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HISTOLOGY > Digestive System > Flashcards

Digestive System Flashcards

1
Q

The digestive system consists the ff.

A

oral cavity
pharynx
alimentary tract (canal)
anal canal

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2
Q

It lies within the mucosa or submucosa of their organ of origin.

A

intrinsic glands

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3
Q

It communicates with their organ of origin through ducts.

A

extrinsic glands

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4
Q

extrinsic digestive glands

A

major salivary glands including the parotid, sublingual, and submandibular (submaxillary) glands; the pancreas; and the liver.

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5
Q

Organs of the digestive tract typically have 4 concentric coats. Proceeding outward from the lumen these are:

A

(1) the mucosa (mucous membrane)
(2) the submucosa
(3) the muscularis (muscularis externa)
(4) the adventitia or serosa.

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6
Q

The mucosa has three components: .

A

(a) the epithelium and its underlying basement membrane,
(b) a thin underlying layer of loose, cellular connective tissue, the lamina propria, and
(c) a relatively thin layer of smooth muscle called the muscularis mucosae. The latter may consist of both circular and longitudinally arranged layers

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7
Q

The submucosa

A

is composed of a layer of dense, irregularly arranged connective tissue that contains nervous tissue (the submucosal plexus of Meissner) as well as blood vessels

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8
Q

nervous tissue of the submucosa

A

submucosal plexus of Meissner

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9
Q

muscularis externa consists of at least 2 layers of smooth muscle, what are these? Connective tissue separating the muscle layers contains nerves (myenteric plexus of Auerbach) and blood vessels.

A

inner circular and outer longitudinal layer

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10
Q

outermost layer which consists of a thin layer of loose connective tissue. Where the digestive system is covered by peritoneum the adventitial layer is called the serosa.

A

adventitia

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11
Q

Where the digestive system is covered by ______ the adventitial layer is called the _________.

A

peritoneum
serosa

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12
Q

It is a long tube that mechanically and enzymatically digests food into small molecules, then absorbs small molecules and electrolytes, and processes and excretes material that cannot be absorbed.

A

gastrointestinal tract

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13
Q

Different segments of the gastrointestinal tract perform different functions:

A

• Stomach
• Small intestine
• Large intestine (colon)

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14
Q

mechanical disruption of food and some enzymatic digestion

A

Stomach

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15
Q

enzymatic digestion and solubilization into small molecules and absorption of small molecules

A

Small intestine

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16
Q

processing of unabsorbed material into waste

A

Large intestine (colon

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17
Q

These organs contribute enzymes and other material to the gastrointestinal tract that help with digestion and solubilization of food.

A

liver and pancreas

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18
Q

The inner most layer of the wall of the GI tract is the _______. It consists of a layer of epithelium which is in direct contact with the contents in the lumen of the GI tract. The _________ sits on a basement membrane. Beneath the basement membrane is a thin layer of connective tissue called the _______. It contains blood vessels and lymphatics and in certain sections of the GI tract, large aggregates of immune cells localize to the lamina propria.

A

mucosa
epithelium
lamina propria

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19
Q

A thin layer of smooth muscle called the __________ sits beneath the mucosa.

A

muscularis mucosa

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20
Q

The layer beneath the muscularis mucosa is called the _________. It is a thick layer of connective tissue that contains arteries, veins, lymphatics and in some segments of the GI tract, nervous tissue.

A

submucosa

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21
Q

It surrounds the submucosa and is composed of two muscle layers: what are these muscles? an ________ in which the smooth muscle cells are arranged circumferentially around the GI tract and an ________ in which the smooth muscle cells are arranged longitudinally along the GI tract.

A

muscularis externa
inner layer
outer layer

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22
Q

The outer most layer of the GI tract is the _________.

A

adventitia

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23
Q

Adventitia which consists of the ff.

A

connective tissue containing blood vessels, nerves, and fat

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24
Q

The greatest structural and functional variations occur in the ___________, specifically the _________.

A

mucosal layers
epithelium

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25
Q

four distinct types of mucosa in the gastrointestinal tract:

A

• Protective mucosa
• Secretory
• Absorptive mucosa
• Absorptive mucosa

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26
Q

It is characterized by a stratified squamous epithelium and is found in the oral cavity, pharynx, esophagus, and anal canal.

A

Protective mucosa

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27
Q

It contains cells that are responsible for the secretion of digestive enzymes and acid and is found exclusively in the stomach.

A

Secretory mucosa

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28
Q

It is responsible primarily for absorbing digested nutrients and is found along the entirety of the small intestine.

