DIGESTIVE SYSTEM 1 Flashcards
what is an alimentary tract?
A muscular tube, lined internally by an epithelium
what epithelium lines the alimentary tract?
Epithelial type varies along length, depending upon function
what are the structures of the oral cavity?
Teeth and periodontium (supporting tissue)
Tongue
Salivary glands
what is the major functions of the oral cavity?
Ingestion + mechanical fragmentation of food
what is the major histology of the oral cavity?
Lining of stratified squamous epithelium
what is the structure of the tongue?
highly muscularised
what is the function of the tongue?
Manipulates food for mastication
Taste
what is the surface of the tongue covered by?
lingual papillae
what does the lingual papillae include?
Filiform (most numerous)
Fungiform
Circumvallate
Foliate
what are the structures of the transport passages?
Pharynx
Oesophagus
Anal canal
what is the structure of the transport passages?
Simple muscular transport tubes
Lined with stratified squamous epithelium
Some mucous glands for lubrication
what are the 3 layers of the oesophagus?
mucosa
muscular externa
adventitia
what is the structure of the mucosa of the oesophagus?
Stratified squamous epithelium (above diaphragm) Columnar epithelium (below diaphragm) Well defined lamina propria + muscularis mucosae
what is the structure of the muscular externa of the oesophagus?
Striated muscle (upper third) Striated and smooth muscle (central section) Smooth muscle (lower third)
what is the structure of the adventitia of the oesophagus?
Layer of loose connective tissue
what are the structure so the digestive tract?
Stomach Small intestine (Duodenum, jejunum, ileum) Large intestine (Caecum, appendix, colon, rectum)
what is the histology of the tract?
Mucosa
Many epithelial types
Efficiency of absorption
Formation of complex glands
what is the mucosa of the tract?
Inner layer surrounding tract – most variable component
what are the epithelial types of the tract?
Absorptive
Secretory
what is the efficiency of absorption of the tract?
Intrusions/folding of epithelium Villi/plicae
Inversions
what are the 4 layers of the tract?
mucosa
submucosa
muscular externa
serosa
what does the mucosa contain?
epithelium
lamina propria
what is the epithelium of the mucosa?
Mainly columnar epithelial cells
Glandular secretions moisten surface
what is the lamina propria?
Composed of loose CT
Contains small blood vessels, lymphatics, nerve fibres
Other specialist cells e.g. macrophages & lymphocytes
what is the function of the submucosa?
Separates mucosa from underlying muscle layers
what does the submucosa contain?
More neural tissue
Submucosal plexus (Meissner’s plexus)
Regulates contractions + glandular secretions
what does the muscular externa contain?
smooth muscle
Layers allow peristaltic contractions
2nd nerve plexus located between muscular layers - Myenteric (Auerbach’s) plexus
what are the 2 layers of smooth muscle in the muscularis externa?
Inner: circular layer
Outer: longitudinal
how do the layers allow peristaltic contractions?
Circular layer is actually a compact spiral
Longitudinal layer is actually an elongated helix
what is the serosa+adventitia layer?
Covers muscularis
Delimits alimentary canal
what is the serosa?
When outermost layer lies adjacent to peritoneal cavity