Chapter 22- The Digestive System Flashcards
1
Q
What are the organs of the alimentary, or gastrointestinal, tract?
A
Oral cavity Pharynx Esophagus Stomach Small intestine Large intestine
2
Q
What are the accessory organs of the digestive tract?
A
Teeth Tongue Salivary glands Liver Gallbladder Pancreas
3
Q
Basic processes of the digestive system
A
Ingestion Secretion Propulsion Digestion Absorption Defecation
4
Q
What is the largest serous membrane in the body and what is it composed of?
A
Peritoneal membrane
Consists of outer parietal membrane and inner visceral membrane I
5
Q
Type of fluid that fills the peritoneal cavity between the two layers
A
Serous fluid
6
Q
What are mesentries?
Name both of them
A
Mesenteries are folds of the peritoneum that attach the organs of the digestive system to the posterior wall of the abdomen
They are the greater and lesser omentum
7
Q
What do we call the blood vessels that supply and drain the abdominal digestive organs?
A
Splenic circulation
8
Q
What are the 3 main clusters of nerves from the sympathetic and parasympathetic nervous systems that serve the digestive organs?
A
Celiac plexus
Superior mesenteric plexus
Inferior mesenteric plexus
9
Q
Describe the submucosa layer of the organs of the alimentary canal
A
Made of dense irregular connective tissue with blood/lymphatic vessels and submucosal glands
10
Q
What is the submucosal plexus?
A
Nerves clusters of the enteric NS
Regulates secretion from and blood flow to its area of the alimentary canal
11
Q
Describe the muscularis externa of the organs of the alimentary canal
A
Thick layer of smooth muscle
12
Q
What is the myentric plexus?
A
Group of nerves of the enteric NS that regulates motility of the muscularis externa
13
Q
Describe the serosa layer of the organs of the alimentary canal
A
Outer layer of connective tissue in the organs of the peritoneal cavity
It is called the adventitia for organs located outside the peritoneal cavity
14
Q
Different forms of motility
A
Swallowing
Churning
Peristalsis
Defecation
15
Q
Which nervous system regulates motility?
A
Nerves of the autonomic nervous system
Group of nerves known as the enteric nervous system
16
Q
4 processes that occur at the oral cavity
A
Ingestion
Secretion
Chemical/mechanical digestion
Propulsion
17
Q
Structural features of the oral cavity
A
Cheeks Lips Gums Vestibule Oral cavity proper Hard/soft palate
18
Q
Key organs of mastication
A
Teeth
19
Q
Bony sockets where teeth are located and connective tissue that holds them in place
A
Alveoli
And
Periodontal ligament
20
Q
3 types of teeth
A
Incisors
Canines
Premolars/molars
21
Q
Two components of a tooth
A
Crown and root
22
Q
What does the tongue consist of?
A
Skeletal muscle covered with a layer of stratified squamous epithelium
23
Q
What is the lingual frenulum?
A
Thin band the attached the tongue to the floor of the oral cavity
Prevents the tongue from moving too far posteriorly
24
Q
What is the epithelium of the tongue arranged into?
How many are there and what are they called?
A
Papillae
There are 4 kinds: filiform, fungiform, circumvallate, foliate
25
All papillae contain epithelium with sensory receptors except:
Filiform
26
What are the two groups of skeletal muscle that control tongue movement?
Extrinsic and intrinsic
27
What are the components of saliva?
```
Water
Enzymes
Mucous
Electrolytes like sodium/chloride/potassium
Salivary amylase
Lysozyme
Bicarbonate ions
```
28
What is the function of saliva?
Moistens, lubricates and cleanses oral mucosa
Deters growth of pathogenic bacteria
29
What is salivation?
Process of secretion from salivary glands
| Controlled by parasympathetic nervous system
30
What are the three divisions of the pharynx?
Nasopharynx
Oropharynx
Laryngopharynx
31
Which divisions of the pharynx are part of the alimentary canal?
Oropharynx and laryngopharynx
32
What is the primary function of the pharynx?
Propulsion in the form of swallowing
Bolus passes through pharynx and into esophagus
33
What is the opening called at the inferior end of the esophagus?
Gastroesophageal sphincter
Prevents food from reentering the esophagus
34
What are the primary functions of the esophagus?
