Digestive System Flashcards
1
Q
Digestive system consists of the ____ and ____
A
Digestive tract & it’s associated glands
2
Q
Digestive tract consists of
A
Oral cavity
Esophagus
Stomach
Small intestine
Large intestine
Anus
3
Q
4 main layers of walls of GI tract
A
- Mucosa
- Submucosa
- Muscularis externa
- Serosa & adventitia
4
Q
Functions of mucosal layer of GI tract
A
Protection
Absorption
Secretion
5
Q
3 sub layers of mucosa
A
Epithelium
Lamina propria
Muscularis mucosae
6
Q
Define lamina propria
A
Loose CT which supports epithelium of a mucosal surface
7
Q
Lamina propria contains…
A
- blood & lymphatic vessels
- Glands
- lymphatic tissue (GALT/MALT)
8
Q
Define Muscularis mucosae
A
Smooth muscle which allows for local movement of mucosa
9
Q
Submucosa contains…
A
- Dense irregular CT
- Submucosal plexus (Meissner’s plexus)
- Supports larger blood vessels & lymphatic vessels
- some glands
- lymphatic tissue (GALT/MALT)
10
Q
Submucosal plexus (Meissner’s plexus)
A
Autonomic nerves that innervate the Muscularis mucosae (smooth muscle)
11
Q
Muscularis externa usually consists of…
A
2 layers of smooth muscle (sometimes 3)
12
Q
Layers of muscularis externa
A
- inner: generally circular
- outer: generally longitudinal
- CT between 2 layers
13
Q
Function of muscularis externa
A
Layered smooth muscle in opposite planes aids in peristalsis
14
Q
CT between muscle layers of muscularis externa contains….
A
- blood & lymphatic vessels
- myenteric plexus (Auerbach’s plexus)
15
Q
Myenteric plexus
A
Autonomic nerves that innervate smooth muscle of muscularis externa
16
Q
Define serous
A
- Thin layer of CT with outer covering of mesothelium (simple squamous epithelium
- serous membrane (free surface) is continuous with mesentary)
17
Q
Define adventitia
A
CT layer that merges with surrounding tissues
- not a free surface (no mesothelium)
18
Q
Define esophagus
A
Muscular tube that transports swallowed material to the stomach
19
Q
Features of esophageal mucosa
A
- epithelium= stratified squamous (nonkeratinized)
- lamina propria: esophageal cardiac glands
20
Q
Esophageal cardiac glands
A
- located near cardiac portion of stomach
- produce neutral mucous to protect esophagus from regurgitated stomach contents
21
Q
Features of esophageal Submucosa
A
Esophageal glands
22
Q
Esophageal glands
A
- More numerous
- produce slightly acidic mucous to lubricate & protect mucosa
23
Q
Features of esophageal muscularis externa
A
- contains skeletal muscle in upper 1/3 of esophagus
- middle 1/3 skeletal mixed with smooth muscle
- lower 1/3 only smooth muscle
*swallowing begins as voluntary and ends with involuntary peristalsis
24
Q
Functions of esophagus
A
Transport
25
Function of stomach
Adds acid fluid to ingested food creating viscous mass (chyme)
26
# stomach
Mucosa & Submucosa thrown into large longitudinal folds called ____
Rugae
27
Chyme
Mixture of food & stomach acid
28
# stomach
Function of rugae
Allow for distension as stomach fills with food
29
Regions of stomach
1. Cardiac stomach/region (cardia)
2. Pyloric stomach/region (pylorus)
3. Fundic stomach/region (fundus)
4. Body (similar to fundus)
30
# stomach
Features of mucosa
- Epithelium= simple columnar
- surface mucous cells
- gastric glands
31
Simple columnar epithelium of stomach invaginates into the ____
Lamina propria
32
# stomach
Invaginations into the lamina propria form millions of ____ which lead to ____
Gastric pits lead to gastric glands
33
# stomach
Surface mucous cells
- line lumen & gastric pits
- secrete thick viscous insoluble mucous layer rich in bicarbonate (alkaline)
- protection against chyme & stomach acid
34
Gastric glands of fundus
Fundic glands
Long, tubular
35
4 main cell types of Fundic glands
1. Mucous neck cells
2. Parietal cells
3. Chief cells
4. Enteroendocrine cells (argent affine cells)
36
Mucous neck cells
In upper portion
Secrete soluble mucous (slightly acidic)
37
Parietal cells
Stain eosinophilic
Produce HCL and intrinsic factor
38
Intrinsic factor
Glycoprotein required for protection & uptake of vitamin B12
39
Chief cells
Stain basophilic
Located in lower 1/2 of gland
Secrete pepsinogen
40
In an acidic environment, pepsinogen is converted to ____
Pepsin
41
Pepsin
Protease that begins breakdown of proteins
42
What begins to digest lipids?
