Histology of the GI Tract Flashcards
What covers the oral cavity, oropharynx and laryngopharynx
Stratified squamous epithelium
What covers the nasal cavity and the nasopharynx
Respiratory epithelium
What covers the anterior 2/3rd of the tongue
Stratified squamous epithelium
What covers the posterior 1/3rd of the tongue
Smooth stratified squamous epithelium
Name the 4 types of papillae on the tongue
Fungiform
Circumvallate
Foliate
Filiform
Describe the filiform
They have no taste buds
Describe the fungiform
Strawberry pips - lots of taste buds
Describe the foliate
Little slits, lined by taste buds- largest surface area due to the presence of slits
Describe the circumvallate
Obvious growth structures - serous glands
What 4 major layers compose the stereotypical GI tract?
Mucosa
Submucosa
Muscularis Externa
Serosa / Adventitia
What are the 3 parts of the mucosa
Epithelium
Lamina propria
Muscularis mucosae
What comprises the submucosa
Loose connective tissue
What comprises the muscularis externa
Two thick layers of smooth muscle, an inner cicrular layer and an outer longitudinal layer
What comprises the serosa or adventitia
Outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs.
What is the difference between serosa and adventitia
Serosa - something you can pick up such as the stomach.
The adventitia is something that is more bound down eg the oesophagus
Describe the change in cells at the gastro-oesophageal junction
Abrupt transition from stratified squamous epithelium of the oesophagus to the columnar epithelium of the cardia of the stomach
What does 1 gastric pit branch into
1-7 gastric glands
What are the gastric pits lined by?
Surface mucous cells
What are the types of mucosa that can be found in the stomach
Cardia (deep gastric pits that branch into loosely packed tortuous glands)
Body (shallow gastric pits with long straight gastric glands)
Pylorus (deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia
Why is the muscularis externa of the stomach unusual?
It contains an additional layer - it is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer. This layer aids the churning action of the stomach
What is the thickened inner circular layer of smooth muscle?
Pyloric sphincter
What are the pits in the small intestine called?
Crypts of Lieberkuhn
Describe the length of the duodenum in terms of its different components
Duodenum (25cm)
Jejunum (2m)
Ileum (2.75m)
What type of glands can be found in the duodenum
Brunner’s glands
What is the name of the specialised lymphoid follicles in the ileum
Peyer’s patches
Where is the plicae circularis found?
Jejunum
What is the function of enterocytes
Absorptive cell
What is the function of Goblet cells
Produce mucin for protection and lubrication
What is the function of paneth cells
Defensive function and a regulating role in bascterial flora
What is the function of neuroendocrine cell
Produce hormones
What is the function of stem cells
Divide to replenish the epithelium
Where are fats deposited
In the lacteal
How are Brunner’s glands stimulated
With the presence of chyme
What do Brunner’s glands produce when stimulated
thin, alkaline, mucous to neutralise the chyme
What do the colonic glands or the colonic crypts produce
Mucus
What are the two principle types of cells in the Large intestine
Absorptive and goblet cells
How are the cells in the large intestine arranged
In straight, tubular glands referred to as crypts that extend down the muscularis mucosae
Describe the longitudinal smooth muscle in the large intestine
Not continuous
found in 3 muscular strips called teniae coli
What is the name of the guts nervous system
Enteric nervous system
Where does the ENS receive input from
The autonomic nervous system
What else helps to regulate the secretion in the epithelium?
The second netowrk of neurones in the submucosa (submucosal plexus)
