CH 26 Flashcards
Digestive system
1
Q
Digestive system functions
A
- Ingestion
- Digestion
- Propulsion
- Secretion
- Absorption
- Elimination
2
Q
Ingestion
A
Introduction of solid and liquid materials into the oral cavity (mouth); first process of digesting and absorbing nutrients
3
Q
Digestion
A
Breakdown of nutrients into molecules that can be absorbed
4
Q
Propulsion
A
Movement of contents through smooth muscle of organs
5
Q
Secretion
A
Process of producing and releasing mucin or fluids like acids, bile, or digestive enzymes
Mucin is protective. It mixes with water to produce mucus, which coats the GI wall to protect and lubricate it against acidic secretions and abrasion from passing materials
6
Q
Absorption
A
Passive or active transport of electrolytes, digestion products, vitamins, and water across the GI tract epithelium into GI tract blood and lymph vessels
7
Q
Elimination
A
Undigestible material that cannot be absorbed becomes waste product and is expelled as feces during the process of defecation
8
Q
Organs of the digestive system
A
- Digestive organs
- Accessory digestive organs
9
Q
Digestive tract/ Gastrointestinal (GI) tract/ alimentary canal
A
Continuous tube including the oral cavity (mouth), pharynx (throat), esophagus, stomach, small intestine, large intestine, anal canal, and anus
Contraction of muscle in the tract propels material
10
Q
Tract/ canal
A
All organs connected in sequence
11
Q
The entire GI tract is lined by a(n) _________
A
mucous membrane
12
Q
Accessory digestive organs
A
Connected to the GI tract and typically develop as outgrowths of the tract; Assists the GI tract in digestion of materials
- Teeth
- Tongue
- Salivary glands
- Liver
- Gallbladder
- Pancreas
13
Q
Muscular contractions in the GI tract
A
- Peristalsis
- Segmentation
14
Q
Peristalsis
A
Wave of muscular contraction that moves material through the GI tract
15
Q
Segmentation
A
Churning and mixing of materials in the small intestine; disperses the material that is being digested
16
Q
Digestive processes
A
- Mechanical
- Chemical
17
Q
Mechanical digestion
A
Physically breaks down large food items into smaller pieces
Includes mastication (chewing), segmentation
18
Q
Chemical digestion
A
Breakdown of larger molecules into smaller molecules by digestive enzymes
19
Q
Mouth/ oral cavity
A
Entrance to the GI tract, initial site of mechanical digestion (via mastication) and chemical digestion (via an enzyme in saliva)
Lining is nonkeratinized stratified squamous - protects against abrasion. Also lines esophagus, oropharynx, and laryngopharynx
20
Q
2 regions of oral cavity
A
- Oral cavity proper
- Vestibule
21
Q
Oral cavity proper
A
Central to alveolar processes of mandible and maxilla
22
Q
Vestibule
A
Space between the teeth and mouth
23
Q
Structures of the mouth
A
- Cheeks
- Roof of mouth
- Gums
- Lips
- Fauces
24
Q
Buccae/ cheeks
A
Buccinator muscle compresses the cheeks against the teeth to hold solid material in place while chewing
25
Palate/ roof of mouth
- Hard
- Soft
26
Hard palate
- Hard and bony
- Anterior 2/3 of palate
- Formed by palatine processes of maxillae and horizontal plates of palatine bones
- Dense CT and nonkeratinized stratified squamous ET
- Has transverse palatine folds/ friction ridges to assist the tongue in manipulating ingested material prior to swallowing
- Separates nasal and oral cavities
27
Soft palate
- Posterior 1/3
- Soft and muscular
- Mostly skeletal muscle and nonkeratinized stratified squamous ET
- Conical projection: uvula
