Digestive System Flashcards
1
Q
What is the digestive tract (proper)
A
The tube from the mouth to the anus. Including the oral cavity pharynx esophagus, stomach, small intestine, and large intestine
2
Q
What are accessory organs to the digestive tract?
A
tongue, teeth, salivary glands, liver, gallbladder, pancreas; includes glands that secrete substances into digestive tract.
3
Q
What is ingestion?
A
Introduction of food into the oral cavity
4
Q
What is mastication
A
Process of chewing to mechanically break foods down
5
Q
What is propulsion?
A
Movement of food down the GI tract
6
Q
What is swallowing (deglutition)?
A
Bolus moves from the oral cavity to the esophaghus
7
Q
What is a bolus
A
A mass. In reference to the digestive tract it is often a mass of chewed food.
8
Q
What is peristalsis?
A
The wave of circular muscle relaxation ahead and contraction behind the bolus that moves it to the digestive tract
9
Q
What is chyme?
A
Food as soon as it enters the stomach
10
Q
How does propulsion occur in the stomach?
A
By contraction that cause stomach acid “waves”
11
Q
How does propulsion occur in the small intestine?
A
Segmental contraction
12
Q
What is the function of secretions?
A
To lubricate liquefy and digest
13
Q
What are the three major secretions in the digestive tract?
A
Mucus, Water, and Enzymes
14
Q
What is digestion?
A
The mechanical and chemical processes that break down food
15
Q
What is absorption?
A
Movement of molecules from food from the tract into the blood or lymph
16
Q
What is elimination?
A
Poo
17
Q
What are the Functions of the digestive system?
A
Ingestion and Mastication
Propulsion and Mixing
Secretion
Digestion
Absorption
Elimination
18
Q
What is the order of the digestive tract?
A
Oral Cavity (mouth)
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
19
Q
What are the four layers of the digestive tract?
A
Mucosa
Submucosa
Muscularis
Serosa
20
Q
What is the mucosa layer of the digestive tract?
A
The innermost layer
Contains in order:
Mucous epithelium
Lamina Propria
Muscularis Mucosae
21
Q
What layer contains the lamina propria?
A
The mucosa Layer
22
Q
What is the Lamina Propria?
A
Connective tissue that holds epithelial cells together allows passage of blood vessels and nutrients
It also contains the intestinal glands/crypts
23
Q
Where are the intestinal glands/crypts found?
A
In the Lamina Propria of the Mucosa layer
24
Q
What is the second layer of the digestive tract?
A
The submucosa layer
25
What are the four parts of the Submucosa layer?
A thick CT layer that has nerves, blood vessels, lymphatics, and small glands
The submucosal plexus
A network of neurons and glial cells (enteric NS)
26
What organs lack the submucosal plexus?
The stomach and the esophagus
27
What is the third layer of the digestive tract?
The muscularis
28
What is the muscularis?
It is 2 or 3 layers of smooth muscle (both circular and longitudinal layers)
29
What lies between the layers of smooth muscle in the muscularis?
Myenteric Plexus acts to control the movement along the GI tract.
Interstitial pacemakers to promote rhythmic contraction.
30
What is the 4th, most superficial layer of the digestive tract?
The serosa (adventitia)
31
What is the serous membrane of the digestive tract called?
The peritoneum
32
What is the serosa made of
Connective tissue
33
How is the digestive system regulated?
Nervous regulation
Chemical Regulation
34
What is the local nervous regulation of the digestive system called?
The enteric nervous system
35
What does the enteric nervous system do?
Coordinates peristalsis and regulates local reflexes
36
What is the general nervous system regulation of the digestive system controlled by?
The Central Nervous System
37
What are the two types of nervous regulation of the digestive system?
Local (enteric)
General (systemic)
38
What would cause a reflex based on the sight, smell, or taste of food?
General nervous regulation of the digestive system
39
What are the two types of chemical regulation of the nervous system?
Neurotransmitters (ACh Stimulates, NE inhibits)
Hormones
40
What are the main hormones used in regulation of the digestive system
Gastrin
Secretin
Paracrine Factors (histamine)
41
What does serotonin's role in regulation of the digestive system?
