Q

describe the buccal phase

A

the bolus is compressed against the hard palate. tongue is retracted which forces the bolus into the oropharynx

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21
Q

Describe the pharyngeal phase

A

bolus comes into contact with posterior pharyngeal wall. Larynx elevates. Folding of the epiglottis directs the bolus past the closed glottis. The uvula and soft palate block passage to the nasopharynx

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22
Q

Describe the esophageal phase

A

the contraction of the pharyngeal muscles forces the muscles through the entrance of the esophagus. Bolus is pushed towards stomach through peristalsis

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23
Q

The esophagus goes through what?

A

the diaphragm

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24
Q

Name the 4 major functions of the stomach

A

-temporary storage of ingested food
-mechanical breakdown of ingested food
-disruption of chemical bonds in food (through the action of acids and enzymes)
-production of “intrinsic factor”

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25
Q

What is “intrinsic factor”?

A

a GLYCOPROTEIN needed for the absorption of vitamin b12

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26
Q

What is chyme and where is it produced?

A

produced in the stomach
ingested substances combined with the secretions of the glands of the stomach. HIGHLY ACIDIC

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27
Q

What is the shape of the stomach?

A

an expanded “J” with a short lesser curvature and a long greater curvature

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28
Q

The stomach can be divided into 4 regions?

A

-the cardia
-the fundus
-the body
-the pylorus

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29
Q

what is the smallest part of the stomach?

A

the cardia

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30
Q

what is the smallest part of the stomach?

A

the cardia

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31
Q

Which part of the stomach has many mucous glands whose secretions coat the connection with the esophagus and help protect that tube from the acids and enzymes of the stomach?

A

the cardia

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32
Q

what is the largest region of the stomach?

A

the body

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33
Q

Which region of the stomach acts as a “mixing tank” for ingested foods and secretions produced by the stomach?

A

the body

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34
Q

which region of the stomach forms the sharp portion of the “j”

A

the pylorus

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35
Q

what regulates the release of chyme into the duodenum?

A

the pyloric sphincter

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36
Q

what kind of epithelium lines all the portions of the stomach?

A

simple columnar epithelium

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37
Q

what glands secrete gastric juice and in which regions of the stomach are these glands located?

A

gastric glands secrete gastric juice
gastric glands are found in the FUNDUS and BODY of the stomach

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38
Q

GASTRIC GLANDS are dominated by 2 types of secretory cells:

A

parietal cells
chief cells

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39
Q

which cells secrete intrinsic factor?

A

parietal cells

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40
Q

besides gastric juices and intrinsic factor, what else do parietal cells secrete?

A

hydrochloric acid

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41
Q

Why is hydrochloric acid NOT produced in the cytoplasm?

A

HCl is such a strong acid that it would erode a secretory vessel and destroy the cell

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42
Q

How is HCl produced since it cannot be produced in the cytoplasm?

A

CO2 + H2O becomes carbonic acid (H2CO3) which then dissociates into H+ + HCO3-

the bicarbonate ions are ejected into the interstitial fluid and chloride ions are transported in

the chloride ions diffuse across the cell and exit through open chloride channels into the LUMEN of the gastric gland where it combines with the H ions that are actively transported also into the lumen of the gastric glands

43
Q

the secretions of parietal cells keep the pH of the stomach at ___-____

A

1.5-2

44
Q

What are 4 reasons for the pH of the stomach being so low?

A

-the acidity of gastric juices kills any microorganisms ingested with food

-the acidity denatures proteins and inactivates most of the enzymes in food

-the acidity helps break down plant cell walls and the connective tissues in meat

-an acidic environment is essential for the activation and function of PEPSIN, a protein-digesting enzyme secreted by chief cells

45
Q

What is pepsin and what secretes it?

A

a protein digesting enzyme secreted by chief cells

46
Q

Where are chief cells most abundant in a gastric gland?

A

at the base

47
Q

What 2 enzymes are produced by the stomachs of newborn infants and are important in the digestion of milk?

A

rennine (aka chymosin)
gastric lipase

48
Q

Glands in the pylorus primarily produce…

A

a mucous secretion (rather than enzymes or acid)

49
Q

gastrin is produced by…..

A

G cells

50
Q

What does Gastrin stimulate?

A

stimulates secretion by both parietal and chief cells as well as contractions of the gastric wall

51
Q

besides G cells, the pyloric glands also contain ___ cells which release ___

A

D cells which release somatostatin

52
Q

What is somatostatin?

A

a hormone that inhibits the release of gastrin

53
Q

Name the 4 major regions of the stomach

A

cardia
fundus
body
pylorus

54
Q

Discuss the significance of the low pH in the stomach

A

this creates an acidic environment that kills most microbes ingested with food, denatures proteins and inactivates most enzymes in food, helps break down plant cell walls and meat connective tissue, and activates pepsin

55
Q

How does a large meal affect the pH of blood leaving the stomach?

A

Big meals (especially with a high protein content) stimulate INCREASED STOMACH ACID SECRETION. When gastric glands are secreting, bicarbonate ions enter the blood stream to increase the blood pH. This vascular phenomenon is known as the alkaline tide

56
Q

When a person suffers from chronic gastric ulcers, the branches of the vagus nerves that serve the stomach are sometimes cut in an attempt to provide relief. Why might this be an effective treatment?

A

The vagus nerves contain parasympathetic motor fibers that can stimulate gastric secretions, even if food is not present in the stomach (the cephalic phase of gastric digestion)
Cutting the branches of the vagus nerves that supply the stomach would prevent this type of secretion from occurring and thereby reduce the likelihood of ulcer formation

57
Q

What structure allows for expansion of the gastric lumen

A

ruggae - prominent folds in mucosa of empty stomach

58
Q

Are nutrients absorbed in the stomach?