Propulsion and a small amount of secretion of mostly mucus
35
What is deglutition?
Swallowing
Specialized type of propulsion that pushes a bolus from the oral cavity through the pharynx and esophagus to the stomach
36
What are the three phases of swallowing?
Voluntary- controlled by cerebral cortex
Pharyngeal-medulla/enteric NS
Esophageal- medulla/enteric NS
37
Summarize the voluntary phase of swallowing
Tongue pushes bolus toward oropharynx
38
Summarize the pharyngeal phase of swallowing
Bolus enters oropharynx
Soft palate and epiglottis seal off the nasopharynx and larynx
39
Summarize the esophageal phase of swallowing
Peristaltic waves move the bolus down the esophagus to the stomach
40
5 anatomical regions of the stomach
```
Cardia
Fundus
Body
Pyloric antrum
Pylorus
```
41
What is the pyloric sphincter?
Sphincter that controls the flow of ingested food between the stomach and small intestine
42
What are Rugae?
Folds on the interior of the stomach that allow it to expand considerably
43
What is chyme?
Liquid that is formed from the muscles of the stomach churning and pummeling food
44
What are gastric pits?
Deep structures in the mucosa of the stomach that contain gastric glands
45
What are gastric glands?
Contain endocrine cells that secrete hormones into blood stream and exocrine glands that secrete gastric juice
46
What is gastric juice?
Acidic, enzyme-containing fluid
47
What are the 4 main types of cells in gastric glands?
From deep to superficial
Enteroendocrine cells
Chief cells
Parietal cells
Mucous neck cells
48
What are enteroendocrine cells?
Near bottom of gastric pit, secrete hormones that influence digestion
G cells secrete the hormone gastric which stimulates secretions from parietal cells
49
What are chief cells?
Secrete precursor enzyme pepsinogen
Becomes pepsin when encounters an acidic pH, begins protein digestion
50
What are parietal cells?
Secrete hydrochloride acid
That acid: activated pepsinogen, destroys pathogens and produces intrinsic factor which helps us absorb B12
51
What are mucous neck cells?
Near the top of the gastric gland
Secrete acidic mucus that prevents mucus from becoming neutralized
52
3 primary functions of the stomach
Secretion
Propulsion
Digestion
53
Three phases of gastric acid secretion during eating
Cephalon phase
Gastric phase
Intestinal phase
54
3 actions of the stomach enabled by its motility
Receive food from stomach
Churn bolus into chyme
Control the rate at which chyme enters the small intestine
55
Four main processes occurring in the small intestine:
Secretion
Digestion
Absorption
Propulsion
56
What are the cells of the small intestine called?
What do they produce?
Enterocytes
Produce digestive enzymes, hormones and mucus
57
Three divisions of the small intestine
Duodenum
Jejunum
Ileum
58
What is the duodenum?
First and shortest segment of the small intestine
Houses major duodenal papilla where secretions from the gallbladder and pancreas enter the small intestine
59
What are Brunner’s glands?
Specialized glands in the duodenal submucosa that produce alkaline mucus to protect the duodenum from the acidic chyme
60
What is the jejunum?
Middle part of the small intestine
Most active site for chemical digestion and absorption
61
What is the ileum?
Final segment of the small intestine
Terminates at the cecum
62
What is the ileocecal?
Sphincter that controls the movement of materials from the ileum into the large intestine
Prevents backflow of materials
63
What are the largest type of folds visible in the small intestine?
What do they do?
Circular folds- invoking mucosa and submucosa
Slow the movement of chyme which gives nutrients more time to be digested and absorbed
64
What are villi?
Projections in mucosa folds that contain a layer of wnterocytes that surround a central core of blood capillaries and a lymphatic vessel
65
What are lacteals?
Lymphatic vessels in villi
66
What are intestinal crypts?
Indents between villi which house glands with both enteroendocrine cells and goblet cells
67
What are microvilli?
Smallest folds found in the plasma membrane of enterocytes
Give the cells a brush border
68
What is the function of the migrating motor complex?