It stimulates digestive motility
42
What is digestive motility?
Digestive movement
43
How many sets of teeth do humans have?
2 (deciduous and permanent)
44
What are the 4 types of teeth found in humans?
Incisors, Canines, Premolars, and Molars
45
What are the three layers of teeth in order of outermost to innermost?
Enamel
Dentin
Pulp
46
What is the muscle that humans use to chew?
Masseter
Temporalis
(Medial and Lateral pterygoids)
47
What are the three salivary glands?
Parotid
Submandibular
Sublingual
48
What is found in saliva?
Other than mostly water
Salivary amylase (starch)
Lingual Lipase (lipid)
Lysozyme (antibacterial)
IgA
49
What are the three stages of swallowing?
Voluntary
Pharyngeal (reflex)
Esophageal (reflex)
50
What organs are involved in reflexive swallowing?
The pharynx and the esophagus
51
What are the sphincters in the esophagus called?
The upper (striated) and lower (smooth) sphincters
52
What is the voluntary phase of swallowing?
Pushing the bolus of food into the oropharynx which initiates the pharyngeal phase
53
What happens during the pharyngeal phase of swallowing?
Pharyngeal constrictor muscles contract in succession
Upper esophageal sphincter relaxes for food to be pushed in
54
What is special about the pharyngeal phase of swallowing?
The muscles involved are skeletal, but the phase is involuntary
55
What happens during the esophageal phase of swallowing?
Peristaltic waves and gravity push the bolus through the esophagus
The lower esophageal sphincter relaxes
56
Why is the lower esophageal sphincter tonically constricted?
To prevent gastric reflux
57
What are the Rugae in the stomach?
They are a series of ridges produced by the folding of the organ wall.
58
What is the significance of the rugae in the stomach?
It increases the surface area (area of absorption) by 20X
59
What are the four excretory cells in the stomach called?
Mucus cells
Parietal cells
Chief cells
Endocrine cells
60
What do Chief cells excrete?
Pepsinogen and gastric lipase
61
What do parietal cells excrete?
HCl
Intrinsic Factor
62
What does intrinsic factor do? What type of cell releases it?
Binds Vitamin B12
Parietal cells
63
What does hydrochloric acid do in the stomach? What type of cell releases it?
It kills bacteria, inactivates salivary amylase, denatures proteins, and converts pepsinogen to pepsin
Parietal cells release it
64
What does pepsinogen do in the stomach? What type of cell releases it?
It turns to pepsin when in the presence of HCl. This catalyzes the breaking of covalent bonds in proteins.
Chief Cells release it
65
What are the three phases that regulate stomach secretions?
The Cephalic Phase (brain phase)
The Gastric Phase
The Intestinal Phase
66
How does the cephalic phase of stomach secretion regulation work?
When presented with stimuli such as the taste/smell of food centers inside the medulla oblongata signal the stomach (via the vagus nerve) to stimulate secretion
67
Which phase of secretion regulation produces the greatest volume of gastric secretions?
The gastric phase
68
What initiates the gastric phase?
The presence of food in the stomach causes distension which sends a signal to the medulla which sends another signal back to the secretory cells
69
What prevents the pH of the stomach from getting too acidic?
Negative Feedback Loop
When the pH falls below two a negative feedback loop prevents gastric secretions from occurring
70
What is the intestinal phase of regulation of secretions?
It's the phase where secretions are inhibited
71
What are the two hormones involved in the intestinal phase of regulation of secretions?
Secretin
Cholecystokinin
72
What is the function of secretin? What causes its release?
It inhibits gastric secretions
It is released in response to acidic solutions entering the duodenum
73
What is the function of cholecystokinin? What causes its release?
It inhibits gastric secretions
It is released in response to fatty acids, other lipids, and protein digestion products in the duodenum and the proximal jejunum
74
What is the enterogastric reflex?
A local reflex that also inhibits gastric secretion. It is integrated within the medulla oblongata.
