Digestive Tract Flashcards
Constituents of digestive system
Digestive tract_. Oral cavity, esophagus, stomach, small intestine, large intestine,anus and its associated glands , salivary glands, liver, pancreas
Functions of gi tract
To obtain molecules from ingested food , that is necessary for the maintenance, growth and energy needs of the body
Functions of structures of the digestive tract
Ingestion
Mastication
Motility
Secretion
Hormone release
Chemical digestion
Absorption
Elimination
General structure of digestive tract
It is an hollow tube , with a lumen made up of variable diameter, its walls are made up of 4 layers
Mucosa
Submucosa
Muscularis
Serosa
Another name for mucosa is
Mucous membrane
Describe the mucosa
It has an epithelial lining
With an underlying lamina propria rich in blood vessels, lymphatics lymphocytes, small glands
And a thin layer of smooth muscle called muscularis mucosae
Functions of muscularis mucosae
Separates the mucosa from submucosa
Facilities local movement of mucosa
Describe the submucosa
It contains denser connective tissues with larger blood and lymph vessels
Contains the submucosa/meissner plexus of autonomic nerves
It may also contain glands and significant lymphoid tissues
Another name for muscularis layer
Muscularis externa
Describe the muscularis layer
It is a thick layer
Made up of 2 or more sublayers
In the inner layer, the fiber orientation is circular
In the external sublayer, the fiber orientation is mainly longitudinal.
The connective tissue between the muscle sublayers contains what
It contains blood and lymph vessels as well as the myenteric/Auerbach nerve plexus of many autonomic neurons aggregated into small ganglia
What makes up the enteric nervous system
The myenteric/ Auerbach nerve plexus
And the meissner or submucosa plexus
Describe the serosa
It is a thin sheet of loose connective tissue, rich in blood vessels lymphatics and adipose tissue
It is covered with a simple squamous epithelium or mesothelium
What is the serosa of small and large intestine continuous with
It is continuous with the portions of the mesentery
What is mesentery
It is a large fold of adipose connective tissue covered on both sides by mesothelium that suspends the intestine
The mesentery is continuous with what
Peritoneum
Is the esophagus suspended in a cavity?
No it is not, it is bound directly to adjacent structures and therefore lacks a serosa having a thick adventita instead
Describe the oral cavity
It is made up of stratified squamous epithelium, which may be keratinized, non keratinized or partially keratinized
The keratinized cell layers resist damage from abrasion and are best developed where
In the masticatory mucosa on the gingiva(gum)
And hard palate
The lamina propria in these keratinized layer rests where
They rest directly on the periosteum of underlying bone
The no keratinized squamous epithelium predominates where
In the lining mucosa over the soft palate,cheeks, floor of the mouth and the pharynx or throat, posterior region of the oral cavity leading to the esophagus
Surfaces of the lips
The internal mucosa surface, has lining mucosa with thick non keratinized epithelium with many minor labial salivary gland
The red vermilion zone of each lip is covered by very thin keratinized stratified squamous epithelium and is transitional between the oral mucosa and skin
The outer surface , has thin skin consisting of epidermal and dermal layers , sweat glands and many hair follicles with sebaceous glands
The tongue is a striated muscle covered by
Mucosa
How are the muscle fibers in the tongue oriented
They are oriented in all directions, allowing a high level of motility