Gastric lipase
43
Enteroendocrine cells secretions
Various peptide hormones:
- serotonin, increases gut motility
- gastrin promotes acid production
44
Cardia & pylorus contain
tubular glands -> long pits -> gastric glands (cardiac & pyloric glands)
45
Cardiac & pyloric glands composed mostly of ____
Mucous-secreting cells (no chief or parietal cells)
46
# stomach
Layers of muscularis externa
- outer longitudinal
- middle circular
- inner oblique
47
# stomach
Function of muscularis externa
Rhythmic contractions of muscle mix food & chyme with mucous, HCL and digestive enzymes
48
Pyloric sphincter
Thickening of middle muscle layer at end of pylorus
Controls release of chyme into duodenum
49
Muscularis externa of the stomach is innervate by ____
Auerbach’s/Myenteric plexus
50
Function of small intestine
Site where digestion is completed & nutrients are absorbed
51
3 anatomical segments of small intestine
Duodenum
Jejunum
Ileum
52
# small intestine
Mucosa & Submucosa are thrown into ____
Permanent circular folds (plicae circulares)
53
Function of plicae circulares
Increase surface area
54
# small intestine
Villi are located in the ____ layer
Mucosa
55
# small intestine
Villi
Finger-like projections of mucosa, covered by epithelium with a core of lamina propria
56
Function of villi
Increase surface area of mucosa for absorption
57
# small intestine
Epithelium of mucosa
Simple columnar:
- enterocytes (absorptive cells) contain thousands of microvilli
- goblet cells (mucous production) interspersed among enterocytes
58
# small intestine
In the Lamina propria of the mucosa, villi contain a central ____
Lacteal
59
Lacteal
Highly permeable lymphatic vessel, closed at one end
Important for absorption of lipids
60
# small intestine
In the Lamina propria of the mucosa, between villi, short tubular glands open into ____
Crypts of Lieberkuhn (intestinal glands)
61
Crypts of Lieberkuhn (intestinal glands) are lined with ____
- Mainly Enterocytes & goblet cells
- paneth cells (in basal portions of crypts)
- Enteroendocrine cells
62
Paneth cells
In basal portion of crypts
Secrete antimicrobial substances
63
# small intestine
In the Lamina propria of the mucosa, Enteroendocrine cells produce…
Various peptide hormones
- cholecystokinin: promotes pancreatic enzyme secretion, gall bladder contraction, inhibits gastric acid secretion, and **secretin**, promotes pancreatic water & bicarbonate secretion, inhibits gastric acid secretion & stomach emptying
64
Submucosa of duodenum contains ____
Brunner’s glands (duodenal glands)
65
Brunner’s glands produce….
Alkaline mucus (neutralize chyme, optimal pH for pancreatic enzymes)
66
Ducts of Brunner’s glands open into ____
Crypts of Lieberkuhn (mucosa)
67
How is the jejunum differentiated?
Lack of submucosal glands
Lack of Peyer’s patches
68
In the ileum, the mucosa (lamina propria + submucosa) contains ____
Peyer’s patches
69
Peyer’s patches
Permanent lymphatic nodules
70
How do Peyer’s patches differ from GALT/MALT?
GALT/MALT is transient
Peyer’s patches are permanent
71
Principle functions of large intestine
- Absorption of electrolytes and water
- elimination of undigested food/waste
72
3 parts of large intestine
Cecum
Colon
Rectum
73
Cecum
Short piece, forms blind pouch from which the appendix projects
74
Colon
Subdivided into ascending, transverse, descending, sigmoid
75
Rectum
Dilated distal portion, stores feces prior to evacuation
76
Mucosal surface of large intestine
Smooth surface - no plicae circulares or villi
77
Epithelium of mucosal layer of large intestine
Simple columnar: many goblet cells interspersed with enterocytes which have microvilli
78
Lamina propria of mucosal layer of large intestine
Contains crypts of Lieberkuhn
79
Muscularis externa of colon is condensed into 3 separate longitudinal bands of muscle called ____
Teniae coli
80
Teniae coli
Contract lengthwise, aid in peristalsis
81
Epithelium of anal canal
Simple columnar of rectum shifts abruptly to stratified squamous of skin at the anus
82
Near the anus, the circular layer of muscularis externa forms the ____
Internal anal sphincter
83
Internal anal sphincter has further control exerted by ____
Skeletal muscle of external anal sphincter
