Takes in food and breaks it down into nutrient molecules
absorbs nutrients into the bloodstream
excretes the indigestible remains and metabolic products
What are the organs of the digestive system; two main groups
alimentary canal (nourish) and accessory digestive organs.
The alimentary canal is also known as what?
GI (gastrointestinal tract) or gut
This is the a continuous, muscular tube, about 20-25ft long
alimentary canal
This is the a continuous, muscular tube, about 20-25ft long
alimentary canal
What is the function(s) of the alimentary canal?
It digests food and absorbs through its lining into the blood
The organs of the alimentary canal are? (6)
the mouth, pharynx, esophagus, stomach, small and large intestine
The large intestine leads to where?
the terminal opening, or anus.
The accessory digestive organs are what (3) and what digestive glands (3)?
The teeth, tongue, gallbladder, and a number of large digestive glands (the salivary glands, liver, and pancreas)
What is the fuction of the accessory digestive organs?
To produce a variety of secretions that assist in the breakdown of food.
The processing of food by the digestive system involves six essential activities, what are they?
Ingestion, Propulsion, Mechanical digestion, Chemical digestion, Absorption and Defection.
What is the function of ingestion?
To taking food into the digestive tract, usually via the mouth.
What is the function of propulsion?
To move food through the alimentary canal (pushing forward)
What is the major means of propulsion? This involves alternate wave of contraction and relaxation of the muscles in the organ walls.
Peristalsis
The function of mechanical digestion?
to prepare food for chemical digestion by enzymes.
This type of digestive process includes chewing, mixing of food with saliva by the tongue, churning food in the stomach, and segmentation, or rhythmic local constrictions of the intestine, mixing digestive juices.
Mechanical digestion
The function of Chemical digestion is what? (it begins in the mouth and is complete in the small intestine)
to break down food by enzymes
This digestive process moves products into the blood or lymph? (the small intestine is the major site for this)
Absorption
This digestive process eliminates the indigestible substances via the anus in the form of feces.
Defecation
The abdominal aorta branches off into arteries for blood supply to where?
the spleen, liver, and stomach, small and large intestines
How much of the of the cardiac output is in the digestive organs
1/4 of the output
The Hepatic portal circulation supplies blood to where?
the liver
This circulation collects nutrient-rich venous blood draining from the digestive viscera and delivers it to where?
The liver
The liver collects the nutrients for metabolic processing or for storage before releasing them to where?
the bloodstream for general cellular use.
From the esophagus to the anal canal, the walls of the alimentary canal have the same four basic layers what are they? (4)
mucosa, submucosa, muscularis externa and serosa
What is the inner most layer of the alimentary canal
mucosa or mucous membrane
This is a moist epithelial membrane lining the GI lumen.
The mucosa or mucous membrane
The mucosa or mucous membranes' major function are? (3)
secretion, absorption, and protection against infectious disease.
The layer of the alimentary canal that has dense connective tissue containing blood and lymphatic vessels, lymphoid follicles, and nerve fibers.
The submucosa
This submucosa layer of the alimentary canal has abundant elastic fibers for what purpose?
enables the stomach to regain its normal shape after temporarily storing a large meal.
The submucosa layer of the alimentary canal has a rich supply of blood supply to supply surrounding tissues. True or False
True
This layer of the alimentary canal surrounds the submucosa?
The muscularis externa
The muscularis externa layer of the alimentary canal is responsible for what? (2)
segmentation and peristalsis
In several places along the tract, the circular layer thickens, forming sphincters controlling food passage in what layer of the alimentary canal?
The muscularis externa
The serosa is the the intermost layer of the alimentary canal? True or false
False: the serosa is the outermost layer of the alimentary canal
This layer of the alimentary canal is a single layer of squamous epithelial cells?
