Digestive System Flashcards
includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body.
digestive system
includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body.
digestive system
is broken down, bit by bit, until the molecules are small enough to be absorbed and the waste products are eliminated
foodd
digestive tract is also called the
alimentary canal or GI tract
consists of a long continuous tube that extends from the mouth to the anus.
digestive tract
are accessory structures located in the mouth.
tongue teeth
major accessory organs that have a role in digestion.
liver
gallbladder
pancreas
Food undergoes three types of processes in the body:
digestion
absorption
elimination
processes that occur in the digestive tract
digestion
absorption
After the nutrients are absorbed, they are available to all cells in the body and are utilized by the body cells in
metabolism
prepares nutrients for utilization by body cells through six activities, or functions.
digestive system
The first activity of the digestive system is to take in food through the mouth. This process, called
ingestion
begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach.
mechanical digestion
The complex molecules of carbohydrates, proteins, and fats are transformed by chemical digestion into smaller molecules that can be absorbed and utilized by the cells.
chemical digestion
uses water and digestive enzymes to break down the complex molecules.
hydrolysis
speed up the hydrolysis process, which is otherwise very slow.
digestive enzymes
Mixing movements occur in the stomach as a result of
smooth muscle contraction
The movements that propel the food particles through the digestive tract are called
peristalsis
rhythmic waves of contractions that move the food particles through the various regions in which mechanical and chemical digestion takes place.
peristalsis
The simple molecules that result from chemical digestion pass through cell membranes of the lining in the small intestine into the blood or lymph capillaries. This process is called
absorption
The removal of indigestible wastes through the anus, in the form of feces is
defecation
digestive tract is how long
9 meters in length
The wall of the digestive tract has four layers or tunics:
mucosa
submucosa
muscular layer
serous layer or serosa
the innermost tunic of the wall. It lines the lumen of the digestive tract.
mucosa or mucous membrane layer
The mucosa consists of epithelium, an underlying loose connective tissue layer called
lamina propria
thin layer of smooth muscle in the mucosa called the
muscularis mucosa
In certain regions, the mucosa develops folds that increase the
surface area
. Ducts from other glands pass through the mucosa to the
lumen
In the mouth and anus, where thickness for protection against abrasion is needed, the epithelium is ___
stratified squamous epithelium
The stomach and intestines have a thin ____ for secretion and absorption
what kind of tissue
simple columnar epithelial layer
is a thick layer of loose connective tissue that surrounds the mucosa
submucosa
This layer also contains blood vessels, lymphatic vessels, and nerves. Glands may be embedded in this layer.
submucosa
The smooth muscle responsible for movements of the digestive tract is arranged in two layers
inner circular layer
outer longitudinal layer
is between the two muscle layers in the digestive tract
myenteric plexus
principally responsible for the peristaltic movement of the bowels.
myenteric plexus
Above the diaphragm, the outermost layer of the digestive tract is a connective tissue called
adventitia
Below the diaphragm, the connective tissue is called
serosa
is a tube running from mouth to anus.
digestive system
chief goal is to break down huge macromolecules (proteins, fats and starch), which cannot be absorbed intact,
digestive system
that can be absorbed across the wall of the tube, and into the ___ for dissemination throughout the body
circulatory system
Regions of the digestive system can be divided into two main parts:
alimentary tract
accessory organ
The alimentary tract of the digestive system is composed of the
mouth
pharynx
esophagus
stomach
small and large intestine
rectum
anus
Associated with the alimentary tract are the following accessory organs
salivary glands
liver
gallbladder
pancreas
is the first part of the digestive tract. It is adapted to receive food by ingestion, break it into small particles by mastication, and mix it with saliva.
mouth or oral cavity
The lips, cheeks, and palate form the boundaries.
mouth
contains the teeth and tongue and receives the secretions from the salivary glands.
oral cavity
help hold food in the mouth and keep it in place for chewing.
lips and cheeks
used in the formation of words for speech.