75
What do weak contractions in the stomach cause?
Mixing waves
the most fluid part is pushed to the pyloric sphincter the solid part is pushed back towards the body of the stomach
76
What do strong contractions in the stomach cause?
Peristaltic waves that force chyme into the pyloric sphincter
77
How long does it take for a typical meal to exit the stomach?
3-4 hours
78
How does peristaltic contraction cause the pumping of chyme?
Each contraction is strong enough to partially relax the pyloric sphincter and pump a few mL of chyme through the opening into the duodenum
79
What causes hunger pangs?
Contractions caused by low blood glucose levels
80
What happens if the stomach empties too quickly?
Digestive efficiency is reduced and the acidic chyme may damage the duodenum
81
What happens if the stomach empties too slowly?
The stomach wall could be damaged from the acid
82
Why is vomiting important?
It is a protective mechanism against toxic or harmful substances
83
What can cause vomiting?
Irritation anywhere along the GI tract
84
What are the steps of the vomiting reflex?
Deep breath
Hyoid bone and larynx elevate opening the upper esophageal sphincter
The opening of the larynx is closed
The soft palate is elevated closing the connection between the oropharynx and the nasopharynx
The diaphragm and abdominal muscles are forcefully contracted strongly compressing the stomach and increasing the intragastric pressure
The lower esophageal sphincter is relaxed
The gastric contents are forced out of the stomach through the esophagus and oral cavity, to the outside
85
What are the parts of the small intestine?
The duodenum (first 25cm)
The jejunum
The ileum
86
Where are Peyer's patches located?
In the ileum
87
What is the significance of the small intestine?
It is the site of greatest amount of digestion and absorption of nutrients and water
88
How does the diameter, wall thickness, and villi number change through the tube?
All three decrease along the tube
89
What are the 5 cell types in the small intestine?
Absorptive cells
Goblet cells
Paneth cells
Endocrine cells
Stem Cells
90
What is secreted by the small intestine?
Water
Electrolytes
Mucus
Enzymes
91
What enzymes are secreted by the small intestine?
Disaccharidases and Peptidases
92
How long does it take for chyme to travel from the pyloric sphincter to the ileocecal sphincter?
~3.5 hours
93
What are the three accessory organs of the small intestine?
The liver
Gallbladder
Pancrease
94
What is the Porta hepatitis?
The place where vessels enter and exit the liver
95
What do the lobules of the liver contain?
The hepatic triad which is:
Hepatic portal vein
Hepatic artery
Hepatic duct
96
What are the functions of the liver?
Bile production (for digestion)
Store nutrients
Processes nutrients
Detoxification
Synthesis of new molecules
97
What does bile do in the stomach?
Neutralizes and dilutes stomach acid and emulsifies lipids
98
What nutrients does the liver store?
Glycogen, fat, Vitamins (A, B12, D, E, K), Copper, and Iron
99
How does the liver detoxify?
It removes ammonia and converts it to urea
It removes worn-out red and white blood cells, bacteria, and other debris
100
What is the path bile takes to get to the duodenum?
It flows the left and right hepatic ducts into the common hepatic duct and then goes to the common bile duct (cystic duct) the bile duct then joins the pancreatic duct merging at the hepatopancreatic ampulla then empties into the duodenum at the major duodenal papilla
101
What ducts create the hepatopancreatic ampulla?
Common bile duct
Pancreatic duct
102
What ducts combine to form the common hepatic duct?
Right hepatic duct
Left hepatic duct
103
What ducts combine to form the common bile duct?
Common hepatic duct
Cystic duct
104
What artery carries oxygenated blood from the aorta into the liver?
The hepatic artery
105
What vein carries nutrient-rich deoxygenated blood from the intestines?
The hepatic portal vein
106
What veins make up the hepatic triads?
Hepatic artery
Hepatic portal vein
Common bile duct
107
What is special about blood in the hepatic sinusoids?
It has picked up processed molecules and waste products produced by the hepatocytes
108
Where does blood from the hepatic sinusoids come from?
Hepatic artery
Hepatic portal vein
109
Where do the hepatic sinusoids empty?