The Serosa
The mouth is also known as this?
the oral cavity, or buccal cavity
This provides a rough surface for which the tongue forces food during chewing, and forward motion for swallowing
The palate
The tongue initiates what? (2)
movement and swallowing
The salivary glands secrete what?
saliva
The function(s) of saliva is what? (4)
to cleanse the mouth, dissolves food chemicals so that they can be tasted, moistens food and aids in compacting it into a bolus, and contains enzymes that begin the chemical breakdown of starchy foods).
What percentage of Saliva is water?
97 to 99.5%
What is the pH of saliva
6.75 - 7.00 slightly acidic
Saliva's solutes include electrolyes such as? (5)
Sodium, potassium, chloride, phosphate, and bicarbonate
Saliva has a digestive enzyme called what?
salivary amylase
All of the following; the proteins mucin, Lysozyme, IgA and metabolic wastes (urea and uric acid) can be found where?
In saliva
These lie in sockets (alveoli) in the gum-covered margins of the mandible and maxilla?
Teeth
Another name for chewing?
Masticate
This is done by opening and closing jaws and moving the teeth from side to side using the tongue to move the food between teeth?
chewing or mastication
From the mouth, food passes posteriorly into this?
oropharynx
After the food passes through the oropharynx and then to the what?
the laryngopharynx
The oropharynx and laryngopharynx are both uncommon passageways for food, fluids, and air. True or False
False: its a common passageway
The mucosa layer of this organ, (part of the alimentary canal) contains a friction-resistant stratified squamous epithelium with mucus-producing glands.
The pharynx
The muscle layers propel food into the esophagus by contractions from this area of the alimentary canal?
Pharynx
This is a muscular tube about 25 cm (10 inches) long?
The esophagus
The esophagus does not collapsed when not involved in food propulsion. True or false
Fales: the esophagus is collapsed when not involved in food propulsion
After food moves through the laryngopharynx, it is routed into this?
The esophagus
After food moves through the laryngopharynx, it is routed into this posteriorly as the epiglottis closes off the larynx to food entry.
the esophagus
Simple columnar epithelium secretes enzymes for digestion in this organ of the alimentary canal
The esophagus
Where the esophagus joins the stomach is called what?
the cardiac orifice, it acts as a sphincter
This is known as a temporary "storage tank"
stomach
What is the function of the stomach?
to begin the chemical breakdown of proteins and food
In the stomach food is converted to a creamy paste called what?
chyme
The stomach it self quite movable, this is unexpected why?
the stomach is relatively fixed at both ends
This is considered the major digestive organ
The small intestine
This is a convoluted tube extending from the pyloric sphincter in the epigastric region to the ileocecal valve?
The small intestine
The small intestine extends from the pyloric sphincter in the epigastric region to the ileocecal valve then joins what?
the large intestine
This is the longest part of the alimentary canal
The small intestine
The small intestine is about half the diameter of the large intestine. true or false
True
What is the diameter of the small intestine?
it ranges from 2.5 to 4 cm (1–1.6 inches).
How long is the small intestine?
about 2–4 m (7–13 ft) long in a live person
What are the three subdivisions of the small intestines
the duodenum, the jejunum and the ileum
The duodenum is immovable, curves around the head of the what?
Pancreas
The duodenum is a subdivision of the small intestine and is how long?
10 inches
The bile duct with bile from the liver, and the main pancreatic duct, carrying pancreatic juicefrom the pancreas, unite in the wall of the duodenum in a bulblike point called what?
the hepatopancreatic ampulla
The hepatopancreatic ampulla opens into the duodenum via the what?
duodenal papilla
The entry of bile and pancreatic juice into the duodenum is controlled by a muscular valve called what?
the hepatopancreatics phincter, or sphincter of Oddi
The jejunum("empty"), a subdivision of the stomach, is how long?
about 2.5 m (8 ft) long
This extends from the duodenum to the ileum, a subdivision of the stomach
jejunum
The ileum("twisted"), a subdivision of the stomach is how long?
approximately 3.6 m (12 ft) in length
The ileum("twisted"), a subdivision of the stomach, joins the large intestine where?
at the ileocecal valve
The jejunum and ileum hang in coils in the central and lower part of the abdominal cavity, suspended from where?
the posterior abdominal wall
These are fingerlike projections of the mucosa
Villi
The function of the epithelial cells of the Villi is what?
absorption
In the core of each villus is a dense capillary bed called?
lacteal
These are tiny projections of the plasma membrane of the absorptive cells of the mucosa?