A

NO

59
Q

Give 4 reasons why nutrients are not absorbed in the stomach

A

-the epithelial cells are covered by a blanket of alkaline mucus and are not directly exposed to chyme

-the epithelial cells lack the specialized transport mechanisms of cells that line the small intestine

-the gastric lining is relatively impermeable to water

-digestion has not been completed by the time chyme leaves the stomach

60
Q

Most of the important digestive and absorptive steps of digestion take place where?

A

in the small intestine

61
Q

The liver secretes ___ which is stored in the ____ for discharge into the _____

A

the liver secretes BILE which is stored in the GALLBLADDER for discharge into the SMALL INTESTINE

62
Q

What does bile contain which makes it important for digestion?

A

buffers, and bile salts which facilitate the digestion and absorption of lipids

63
Q

What organ produces digestive enzymes as well as buffers that help neutralize chyme?

A

the pancreas

64
Q

99% of nutrient absorption takes place in the small intestine. Where does that other 1% occur?

A

in the large intestine

65
Q

the small intestine has 3 segments:

A

the duodenum (closest to stomach)
the jejunum
the ileum

66
Q

Which segment of the small intestine is a “mixing bowl” that receives chyme from the stomach and digestive secretions from the pancreas and liver?

A

the duodenum

67
Q

The bulk of chemical digestion and nutrient absorption occurs in what segment of the small intestine?

A

the jejunum

68
Q

what is the name of the sphincter that controls the flow of material from the ileum into the “cecum” of the large intestine?

A

the ileocecal valve

69
Q

the small intestine fills much of what cavity?

A

the peritoneal cavity

70
Q

the small intestine is stabilized in the peritoneal cavity by…..

A

mesentary proper

71
Q

the pancreas is a ___ that lies ___ to the stomach

A

gland that lies posterior to the stomach

72
Q

the pancreas produces ___ which buffers stomach acid

A

sodium bicarbonate

73
Q

where does the pancreas empty its contents?

A

into the duodenum

74
Q

What does the small intestine contain which increases its surface area greatly for absorption?

A

villi with microvilli covering it

75
Q

in addition to capillaries and nerve endings, what else does each villus contain in the small intestine?

A

a lymphatic capillary called a lacteal

76
Q

what is the function of a lacteal?

A

they transport materials that cannot enter blood capillaries (absorbed fatty acids are assembled into protein-lipid packages that are too large to diffuse into the bloodstream) CHLYOMICRONS

77
Q

What is the function of intestinal juice?

A

it moistens chyme, helps buffer acids, and keeps digestive enzymes and products of digestion in solution

78
Q

most intestinal juice arrives by _____

A

osmosis

79
Q

name the 3 regions of the pancreas

A

the head
the body
the tail

80
Q

describe the surface of the pancreas

A

lumpy, lobular texture

81
Q

the pancreas is primarily an ___ organ

A

exocrine (produces digestive enzymes and buffers)

82
Q

what delivers the secretions of the pancreas to the duodenum?

A

the large pancreatic duct

83
Q

the pancreas is what type of gland (structurally)

A

compound tubuloalveolar gland

84
Q

the pancreas has 2 distinct functions: 1 __ and the other ___

A

1 endocrine and the other exocrine

85
Q

what is the endocrine function of the pancreas

A

secrete insulin and glucagon into the bloodstream to control blood sugar

86
Q

the exocrine cells of the pancreas secrete….

A

pancreatic juice into the small intestine

87
Q

name 4 pancreatic enzymes

A

-pancreatic alpha amylase
-pancreatic lipase
-nucleases (break down RNA or DNA)
-proteolytic enzymes (proteases, peptidases)

88
Q

____ enzymes account for about 70% of the total pancreatic enzyme production

A

proteolytic

89
Q

proteolytic enzymes are secreted as ___ ___ and dont become activated until…

A

secreted as inactive proenzymes and dont become activated until they reach the small intestine

90
Q

What is the largest visceral organ?

A

the liver

91
Q

liver cells are called…

A

hepatocytes

92
Q

what are the basic functional units of the liver?

A

liver lobules

93
Q

adjacent lobule are separated by….

A

an interlobular septum

94
Q

the liver secretes a fluid called bile into a network of narrow channels (called _____) between the opening membranes of adjacent liver cells

A

bile caniliculi

95
Q

name 3 general categories of functions of the liver

A
  1. metabolic regulation
  2. Hematological regulation
  3. Bile production
96
Q

liver cells extract ___ or ___ from blood before it reaches systemic circulation through the hepatic veins

A

nutrients or toxins

97
Q

the liver can metabolize which 3 things:

A

carbohydrates
lipids
amino acids

98
Q

the liver neutralizes ammonia by converting it to ____

A

urea

99
Q

the liver strips off amino groups when converting amino acids to lipids or carbohydrates, or when breaking down amino acids to get energy. What is this process called?

A

deamination

100
Q

____-soluble vitamins are absorbed from the blood and stored in the liver

A

fat-soluble
A, D, E, K, B12

101
Q

Give an example to show that a function of the liver is “mineral storage”

A

the liver converts iron reserves to ferritin and stores this protein-iron complex

102
Q

the liver participates in ____ inactivation

A

drug inactivation

103
Q

the liver receives ____% of cardiac output

A

25%

104
Q

one of the biggest functions of bile is….

A

emulsification

A&P Final Part 2 (9 decks)

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