The central veins which join and connect to the inferior vena cava
110
How do bile salts increase bile secretion?
Through a positive feedback system
90% of the bile salts are reabsorbed in the ileum and carried in the blood by the hepatic portal circulation
111
What is the gallbladder?
A saclike structure that stores bile
112
How long does the gallbladder receive fresh bile?
It is cycled through the gallbladder constantly allowing storage and concentration
113
What are the endocrine cells of the pancreas?
Pancreatic islet cells (islets of langerhans) produce insulin glucose and somatostatin
114
What are the exocrine cells of the pancreas?
They are acini (grape-like clusters) that form lobules separated by septa
115
Where is insulin, glucose, and somastatin produced?
In endocrine cells of the pancreas
116
What is pancreatic juice made of?
Water
Na+
K+
HCO3 (bicarbonate)
117
What does enterokinase do?
Activates trypsinogen to trypsin
118
Where does enterokinase come from?
The duodenal mucosa
119
What are the 4 major parts of the large intestine?
The cecum, colon, rectum, and anal canal
120
How long does it take for stuff to move through the large intestine?
18-24 hours
121
What happens to chyme in the colon?
It is converted to feces
122
What percent of volume that enters the colon is reabsorbed?
90%Wh
123
What structures are attached to the cecum?
Vermiform appendix
numerous lymph nodes
124
What is the difference between the anal canal and the rectum?
It transitions from simple columnar to stratified squamous epithelium
125
What are the two sphincters in the anus? How are they different?
The internal anal sphincter (smooth muscle)
The external anal sphincter (skeletal muscle)
126
What causes gas?
Microbes breaking down particular kinds of carbohydrates
127
How does the defecation process occur?
Contractions coordinated with the internal and external anal sphincters relaxation
128
Is the external anal sphincter under voluntary control?
Yes
129
Is the internal anal sphincter under voluntary control?
No
130
How long does the defecation reflex last?
Only a few minutes
131
What stimulates the defecation reflex?
Distension of the rectum
132
What nervous system type controls defecation?
The parasympathetic nervous system
133
Where does the digestion of carbohydrates occur?
Mouth
Small intestine
Large intestine
134
Where does the digestion of lipids occur?
Small intestine
Large intestine
135
Where does the digestion of proteins occur?
Stomach
Small intestine
Large intestine
136
What is Cirrhossis?
A liver disease
Death/Damage of hepatic cells and subsequent replacement of connective tissue
Commonly caused by alcoholism
137
What is hepatitis?
A liver disease
Inflammation of the liver
It causes liver cell death leading to loss in liver function
Symptoms include nausea, abdominal pain, fever, chills, malaise, and jaundice
Caused by one of 7 viruses
138
What does IBD stand for?
Inflammatory bowel disease
139
What is Inflammatory bowel disease
Localized inflammatory degeneration occurring anywhere along the digestive tract (most commonly involves the distal ileum and proximal large intestine.
A thickened cell wall constricts the lumen
Symptoms include diarrhea, abdominal pain, fever, fatigue, and weight loss.
Cause is unknown
Anti-inflammatory drugs and food avoidance are used to treat it
140
What does IBS stand for?
irritable bowel syndrome
141
What is irritable bowel syndrome?
A disorder caused marked by alternating bouts of constipation and diarrhea.
May be linked to stress or depression
142
What is Gluten enteropathy (celiac disease)?
Malabsorption in the small intestine due to the effects of gluten
Can destroy newly formed epithelial cells causing blunted villi -> less surface area for absorption
143
What is food poisoning?
Ingestion of bacteria or toxins such as staphylococcus aureus, salmonella, or Escherichia coli
Symptoms include nausea, abdominal pain, vomiting, and diarrhea
144
What is cholera?
Caused by a bacterium (Vibrio cholerae) in contaminated water
Symptoms include severe diarrhea and loss of 12-20 L of fluid per day
145
What is dysentery?
A severe form of diarrhea with blood or mucus in the feces
Caused by bacteria, protozoa, or amoebae