Microvilli
These give the mucosal surface a fuzzy appearance called the brush border.
microvilli
These contains enzymes (brush border enzymes) for complete digestion of carbohydrates and proteins.
Microvilli
Peyer’spatches decrease or increase in numbers at the end of the small intestine?
increase
Peyer's Patches are in abundance at the end of the small intestine. Why is this?
they are involved in preventing bacteria from entering the bloodstream.
How much intestinal juice is produced by the intestinal glands daily?
1 to 2 L of juice
The major stimulus for the production of intestinal juice is what?
distension or irritation of the intestinal mucosa by chyme
What is the normal pH of intestinal juice?
slightly alkaline 7.4 - 7.8
Intestinal juice is isotonic with blood plasma. true or false
true
This is largely water, but it also contains some mucus, secreted by the duodenal glands and by goblet cells of the mucosa.
intestinal juice
This fluid does not contain much enzymes
intestinal juice
In this accessory organ, it's digestive function is to produce bile for export to the duedenum.
the liver
Bile leaves the liver through several bile ducts that fuses to the large common hepatic duct, then to what?
the duodenum
Bile leaves the liver through several ducts. Along its course ducts fuse with the cystic duct to drain what? and form what duct?
draines the gallbladder to form the bile duct
Where is bile stored?
the gallbladder
This is a yellow-green, alkaline solution containing salts, pigments, cholesterol, and a variety of electrolytes.
Bile
Salts and phospholipids from this solution aid the digestive process.
Bile
Bile salts function is to emulsify fats, this is needed to do what?
distribute the fats throughout the watery intestinal contents
Emulsified fats are easily accessible to fat-digesting enzymes called what?
lipases
The chief bile pigment is what?
Bilirubin
This is a waste product of the heme of hemoglobin formed during the breakdown of worn-out erythrocytes.
Bilirubin
This is a protein, released by intestinal cells exposed to fatty chyme, stimulates liver cells to secrete bile.
Secretin
Yellow bile pitments accumulate in the blood and eventually are deposited in the skin causing the skin to become yellow also known as
jaundiced
This is a thin-walled green muscular sac, is an accessory organ?
The gallbladder
The gallbladder is how long?
about 10 cm (4 inches) long.
This snuggles in a shallow fossa on the ventral surface of the liver
The gallbladder
This stores bile that is not immediately needed for digestion
The gallbladder
While storing bile this concentrates the bile by absorbing some of its water and ions.
The gallbladder
When the gallbladder's muscular wall contracts, bile is expelled into its duct, the cystic duct, and then flows where?
into the bile duct.
This is a soft, tadpole-shaped gland that extends across the abdomen
The pancrease
This accessory digestive organ is encircled by the C-shaped duodenum
The pancrease
The pancrease produces enzymes that break down all foodstuffs, which then goes where?
to the duodenum
The pancrease secretes this, via pancreatic duct then fuses with bile duct empty into the duodenum.
pancreatic juice
Within the pancreas are clusters of secretory cells called what?
the acini
The pancrease secrete granules for fermenting. What are the granules called?
zymogen granules
Approximately how much pancreatic juice is produced daily?
1200 to 1500 ml produced daily
Pancreatic juice is a clear, and has water and enzymes. What is its pH
pH 8
The pancrease produces an enzyme called what? the enzyme is produced and released in inactive forms, and then activated when needed
Pancreatic proteases (protein-digesting enzymes)
Once the inactivated enzymes are released from the pancrease, within the duodenum these enzymes are activated to what?
