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89 terms

GI Tract: mouth, stomach, intestine, etc.

copied from another user and from my textbook
small intestine
Approx. 2.5cm wide + 7m long. Arranged in series of orderly loops. Divided into 3 parts.
first 25-30cm, most chemical digestion takes place here.
3m long, absorption into the circulatory and lymph system
3m long, end of small intestine
muscle layers
circular and longitudinal, move material by peristalsis
folds, projecting from folds are small finger like villi. increase surface area
performs more than 500 functions, production of bile, stores glycogen etc.
Stores bile until needed
produces sodium bicarbonate, and many digestive enzymes.
large intestine
shorter than small intestine, but twice the diameter. main use is reabsorption of water and production of vitamin B and K. has three sections
ascending colon
rises up on the right of the abdomen
transverse colon
crosses middle of abdomen
descending colon
goes down left side of abdomen, terminates at rectum.
Mechanical and chemical digestion begins here. Physical breakdown of food by teeth
gastrointestinal tract
a one-way digestive tract that makes possible the seperation of digested and undigested food. (also known as GI tract)
forms a bolus (ball) out of the chewed food + pushes it to the back of the mouth into the pharynx
inner layer called the mucosa, allows for smooth movement of food. Bolus activates stretch receptors which in turn activate smooth muscles that start peristalsis
major means of propulsion (adjacent segments of the alimentary canal relax and contract)
J-shaped - mostly involved in digestion but small amount of absorption
The first main layer. This consists of an epithelium, the lamina propria composed of loose connective tissue and which has gastric glands in it underneath, and a thin layer of smooth muscle called the muscularis mucosae.
protects stomach lining
protein substances that speed up chemical reactions.
enzyme that breaks down proteins
a double layer of peritoneum; holds organs in place, sites of fat storage, provides a route for circulatory vessels and nerves
cardiac sphinctor
Regulates movement of food into stomach and helps to prevent it from going back into the esophagus.
pyloric sphinctor
located between stomach and small intestine, controls the movement of partially, digested food.
the process of taking food into the body through the mouth (as by eating)
The breakdown of complex organic molecules into smaller components by physical and chemical means
the taking up of digested molecules into the cells of the digestive tract
the removal of waste (indigestible substances as feces) from the body
sigmoid colon
the part of the large intestine between the descending colon and the rectum
a digestive chemical that is produced in the liver, stored in the gall bladder, and secreted into the small intestine
food in the stomach that is partly digested and mixed with stomach acids.
Where does chyme go?
Chyme goes on to the small intestine for further digestion.
alimentary canal
the passage through which food passes, including the mouth, esophagus, stomach, intestines, and anus.
This layer lies over the mucosa and consists of fibrous connective tissue, separating the mucosa from the next layer. The Meissner's plexus is in this layer (blood and lymphatic vessels, nerve fibers)
muscularis externa
Over the submucosa, this area in the stomach differs from that of other GI organs in that it has three layers of smooth muscle instead of two.
This layer is over the muscularis externa, consisting of layers of connective tissue continuous with the peritoneum.
is a pouch, connecting the ileum with the ascending colon of the large intestine (it is separated from the ileum by the ileocecal valve) and is considered to be the beginning of the large intestine.
ileocecal valve
separates the ileum from the ascending colon of the large intestine
epiploic appendices
They are small pouches of the peritoneum filled with fat and situated along the colon and upper part of the rectum.
appendix (or vermiform appendix)
is a blind-ended tube connected to the cecum
teniae coli
are three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons. (teniae coli contracts length wise to produce the haustra, the bulges in the colon)
is the final straight portion of the large intestine and terminates in the anus.
(from Latin ānus meaning "ring", "circle") is the external opening of the rectum. (its closure is controlled by sphincter muscles)
Accessory digestive organs
teeth and tongue,gallbladder, salivary glands, liver, and pancreas
Mechanical digestion
prepares food for chemical digestion
Chewing, churning food in stomach, segmentation
is rhythmic local constrictions of intestine and mixes food with digestive juices
Chemical digestion
complex molecules broken down to chemical components; in Mouth, Stomach and Small intestine
two layers of the muscularis externa
Circular muscularis—inner layer
Longitudinal muscularis—outer layer
a serous membrane (2 types)
Visceral peritoneum
surrounds digestive organs
Parietal peritoneum
lines the body wall
Peritoneal cavity
a slit-like potential space
Lesser omentum
attaches liver to lesser curvature of stomach
(one of the two layers of the mesentary)
Greater omentum
a "fatty apron" of peritoneum, small intestine to posterior abdominal wall. (one of the two layers of the mesentary)
labial frenulum
Connects lips to gum
The palate
Forms the roof of the mouth
(2 areas: hard and soft)
Lingual frenulum
Secures tongue to floor of mouth
Deciduous teeth
20 teeth; first appear at 6 months of age
Permanent teeth
32 teeth; most erupt by the end of adolescence
Dental formula
shorthand; way to indicate number and position of teeth
2I, 1C, 2P, 3M (incisor, canine, premolar, molar
superior portion of a tooth
Clinical crown
Crown visible above gingiva
portion of tooth embedded in the alveolar portion of jaw
crown and root meet at gumline
covers the outermost surface of the root
Periodontal ligament
attaches the tooth to bone
the bulk of the tooth is composed of this material. Produced by odontoblasts.
Pulp cavity
central portion of the tooth
Root canal
pulp cavity in the distal portions of the root.
Salivary Glands
3 small glands throughout tongue, palate, cheeks
what do salivary glands produce?
Produce saliva ( water, ions, mucus, and enzymes), to keep mouth moist.
Parotid glands
in the cheek area
Submandibular glands
as the name says in the area of the mandible
Sublingual glands
under the tongue
contains the areas: Oropharynx and laryngopharynx
it is the passages for air and food; lined with stratified squamous epithelium
what type of tissue is the parynx lined with?
stratified squamous epithelium
weakness of the sphincter - heartburn, regurgitation
is stratified squamous epithelium ( adapted for constant abrasion) has mucous glands, muscularis externa (Skeletal muscle) first third of length, differ from other areas: Adventitia—most external layer
unusual layer of esophagus
Adventitia—most external layer
Greater curvature
convex left surface
Lesser curvature
concave right surface
on internal surface of the stomach, with numerous longitudinal folds, which flattens as the stomach fills
oblique layer
helps vigorous churning, third layer of the muscularis externa
gastric pits
narrow tube like structures, mucosa dotted with them; gastric juice is secreted from gastric glands, which are located in them
Gastric glands
deep to gastric pits
top region of the stomach
Peyer's patches
They are aggregations of lymphoid tissue that are usually found in the lowest portion of the small intestine ileum (they differentiate the ileum from the duodenum and jejunum)