A&PII Ch. 26 Digestive System Flashcards
1
Q
What are the two categories of the digestive system?
A
Gastrointestinal (GI) Tract and Accessory Digestive Organs
2
Q
Organs of the GI Tract
A
form a continuous tube lined with a mucous membrane
* oral cavity and pharynx
* esophagus and stomach
* small intestine, large intestine, and anus
3
Q
Within the _____ (inner opening), food broken down into smaller components to be absorbed
A
lumen
4
Q
Functions of Accessory Digestive Organs
A
- assist in breakdown of foods
- some produce secretions that empty into the GI tract
5
Q
What structures/ organs are included in the Accessory Digestive Organs category?
A
Salivary Glands, Liver, Teeth and Tongue, Gallbladder, Exocrine Pancreas
6
Q
Salivary Glands
A
saliva production
7
Q
Liver
A
production of bile
8
Q
Teeth and Tongue
A
participate in chewing and swallowing
9
Q
Gallbladder
A
concentrates and stores liver secretions
10
Q
Exocrine Pancreas
A
secretes digestive enzymes
11
Q
The Digestive Tract generally consists of what 4 layers (bottom to top)?
A
She -> Serosa Layer
Might -> Muscularis Externa Layer
Spit -> Submucosa Layer
Mucus -> Mucosa Layer
12
Q
Mucosa layer of the Digestive Tract
A
- closest to the lumen has 3 sublayers (epithelial tissue, lamina propria, muscularis mucosa)
13
Q
Submucosa layer of the Digestive Tract
A
- secretions
- location of glands
- Contains nerves, circulatory, and lymphatics
14
Q
Muscularis Externa layer of the Digestive Tract
A
*motility
* mostly muscle tissue
* mixing, moving material through GI Tract
* houses inner circular layer, myenteric nerve plexus, and outer longitudinal layers
15
Q
Serosa layer of the Digestive Tract
A
- connections
- contiguous with mesenteries
- contains blood vessels, nerves, lymphatics
16
Q
____________ is a major digestive process
A
Motility
17
Q
Propulsion
A
same as peristalsis a type of motility (pinches to mix) that uses coordinated muscle contraction and relaxation wavelike movements (bolus moves forward)
18
Q
Mixing
A
- a type of motility that stimulates muscle contractions, back and forth movemnets
- bolus gets mixed with digestive secretions
19
Q
Digestion can be ________ or ________.
A
mechanical or chemical
20
Q
Digestion
A
the process of breaking down food molecules
21
Q
Mechanical Digestion
A
- begins in the oral cavity
- does not break chemical bonds
- increases surface area for chemical digestion
22
Q
Chemical Digestion
A
- begins in the oral cavity but PEAKS in the stomach and small intestine
- carried out by enzymes
- breaks chemical bonds to generate small molecules from large molecules
23
Q
________ and _______ are the last of the major digestive processes.
A
Secretion and Absorption
24
Q
Secretion
A
- movement of substance from cells into the lumen
- e.g. secretion of HCl into stomach to start digestion
25
Absorption
* movement of a substance from the lumen to cells
* highly selective process by specific region
26
Which layer of the GI tract contains the lamina propria?
Mucosa
27
In what layers of the GI tract can glands be found?
Mucosa (general glands) and Submucosa (specialized glands)
28
Functions of the Oral Cavity
1) Protection against physical and chemical abrasions, pathogens
2) Increasing surface area of food
3) Coating food with saliva
4) Initiation of swallowing to deliver food to the stomach
29
The digestive tract starts with the...
ORAL CAVITY
30
_________ mechanically digests food into smaller particles.
Mastication
31
Features of mastication
* mechanical digestion
* increases surface area
* mixes food with saliva
* under control of medulla oblongata
32
Incisor and Canine
Cut and Tear food
33
Premolar and Molar
Crush and Grind food
34
________ is the major secretion in the oral cavity.
Saliva
35
What are the components of saliva?
- water
- electrolytes
- mucous
- leukocytes
- epithelial cells
- glycoproteins
- enzymes
- IgA
- lysozyme
36
Main features and functions of Saliva
* ph between 6.5 and 7.5
* moistening: moistens epithelia and liquifies food
* carbohydrates: 5% of polysaccharides breakdown (salivary amylase)
* immunity: due to anti-microbial lysozyme and IgA
* nervous control: secretion stimulated by facial and glossopharyngeal nerves in response to varied stimuli
37
Saliva moistens ingested food to help become _______
bolus
38
Salivary Amylase
initiates chemical breakdown of starch
39
Why do food molecules dissolve in salivary enzymes?
