The GI Tract / Digestive System Flashcards
(123 cards)
1
Q
What are the 2 groups of organs that make up the digestive system?
A
GI tract & Accessory digestive organs.
2
Q
What are the Accessory Digestive organs?
A
Teeth, tongue, Salivary glands, Liver, Gallbladder, Lips and Pancreas.
3
Q
What are the functions of the Digestive system?
A
Ingestion, Secretion, Mixing and Propulsion, Digestion, Absorption and Deification.
4
Q
What are the layers of the GI tract?
A
Mucosa, Sub Mucosa, Musculairs, Serosa.
5
Q
What is the layer of the GI tract “Mucosa”?
A
Composed of a layer of “Epithelium” in direct contact with the contents of the GI Tract.
A layer of connective tissue called “Lamina Propria”.
And a thin layer of smooth mm.
6
Q
What is the layer of the GI tract “Sub Mucosa”?
A
Consist of CT that binds it to the Muscularis Mucosa.
Contains many Blood and Lymph vessels that receive absorbed food molecules.
7
Q
What is the layer of the GI tract “Muscularis”?
A
Muscularis of the (Mouth, Pharynx and superior and middle parts of the esophagus contains skeletal mm that produces Voluntary swallowing.
Thought the rest of the Tract this layer is found in 2 sheets: an inner sheet of circular fibers and an outer sheet of longitudinal fibers.
8
Q
What is the layer of GI tract “Serosa”?
A
It is a serous membrane composed of Areolar CT and simple Squamous Epithelium.
9
Q
What is the Neural innervation of the GI tract?
A
Regulated by an Intrinsic set of nn’s AKA the “Enteric” nn’s.
Also by an Extensive set of nn’s that are also apart of the Autonomic Nervous system.
10
Q
What is the Deepest layer of the GI tract?
A
Mucosa
11
Q
What is the most superficial layer of the GI tract?
A
Serosa
12
Q
What does involuntary contractions of smooth mm in the GI tract help do?
A
This helps move, digest and break down food.
13
Q
What are the GI tract Reflexes?
A
Many neurones of the ENS are components of the GI Reflex pathways that regulate GI Secretion and Motility in response to stimuli present in the lumen of the GI tract.
14
Q
What is the Peritoneum?
A
Largest Serous membrane in the body.
Divided into the Parietal Peritoneum and the Visceral Peritoneum.
15
Q
What are the 5 major portions / Folds of the Peritoneum?
A
Greater Omentum, Falciform Ligament, Lesser Omentum, Mesentery, Mesocolen.
16
Q
What is the Greater Omentum?
A
The largest Fold, drapes over the Transverse colon and coils of the small intestine.
Normally contains a lot of Adipose tissue.
17
Q
What is the Falciform Ligament?
A
Attaches the Liver to the Anterior Abdominal Wall and Diaphragm.
18
Q
What is the Lesser Omentum?
A
It is the Pathway for BV’s entering the Liver and contains: the Hepatic portal Vein, common hepatic artery, common bile duct.
19
Q
What is the Mesentery?
A
Extends from the Posterior abdominal wall to wrap around the small intestine and then returns to its origin.
20
Q
What is the Mesocolon?
A
2 separate folds, Bind the Transverse colon and Sigmoid colon of the large intestine to the posterior abdominal wall.
21
Q
What is the only Digestive Organ attached to the Anterior Abdominal Wall?
A
The Liver.
22
Q
What is the Hard palate of the Mouth?
A
The Anterior portion of the roof of the mouth, It is formed by the Maxillae and Palatine bones.
Forms a bone partition between the Oral and Nasal cavity.
23
Q
What is the Soft Palate of the Mouth?
A
Posterior portion of the roof of the mouth, is arch shaped muscular partition between the Oropharynx and Nasopharynx.
24
Q
What are the Salivary glands?
A
Most saliva is secreted by the Major Salivary glands that lay beyond the Oral Mucosa, into ducts that lead to the Oral Cavity.