- Uvula and soft palate elevate when we swallow to close off the posterior entrance to the nasopharynx
28
Gingivae/ gums
Dense irregular CT with overlaid nonkeratinized stratified squamous ET
Surrounds neck of teeth and cover alveolar processes
29
Labia/ lips
Form anterior wall of oral cavity
Red color from abundance of superficial blood vessels and reduced amount of keratin within the outer ET layer
30
Fauces
Opening between the oral cavity and oropharynx
31
Saliva
Fluid consisting of serous fluid and mucous that assists in initial process of digestion
- Moistens ingested food into bolus
- Moistens, cleans, and lubricates oral cavity
32
Serous fluid
Watery fluid containing digestive enzymes
33
Mucous
Helps hold food particles together and makes bolus slippery
34
Bolus
Clump of food that is easier to swallow
35
3 major salivary glands
- Parotid
- Sublingual
- Submandibular
Secretes saliva
36
Minor salivary glands
- Gingival
- Lingual: surface of tongue
- Buccal
- Labial
- Palatal
37
Parotid salivary gland
- Largest of the salivary glands
- Anterior to ear
- 25-30% of saliva
- Parotid duct secretes into vestibule near upper 2nd molar
- Only serous secretions
38
Sublingual salivary gland
- Smallest of the salivary glands
- Inferior to tongue
- Sublingual duct secretes to floor of oral cavity
- 3-5% of saliva
- Serous and mucous secretions
39
Submandibular salivary gland
- Inferior to mandibular body
- Secretes largest percentage of saliva: 60-70%
- Submandibular duct opens lateral to lingual frenulum
- Serous and mucous secretions
40
Teeth
- Collectively known as dentition
- Responsible for mastication
41
Regions of teeth
- Crown
- Root
- Cervical region
42
Crown
Exposed, visible part of tooth
43
Cervical region/ Neck
Between root and crown, around the gum line
44
Root
Part of teeth embedded in bone; Anchors tooth to jaw
45
Tissues of teeth
- Enamel
- Dentin
- Pulp
- Cementum
- Periodontal ligament
46
Enamel
- Hardest substance in body, composed of calcium phosphate crystals
- Forms crown
47
Cementum
Ensheaths root of teeth
48
Dentin
- Most of teeth
- Harder than bone
- Deep to cementum and enamel
49
Pulp
Connective tissue that is in the center pulp cavity of tooth
50
Periodontal ligament/ membrane
Collagen fibers that hold the teeth in place; most sensitive part of tooth
51
Sets of teeth
- 20 deciduous/ primary teeth (6-30 months) -- no premolar or 3rd molar
- 32 secondary/ permanent teeth
52
Types of teeth
- Incisors
- Canine/ cuspid
- Premolars/ bicuspid
- Molar
53
Incisor
- Most anteriorly placed teeth
- Chisel shaped
- Single root
- Slice or cut into food
54
Canine/ cuspid
- Pointed tip
- Posterolateral to incisors
- Puncture or tear food
55
Cusp
Prominent ridges used to crush or grind ingested materials
56
Premolar/ bicuspids
- Posterolateral to canines
- Flat crown with cusps
- Crush or grind food
- 1 or 2 roots
57
Molar
- Thickest, most posteriorly placed teeth
- Large, broad, flat crown with cusps
- Crush or grind food
- 3+ roots
58
Pharynx
Common space used by digestive and respiratory system
59
Steps of swallowing
Food is broken down mechanically and chemically
1) Bolus formed
2) Bolus is pushed to oropharynx by tongue against hard palate
3) Swallowing reflex is stimulated
4) Nasal cavities, trachea, and oral cavity are closed off by soft palate and uvula
5) Bolus enters oropharynx, larygnopharynx, and esophagus
60
Layers of alimentary canal from esophagus to large intestine
- Mucosa
- Submucosa
- Muscularis
- Serosa or adventitia
61
Mucosa/ mucous membrane
Innermost layer of alimentary canal
- Epithelium
- Lamina propria