so taste receptors can be stimulated
40
Saliva and Salivary enzymes
* Cleanses oral cavity structures
* Antibacterial substances inhibit bacterial growth
(lysozyme, IgA antibodies)
41
Anatomy of the pharynx
* tube connecting the inner ear, oral cavity and larynx
* provides a passageway for food, liquid, and air into the esophagus or trachea
42
_______ moves to pharynx during swallowing.
Bolus
43
___________ connects the oral cavity to the stomach.
Swallowing
44
Pharyngeal Phase of Swallowing
* food contact sensors
* info sent to medulla
* motor information travels back to the soft palate and pharynx
* soft palate elevation
* nasopharynx- oropharynx passage closed
45
Epiglottis Bends
* Epiglottis cartilage covers the opening the larynx
* Upper esophageal sphincter relaxes (involuntary)
* Food moves safely into esophagus
46
Esophageal Phase
* Passageway for food, water from pharynx to stomach
* Food bolus moves by peristalsis
* Upper esophagus: voluntarily- controlled
* Lower esophagus: involuntarily- controlled
47
Food travels through the __________ to reach the stomach.
esophagus
48
Nervous control of the esophagus
* stretch receptors signal through enteric nerve plexus to smooth muscle, stimulus contraction
* efferent neurons further stimulate contraction
49
Esophagus Peristalsis and Gravity
* swallowing is aided by gravity
* peristaltic waves aid
50
Esophagus Connection to Stomach
* as food approaches the stomach, lower esophageal sphincter relaxes to allow food bolus in
51
What are the several unique functions of the stomach?
* short-term, storage (2-6 hours)
*mix and grind contents with HCl and pepsin
* continue chemical and mechanical digestion (especially for proteins and fats)
* Move contents (chyme) into small intestine for further processing
52
Stomach Anatomy
* Outer Longitudinal layer
* Middle Circular muscle layer
* Inner Oblique muscle layer
53
Gastric folds of the stomach
Rugae
54
Rugae
* found on the internal stomach lining when stomach is empty
* allows the stomach to expand greatly when it fills with food= more surface area for chyme to contact digestive juices
* returns to normal when empty
55
Surface Muscle Cells
* line stomach lumen and extend into gastric pits
* continuously secrete alkaline product containing mucin
* mucous layer helps to prevent ulceration of stomach lining
* protects from gastric enzymes and high acidity
* help protect the stomach lining from abrasion and injury
56
Mucus Neck Cells
* immediately deep to base of gastric pit
* produce acidic mucin
* help maintain acidic conditions
* help protect the stomach lining from abrasion and injury
57
True or False? All the cells in the gastric pit have the same digestive secretions.
FALSE Each cell type in the gastric pit has UNIQUE digestive secretion
58
Chief Cells
* Secrete pepsinogen (inactive enzyme)= precursor to pepsin
* HCl stimulates conversion of pepsinogen to pepsin (breaks down peptides- proteins)
* Secrete gastric lipase= fat digestion
59
Enterochromaffin (ECL) Cells
* Secrete histamine
* Binds H2 receptors on parietal cells to stimulate their HCl secretion
* Stimulates motility of stomach
60
D Cells
* Secrete somatostatin (same as GHIH)
* Inhibits gastrin and histamine secretion
61
Parietal Cells
* Secrete HCl into stomach lumen
* Maintains an acidic pH (0.8) in stomach; denatures proteins, kills most microorganisms
* Secrete intrinsic factor (required for Vitamin B12 absorption)
62
G Cells
* Senses food (pressure) in the stomach
* Secrete gastrin in response to food in lumen and stomach distension
* Stimulates parietal cells to release HCl
* Also stimulate pepsin (chief cells) and histamine (ECL cells) secretion
63
Stomach motility performs two primary functions: _______ ____ ______ to form chyme and emptying chyme from stomach to small intestine.
mixing the bolus
64
Gastric Mixing
* Form of mechanical digestion
* Changes semi-digested bolus into chyme
* Churned and mixed, leading to a reduction in size of swallowed particles
65
Gastric Emptying
* movement of acidic chyme from stomach into duodenum
* pressure gradient moving contents toward pylorus
* gradient increasing force against pyloric sphincter
* sphincter opens, with entrance of small volume of chyme
* sphincter closes, with retropulsion
66
Retropulsion
reverse flow of some contents from small intestine (duodenum) back toward the stomach allowing chyme to spend more time in the stomach
67
Step 1 of Gastric Mixing that leads to Gastric Emptying
contractions of smooth muscle in stomach wall mix bolus with gastric secretions to form chyme
68
Step 2 of Gastric Mixing that leads to Gastric Emptying
peristaltic waves result in a pressure gradients that move stomach contents toward pyloric sphincter
69
Step 3 Gastric Emptying that starts with Gastric Mixing
pressure gradient increases force in pylorus against pyloric sphincter
70
Step 4 Gastric Emptying that starts with Gastric Mixing
pyloric sphincter opens, small volume of chyme enters the duodenum
71
Step 5 Gastric Emptying that starts with Gastric Mixing
pyloric sphincter closes, and retropulsion occurs
72
Surface mucus cells in the stomach produce ______ mucus.
