Digestive System

Question 1

The digestive system consists the ff.

Answer 1

oral cavity
pharynx
alimentary tract (canal)
anal canal

Question 2

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

Answer 2

intrinsic glands

Question 3

It communicates with their organ of origin through ducts.

Answer 3

extrinsic glands

Question 4

extrinsic digestive glands

Answer 4

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

Question 5

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

Answer 5

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

Question 6

The mucosa has three components: .

Answer 6

(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

Question 7

The submucosa

Answer 7

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

Question 8

nervous tissue of the submucosa

Answer 8

submucosal plexus of Meissner

Question 9

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.

Answer 9

inner circular and outer longitudinal layer

Question 10

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.

Answer 10

adventitia

Question 11

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

Answer 11

peritoneum
serosa

Question 12

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.

Answer 12

gastrointestinal tract

Question 13

Different segments of the gastrointestinal tract perform different functions:

Answer 13

• Stomach
• Small intestine
• Large intestine (colon)

Question 14

mechanical disruption of food and some enzymatic digestion

Answer 14

Stomach

Question 15

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

Answer 15

Small intestine

Question 16

processing of unabsorbed material into waste

Answer 16

Large intestine (colon

Question 17

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

Answer 17

liver and pancreas

Question 18

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.

Answer 18

mucosa
epithelium
lamina propria

Question 19

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

Answer 19

muscularis mucosa

Question 20

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.

Answer 20

submucosa

Question 21

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.

Answer 21

muscularis externa
inner layer
outer layer

Question 22

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

Answer 22

adventitia

Question 23

Adventitia which consists of the ff.

Answer 23

connective tissue containing blood vessels, nerves, and fat

Question 24

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

Answer 24

mucosal layers
epithelium

Question 25

four distinct types of mucosa in the gastrointestinal tract:

Answer 25

• Protective mucosa • Secretory • Absorptive mucosa • Absorptive mucosa

Question 26

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

Answer 26

Protective mucosa

Question 27

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

Answer 27

Secretory mucosa

Question 28

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

Answer 28

Absorptive mucosa

Question 29

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

Answer 29

Absorptive mucosa

Question 30

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

Answer 30

pseudo-stratified to columnar to cuboidal to squamous

Question 31

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

Answer 31

stratified squamous to simple columnar

Question 32

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

Answer 32

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

Question 33

• Gastro-esophageal junction

Answer 33

at the transition from esophagus to stomach

Question 34

Gastro-duodenal junction

Answer 34

at the transition from stomach to small intestine

Question 35

• Ileo-cecal junction

Answer 35

at the transition from small intestine to large intestine

Question 36

Recto-anal junction

Answer 36

at the transition from rectum to anus

Question 37

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

Answer 37

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

Question 38

controls the passage of material across the junction

Answer 38

sphincter

Question 39

two basic structures to increase its surface area

Answer 39

Glands and outward folding into the lumen of the GI tract

Question 40

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

Answer 40

glands

Question 41

Glands are found in the ff organs.

Answer 41

stomach, small intestine and colon

Question 42

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 _________.

Answer 42

small intestine

Question 43

Segments of the Gastrointestinal Tract

Answer 43

Esophagus Stomach Gastric glands Cells of gastric glands Parietal cells

Question 44

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

Answer 44

esophagus

Question 45

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

Answer 45

stratified squamous epithelium

Question 46

The esophagus ends in what junction?

Answer 46

gastro-esophageal junction

Question 47

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

Answer 47

gastro-esophageal junction

Question 48

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

Answer 48

lower esophageal sphincter

Question 49

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

Answer 49

sphincter

Question 50

mechanically and chemically digests food

Answer 50

stomach

Question 51

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

Answer 51

chyme

Question 52

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

Answer 52

cardia, fundus, body and antrum.

Question 53

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

Answer 53

pyloric sphincter

Question 54

Cardia

Answer 54

Mucus and bicarbonate

Question 55

Body

Answer 55

Mucus Bicarbonate HCl Pepsin

Question 56

Antrum

Answer 56

Mucus Bicarbonate Pepsin

Question 57

stomach mucosa is found in prominent folds called ____

Answer 57

rugae

Question 58

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

Answer 58

Rugae

Question 59

The functional unit of the stomach

Answer 59

gastric gland

Question 60

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.