lips and cheek
numerous sensory receptors that are useful for judging the temperature and texture of foods.
lips
is the roof of the oral cavity.
palate
separates the oral cavity from the nasal cavity.
palate
The anterior portion supported by bone
hard palate
posterior portion of palate, a skeletal muscle and connective tissue
soft palate
Posteriorly, the soft palate ends in a projection called the
uvula
During swallowing, the soft palate and uvula move upward to direct food away from the nasal cavity and into the
oropharynx
manipulates food in the mouth and is used in speech.
tongue
covered with papillae that provide friction and contain the taste buds.
tongue
A complete set of deciduous (primary) teeth contains ___ teeth
20 teeth
There are __ teeth in a complete permanent (secondary) set.
32 teeth
he shape of each tooth type corresponds to the way it handles ___
food
Food is forced into the pharynx by the
tongue
When food reaches the opening, sensory receptors around the fauces respond and initiate an
involuntary swallowing reflex
involuntary swallowing reflex has several parts
(1) The uvula is elevated to prevent food from entering the nasopharynx.
(2) he epiglottis drops downward to prevent food from entering the larynx and trachea in order to direct the food into the esophagus.
(3) Peristaltic movements propel the food from the pharynx into the esophagus.
is a collapsible muscular tube that serves as a passageway between the pharynx and stomach
esophagus
it is posterior to the trachea and anterior to the vertebral column
esophagus
it passes through an opening in the diaphragm, called the
esophageal hiatus
has glands that secrete mucus to keep the lining moist and well lubricated to ease the passage of food
mucosa
control the movement of food into and out of the esophagus
upper and lower esophageal sphincter
The lower esophageal sphincter is sometimes called the
cardiac sphincter
resides at the esophagogastric junction
what sphincter
lower esophageal sphincter
which receives food from the esophagus, is located in the upper left quadrant of the abdomen.
stomach
The stomach is divided into the
fundic
cardiac
body
pyloric end
lesser curvature is located on the ___
right side
greater curvature on the __ side
left
The mucosal lining of the stomach is what kind of tissue
simple columnar epithelium with numerous tubular gastric glands
The gastric glands open to the surface of the mucosa through tiny holes called
gastric pits
Four different types of cells make up the gastric glands:
mucous cells
parietal cells
chief cells
endocrine cells
The secretions of the exocrine gastric glands - composed of the mucous, parietal, and chief cells - make up the
gastric juice
The products of the _____ cells are secreted directly into the bloodstream and are not a part of the gastric juice
endocrine
The endocrine cells secrete the hormone ___ which functions in the regulation of gastric activity.
gastrin
The regulation of gastric secretion is accomplished through what kind of mechanism
neural and hormonal mechanism
is produced all the time but the amount varies subject to the regulatory factors.
gastric juice
Regulation of gastric secretions may be divided into what phases
cephalic
gastric
intestine
houghts and smells of food start what phase
cephalic
the presence of food in the stomach initiates the ___ phase
gastric phase
and the presence of acid chyme in the small intestine begins the
intestinal phase
Relaxation of the pyloric sphincter allows chyme to pass from the stomach into the
small intestine
The rate of which this occurs depends on the nature of the chyme and the receptivity of the small intestine.
stomach emptying
extends from the pyloric sphincter to the ileocecal valve, where it empties into the large intestine.
small intestine
he small intestine finishes the process of absorbs the nutrients, and passes the residue on to the large intestine.
digestion
are accessory organs of the digestive system that are closely associated with the small intestine.
liver
gallbladder
pancreas
The small intestine is divided into the
duodenum
jejunum
ileum
The absorptive surface area of the small intestine is increased by
plicae cirulares
villi
microvilli
cells in the mucosa of the small intestine secrete mucus, peptidase, sucrase, maltase, lactase, lipase, and enterokinase.
exocrine cell
cells secrete cholecystokinin and secretin.
endocrine cells
The most important factor for regulating secretions in the small intestine is the presence of
chyme
largely a local reflex action in response to chemical and mechanical irritation from the chyme and in response to distention of the intestinal wall.