25
What are the Major Salivary Glands?
Parotid, Submandibular, Sublinginul.
26
What does the Tongue consist of?
Divided into halves by a Median Septum.
| There are Intrinsic and Extrinsic mm's.
27
What do Intrinsic mm's of the Tongue do?
The alter shape of the Tongue for speech and Swallowing.
28
What do Extrinsic mm's of the Tongue do?
They help move food for chewing.
29
What do the Teeth consist of?
The typical tooth has 3 Major External regions, The Crown, Root & Neck.
30
What is the Crown of a Tooth's External Layer?
This is the Visible portion above the gums.
31
What is the Root of a Tooth's External Layer?
Embedded in the socket where the Tooth sits are 1-3 Roots.
32
What is the Neck of a Tooth's External layer?
The Neck is the constricted junction of the crown and Root near the Gum line.
33
What forms the Majority of the Tooth?
Internally Dentin forms the majority of the Tooth.
Dentin of the Crown is covered in Enamel.
Dentin of the Root is covered by Cementum.
34
What are the 2 Enzymes in the mouth that help with Chemical digestion?
Salivary Amylase & Lingual Lipase.
35
What does the Pharynx consist of?
A funnel shaped tube that extends from internal nares to the Esophagus posteriorly and to the Larynx Anteriorly.
36
When food is first swallowed where does it go?
Composed of skeletal mm and lined by mucus membrane and is divided into 3 parts:
Nasopharynx, Oropharynx and Larnyngopharynx.
37
What does the Esophagus consist of?
The Esophagus begins at the inferior end of the Laryngopharynx, Passes through the inferior aspect of the of the neck and enters the Mediastinum anterior to the vertebral column.
After this it pierces through the Diaphragm through an opening called the Esophageal hiatus.
38
What is at the End of each part of the Esophagus?
At each end "Muscularis" becomes slightly more prominent and forms 2 Sphincters.
The "Upper Esophageal Sphincter" (UES) & "Lower Esophageal Sphincter" (LES).
39
What Esophageal Sphincter is Skeletal mm and what one is Smooth mm?
The (UES) is Skeletal mm and the (LES) is Smooth mm.
40
What is the function of the UES?
Regulates movement of food from pharynx into the Esophagus.
41
What is the Function of the LES?
Regulates movement from Esophagus into stomach.
42
What is Deglutition?
The movement of food from Mouth to stomach.
| Occurs in 3 stages.
43
What are the 3 stages of Deglutition?
1: Voluntary
2: Pharyngeal stage
3: Esophageal stage
44
What does Deglutition involve anatomically?
Facilitated by secretion of Saliva, and mucus and involves the mouth, Pharynx and Esophagus.
45
During Deglutition what does the Bolus do?
Stimulating receptors in the Oropharynx which sends impulses to the Deglutition enter of the medulla and lower parts of the brain.
The returning impulses causes the soft palate and uvula to move upward to close off the Nasopharynx.
In addition the epiglottis closes off the opening to the Larynx.
46
What does the Stomach connect the Esophagus to?
It connects the Esophagus to the Duodenum, The first part of the small intestine.
47
What are the main regions of the Stomach?
The 4 main regions: Cardia, Fundus, Body, and Pyloric part.
48
Where is the Cardia of the Stomach located?
Surrounds the superior opening of the Stomach.
49
Where is the Fundus portion of the Stomach located?
The Rounded portion superior and to the left of the Cardia is the Fundus.
50
Where is the Body of the Stomach located?
Inferior to the Fundus is the large central portion of the stomach, the Body.
51
Where is the Pyloric Part of the Stomach located?
Divided into 3 regions:
| Pyloric Antrum, Pyloric canal and the Pylorus.
52
What is the purpose of the Pyloric Antrum?
Connects to the Body of the Stomach.
53
What is the purpose of the Pyloric Canal?
Leads to the 3rd region, the pylorus which in turn connects to the Duodenum.
54
What is the Purpose of the Pylorus?
