Card Set Information
What are the four functions of the digestive system?
Take in food,
Break it down into nutrient molecules,
Absorb nutrients into the bloodstream,
Excrete indigestible remains and metabolic products.
What is the continuous, muscular tube, about 20 to 25 ft. long that digests food and absorbs through its lining into the blood?
Alimentary canal, GI, or gut
Name the 6 structures that make up the alimentary canal.
What type of organs produce a variety of secretions that assist in the breakdown of food?
Accessory digestive organs
Name 4 accessory digestive organs.
Large digestive glands (salivary glands, liver, pancreas)
What are the 6 digestive processes?
This is the elimination of indigestible substances via the anus in the form of feces.
This is taking food into the digestive tract, usually via the mouth.
This is the movement of products into the blood or lymph.
What is the major absorption site?
This is the process of moving food into the next organ.
What is the process in which food is broken down by enzymes?
Where does chemical digestion begin? Where is it completed?
This is the process by which food is prepared for chemical digestion.
What are 5 things included in mechanical digestion?
Mixing of food with saliva by the tongue,
Churning food in the stomach,
Mixing digestive juices
The abdominal aorta supplies which 5 organs of the digestive system?
This circulation collects nutrient-rich venous blood draining from the digestive viscera and delivers it to the liver.
Hepatic portal circulation
What organ uses the nutrients for metabolic processing or for storage before releasing them to the blood stream for general cellular use?
The walls of the alimentary canal have what four basic layers?
What is the outermost layer of the alimentary canal wall?
The serosa is a single layer of what type of cell?
What layer of the alimentary canal wall is responsible for segmentation and peristalsis?
The muscularis externa may thicken forming these in several places along the tract. They control food passage.
What is the innermost layer of the alimentary canal?
Mucosa or mucous membrane
The mucosa is involved in what three functions?
Protection against infectious disease
What layer of the alimentary canal wall enables the stomach to regain its normal shape after storing a large meal due to the presence of elastic fibers?
What layer of the alimentary canal is composed of dense connective tissue containing blood and lympatic vessels, lymphoid follicle, and nerve fibers?
What is another name for the mouth or oral cavity?
Organ which provides movement and aids in swallowing?
This provides a rough surface and a forward motion for swallowing food.
These secrete saliva.
Enzymes begin the chemical breakdown of what type foods?
What are the 4 functions of saliva?
Cleanse the mouth
Dissolve food chemicals so they can be tasted
Aids in compacting food into a bolus
What percentage of saliva is water?
97 to 99.5%
What is the pH of saliva?
6.75 to 7 (slightly acidic)
What type of antibody can be found in saliva?
What digestive enzyme can be found in saliva?
These tear and grind food, breaking down into smaller fragment.
Teeth lie in sockets in the gum covered margins of what bones?
The sockets that teeth lie in are also known as what?
The side to side movement and the opening and closing of jaws along with the use of the tongue to move food between teeth is what?
Chewing or mastication
What is the dental formula for permanent teeth?
2, 1, 2, 3 (incisors, canines, premolars, molars)
What is the dental formula for deciduous teeth?
2, 1, 2, 2
From the mouth, food passes through which 2 common passageways for food, fluid, and air?
The mucosa of the pharynx contains what type of friction-resistant epithelium?
The muscle layers of the pharynx propel food where?
What is the length of the esophagus?
25 cm (10 in)
Is food routed posteriorly or anteriorly into the esophagus?
At which point does food get routed into the esophagus?
The epithelium of the esophagus secretes digestion enzymes and is composed of what type of cell?
Simple columnar epithelium
The esophagus joins the stomach here. It acts as a sphincter.
This surrounds the sphincter at the cardiac orifice and helps keep it closed when food is not being swallowed.
The chemical breakdown of proteins occurs in what organ?
Food is converted into this creamy paste in the stomach.
The small intestine extends from this point in the epigastric region and ends at this valve.
What is the length of the small intestine?
2 - 4m (7 - 13 ft)
What are the 3 subdivisions of the small intestine?
What is the "empty" portion of the s. intestine that extends from the duodendum to the ileum? How long is it?
Jujenum, 8 ft
What is the "twisted" portion of the s. intestine that joins the l. intestine at the ileocecal valve? How long is it?