Trypsinogen then to Trypsin then back to more trypsinogen which activates carboxypeptidase and chymotrypsin
These are pancreatic enzymes secreted in an active form? (3)
Amylase(on carbohydrates), lipases(on fats), and nucleases(on nucleic acid)
This frames the small intestine on three sides and extends from the ileocecal valve to the anus.
The large intestine
The diameter and length of the large intestine?
about 7cm in diameter and 1.5 m long
This main function of the large intestine is what? (3)
absorb most of the remaining water from indigestible food residues (delivered to it in a fluid state), store the residues temporarily, and then eliminate them from the body as semisolid feces(fe′sē).
This is a double layer of peritoneum—a sheet of two serous membranes fused back to back
Mesentrey
Most of the bacteria in the GI system are dead, how many species are there?
over 700 species
These bacteria colonize in the colon, metabolize proteins and ferment indigestible carbohydrates (ex. cellulose)
bacterial flora
What bacteria synthesize B complex vitamins and most of the vitamin K (blood clotting).
Bacterial flora
B12 is an essential vitamin synthesized by the gut by what bacteria
bacterial flora
Most enteric bacteria coexist peacefully (mutualism) with their host as long as they remain where?
in the gut lumen
The rectum is usually empty, but when feces are forced into it by mass movements, stretching of the rectal wall initiates what?
the defecation reflex
This is a spinal cord–mediated parasympathetic reflex that causes the colon and the rectum to contract, the internal anal sphincter to relax, and the external anal sphincter to contract (initially). What is this reflex?
defecation
Eventhough feces are forced into the anal canal, how can defecation can be delayed?
a message reaches the brain allowing us to decide whether the external (voluntary) anal sphincter should be opened or remain constricted to stop feces passage temporarily.
What vitamins are absorbed by the small intestines and what vitamins are absorbed by the large instestine?
The small intestine absorbs dietary vitamins, and the large intestine absorbs some of the K and B vitamins
What vitamins are absorbed by the small intestines and what vitamins are absorbed by the large instestine?
The small intestine absorbs dietary vitamins, and the large intestine absorbs some of the K and B vitamins
What vitamins are absorbed by the small intestines and what vitamins are absorbed by the large instestine?
The small intestine absorbs dietary vitamins, and the large intestine absorbs some of the K and B vitamins
What vitamins are absorbed by the small intestines and what vitamins are absorbed by the large instestine?
The small intestine absorbs dietary vitamins, and the large intestine absorbs some of the K and B vitamins
What vitamins are absorbed by the small intestines and what vitamins are absorbed by the large instestine?
The small intestine absorbs dietary vitamins, and the large intestine absorbs some of the K and B vitamins
What vitamins dissolve in dietary fats, become incorporated into the micelles, and move across the villus epithelium by passive diffusion.
Fat-soluble vitamins (A, D, E, and K)
What vitamins are absorbed easily by diffusion or via specific active or passive transporters.
Most water-soluble vitamins (B vitamins and vitamin C)
After binding with this vitamin, The intrinsic factor complex is produced by the stomach, it then binds to specific mucosal receptor sites in the terminal ileum, which trigger its active uptake by endocytosis. What is the vitamin?
B12
Iron and calcium absorption is largely limited to what area?
the duodenum
Absorption of these ions in the small intestine is coupled to active absorption of glucose and amino acids.
sodium ion
These electrolytes move across the intestinal mucosa passively by facilitated diffusion
Potassium ions
Calcium absorption is closely related to blood levels of ionic calcium and what vitamin in the small intestine
D
How much water enters the small intestine daily?
Approximately 9 L of water
Water is the most abundant substance in chyme. What percentage of water is absorbed in the small intestine by osmosis.
95%
What is the normal rate of water absorption per hour?
300 to 400 ml
Water moves freely in both directions across the intestinal mucosa, by what active transport?