- Muscularis mucosae
62
Epithelium of mucosa
Inner superficial layer lining lumen of alimentary canal, usually simple columnar or nonkeratinized stratified squamous
63
Lamina propria
Underlying areolar CT
64
Muscularis mucosae
Relatively thin layer of smooth muscle
65
Submucosa
- Blood vessels
- Glands (secretes mucin)
- Submucosal/ Meissner's plexus
66
Tissue of submucosa
Dense irregular or areolar CT
67
Submucosal/ Meissner plexus
Nerve fibers and associated ganglia (sensory neurons, sympathetic postganglionic axons, parasympathetic ganglia); component of enteric nervous system
68
Muscularis
- Inner circular layer (smooth muscle)
- Outer longitudinal layer (smooth muscle)
- Myenteric/ Auerbach's plexus
69
Myenteric/ Auerbach's plexus
Controls smooth muscle layers of muscularis
70
Adventitia/ serosa
Adventitia: fibrous CT/ areolar CT with dispersed collagen and elastic fibers
Serosa: adventitia but covered visceral peritoneum; serous membrane
71
Esophagus
- Tubular pathway that moves food from the laryngopharynx to stomach by peristalsis
- Passes through the esophageal hiatus in diaphragm to connect to the stomach
- Travels posterior to trachea
72
Wall of esophagus
- Mucosa : stratified squamous epithelium, lamina propria, muscularis mucosae
- Submucosa: blood vessels, glands, submucosal plexus
- Muscularis: upper 1/3 all skeletal muscle, middle 1/3 skeletal and smooth muscle, lower 1/3 all smooth muscle
- Adventitia
73
Esophageal sphincter
- Superior esophageal sphincter
- Inferior esophageal/ cardiac sphincter
74
Superior esophageal sphincter
At junction of laryngopharynx and esophagus; closes during inhalation preventing air from entering the GI tract
75
Inferior esophageal/ cardiac sphincter
At junction of esophagus and stomach; prevents materials from regurgitating from stomach into esophagus
76
Stomach
- Left upper quadrant of abdomen
- Continues mechanical and chemical digestion of food (secretes digestive enzyme)
- Some absorption occurs across the stomach lining (water, simple drugs, some drugs)
77
Chyme
Pastelike substance after the bolus is processed in the stomach
1) mechanical digestion by contractions of muscularis layer that churns and mixes the bolus with gastric secretions
2) chemical digestion through its gastric secretions of acid and enzymes
78
Regions of stomach
- Cardia
- Fundus
- Body
- Pylorus
79
Cardia/ cardiac region
Small, narrow, superior entryway into stomach lumen from esophagus
Cardiac orifice: internal opening where the cardia meets the esophagus
80
Fundus/ fundic region
Dome-shaped region lateral and superior to connection of esophagus and stomach
Superior surface makes contact with diaphragm
81
Body/ corpus
Largest region of the stomach; Inferior to fundus and cardiac orifice
82
Pylorus/ pyloric region
Narrow, medially direct, funnel-shaped pouch that forms the terminal region of the stomach
83
Components of pylorus
- Pyloric antrum
- Pyloric canal
84
Pyloric antrum
More expanded region of the pylorus near the body of the stomach
85
Pyloric canal
More narrow region that connects to the duodenum
86
Pyloric orifice
Opening into the small intestine
87
Pyloric sphincter
Ring of smooth muscle surrounding the pyloric orifice ; regulates entrance of chyme into small intestine
Closes upon on sympathetic innervation and opens up upon parasympathetic innervation
88
Greater curvature
Inferior convex border; Attaches to the greater omentum
89
Lesser curvature
Superior concave border; Attaches to lesser omentum
90
Gastric folds/ rugae
Folds in the inner surface of the stomach to allow for expansion