It communicates with the Duodenum of the small intestine Via a smooth mm Sphincter called "Pyloric Sphincter".
55
What is the Concave medial border called?
It is known as the "Lessor Curvature".
56
What is the Convex Lateral border of the Stomach called?
It is known as the "Greater Curvature".
57
What are the Gastric Glands of the Stomach?
Epithelial cells extend down into the Lamina Propria where they form columns of Secretory cells called "Gastric Glands".
58
What are Gastric Pits of the Stomach?
Several Gastric Glands open into the bottom of narrow channels called "Gastric Pits".
59
How do secretions from Gastric Glands reach the Stomach?
Secretions from several Gastric Glands flow into each Gastric Pit and then into the Lumen of the Stomach.
60
What are the 3 types of Exocrine gland cells that secrete their products into the Lumen of the Stomach?
Mucous Neck cells, Chief Cells, and Parietal cells.
| Secretion from these cells form Gastric Juice / Acid.
61
As food reaches the Pylorus what occurs?
Each mixing wave periodically forces about 3ml of Chyme into the Duodenum thru the Pyloric Sphincter.
This is known as Gastric Emptying.
62
What is Pepsin in the Stomach?
This is the only Proteolytic Digesting enzyme in the stomach.
Secreted by Chief cells.
Secreted in an inactive form called "Pepsinogen", this is to prevent digestion of the chief cells that secrete it.
63
When does Pepsinogen become Active?
When pepsinogen comes in contact with Hydrochloric acid.
64
What are the Important portions for the Pancreas?
In most people the Pancreatic duct joins the common bile duct from the liver and Gallbladder and enters the Duodenum as a Dilated common duct called the "Hepatopancreatic Ampulla".
The other major duct is the Accessory duct.
65
What is the Accessory duct of the Pancreas?
leads from the Pancreas and empties into the Duodenum Just superior to the "Hepatopancreatic ampulla".
66
What is the Histology of the Pancreas?
The pancreas is made up of clusters of glandular epithelial cells.
99% of the clusters are called Acini constitute the Exocrine portion of the pancreas.
1% of the clusters are Pancreatic Islets, forming the Endocrine portion of the Pancreas.
67
What do the Pancreatic clusters produce?
These cells secrete hormones, Glucagon, Insulin, Somatosatin and Pancreatic Polypeptide.
68
What is the Histology of the Liver?
Composed of several components, Hepatocytes, Bile Canaliculi, Hepatic Sinusoids.
69
Within the Histology of the Liver what is the Purpose of the Hepatocytes?
These are the major functional cells of the liver.
| They secrete Bile, a yellowish brownish liquid, serving as both a Excretory product and a digestive secretion.
70
What is the Purpose of the Bile Canaliculi of the Liver?
These are small ducts between hepatocytes that collect Bile produced by hepatocytes.
From "Bile Canaliculi" bile passes through Ductules and then Ducts.
These Bile Ducts form the larger Right and Left Hepatic Ducts and unite at the liver to form the Common Hepatic Duct.
71
What are the Functions of the Gallbladder?
Between meals, after most absorption has occurred bile flows into the Gallbladder for storage.
72
What is the Principle Bile pigment?
Bilirubin
73
What gives Feces it normal colour?
A breakdown product of the Liver called Stercobilin.
74
What dose the Small intestine consist of?
Most absorption occurs within the Small intestine.
Divided into 3 regions:
Duodenum, Jejumum, Ileum.
75
What is the Duodenum portion of the small intestine?
Starts at the Pyloric Sphincter and is in form of a C shaped tube and merges with the Jejumum.
76
What is the Jejumum portion of the Small intestine?
Extends to the Ilium.
77
What is the Ileum portion of the Small intestine?
Final and longest portion of the Small intestine.
| Joins the large intestine at a smooth mm sphincter called the "Ileocecal Sphincter".
78
What is the Function of the Small intestine?
Segmentations help mix chyme with digestive fluid.