regulating secretion
This is a direct reflex action, thus the greater the amount of chyme, the greater the ___
secretion
is larger in diameter than the small intestine.
large intestine
It begins at the ileocecal junction, where the ileum enters the large intestine, and ends at the anus.
large intestine
consists of the colon, rectum, and anal canal.
large intestine
has a large number of goblet cells but does not have any villi in the large intestine
mucosa
The longitudinal muscle layer, although present, is ___ in the large intestine
incomplete
The longitudinal muscle is limited to three distinct bands, called that run the entire length of the colon
teniae coli
Contraction of the teniae coli exerts pressure on the wall and creates a series of pouches,
haustra
, pieces of fat-filled connective tissue that are attached to the outer surface of the colon.
epiploic appendages
Unlike the small intestine, the ___ intestine produces no digestive enzymes
large
completed in the small intestine before the chyme reaches the large intestine.
chemical digestion
Functions of the large intestine include the
absorption of water and electrolytes
elimination of feces
continues from the sigmoid colon to the anal canal and has a thick muscular layer.
rectum
rectum follows the curvature of
sacrum
It follows the curvature of the sacrum and is firmly attached to it by ___ tissue
connective
ends about 5 cm below the tip of the coccyx, at the beginning of the anal canal.
rectum
The last 2 to 3 cm of the digestive tract is the
anal canal
continues from the rectum and opens to the outside at the anus.
anal canal
The mucosa of the rectum is folded to form longitudinal
anal columns
the smooth muscle layer in anal canal is thick and forms the
internal anal sphincter
sphincter is under involuntary control
internal anal sphincter
located at the inferior end of the anal canal.
external anal sphincter
This sphincter is composed of skeletal muscle and is under voluntary control.
external anal sphincter
The salivary glands, liver, gallbladder, and pancreas are not part of the digestive tract, but they have a role in digestive activities and are considered
accessory organs
Three pairs of major salivary glands
parotid
submandibular
sublingual
numerous smaller ones secrete saliva into the oral cavity, where it is mixed with food during mastication.
salivary glands
contains water, mucus, and enzyme amylase.
saliva
functions of saliva
=It has a cleansing action on the teeth.
=It moistens and lubricates food during mastication and swallowing.
-It dissolves certain molecules so that food can be tasted.
=It begins the chemical digestion of starches through the action of amylase, which breaks down polysaccharides into disaccharides.
s located primarily in the right hypochondriac and epigastric regions of the abdomen, just beneath the diaphragm.
liver
largest gland in the body
liver
On the surface, the liver is divided into
2 major lobes
2 smaller lobes
he functional units of the liver are
lobules with sinusoids
that carry blood from the periphery to the central vein of the lobule.
lobules with sinusoids
Freshly oxygenated blood is brought to the liver by the
common hepatic artery
branch of the celiac trunk from the abdominal aorta.
common hepatic artery
Blood that is rich in nutrients from the digestive tract is carried to the liver by the
hepatic portal vein
perform most of the functions attributed to the liver
hepatocytes
line the sinusoids are responsible for cleansing the blood in the liver
kupffer cells
Liver functions include the following:
-secretion
-synthesis of bile salts
-synthesis of plasma protein
-storage
-detoxification
-excretion
-carbohyrate metabolism
-lipid metabolism
-protein metabolism
-filtering
is a pear-shaped sac that is attached to the visceral surface of the liver by the cystic duct.
gallbladder
erve as a storage reservoir for bile.
gallbladder
is a yellowish-green fluid produced by liver cells.
bile
main components are are water, bile salts, bile pigments, and cholesterol.
bile
act as emulsifying agents in the digestion and absorption of fats.
bile salts
Cholesterol and bile pigments from the breakdown of ____ are exerted from the body in the bile
hemoglobin
has both endocrine and exocrine functions.
pancreas
portion of pancreas that consist of the scattered islets of Langerhans,
endocrine