A

Absorptive mucosa

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29
Q

It primarily involved in water absorption and electrolyte balance is found in the large intestine.

A

Absorptive mucosa

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30
Q

Unlike the lung where the epithelium undergoes gradual transitions from _________ to __________.

A

pseudo-stratified to columnar to cuboidal to squamous

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31
Q

esophagus to stomach has a sharp change in epithelia from _________ to ___________

A

stratified squamous to simple columnar

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32
Q

Four junctions in the GI tract that are characterized by abrupt changes in the mucosal lining:

A

• Gastro-esophageal junction
• Gastro-duodenal junction
• Ileo-cecal junction
• Recto-anal junction

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33
Q

• Gastro-esophageal junction

A

at the transition from esophagus to stomach

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34
Q

Gastro-duodenal junction

A

at the transition from stomach to small intestine

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35
Q

• Ileo-cecal junction

A

at the transition from small intestine to large intestine

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36
Q

Recto-anal junction

A

at the transition from rectum to anus

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37
Q

The first three junctions have a sphincter of smooth muscle that controls the passage of material across the junction.

A

Gastro-esophageal junction
Gastro-duodenal junction
Ileo-cecal junction

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38
Q

controls the passage of material across the junction

A

sphincter

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39
Q

two basic structures to increase its surface area

A

Glands and outward folding into the lumen of the GI tract

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40
Q

It is where the epithelia invaginates toward and occasionally into the sub-mucosal layer. .

A

glands

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41
Q

Glands are found in the ff organs.

A

stomach, small intestine and colon

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42
Q

The second structure involves outward folding into the lumen of the gastrointestinal tract of the mucosal and even sub-mucosal layer. These structures are found in the _________.

A

small intestine

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43
Q

Segments of the Gastrointestinal Tract

A

Esophagus
Stomach
Gastric glands
Cells of gastric glands
Parietal cells

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44
Q

It is a muscular tube that transports food from the pharynx to the stomach.

A

esophagus

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45
Q

Esophagus is lined by a ___________ and has a prominent muscularis mucosa and thick muscularis externa

A

stratified squamous epithelium

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46
Q

The esophagus ends in what junction?

A

gastro-esophageal junction

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47
Q

It is notable because the epithelium transitions from stratified squamous in the esophagus to simple columnar epithelium in the stomach

A

gastro-esophageal junction

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48
Q

The ________ is a distinct layer of smooth muscle that separates the esophagus from the stomach.

A

lower esophageal sphincter

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49
Q

It allows coordinated movement of food from the esophagus into the stomach while preventing reflux of acidic gastric fluids into the esophagus.

A

sphincter

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50
Q

mechanically and chemically digests food

A

stomach

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51
Q

The mixture of food, enzymes and acid generate a fluid mass called ______.

A

chyme

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52
Q

The stomach is functionally divided into four functional regions: what are these?

A

cardia, fundus, body and antrum.

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53
Q

It controls passage of chyme from the stomach into the duodenum which is the initial segment of the small intestine.

A

pyloric sphincter

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54
Q

Cardia

A

Mucus and bicarbonate

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55
Q

Body

A

Mucus
Bicarbonate
HCl
Pepsin

56
Q

Antrum

A

Mucus
Bicarbonate
Pepsin

57
Q

stomach mucosa is found in prominent folds called ____

A

rugae

58
Q

It allows for distension of the stomach after a large meal.

A

Rugae

59
Q

The functional unit of the stomach

A

gastric gland

60
Q

It contains secretory cells that release enzymes or acid into the lumen of the stomach and endocrine cells that mediate communication between the sections of the stomach to regulate the activity of the secretory cells in the epithelium.

A

Gastric glands

61
Q

It also releases hormones that regulate the activities of cells in other organs.

A

endocrine cells

62
Q

begins at the gastric pit which opens to the lumen of the stomach

A

gastric gland

63
Q

deepest portion of the gland called the ________

A

base

64
Q

Both of which protects the stomach epithelium from the damaging effects of acid.

A

mucus and bicarbonate ions

65
Q

It coats the surface of stomach epithelium and traps bicarbonate which neutralizes acid in the stomach before it can damage the epithelium.

A

Mucus

66
Q

It secrete hydrochloric acid and intrinsic factor, which is important for the absorption of vitamin B12 in the ileum.

A

Parietal cells

67
Q

Parietal cells secrete what?

A

hydrochloric acid and intrinsic factor

68
Q

Hydrochloric acid and intrinsic factor is important for the absorption of ________ in the ileum.

