Module 3- Digestive System Flashcards
Alimentary canal (GI tract)
Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus
Accessory GI organs
Teeth, tongue, galbladder, salivary glands, liver, and pancreas
Lingual frenulum
Vertical mucous membrane by which the body of the tongue is attached to the floor of the mouth
What are the tongue’s attachments?
Hyoid bone, mandible, lingual frenulum
Salivary gland contains
Amylase, an enzyme that breaks down starches
Where are the upper and lower arches of the teeth situated?
The maxilla and the mandible
Describe the four types of teeth and their functions
Two chisel-shaped incisors for biting, one pointed incisor for tearing, two increasingly flat pre-molars for grinding, and three molars for crushing
Describe the three parts of teeth
The root, which is located in the alveolar process of the jaw bone, the neck, which is located in the upper portion of the gingiva, and the crown, which is most superior and lies above the gum line
Pulp
Portion of teeth that contains nerves and blood vessels
Dentin
Bone-like substance that makes up most of the tooth
Enamel
Very hard connective tissue that covers the outer surface of the tooth, providing protection
The tongue functions to
Grip the food and constantly reposition it between the teeth, as well as push the bolus back towards the pharynx to begin the process of swallowing
What are the three types of papillae on the tongue? What are their functions? Which contain taste buds?
Circumvallate (largest), fungiform (I think middle sized), filiform (smallest size I think). They help grip food. The circumvallate and fungiform papillae contain taste buds.
What are taste buds? Where are they found?
They are receptors that are stimulated by the chemical composition of food. They are found on the tongue, the surface of the mouth, and in the walls of the pharynx.
What are the two types of skeletal muscle lining the pharynx?
A circumferential outer layer and a longitudinal inner layer. They alternatively contract to squeeze food into the esophagus.
What four layers of tissue compose the esophagus?
Mucosa- innermost layer that secretes mucous into the interior of the digestive tract
Submucosa- second innermost layer contains blood and lymph vessels, lymph nodes, nerves, and mucous glands
Muscularis externa- secondmost superficial layer that contains the outermost longitudinal and innermost circumferential muscle layers
Serosa- outermost layer made up of cells that make serous fluid
Describe the location of the stomach
Backward C-shaped organ in the left side of the stomach below the diaphragm
Where does food enter the stomach from?
The cardiac spinchter/lower esophageal spinchter/gastroesophageal sphincter
Lesser curvature of the stomach
Extends inward on the shorter side of the stomach
Greater curvature of the stomach
Extends outward on the longer side of the stomach
Peritoneum
Serious membrane forming the lining of the abdominal cavity
Lesser omentum
Attaches the lesser curvature of the stomach to the liver
Greater omentum
Attaches the greater curvature of the stomach to the posterior wall of the abdomen. Hangs down almost like an apron, covering the transverse colon and anterior surface of the small intestines
Cardia
First part of the stomach where food enters from the esophagus
Fundus
Dome-shaped top of the stomach just under the diaphragm
Body
Wider mid-portion located between the fundus and pyloric region
Pyloric region
Funnel-shaped fourth portion of the stomach
How much food can the stomach hold
2 liters
Rugae
Folds within the stomach wall that allow it to expand when full
Oblique layer of stomach
Allows stomach to mix food more efficiently with gastric juices
A thick layer of ___________ protects the gastrointestinal tract
Mucous
Duodenum
Shortest 1st section of the small intestine. Where enzymes from the pancreas and bile from the liver enter the small intestine.
Ulcer
Open sore in the wall of the stomach or duodenum where gastric juices penetrate the protective mucous. Pepsin begins to digest the gastric or duodenal lining.
H pylori
Eats away at the gastrointestinal lining and causes stomach ulcers. Once a hole is formed, gastric juices leak into the abdominal cavity and cause bleeding or damage to other organs.
Overuse of ____________ can result in gastric ulcers
NSAIDs
Chyme
Stomach contents- thick, soupy consistency
Pyloric sphincter
Spinchter between the base of the stomach and the duodenum. Negative feedback loop type mechanism- Spinchter relaxes and releases a small amount of chyme into duodenum, then sets of a reflex in duodenum which closes the spinchter. Spinchter relaxes again and allows more chyme to enter duodenum. Allows for slow digestion.
Ileocecal valve
Controls entrance to the large intestine
Jejunum
Second section of the small intestine, slightly longer than the ileum
ileum
Third and shortest section of the small intestine
List and describe the functions of the three structures in the intestinal wall.
Circular folds, which feature small, finger-like projections called villi, upon which microvilli are situated. These structures cooperate to increase the surface area of the small intestine from 20 ft to 1800 ft.
How long is the human small intestine? How much do microstructures increase the surface area?
Approx 20 ft to approx 1800 ft
What processes of digestion occur in the duodenum?
Partial digestion of proteins and carbohydrates, fats remain completely intact.
Lacteals
Lymphatic vessels that carry molecules that are too large to be absorbed by villi capillaries into general circulation via the thoracic duct. An example is glycerol and fatty acids, which are assembled into triacylglycerides before being transported into general circulation via thoracic ducts.
How do sugars and amino acids enter circulation?
They are absorbed by capillaries in the villi, enter into hepatic circulation, and then general circulation
What are the eight parts of the large intestine?
Cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
R Colic/hepatic flexure
On the right, connects ascending colon to the transverse colon
L colic/splenic flexure
On the left, connects transverse colon to the descending colon
Intestinal bacteria produce __________ and ___________ that are absorbed in the colon.
Vitamin B and vitamin K
Rectum
Last 20 cm of the digestive tract
Describe the composition of feces
75% water and 25% solid matter. 1/3 is intestinal bacteria, remainder is undigested plant material, fats, waste products (such as bile pigments), inorganic material, mucus, and dead cells from the intestinal lining
Pancreatic juice
Contains sodium bicarbonate which neutralizes chyme and makes the pH of the small intestine slightly basic
List the pancreatic enzymes and what components of food they act on. How do they enter the duodenum?
Amylase- starch to maltose, trypsin- protein to peptides, lipase- fat droplets to glycerol and fatty acids. By way of the pancreatic duct into the hepatopancreatic ampulla into the duodenum.
What is the function of bile?
Emulsifies fats
Where is bile produced? Stored? How does it enter the duodenum?
Liver, galbladder, common bile duct.
Why is bile green?
It contains pigments derived from hemoglobin breakdown
What are the three functions of the liver that aid in digestion?
Produce bile, store glucose as glycogen, produce urea from amino groups
What are the four roles of the digestive system?
1.) Ingestion- food enters the mouth
2.) Digestion- food is moved, mixed, and exposed to enzymes along the gastrointestinal tract.
3.) Absorption- process of moving digested food into the bloodstream
4.) Defecation- process of excreting indigestible food through the anus