Ileum, 12 ft
What 2 subdivisions of the s. intestine hang in coils in the central and lower part of the abdominal cavity, suspended from the posterior abdominal wall?
What "tufts of hair" are fingerlike projections of the mucosa that have columnar epithelial cells?
What is in the core of each villus?
Dense capillary bed
What are the tiny projections of the plasma membrane of the absorptive cells of the mucosa? The fuzzy appearance that it gives to the mucosal surface is called the brush border.
What type of enzymes are needed for complete digestion of carbs and proteins?
Brush border enzymes
These are found in increased numbers at the end of the s. intestine and are involved in preventing bacteria from entering the bloodstream.
The intestinal glands produce how many L of juice daily?
The distension or irritation of the intestinal mucosa by this stimulates intestinal juice production.
Intestinal juice is isotonic with blood plasma with an alkaline level of what?
pH 7.4 - 7.8
What two structures secrete intestinal juice?
Goblet cells of the mucosa
Bile is produced in what organ before being sent to the duodenum?
Where is bile stored?
What is a major function of bile?
Aid in digestion - break up fats
Name 4 things that can be found in bile.
Variety of electrolytes
What component of bile is derived from cholesterol and emulsifies fats?
Emulsified fats are easily accessible to what fat-digesting enzymes?
The bile pigment bilirubin is a waste product of the breakdown of what type of cells?
Exposure of the intestinal cells to fatty chime releases this protein which stimulates the liver cells to secrete bile.
Organ that is a thin-walled green muscular sac about 4 in long.
The gallbladder concentrates bile by absorbing what?
Water and ions
What gland is encircled by the C-shaped duodenum and extends across the abdomen?
What are the clusters of secretory cells within the pancreas?
Enzymes produced in the pancreas end up where?
The pancreas secretes these "fermenting" granules.
The pancreatic islets house what three types of hormone secreting cells?
The hormone glucagon has what effect on blood sugar?
The hormone insulin has what effect on blood sugar?
What cells of the islets of Langerhans produce somatostatin (slows growth, works against pituitaries)?
What cells of the islets produce insulin?
What cells of the islets produce glucagon?
In what organ are the islets of Langerhans located?
What are the protein digesting enzymes that are produced and released as inactive?
Pancreatic juice is clear, contains water and enzymes, and has a pH of what? How much is produced daily?
1200 - 1500 ml
This activates carboxypeptidase and chymotrypsin.
What pancreatic enzymes are secreted active break down carbs? Fats? Nucleic acid?
Where does the large intestine begin and end?
What does the l. intestine absorb from indigestible food residues?
This double layer of peritoneum is a sheet of two serous membranes fused back to back.
What are three functions of the mesentry?
Provide routes for blood vessels, lymphatic, and nerves
Hold organs in place
These colonize the colon, metabolize proteins, and ferment indigestible carbs.
The bacterial flora in the GI system helps synthesize these 2 types of vitamins.
K - for blood clotting
B complex - B12
What is the peaceful coexistence of bacteria and host?
What initiates the defecation reflex?
Stretching of the rectal wall
Is the initial reflex sympathetic or parasympathetic?
What part of the GI tract absorbs dietary vitamins?
S. intestine (limited in l. intestine)
These vitamins dissolve in dietary fats and move across the villus epithelium by passive diffusion.
Fat-soluble vitamins (A, D, E, K)
This vitamin binds to specific mucosal receptor sites in the terminal ileum. Is taken up by endocytosis.
Vitamin B12 - intrinsic factor complex
What type of vitamins are absorbed easily by diffusion or via active or passive transport?
Water-soluble vitamins (B vitamins, C)
The absorption of iron and calcium is largely limited to what part of the s. intestine?
In what part of the digestive system does absorption of electrolytes occur?
These electrolytes are absorbed in the s. intestine.
Iron in duodenum
Calcium in duodenum
How do potassium ions move across the intestinal mucosa?
Passively - facilitated diffusion
Calcium absorption is closely related to what 2 factors?
Blood levels of ionic calcium
Vitamin D in the s. intestine
How many L of water enter the s. intestine daily?
How is 95% of the water in chyme absorbed?
Osmosis in the s. intestine
What is the normal rate of water absorption?
300 to 400 ml per hour
The absorption of these ions occurs in the small intestine and is coupled to active absorption of glucose and amino acids.