A

vitamin B12

69
Q

It creates a low pH environment in the lumen of the stomach which serves two main functions.

A

Hydrochloric acid

70
Q

Two main functions of hydrochloric acid

A

The first is to activate digestive enzymes such as pepsin. A low pH environment is also inhospitable to bacteria and therefore limits proliferation of bacteria and the risk of infection

71
Q

These are usually found in the isthmus region of the gastric gland. In H&E-stained samples, these cells have a characteristic “fried-egg” appearance, with a basophilic, centrally located nucleus and a rather eosinophilic cytoplasm.

A

Parietal cells

72
Q

Parietal cells are found exclusively in the ______ section of the _______.

A

body
stomach

73
Q

The apical surface of parietal cells forms a narrow channel called a ________.

A

canaliculus

74
Q

It increase acid production before and during eating. Three molecules are primarily responsible for stimulating parietal cells to increase the secretion of HCl.

A

Parietal cells

75
Q

It is released by the vagus nerve onto the surface of parietal cells.

A

Acetylcholine

76
Q

It is produced by endocrine cells (ECL) in the body region of the stomach.

A

Histamine

77
Q

It acts in a paracrine fashion.

A

Histamine

78
Q

It is produced by G cells in the antral region of the stomach and the duodenum (initial segment of the small intestine).

A

Gastrin

79
Q

protein kinases, all of which ultimately increase in acid production.

A

Protein Kinase A and Protein Kinase C

80
Q

It also stimulate ECL cells to produce histamine.

A

acetylcholine and gastrin

81
Q

Have both direct and indirect effects on acid production

A

acetylcholine and gastrin

82
Q

What triggers release of acetylcholine, gastric and histamine?

A

Stimulation of acid production proceeds in three phases: cephalic, gastric and intestinal.

83
Q

It is associated with the sight, smell, taste and even thought of food. Swallowing is also part of this phase.

A

Cephalic phase

84
Q

Stimuli in the cephalic phase trigger ____________ via the vagus nerve and its release of acetylcholine

A

acid production

85
Q

three phases

A

cephalic, gastric and intestinal

86
Q

It stimulate acid production through physical and chemical mechanisms.

A

gastric phase

87
Q

The entry of food into the stomach causes distention which triggers the vagus nerve to release _________.

A

acetylcholine

88
Q

In addition, the presence of digested protein and amino acids in the antrum region of the stomach stimulates G cells to release _____.

A

gastrin

89
Q

Digested protein and amino acids trigger G cells in the duodenum to release gastrin.

A

intestinal phase

90
Q

It inhibits acid production in parietal cells.

A

somatostatin

91
Q

These are found in the base of the gastric glands and produce pepsinogen, which is stored in large apical secretory granules.

A

Chief cells

91
Q

These are found in the base of the gastric glands and produce pepsinogen, which is stored in large apical secretory granules.

A

Chief cells

92
Q

Chief cells produce what?

A

Pepsinogen

93
Q

After pepsinogen is secreted, it is converted by the acidic environment of the stomach to _______ which is an active ________.

A

pepsin
protease

94
Q

It stimulate chief cells to release pepsinogen by activating pathways that increase cytosol IC calcium

A

acetylcholine and gastrin

95
Q

The mucosa in the body section contains __________ that produce histamine.

A

enterochromaffin-like (ECL) cells

96
Q

The antrum also contains ______ that release somatostatin which inhibits acid secretion by parietal cells.

A

D cells

97
Q

It is a circumferential ring about 3 centimeters deep distal to the gastro-esophageal junction.

A

cardia

98
Q

Its glands tend to be convoluted and are lined primarily by mucus-secreting cells that lubricate the incoming food and protect the lining of the stomach near the gastro-esophageal junction.

A

Cardia

99
Q

Below the glands of the mucosal layer are the ______ and ________, which are responsible for support and folding, respectively.

A

lamina propria and muscularis mucosa

100
Q

It is the main part of the stomach and is bounded by the greater and lesser curvatures.

A

body

101
Q

Its glands are straight with limited branching and are lined by a smaller population of mucus-secreting cells than those of the cardia.

A
102
Q

The ____ and _______ contain large numbers of parietal cells whereas the base contains chief cells and enterochromaffin-like (ECL) cells that release hormones. The muscularis mucosa and submucosa are also visible.

A

neck and isthmus

103
Q

It is the distal third of the stomach. It possesses glands with deeper pits and large amounts of coiling and branching.

A

antrum

104
Q

These glands contain many mucus-secreting cells, D-cells, and G-cells but lack parietal cells.