alkaline (to buffer acid)
73
Which cell of the stomach is essential for proper absorption of Vitamin B12 from the diet?
parietal cells
74
The small intestine is responsible for ____% of digestion, plus is a major site of absorption.
90%
75
Small intestine functions->
* mix liver and pancreatic secretions with chyme
* continue digesting of carbohydrates, proteins, and initiate fat digestion
* absorb nutrients
* move chyme towards large intestine
* produce regulatory hormones
* produce immune cells in large numbers
76
What are the three main structures of the small intestine? (top to bottom)
Duodenum, Jejunum, and Ileum
Derick, Jumps Instantly
77
Nutrient digestion and absorption occurs at _______ ______.
brush borders
78
Brush Border
major site of nutrient digestion and absorption
79
The modifications of the brush border...
increase the small intestine surface area by "600-fold"
80
Epithelial cell types that line the small intestine
Columnar Cells, Goblet Cells, Granular Cells, and Endocrine Cells
81
Columnar Cells
extensive microvilli; produce digestive enzymes
82
Goblet Cells
produce protective mucous
83
Granular Cells
immune protection
84
Endocrine Cells
produce hormones
85
______ ______ contribute to immune surveillance in the small intestine.
Peyer's Patches
86
What is the function of the ilium in the small intestine?
it is the main immune surveillance with lymph tissue
87
Peristalsis
regulated contractions
88
Cholecystokinin (CCK)
* hormone released from small intestine in response to fatty chyme
* stimulates gallbladder to strongly contract and release bile (into duodenum)
* relax smooth muscle within hepatopancreatic ampulla
* inhibits stomach motility and release of gastric secretions
89
When the smooth muscle within hepatopancreatic ampulla relaxes->
bile and pancreatic juices are allowed to enter into small intestine
90
Secretin
* released from small intestine in response to increased chyme acidity
* causes release of alkaline solution containing HCO3- (bicarbonate) From liver and ducts of pancreas
* helps neutralize acidic chyme
* inhibits gastric secretions and motility
91
Motility in the small intestine
* Both segmentation and peristalsis
* Slow chyme movement allows time for digestion
* At ileocecal sphincter, chyme moves into large intestine
92
Secretion from the small intestine into the lumen
* contain mucous, electrolytes, and water
* disaccharidases, peptidases, nucleases attached to microvilli
* CCK, secretin released into bloodstream
93
Secretion from accessory organs into small intestine
* pancreas supplies digestive enzymes and alkaline broth to neutralize acid from the stomach
*liver and gallbladder supply bile salts for lipid digestion
94
What is the other name for the large intestine?
The Colon
95
From left to right (anatomically) what are the anatomical structures of the colon?
Sigmoid colon, Descending colon, Transverse colon, Ascending colon, Cecum
96
Large Intestine functions
* Absorption of WATER from remaining chyme, converting it to feces
* Secretion of protective mucous and movement of remaining non-digested food
* Site of bacterial colonization for specific nutrient digestion
* site of immune cell production
97
The large intestine has a _________ appearance. Their _______ contract every 30 minutes.
segmented
haustra
98
_______ moves through the large intestine and is converted to feces.
Chyme
99
Feces is eliminated by _________.
defication
100
More than _____% of chyme entering the cecum each day is reabsorbed.
90%
101
The Defecation Reflex involves relaxation of both the internal and external _____ ________.
anal sphincters
102
Involuntary Control of the colon
* stool in rectum is sensed by nervous system
* parasympathetic relaxation
103
Voluntary Control of the colon
"bearing down" expels feces
104
Motility in the Large Intestine
* mass movements move chyme in the transverse and descending colon
* rectal wall distension and CNS reflexes initiate defecation reflex
105
Secretions of the Large Intestine
* predominantly mucous with little digestive activity
* Feces that leave the GI tract consist of water, mucous, undigested food, microorganisms and slouched-off epithelial cells
106
What are the main functions of the liver?
* detoxifies a wide range of chemicals brought to the body through food digestion
* metabolizes nutrients into other forms for storage or use by other tissues
107
What is the main function of the gallbladder?
stores bile until it is needed for fat digestion
108
The liver secretes and the gallbladder...
