Upper GI Tract Flashcards
What is the upper gastrointestinal tract?
An organ system responsible for transporting and digesting foodstuffs, absorbing nutrients and expelling waste
What is included in the gastrointestinal tract?
Oral cavity, oesophagus, stomach, small intestine, large intestine and anus
What does the muscular wall of the GI tract provide?
Strength and aids in transport of food
What does the mucosa layer of the GI tract consist of?
The epithelium and the lamina propria
What does the lamina propria contain?
Blood vessels, lymphatics, mucous glands
What is the muscularis mucosae?
It is a thin layer of muscle of the gi tract located outside the lamina propria and separates the lamina propria from the submucosa. Involved in local movement and folding of the mucosa
What is contained in the submucosa?
nerves, blood vessels and supporting connective tissue
What is the muscularis propria layer of the GI tract?
Contains two layers, the outer longitudinal layer and the inner circular layer
What is special about the muscularis propria in some places?
In the stomach there is a third inner layer, along with the outer longitudinal layer and inner circular layer, called the third inner oblique layer
What is the adventitia?
A layer of loose supporting tissue within the abdominal cavity
Where the gut lies within the abdominal cavity, what is the adventitia referred to and what type of cells make it up?
Referred to as the serosa and is lined by a simple squamous epithelium called the mesothelium
There are basic mucosal forms in the GI tract, where would you find protective?
In the oral cavity, pharynx, oesophagus, anal canal
There are basic mucosal forms in the GI tract, where would you find secretory?
Stomach
There are basic mucosal forms in the GI tract, where would you find absorptive?
Small intestine
There are basic mucosal forms in the GI tract, where would you find absorptive/protective?
the whole large intestine
What time of epithelium would you find in protective mucosa?
Stratified squamous
Secretory mucosa is only found in which part of the gi tract?
In the stomach
If you had to describe the tongue as a muscle how would you describe it?
A mass of striated muscle
What is the tongue covered by?
By a mucous membrane with a variable structure
What covers the dorsal surface of the tongue?
Numerous papillae
The posterior third of the tongue is separated from the anterior two thirds of the tongue by what?
a v shaped boundary
The posterior portion of the tongue mainly contains what?
Small lymphoid aggregates
Where are filiform papillae found on the tongue and do they contain taste buds?
They are found on the entire surface of the tongue and no they do not contain taste buds
Where are the fungiform papillae found on the tongue and do they contain taste buds?
They are found interspersed among the filiform papilla and they contain taste buds
Where are the foliate papillae found?
They are found towards the back edges of the tongue and they are not well developed in humans
How would you describe the structure of the circumvallate papillae on the tongue?
They are the largest and least common, encircled by a deep cleft,
What is the side of the circumvallate papillae on the tongue?
Very large, 7-12mm
What types of glands are associated with the circumvallate papillae?
With serous glands (von Ebner’s glands)
Where do the serious glands called von ebner’s glands open into in the circumvallate papillae?
Open into the base of the cleft
What do the serous glands called the von ebners glands to be precise found on the circumvallate papillae secrete and what is the function of this secretion?
They secrete lipase which dissolves food constituents and facilitates taste reception
How would you describe the shape of the taste buds?
Onion shaped
Roughly how many cells make up a taste bud?
roughly 50-100 cells
Where are taste buds located on the tongue precisely?
On the basal lamina
How are the taste buds in contact with the surface?
The microvilli are in contact with the surface through taste pores
What are the germinal cells of a taste bud?
The undifferentiated basal cells are the germinal cells
What is a basal lamina?
The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits.
*Label this taste bud
There ya go
The tooth is made of two major segments, what are these?
The crown and the root
Where are the crown and the root of the tooth located?
The crown projects into the buccal cavity and the root is embedded in the jaw
The tooth has the hardest component of the human body, what is it?
The enamel
What is the enamel made of?
96% Ca hydroxyapatite and 2-3% organic materials, no collagen
Where is the enamel derived from when looking at early embryological development?
The ectoderm
Where are the other parts of the tooth, excluding the enamel derived from in terms of embryological development?
From the mesoderm
Does the enamel contain collagen?
No
What two types of extra cellular matrix proteins does the enamel contain?
Contains amelogenins and enamelins
The enamel matrix is secreted by what types of cells?
The ameloblasts
What is the dentine?
Calcified tissue in the form of hydroxyapatite
What makes the dentine harder than bone?
It contains more calcium
What type of collagen composes the dentine?
Composed mainly of type 1 collagen
As well as type 1 collagen what else makes up dentine?
Glycosaminoglycans, phosphoproteins, phospholipids, hydroxyapatite crystals
What types of cells secrete organic material of the dentine?
Odontoblasts
Dentine is sensitive to stimuli, why?
It contains a few unmyelinated nerve fibres
What is the oesophagus?
A muscular tube which transports food from the mouth to the stomach
What drives the transport of food from the mouth to the stomach through the oesophagus?