A

Antrum

105
Q

The _________ is connected to the initial segment of small intestine by short section of stomach called the ________.

A

antrum
pylorus

106
Q

It is responsible for the continued digestion of food and absorption of nutrients and is divided into three segments that have slightly different structures and functions. The first segment is called the ______ which is followed by ________ and then ______.

A

Small Intestine
duodenum
ileum

107
Q

It digest and absorb nutrients, contain microvilli along their apical surfaces.

A

enterocytes

108
Q

These are small projections of the cell membrane that are supported structurally by actin filaments.

A

microvilli

109
Q

It increases the surface area of the apical cell membrane to generate greater capacity for digestion and absorption of nutrients.

A

Microvilli

110
Q

finger-like projections of the epithelium and lamina propria called _______

A

villi

111
Q

one region of the small intestine contains outward foldings of submucosa called ________ which creates a tree-like structure with each branch a villus.

A

Plicae circulares

112
Q

All sections of small intestine contain there.

A

villi

113
Q

Within the lamina propria is a central lymphatic vessel known as a _____, which is crucial for the absorption of lipids from the intestine

A

lacteal

114
Q

It digest macromolecules and absorb nutrients.

A

Enterocytes

115
Q

It secretes mucus which protects the epithelial layer.

A

Goblet Cells

116
Q

The base of a villus that is closest to the submucosa is known as the _______

A

crypt of Lieberkuhn

117
Q

It appear spotted and eosinophilic in H&E stained samples, support the host defense against microbes by releasing several different types of antimicrobial peptides that prevent the growth of enteric pathogens. In addition, it also nurture the stem cells of the epithelium.

A

Paneth cells

118
Q

Segments of the Small Intestine

A

Duodenum
Jejunum
Ileum

119
Q

It contains the same wall layers seen in the previous portions of the GI tract:
mucosa, submucosa, and muscularis externa. The mucosa and lamina propria form long villi. The epithelial cells of the mucosa contain enzymes that facilitated digestions of large macromolecules.

A

Duodenum

120
Q

In addition, it receives digestive enzymes produced in the pancreas. It can be distinguished from the other segments of the small intestine by the presence of glands within its submucosa called Brunner’s glands. The cells in the glands secrete an alkaline mucus that neutralizes the pH of chyme from the stomach and protects the epithelium of the duodenum.

A
121
Q

A region of tremendous nutrient absorption and to support this absorption creates the largest surface area of the three segments of the small intestine.

A

Jejunum

122
Q

It has the shortest villi and is characterized by abundant Peyer’s patches in the submucosa.

A

ileum

123
Q

These are diffuse lymphoid tissue that play an important immunological role in sampling the contents of the GI tract.
The small intestine ends with the ileo-cecal junction

A

Peyer’s patches

124
Q

processes the indigestible material that comes from the small intestine. It absorbs sodium, chloride and water to concentrate waste material that is formed into feces.

A

Large Intestine or colon

125
Q

It can either absorb or secrete potassium and absorbs vitamins.

A

large intestine

126
Q

The large intestine feeds into the ________, which stores the feces and has a columnar epithelium with abundant goblet cells. Feces pass out of here, through the anus, and out of the body.

A
127
Q

The ________ is characterized by a stratified squamous epithelium that undergoes a gradual transition to skin containing sebaceous and apocrine sweat glands.

A
128
Q

features an important change in epithelial structure. The rectum is characterized by the same columnar epithelium that lines the majority of the gastrointestinal tract’s secretory and absorptive areas. The anus, on the other hand, has a stratified squamous epithelium that provides a greater deal of protection to the underlying tissue.

A

Recto-Anal Junction

129
Q

pancreas comprises two functional units

A

Exocrine and endocrine pancreas

130
Q

The largest is the ________ portion that secretes digestive enzymes and bicarbonate. The second is the _______ which secretes hormones that regulate plasma glucose levels (e.g. insulin, glucagon, etc.).

A

exocrine
endocrine pancreas

131
Q

exocrine pancreas has two main cell types

A

Acinar cells and Duct cells

132
Q

It synthesize and secrete digestive enzymes.

A

Acinar cells

133
Q

Mainly secrete fluid rich in bicarbonate

A

duct cells

134
Q

The acinar cells form a small cluster called an ______ with their apical surfaces facing a central lumen.

A

acinus

135
Q

A group of acini form a _________. Ducts from different acini in a lobule merge to and empty into interlobular ducts

A

lobule

HISTOLOGY (11 decks)

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