Completes digestion of Carbs, proteins and fats.
Absorbs about 90% of nutrients and water that passes through the Digestive system.
79
What is the Histology of the Small Intestine?
The Wall of the Small intestine is composed of the 4 Same layers as the rest of the GI tract.
Mucosa, Submucosa, Muscularis, Serosa.
80
What does the Mucosa of the Small intestine consist of?
Absorptive cells digest and absorb nutrients in small intestine chyme.
Goblet cells secret mucus.
The mucosa contains deep creases lined with cells. These cells form "Intestinal glands" or "Crypts of Lieberkuhn".
81
What does the Submucosa of the Small intestine consist of?
Submucosa of the Duodenum contains "Duodenal Glands" that secrete an alkaline mucus that helps neutralize gastric acid in the chyme.
82
What path does the Hepatic Blood flow take through the Liver and back to the Heart?
Nutrient rich, De-oxygenated blood from the Hepatic portal Vein / Oxygenated blood from the Hepatic Artery.
Liver Sinusoids
Central Vein
Hepatic Vein
Inferior Vena Cava
Right Atrium
83
What do the intestinal Glands in the Intestinal creases contain?
Intestinal Glands contain "Paneth cells" and "Enteroendocrine cells".
84
What are "Paneth" cells in the small intestine?
They secrete Lysosome, has phagocytic abilities.
85
What are all the Types of "Enteroendocrine cells"?
There is 3 types within the Intestinal Glands.
| S cells, CCK cells, and K cells.
86
What are Duodenal Glands in the Small intestine Submucosa layer used for?
They secrete an alkaline Mucus that helps neutralize Gastric Acid in the Chyme.
87
What does the Serosa layer of the Small intestine consist of?
Circular folds, are found in the mucosa and Submucosa.
Used for enhanced absorption by increasing surface area.
Microvilli are projections of the free membrane absorptive cells.
88
How do the Microvilli appear under a microscope?
Too small to see under a microscope, they appear as a fuzzy line called a "Brush Line".
89
What is the role of the Intestinal Juice?
Pancreatic and Intestinal Juices provide a liquid Medium that aids in absorption of of substances and chyme in the small intestine.
90
What is the role of the Brush Border Enzymes?
The Absorptive cells in the small intestine create several digestive enzymes called brush border enzymes, and insert them into the plasma membrane of the microvilli.
91
Why does some of the enzymatic digestion occur at the surface of the Absorptive cells?
This occurs due to absorptive cells creating their own digestive enzymes and inserting them into the surface of the microvilli.
92
What is mechanical digestion in the small intestine?
Segmentations are localized, mixing mixing contractions occur in portions of the intestine distended by a large volume of chyme.
93
How does a Segmentation in the small intestine work?
Starting with the contractions of circular mm in a portion of the small intestine, helping contracts the intestine into segments.
Next mm fibers encircling each segment also contract dividing each segment again.
Then the segments that first contracted now relax.
94
What is (MMC) Migrating Motility Complex?
Beginning in the lower part of the stomach and pushes chyme forward along a short stretch of small intestine before dying out.
95
How long does (MMC) Migrating Motility Complex last?
```
Slowly migrating down the small intestine, reaching the end of the Ilium in 90 - 120 mins.
Then another (MMC) begins in the stomach.
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96
What are the 4 major parts of the Large intestine?
Structurally the 4 major portions are:
| Cecum, Colon, Rectum, and Anal canal.
97
What is the Cecum of the Large intestine?
Inferior to the Ileocecal Sphincter is the "Cecum".
| A small pouch, and attached to this is the Appendix.
98
What is the opening of the Ileum into the large intestine guarded by?
Guarded by the "Ileocecal Sphincter", which allows material from the small intestine to pass into the large intestine.
99
What is the Colon of the Large intestine?
The open end of the Cecum merges with a long tube called the Colon.
The Colon is divided into Ascending, Transverse and Descending.
100
What is the Rectum of the Large intestine?