Answer 60

Gastric glands

Question 61

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

Answer 61

endocrine cells

Question 62

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

Answer 62

gastric gland

Question 63

deepest portion of the gland called the ________

Answer 63

base

Question 64

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

Answer 64

mucus and bicarbonate ions

Question 65

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

Answer 65

Mucus

Question 66

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

Answer 66

Parietal cells

Question 67

Parietal cells secrete what?

Answer 67

hydrochloric acid and intrinsic factor

Question 68

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

Answer 68

vitamin B12

Question 69

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

Answer 69

Hydrochloric acid

Question 70

Two main functions of hydrochloric acid

Answer 70

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

Question 71

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.

Answer 71

Parietal cells

Question 72

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

Answer 72

body stomach

Question 73

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

Answer 73

canaliculus

Question 74

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

Answer 74

Parietal cells

Question 75

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

Answer 75

Acetylcholine

Question 76

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

Answer 76

Histamine

Question 77

It acts in a paracrine fashion.

Answer 77

Histamine

Question 78

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

Answer 78

Gastrin

Question 79

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

Answer 79

Protein Kinase A and Protein Kinase C

Question 80

It also stimulate ECL cells to produce histamine.

Answer 80

acetylcholine and gastrin

Question 81

Have both direct and indirect effects on acid production

Answer 81

acetylcholine and gastrin

Question 82

What triggers release of acetylcholine, gastric and histamine?

Answer 82

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

Question 83

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

Answer 83

Cephalic phase

Question 84

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

Answer 84

acid production

Question 85

three phases

Answer 85

cephalic, gastric and intestinal

Question 86

It stimulate acid production through physical and chemical mechanisms.

Answer 86

gastric phase

Question 87

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

Answer 87

acetylcholine

Question 88

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

Answer 88

gastrin

Question 89

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

Answer 89

intestinal phase

Question 90

It inhibits acid production in parietal cells.

Answer 90

somatostatin

Question 91

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

Answer 91

Chief cells

Question 91

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

Answer 91

Chief cells

Question 92

Chief cells produce what?

Answer 92

Pepsinogen

Question 93

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

Answer 93

pepsin protease

Question 94

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

Answer 94

acetylcholine and gastrin

Question 95

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

Answer 95

enterochromaffin-like (ECL) cells

Question 96

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

Answer 96

D cells

Question 97

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

Answer 97

cardia

Question 98

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.

Answer 98

Cardia

Question 99

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

Answer 99

lamina propria and muscularis mucosa

Question 100

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

Answer 100

body

Question 101

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

Question 102

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.

Answer 102

neck and isthmus

Question 103

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

Answer 103

antrum

Question 104

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

Answer 104

Antrum

Question 105

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

Answer 105

antrum pylorus

Question 106

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 ______.

Answer 106

Small Intestine duodenum ileum

Question 107

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

Answer 107

enterocytes

Question 108

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

Answer 108

microvilli

Question 109

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

Answer 109

Microvilli

Question 110

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

Answer 110

villi

Question 111

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

Answer 111

Plicae circulares

Question 112

All sections of small intestine contain there.

Answer 112

villi

Question 113

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

Answer 113

lacteal

Question 114

It digest macromolecules and absorb nutrients.

Answer 114

Enterocytes

Question 115

It secretes mucus which protects the epithelial layer.

Answer 115

Goblet Cells

Question 116

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

Answer 116

crypt of Lieberkuhn

Question 117

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.

Answer 117

Paneth cells

Question 118

Segments of the Small Intestine

Answer 118

Duodenum Jejunum Ileum

Question 119

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.

Answer 119

Duodenum

Question 120

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.

Question 121

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

Answer 121

Jejunum

Question 122

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

Answer 122

ileum

Question 123

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

Answer 123

Peyer’s patches

Question 124

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.

Answer 124

Large Intestine or colon

Question 125

It can either absorb or secrete potassium and absorbs vitamins.

Answer 125

large intestine

Question 126

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.

Question 127

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

Question 128

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.

Answer 128

Recto-Anal Junction

Question 129

pancreas comprises two functional units

Answer 129

Exocrine and endocrine pancreas

Question 130

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.).

Answer 130

exocrine endocrine pancreas

Question 131

exocrine pancreas has two main cell types

Answer 131

Acinar cells and Duct cells

Question 132

It synthesize and secrete digestive enzymes.

Answer 132

Acinar cells

Question 133

Mainly secrete fluid rich in bicarbonate

Answer 133

duct cells

Question 134

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

Answer 134

acinus

Question 135

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

Answer 135

lobule