91
Wall of the stomach
- Mucosa: simple columnar ET, lamina propria, lymph vessel, muscularis mucosae
- Submucosa: submucosal nerve plexus
- Muscularis: oblique layer, circular layer, longitudinal layer
- Serosa
92
Gastric glands
Branched tubular glands, secrete products into the stomach
93
Gastric pits
Opening of gastric glands; depression that distinguishes stomach mucosa
94
Cells of gastric glands
- Surface mucous cells
- Mucous neck cells
- Parietal cell
- Chief cell
- Enteroendocrine cell
95
Surface mucous cell
Line stomach lumen and secrete mucin to prevent ulceration of lining upon exposure to acid; protect epithelium from gastric enzymes
96
Mucous neck cell
Secretes acidic mucin to keep acidic condition of stomach
97
Parietal cell
Secrete hydrochloric acid (HCl) to denature proteins for chemical digestion and intrinsic factor that binds to vitamin B12 to help absorption of the vitamin
98
Chief cell
Secretes inactive pepsinogen, which, with acid, is converted into pepsin that chemically digests denatured proteins into smaller fragments
99
Small intestine
- Region where chemical digestion is completed and nutrients are absorbed
- Ingested materials (chyme) spend at least 12 hours
- 20 feet in cadaver, 10 ft in living humans
100
3 regions of small intestine
- Duodenum
- Jejunum
- Ileum
101
Duodenum
- C-shaped
- Upper right quadrant
- Only part of small intestine that is retroperitoneal
- Major duodenal papilla
- 10" (in)
102
Major duodenal papilla
Site where pancreatic secretions and bile enter the duodenum
103
Jejunum
- Middle portion of small intestine
- Primary region for chemical digestion and nutrient absorption
- 3' (ft)
104
Ileum
- Distal end terminates at ileocecal valve, sphincter that controls the entry of materials into large intestine
- 6'
105
Wall of small intestine
- Mucosa: simple columnar ET, lamina propria, muscularis mucosae
- Submucosa
- Muscularis: inner circular layer, outer longitudinal
- Serosa
106
Special features of small intestine that increases surface area
- Circular folds
- Villi
- Intestinal glands/ crypts
- Microvilli
107
Circular folds/ plicae circularis
Folds in mucosa and submucosa of small intestine
108
Villi
Fingerlike projections on surface of circular folds of mucosa to increase SA and slowdown movement of chyme to maximize nutrient absorption
Each has their own blood capillary
109
Intestinal glands/ crypts
Short-tunnel like depressions between villi
110
Microvilli
On absorptive cells
111
Cells of mucosa of small intestine
- Absorptive cells
- Goblet cells
- Enteroendocrine cells
- Paneth cells
112
Absorptive cells
Have microvilli
113
Goblet cells
Secrete mucous
114
Enteroendocrine cells
Secrete digestive enzymes (coordinates activities of stomach, pancreas, and gallbladder)
115
Paneth cells
Located at base of intestinal gland; secrete bacteriocidal enzymes
116
Duodenal glands/ submucosal glands/ Brunner's glands
Glands in the submucosa of small intestine; secrete alkaline mucous
117
Peyer's patches
Lymphatic nodules in submucosa of ileum
118
Large intestine/ colon
- Forms 3 sided perimeter around centrally located small intestine
- Large diameter than small intestine (hence name; small intestine longer)
- Absorbs fluids and ions and compacts indigestible waste and solidifies into feces
- Stores feces until defecation (expulsion of feces)
119
Segments of large intestine
- Ascending colon
- Descending colon
- Transverse colon
- Sigmoid colon
120
Ascending colon
- From ileoccal valve to superior edge of cecum
- Retroperitoneal