The Rectum lays anterior to the Sacrum and the Coccyx. The terminal 2-3 cm of the Rectum is the Anal canal.
101
What is the Anal Canal of the Large intestine?
The terminal 2-3 cm of the Rectum is the Anal canal.
102
What forms the Right Colic Flexure?
This occurs where the Ascending colon takes a abrupt left turn just inferior to the Liver.
103
What does the descending portion of the Colon consist of?
After the Left Colic Flexure, the colon passes inferiorly to the level of the iliac crest as the Descending colon.
104
What does the Transverse colon consist of?
Curving beneath the inferior end of the Spleen on theft side as the "Left Colic Flexure"
105
Where does the "Left Colic Flexure" occur in the Large intestine?
In the colon portion of the large intestine, it occurs when the transverse colon takes a abrupt curve inferior to the spleen on the left side.
106
Where does the "Left Colic Flexure" occur in the Large intestine?
In the colon portion of the large intestine, it occurs when the transverse colon takes a abrupt curve inferior to the spleen on the left side.
107
What makes up the Sigmoid colon?
Beginning near the left iliac crest, projects medially to the midline and terminates as the rectum at about the level of the 3rd sacral vertebrae.
108
What is the "Anus"?
The opening of the Anal canal to the Exterior is called the Anus.
It is guarded by the "Internal Anal Sphincter" a smooth m that is involuntary.
And an "External Anal Sphincter" of skeletal mm that is voluntary.
109
What does the Muscularis layer of the Large intestine consist of?
Longitudinal mm's are thickened forming 3 bands called "Teniae Coli" that run most of the length of the large intestine.
110
What gather colon into series of pouches called "Haustra"?
This is what gives the Colon its puckered appearance.
| "Tonic contractions" of bands gather the colon into series of pouches.
111
What is involved in the Mechanical Digestion in the large intestine?
After substance pass through the "Ileocecal Sphincter" and accumulates in the ascending colon.
A movement characteristic of the large intestine is "Haustral Churning".
112
What occurs in the Large intestine immediately after a meal?
The "Gastrointestinal Reflex".
Intensifying peristalsis in the Ilium and forces any chyme Ito the Cecum, movement of the Colon begins when substances pass the "Ileocecal Sphincter".
113
When does movement of the colon begin?
When food / Substances pass through the "Ileocecal Sphincter".
114
What is the characteristic movement of the Large intestine called "Haustral Churning"?
This is the process of the Haustra remaining relaxed and become distended while they fill up.
When the distension reaches a certain point, the walls contract and squeeze the contents into the next Haustra.
115
What is "Mass Peristalsis"?
In the large intestine a strong peristaltic wave that begins at about the middle of the Transverse colon and quickly drives the contents of the colon into the rectum.
116
How many times a day would "Mass Peristalsis" occur?
Takes place around 3-4 times a day. during or immediately after a meal.
117
What is involved in the chemical digestion in the Large intestine?
The final stage of digestion takes place in the colon through the activity of Bacteria that inhabit the Lumen.
118
How is Chyme prepared for elimination in the Large intestine?
Through the action of bacteria, which ferment any remaining carbs and release Hydrogen, CO2 and methane gas.
119
What are the bacterial products that are absorbed in the large intestine?
Includes several Vitamins needed for normal metabolism among some B vitamins and K.
120
What happens after chyme has remained in the Large intestine for 3-10 hours?
It has become solid or semisolid from absorption of water, this is now called Feces.
121
What are the Phases of Digestion?
Occurs in 3 overlapping phases:
| Cephalic, Gastric, and Intestinal.
122
What is the Cephalic phase of Digestion?
The smell, site, thought or even the initial taste of the food triggers the areas of the cerebral cortex hypothalamus and the brain stem.
Helps prepare mouth and Stomach for food.
123
What is the Gastric phase of Digestion?
Once food reaches the stomach, Gastric phase of Digestion begins.
Neural and hormonal mechanisms regulate gastric acid secretions.