Peristaltic contractions
What two parts of the oesophagus have a protective role?
The lower oesophageal sphincter and the upper oesophageal sphincter
What type of epithelium lines the oesophagus?
Non keratinised squamous epithelium
In the sub mucosa of the oesophagus what is found?
Small mucus secreting glands called oesophageal glands
What is the purpose of the oesophageal glands found in the oesophagus?
Secretion of mucus that provides lubrication and protection
Closer to the stomach what types of glands are found in the lamina propria?
Stomach oesophageal cardiac glands - to secrete mucus that protects the oesophagus from acidic gastric juices
The oesophagus has five major labels identifiable on a histological image. what are these?
Stratified squamous epitheium Lamina propria Smooth muscle Esophageal glands Skeletal muscle
What is special about the gastro-oesophageal junction?
At the junction of oesophagus and stomach the mucosa abruptly changes to glandular secretory
Anatomically, the stomach is divided into four regions, what are these regions?
The cardia, the fundus, the body of the stomach/corpus, and the pylorus
*Label this stomach
Done
What is the cardia of the stomach?
A small area of mucus secreting glands surrounding the entrance of the oesophagus
What do the glands present in the body of the stomach release?
Secrete acid, pepsin as well as mucus
What do the glands in the pylorus secrete?
Glands secrete two types of mucus and associated endocrine cells secrete gastrin
The stomach cardia is a narrow circular band of what length?
The mucosa contains what type of glands?
Contains simple or branched cardiac glands, coiled with large lumens
Most of the glands present in the stomach cardia portion of the stomach produce which two substances?
They produce, mucus and lysozyme
What is the function of the lysozyme produced by the glands present in the cardia portion of the stomach?
They attack bacterial cell walls
There are a few parietal cells found in the cardia portion of the stomach, what is the function of these parietal cells?
They are HCl secreting
If you were to compare the stomach cardia glands to another type of glands, what would you say they were similar to?
Similar to the cardiac glands of the oesophagus
The lamina propria of the fundus and body portion of the stomach contains an abundant number of what?
GAstric glands
The distribution of epithelial cells in the fundus and the body of the stomach is not
unifrom
Each gastric gland has three main areas, what are these areas called?
The isthmus, the neck and the base
*Label the gland on the fundus and the body of the stomach
There you go
What type of cells are present in the gastric glands of the fundus and body of the stomach.
Stem cells, mucous neck cells, parietal (oxyntic) cells, chief (zymogenic) cells, neuroendocrine cells,
What rate of mitosis do stem cells experience in the gastric glands?
High rate of mitois
Some of the stem cells in the gastric glands move ____ to replace the mucous cells, how many days turnover?
upwards. 4-7days turnover
Some stem cells migrate downwards for what reason?
To differentiate into parietal, chief and endocrine cells
Where and how are the mucous neck cells present in the gastric glands?
Are present in clusters or single cells in the necks of gastric glands
Roughly where are the parietal cells located in the gastric glands of the fundus
Present mainly in the upper half of the gastric glands,
How would you describe the parietal cells on a histology slide?
Large round cells with eosinophilic cytoplasm
What two substances do the parietal cells secrete?
They secrete hcl and intrinsic factor
What is the most striking feature of active parietal cells?
The presence of numerous mitochondria and intracellular canaliculi
What is intracellular canaliculi?
a fine canal formed by invagination of the cell membrane into the cytoplasm of a cell, such as those of the parietal cells of the stomach.
What is found in the resting parietal cell type of the gastric gland present in the fundus of the stomach?
Tubovesicular structures
The intrinsic factor secreted by parietal cells helps in the absorption of which vitamin?
b12
Which part of the gastric glands are the chief zymogenic cells found?
They predominate in the lower part of the tubular glands
How would you describe the chief zymogenic cells of the gastric glands present in the stomach? organelle wise
They have an abundant rough endoplasmic reticulum, condensed basal nuclei, basophilic granular cytoplasm
What inactive enzyme do the chief zymogenic cells of the gastric glands secrete?
They secrete pepsinogen
The inactive enzyme pepsinogen rapidly converts into the active form known as?
pepsin
What type of enzyme is pepsin?
It is a proteolytic enzyme, it breaks down proteins into smaller polypeptides or amino acids
What active enzyme do the chief zymogenic cells of the gastric glands of the fundus or body of the stomach release and what do they do?
They secrete lipase which catalyses the hydrolysis of lipids
Where are the neuroendocrine cells of the gastric glands of the stomach found
They are found in the necks and the base of the gastric glands
In the fundus of the stomach what is one of the principal secretory products of the neuroendocrine cells of the gastric glands?
5-hydroxytryptamine, serotonin
What are enteroendocrine cells?
Enteroendocrine cells are specialized cells of the gastrointestinal tract and pancreas with endocrine function.
Why is a better name forr enteroendocrine cells argentaffin cells?
Argentaffin refers to cells which take up silver stain.
What do enteroendocrine cells do?
They secrete hormones