- Posterior wall directly adheres to posterior abdominal wall
121
Right colic/ hepatic flexure
90 degree turn of ascending colon toward left side of abdominal cavity as it approaches the inferior side of the liver
122
Transverse colon
From right colic flexure, curves and projects horizontally across the anterior region of the abdominal cavity
Intraperitoneal
123
Left colic/ splenic flexure
90 degree inferior turn as the transverse colon approaches the spleen in the left upper quadrant
124
Descending colon
- Retroperitoneal
- Along left side of abdominal cavity
- Descends vertically from left colic flexure until termination at sigmoid colon
125
Sigmoid colon
- Intraperitoneal
- S-shaped
- Terminates at the rectum
126
Sigmoid flexure
Where descending colon curves and turns inferomedially into pelvic cavity
127
Rectum
Retroperitoneal structure that connects to sigmoid colon; Muscular tube that expands to store accumulated feces before defecation
128
Anal canal
Passes through opening in levator ani muscles of pelvic floor and terminates at anus
129
Internal anal sphincter
Involuntary smooth muscle
130
External anal sphincter
Voluntary smooth muscle
131
Cecum
Initial region of colon that is a blind sac to the right of the lower abdominal quadrant
132
Vermiform appendix
Thin, hollow, fingerlike sac that extends inferiorly to the cecum; Lined with lymphocyte-filled lymphatic nodules
133
Teniae coli
3 thin, longitudinal bundles of smooth muscle fibers in outer longitudinal layer , help bunch up into sacs called haustra
*muscularis of cecum and large intestine has 2 layers of smooth muscle, the outer longitudinal layer isn't fully enclosed
134
Omental appendices/ epiploic appendages
Lobules of fat hanging off haustra
135
Mucosa of large intestine
- Lined with simple columnar ET
- Goblet and absorptive cells
- Has intestinal glands/ crypt
136
Peritoneum
Serous membrane surrounding abdominal organs
137
Intraperitoneal
Organs completely surrounded by visceral peritoneum
Include stomach, most of small intestine
138
Retroperitoneal
Organs behind the peritoneum; lie in direct contact with posterior abdominal and pelvic walls
Only covered on anterolateral surfaces with visceral peritoneum
Include pancreas, ascending and descending colon, rectum
139
Mesentery
Fold of peritoneum that support and stabilize intraperitoneal GI tract organs
Blood vessels, lymphatic vessels, and nerves are sandwiched between 2 folds to supply digestive organs
140
What are the mesenteries?
- Greater omentum
- Lesser omentum
- Transverse mesocolon
- Sigmoid mesocolon
- Mesentery (proper)
- Parietal peritoneum
- Visceral peritoneum
141
Greater omentum
Stores fat; Extends inferiorly from greater curvature of stomach, covers most abdominal organs
142
Lesser omentum
Connects to lesser curvature of stomach to liver
143
Mesentery (proper)
Suspends most of small intestine from posterior abdominal wall
144
Transverse mesocolon
Peritoneal fold that attaches the transverse colon to the posterior abdominal wall
145
Sigmoid mesocolon
Fold that attaches the sigmoid colon to the posterior abdominal wall
146
Liver
- Largest internal organ
- Located in right upper quadrant
- One of functions is to produce bile
147
2 ligaments supporting the liver
- Coronary ligament
- Falciform ligament
Both formed by peritoneum
148
Coronary ligament
Attaches liver to diaphragm
149
Falciform ligament
Attaches liver to anterior abdominal wall
150
Lobes of liver
- Right lobe
- Left lobe
- Caudate lobe
- Quadrate lobe
151
Which ligament separates the bigger right and left lobes?