To move food from the duodenum to the ileocecal valve to clear the small intestine
69
Two types of movement the small intestine undergoes during eating
Peristalsis
| Segmentation
70
Nerve that regulates both peristalsis and segmentation
Vagus nerve
71
Functions of the large intestine
Secretion, propulsion, defecation
Receives materials not absorbed by the small intestine
Passageway first feces to exit the body
Active in absorbing water and electrolytes
72
Anatomical regions of the large intestine
Cecum with vermiform appendix
Colon (ascending, transverse, descending, sigmoid)
Rectum
Anal canal
73
What are taeniae coli?
Three bands of muscle made by the gathering of the longitudinal layer of the muscularis externa of the large intestine
74
What are haustra?
Pockets in the colon caused by constant tension bunching
75
What are epiploic appendages?
Fat-filled pouches contained in the serosa or visceral peritoneum
76
Two functional segments of the large intestine
Proximal and distal
77
What is contained in the proximal large intestine?
Ascending and transverse colon
78
What is contained in the distal large intestine?
Descending and sigmoid colon
| Rectum and anal canal
79
Two main types of motility in the proximal large intestine
Segmentation and mass movement or mass peristalsis
80
Main role of distal large intestine
Storing fecal matter until defecation
81
What NS mediates defecation?
Parasympathetic
Causes smooth muscle in the sigmoid colon and rectum to contract and the internal anal sphincter to relax
82
Three regions of the pancreas
Head
Body
Tail
83
What is the composition of pancreatic juice?
Water and multiple digestive enzymes and other proteins
84
When does pancreatic secretion rise and why?
During eating
Rises because of parasympathetic and hormonal stimulation
85
One hormonal mediator of pancreatic secretion
Cholecystokinin
Produced by duodenal enteroendocrine cells in response to the presence of lipids and partially digested proteins in the duodenum
86
What is secretin?
Stimulators hormone released by duodenal cells in response to acid and lipids in the duodenum
87
What are the four lines of the liver?
Right
Left
Caudate
Quadrate
88
What is the basic unit of the liver?
Liver lobule
Separated by septa
Composed of heoatocytes
89
What are hepatocytes?
Compose liver lobules
Flattened plates of cells arranged in the shape of a hexagon stacked on top of one another
90
What are hepatic sinusoids?
Large leaky capillaries that pass between rows of hepatocytes
91
What is the main function of the liver?
To produce bile
92
What is in bike and what are it’s functions?
Water, electrolytes and organic compounds
Functions: required for the digestion and absorption of lipids, and it is the mechanism by which the liver excretes wastes and other substances the kidneys cannot excrete
93
What does the gallbladder do and what stimulates it?
Stores bile
Stimulated by the hormone CCK which triggers it to contract and release bile into the cystic duct
94
What from the salivary glands helps begin digestion in the mouth? What does it break down?
Salivary amylase
Breaks down polysaccharides into shorter oligosaccharides
95
Where does chemical digestion of carbohydrates continue after the mouth? What enzyme do they encounter there? When can they be absorbed?
In the small intestine where they are encountered by pancreatic amylase.
They must be broken down all the way to various monosaccharides like glucose and fructose before they can be absorbed
96
What transports glucose and galactose across the membrane of enterocytes in the liver?
Na+/glucose cotransporter
97
Where does chemical digestion of proteins begin? What enzyme do they encounter there?
Begins in the stomach where they encounter pepsin
98
What does activated pepsin digest proteins down into?
Smaller polypeptides
Oligopeptides
Some free amino acids
99
What mist proteins be broken down to to be absorbed in the small intestine?
Small oligopeptides and free amino acids
100
What composed 90% of the lipids taken in by the diet that consist of three fatty acid molecules and a glycerol?
Triglycerides
101
What two enzymes break down lipids first in the stomach and then in the small intestine?
Gastric lipase in stomach
Emulsified by bile salts in small intestine
Digested by pancreatic lipase in small intestine
102
What are the structures formed when bile salts and digested lipids stay together?
Micelles
103
What is the process of lipid absorption?
Micelles escort lipids to the enterocytes plasma membrane
Lipids diffuse through the phospholipid bilayer and enter cytosol
Lipids are reassembled into triglycerides and packaged into chylomicrons
Chylomicrons are released into the interstitial fluid by exocytosis and then enter a lacteal
104
What pancreatic enzymes help digestion of nucleic acids in the small intestine?
Nucleases
105
How many liters of water enter the small intestine each day on average?
9 liters
106
How does water absorption occur in the body?
Osmosis