Stores Bile!
109
Bile is..
a complex fluid containing water, electrolytes, and organic molecules
110
Bile Emulsifies..
fat particles in the small intestine, making them easier to absorb
111
Bile Aids..
in digestion of fat-soluble vitamins and neutralizes acidic chyme
112
Bile Flows..
through the biliary tract and the sphincter of Oddi into the small intestine
113
Bile is stored..
in the gallbladder, released upon stimulation of CCK
114
Emulsion droplets of fat stabalized by bile salts in the process of being digested by..
pancreatic lipase
115
Soapy Layer
bile salts and phosphatidyl choline ("Lecithin")
116
Main functions of the Pancreas..
* acinar cells produce enzymes that aid in CHEMICAL digestion in the small intestine
* duct cells produce a watery secretion rich in HCO3
117
Pancreatic Exocrine glands contain ______ and _____.
acini and ducts
118
Acini
grape-like clusters of exocrine cells that secrete digestive enzymes
119
Islets of Langerhans
secrete insulin, glucagon, and other hormones
120
Ducts
fuse and drain into duodenum
121
Digestive Enzyme Endopeptidases including trypsin and chymotrypsin
responsible for bulk of protein digestion
122
Digestive Enzyme Exopeptidases, including carboxypeptidase
cleaves peptides into single amino acids
123
Digestive Enzyme Lipases
works together with liver bile salts to digest fats
124
Digestive Enzyme Pancreatic Amylase
Digests starch
125
What are the names of some other digestive enzymes?
ribonuclease, deoxyribonuclease, gelatinase, and elastase
126
Digestion of Carbohydrates
* Ingested carbohydrates include polysaccharides, disaccharides, monosaccharides, glycogen, and starch
* Amylase breaks down polysaccharides
* Brush border enzymes digest disaccharides and monosccharides
127
Digestion of Proteins
* digestion beings in the stomach and continues in the small intestine
* only peptides smaller than 3 amino acids are absorbed
128
Digestion of Lipids
* emulsification increases the surface area for lipid digestion
* lipases (primarily from pancreas) produce free fatty acids, diglycerides and glycerol
* these components then form micelles which combine with bile salts
129
What does GERD stand for?
Gastroesophageal Reflux Disease
130
What is GERD?
backflow of acid stomach contents into the esophagus
131
Why does GERD occur?
* lower esophageal sphincter doesn't close properly
* causes heartburn feeling
132
Implications of Chronic Acid Reflux
* chronic acid reflux can erode esophageal tissue
* scar tissue buildup, leading to narrowed lumen
* may change from stratified squamous to columnar secretory epithelium, Barrett's esophagus
-increased risk of cancerous growth
133
What are the causes Gastric Ulcers?
* imbalance between acid/ pepsin secretions and mucosal lining defenses
134
Risk factors of Gastric Ulcers
* bacterial infection with H. pylori
* chronic inflammation, use of NSAIDs
135
What is a Gastric Ulcer?
break in the normal tissue lining the stomach or small intestine
136
What are the symptoms of gastric ulcers?
abdominal pain, nausea, indigestion, vomiting blood, blood in stool, weight loss
137
Treatments for gastric ulcers
* antacids, antibiotics, and dietary changes
* H2 receptor antagonists, proton pump inhibitors
138
What is Cirrhosis of the Liver?
hepatocytes replaced by fibrous scar tissue
139
What does Cirrhosis of the Liver cause?
* hepatic portal hypertension
* compression blood vessels
* compression bile duct in the liver
140
What causes Cirrhosis of the Liver?
* Chronic injury to hepatocytes due to chronic alcoholism, liver disease, drug or toxins
* Most frequently viral infections hepatitis B or C
141
What are symptoms of Cirrhosis of the Liver?
fatigue, weight loss, nausea, pain in right upper quadrant
142
What are advanced symptoms of Cirrhosis of the Liver?
Jaundice, Edema, Toxin Accumulation
143
What is Appendicitis?
Inflammation of the appendix
144
What is most Appendicitis due to?
Fecal matter obstructing the appendix
145
Causes of Appendicitis
lymphoid tissue, parasites, gallstones, tumors
146
What are signs of appendicitis?
appendix swells, blood supply compromised, bacterial growth, may burst if untreated, pain localized to lower quadrant, nausea or vomiting, abdominal tenderness, fever
147
What happens if an appendix bursts?
dangerous infection, peritonitis eventually involves peritoneum
148
What is the treatment for appendicitis?
appendix surgically removed through appendectomy