Vertical falciform ligament
152
Round ligament of liver
Inferior free edge of falciform ligament; previously fetal umbilical vein
153
Caudate lobe
Subdivision of right lobe adjacent to the inferior vena cava
154
Quadrate lobe
Subdivision of the right lobe adjacent to the gallbladder
155
Ligamentum venosum
Vertical inferior part of liver; previously fetal ductus venosus
156
Porta hepatis
Horizontal crossbar where blood and lymph vessels, bile ducts, and nerves enter and leave the liver
- Hepatic artery proper
- Common hepatic duct
- Hepatic portal vein
157
Hepatic artery proper
Branch of celiac trunk
158
Hepatic arteries
Left and right branching of hepatic artery proper
159
Hepatic portal vein
Receives blood from digestive organs
160
Lobules
Functional unit of liver; division of liver lobes
161
Lobule components
- Central vein
- Hepatocytes
- Kupffer cells
- Bile canaliculi
- Portal triad
- Hepatic sinusoids
162
Central vein
Vein in center of liver lobules that collect venous blood and drain blood from the lobule
163
Hepatic veins
Union of central veins that empty into the IVC
164
Hepatic sinusoids
Channel that blood flows that contain Kupffer cells; thin walled leaky capillaries where arterial and venous blood mix and flow into the hepatic lobule toward the central vein
165
Kupffer/reticuloendothelial cells
Kill pathogens in blood as blood flows through hepatic sinusoids (phagocytic and immune functions), recycle old erthrocytes and worn out formed elements
166
Bile canaliculi
Channel where bile flows through
167
Hepatocyte/ hepatic cell/ liver cell
Performs functions of liver including producing bile, detoxing drugs, metabolites, and poisons, storing excess nutrients and vitamins, synthesizing blood plasma proteins
168
Portal triad
Carries blood to liver from digestive organs
- Branch of bile duct
- Branch of hepatic portal vein
- Branch of hepatic artery
169
Hepatic portal system
branch of hepatic artery + branch of hepatic vein
hepatic sinusoid
central vein
intralobular vein
hepatic veins
IVC
RA
170
Bile
- Greenish fluid containing water, bile salts, bile pigments, cholesterol, electrolytes
- Emulsifies fats, breaks larger clumps of fat into droplets
- Increases SA for lipase (fat digesting enzyme) to bind to
171
Hepatic ducts
L/R; where left and right lobes of liver drain bile into
172
Common hepatic duct
Union of left and right hepatic ducts
173
Cystic duct
Attaches to common hepatic duct to carry bile to and from the gallbladder
Direction of flow directed by hormones
174
Common bile duct
Union of cystic and common hepatic duct
175
Biliary apparatus
Network of thin ducts that carry bile from liver and gallbladder to duodenum
R/L hepatic ducts
common hepatic duct
cystic duct
common bile duct
1) left and right hepatic ducts merge to form common hepatic duct
2) common hepatic and cystic ducts merge to form a common bile duct
3) Pancreatic duct merges with common bile duct at hepatopancreatic ampulla
4) Bile and pancreatic juices enter the duodenum at the major duodenal papilla
176
Hepatopancreatic ampulla
Posteriorly placed swelling in duodenal wall where common bile duct and main pancreatic duct merge and pierce the duodenal wall; where bile and pancreatic juices mix
177
Major duodenal papilla
Where bile-pancreatic juice mixture leaves and empties into the duodenum
178
Gallbladder
- Stores and concentrates bile until we eat a fatty meal
- Embedded on inferior surface of liver
- Cystic duct connects gallbladder to common bile duct
179
Layers of gallbladder wall
- Mucosa: simple columnar ET with rugae
- Muscularis: smooth muscle
- Serosa
180
Pancreas
- Posterior to stomach in LUQ
- Retroperitoneal
- Endocrine (hormones) and exocrine (enzymes) gland
181
Regions of pancreas
- Head: fit in C-shaped curve of duodenum
- Body
- Tail
182
Pancreatic acini
- Exocrine gland - 99% of pancreas
- Secretes pancreatic juices into ducts
183
Pancreatic juice
- Alkaline fluid: neutralizes acidic chyme
- Digestive enzymes: breaks down all nutrients (proteins, fats, nucleic acids, carbohydrates)
184
Pancreatic islet
- Endocrine - 1% of pancreas
- Secretes insulin- hormone which regulates glucose in blood
185
Acinar cells
Simple cuboidal ET cells that line the pancreatic ducts
186
Acini
Clusters of acinar cells
187
Main pancreatic duct
Union of pancreatic ducts where most of pancreatic juices travel through
188
The main pancreatic duct drains into the _______
major duodenal papilla
189
The small accessory pancreatic duct drains into the _________
minor duodenal papilla
190
Bile and pancreatic ducts
1) Left and right lobes of liver drain into left and right hepatic ducts
2) Left and right hepatic ducts merge to form common hepatic duct
3) Cystic and common hepatic duct to form common bile duct
4) Common bile duct and main pancreatic duct merge to form hepatopancreatic ampulla, which enters duodenum at greater duodenal papilla
5) Accessory pancreatic duct enters duodenum at lesser duodenal papilla
