Digestive System Flashcards
What is the primary purpose of the digestive system?
To break down food into molecules small enough to pass through the plasma membrane of the cells lining the gastrointestinal tract
The breakdown of food is termed
“digestion”
The movement of molecules through the wall of the GI tract to enter either blood capillaries or lymphatic capillaries (lacteals)
“absorption”
Lymphatic capillaries are also called
lacteals
The anatomical structures of the digestive system can be divided into the:
- Gastrointestinal (GI) tract
- Accessory organs
The GI tract (or digestive tract or alimentary canal) extends from the
mouth to the anus
The accessory organs (which produce secretions that are released into the GI tract) include what organs?
liver, gallbladder, pancreas, and salivary glands
The liver and gallbladder secrete:
bile (aids in fat digestion)
The pancreas secretes:
- sodium bicarbonate (neutralizes acids) and the enzymes: - tripsin (proteins) - amylase (carbs) - lipase (triglycerides)
The salivary glands secrete:
amylase (carbs)
Most of the gastrointestinal tract is composed of four layers of tissues:
- mucosa
- submucosa
- muscularis externa
- serosa
The innermost layer of tissue in the GI tract; In most areas it is simple columnar epithelium that is replaced approximately every 5-7 days; In areas of high abrasion (such as the mouth, pharynx, esophagus, and anal canal), this epithelium is replaced by stratified squamous epithelium similar to your epidermis
mucosa
The connective tissue layer in the GI tract with blood vessels, glands, nerves, and lymphatic vessels
submucosa
The layer of tissue of the GI tract that is usually composed of two layers of smooth muscle that produce waves of contraction called peristalsis to propel food through the GI tract; In certain areas, the circular muscle is thickened to form valves called sphincters that regulate the passage of materal
muscularis externa
The thin outer layer of tissue of the GI tract that is also known as the visceral peritoneum
serosa
In areas without a serosa (such as the esophagus), the outer layer is called the
adventitia
The wall of the abdominal cavity is also lined with a serous membrane. This is called the
parietal peritoneum
What does “retroperitoneal” mean?
behind the peritoneum
Several extensions of the peritoneum help to hold the organs loosely in place. These include the:
- Greater omentum
- Messentery
A membranous “apron” attached to the greater curvature of stomach that covers the intestines; It contains a large quantity of lymph nodes and fat
Greater omentum
A membrane that loosely holds the small intestine to the posterior wall
Messentery
Three pairs of salivary glands produce saliva for the oral cavity:
- Parotid glands
- Submandibular glands
- Sublingual glands
Glands found anterior to the ears; the opening of the ducts is found in the cheeks
Parotid
Glands found along the body of the mandible
Submandibular
Glands found under the tongue
Sublingual
The primary function of the oral cavity is
Mastication (chewing), mixing the food with saliva, and forming a bolus for swallowing. Saliva contains the enzyme amylase which starts digestion.
The regions of the pharynx used by the digestive system are the
oropharynx and the laryngeal pharynx
The nasopharynx is closed off by what two structures during swallowing?
soft palate and uvula
What requires the coordination of several structures so food passes into the esophagus and not into the larynx or up into the nasopharynx?
deglutition (swallowing)
What structure folds down to close off the opening to the larynx during swallowing?
epiglottis
A collapsible muscular tube found posterior to the trachea. It travels through a hole in the diaphragm called the hiatus and joins the stomach.
esophagus
Sphincter found at the beginning of the esophagus:
upper esophageal sphincter
Sphincter found at the end of the esophagus:
lower esophageal sphincter (or cardiac sphincter)
If the lower esophageal sphincter is malfunctioning, what disorder is produced?
acid reflux
A bolus is pushed down the stomach by muscular contractions called
peristalsis
The stomach consists of four regions:
the cardiac region, fundus (fundic region), body, and pyloric region
The two sphincters in the stomach are:
the lower esophageal (or cardiac) sphincter and the pyloric sphincter
(regulates the passage of chyme out of the stomach into the duodenum
The mucosa of the stomach has many folds called:
rugae (allows room for expansion)
The stomach is the only digestive organ with three layers of smooth muscle in the muscularis externa, this allows the stomach to:
produce waves (peristalsis) that help mix gastric juices with the food
The stomach secretes hydrochloric acid as well as the enzymes:
pepsin and gastric lipase
The small intestine is composed of three sections:
the duodenum, jejunum, and ileum
The first 10 inches of the small intestine. The secretions of the liver, gallbladder, and pancreas enter here.
the duodenum
Makes up 40% of the small intestine
the jejunum
Makes up 60% of the small intestine
the ileum
At the end of the ileum, what valve regulates passage of material into the large intestine?
ileocecal valve (or sphincter)
Most of the digestion and most of the absorption occurs where?
in the small intestine
The large intestine has four regions:
cecum, colon, rectum, and anal canal
The colon’s longitudinal muscle layer forms three thick bands called the taeniae coli/teniae coli, which form pouches called
haustrum
The primary function of the large intestine is
absorption and elimination of feces
The main substance that is absorbed by the large intestine even though most absorption of this substance occurs in the small intestine
water
The only chemical digestion in the large intestine is by the
resident bacteria
Where is the feces temporarily stored until it can be defecated?
the rectum
Where is the pancreas located?
behind the stomach
The liver is divided into the left and right lobes by the
falciform ligament (which attaches the liver to the anterior abdominal wall)
The primary function of the liver in the digestive system is to produce
bile
The hard palate is formed by what bones?
two maxillae bones and two palatine bones
Lips (labia), vestibule, hard palate, soft palate, uvula, and tongue on the floor of the mouth are all structures of:
the oral cavity
The bolus that was previously swallowed eventually becomes:
chyme
Throughout the small intestine are folds that increase surface area; what are these folds called?
Circular Folds (plicae circulares)
Circular folds of the small intestine increase surface area for:
- absorption
- spiraling food through the intestine
(this serves the slow down the movement of food, increasing time for digestion and absorption)
The small intestine enter the large intestine at the:
cecum
This is a blind pouch that has the appendix attached:
cecum
The colon is divided into:
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
90 degree turn between the transverse and descending colon called the:
splenic (or left colic) flexure
90 degree turn between the ascending and transverse colon called the:
hepatic (or right colic) flexure
The colon’s longitudinal muscle layer forms three thick bands called the:
taeniae coli/teniae coli
The taenia coli/teniae coli forms pouches called:
haustrum
Region of the large intestine that contains the internal and external anal sphincters (similar to urethral sphincters
anal canal
Which sphincter is composed of skeletal muscle?
Hint: voluntary
external
Which sphincter is smooth muscle?
Hint: involuntary
internal
What is the only chemical digestion in the large intestine?
The vitamins produced by the bacteria (Vitamin K and some B vitamins) are absorbed and used by our bodies
- By the resident bacteria
Bile is stored and concentrated up to 20x within the:
gallbladder
