Week 7 lecture Hist Flashcards
MUCOSA components
epithelium
lamina propria
muscularis mucosae
SUBMUCOSA components
connective tissue
+/- glands, lymph nodules
large vessels
nerve plexi
MUSCULARIS EXTERNA components
smooth muscle
nerve plexi
serosa components
mesothelium +
connective tissue
mucosa epithelium functions
Most variable layer, adapted to function
* Protection = cell layers, tight junctions
* Absorption = +/- microvilli
* Secretion = +/- glands that open onto
the surface
* +/- goblet cells
ADVENTITIA components
connective tissue
mucosa lamina propria
Loose connective tissue, blood vessels,
immune cells
mucosa - muscularis mucosa
circular layer of smooth muscle
* For localised movement
submucosa consists/made of
Dense irregular connective tissue
* +/- Glands & lymph nodes
* Peripheral nerve plexi & vessels
Muscularis Externa
- Variable
- Smooth Muscle arranged in different orientations
- Function = peristalsis
- Peripheral nerve plexi between muscle layers
Serosa
Simple squamous epithelium = mesothelium
Small amount of loose connective tissue
Numerous adipocytes
Nerves, blood vessels, lymphatic vessel
adventitia
NO epithelium
Loose and/or dense irregular connective tissue
Nerves, blood vessels and lymphatic vessels
What’s unique about the OESOPHAGUS?
Mucosa
Stratified squamous epithelium
Thick muscularis mucosa
Submucosa
Many glands in upper oesophagus for lubrication
Muscularis externa
Striated muscle in upper part
Smooth muscle in lower part
Sphincters
STOMACH
distinguishing histological features : mucosa
- Simple columnar epithelium creating gastric pits
- Gastric glands
- Three layers of smooth muscle in muscularis externa
- Rugae
muscularis mucosae very thin
oesophagus distinguisihng features
Mucosa
Stratified squamous epith.
Thick muscularis mucosae
Submucosa
Glands, CT
lymph nodules
Muscularis externa
muscle
vessels, nerves
Adventitia
CT, adipose
vessels, nerves
STOMACH
distinguishing histological features : lamina propria
Lamina propria
* loose CT with immune cells
* lymphocytes, plasma cells,
eosinophils & macrophages
STOMACH
STOMACH
distinguishing histological features : submucosa
- dense irregular connective tissue
- Vessels
- Meissner’s nerve plexus
- adipose
STOMACH
STOMACH
distinguishing histological features : muscularis externa
- 3 layers of smooth muscle
- nerves & vessels between
- Myenteric (Auerbach’s Plexus)
STOMACH components
Gastric pit
where the surface epithelium
dips down into lamina propria
Gastric gland
branched tubular
variety of cell types
Enteroendocrine cells
Hormones - Gastrin, VIP….
stomach surface - epithelial cells
Entire surface of the gastric mucosa is lined with
columnar epithelial cells that dip down to form gastric pits
Mucous cells located between the epithelial cells
Most abundant in neck of glands
Secrete mucous
Nucleus at base of cell, apical cytoplasm filled with mucous
parietal cells
Parietal cells secrete HCl (digestion) and intrinsic factor (allows body to absorb Vit B12
loss of production Pernicious Anaemia)
- Intracellular canalicular system that opens into lumen of gland
- numerous microvilli projections
- ++ mitochondria
parietal cell TE micrograph
- triangular shaped cell
- central nucleus
- cytoplasm 40% mitochondria
+ sER abundant - intracellular canaliculi
with microvilli
cheif cells
located deep in the gland
protein secreting ( pepsinogen)
rER & granules gives cytoplasm a bluish colour
Pepsinogen + HCl (pepsin) causes protein ==> peptides
Enteroendocrine cells - G cells, enterochromaffin cells
Secrete into the blood vessels which is regulated by gastric contents
Small cells +/- short microvilli
gastrin, histamine, cholecystokinin, somatostatin, VIP, substance P
STOMACH
Small Intestine : Plicae circularis
what : ridge of submucosa & mucosa
where : seen in longitudinal sections
greatest number in the duodenum
Small Intestine : villi
what: projections of the
mucosa (0.5mm –
1.5mm long)
where: epithelium with a
core of lamina
propria
Longest in the
jejunum
small intestine : Striated border
what: microvilli on the
apical surface of
epithelial cells
where: ~ 2,000/cell, actin
core
small intestine mucosa
Simple columnar epithelium
* + goblet, paneth and
enteroendocrine cells
lamina propria
* fibroblasts, lymphocytes,
plasma cells, eosinophils,
macrophages
* smooth muscle cells,
collagen, vessels
* Peyer’s patches in Ileum
ONLY
muscularis mucosae
* thin layer of smooth
muscle
small intestine submucosa
dense irregular CT
* large vessels
* Meissner’s nerve plexi
* Brunner’s Glands
in the Duodenum
* Peyer’s patches
seen in Ileum
lymphoid tissue
small intestine - Muscularis externa
Inner layer
circular smooth muscle
segmental contraction to
mix contents
peristalsis to move
contents
Outer layer
longitudinally arranged
smooth muscle
peristalsis contraction
Auerbach’s plexus of
nerves located
between the 2 smooth
muscle layers
small intestine - serosa
Simple squamous
mesothelium
Rests on a basement
membrane
Dense irregular/loose
connective tissue
Large vessels
Enteroendocrine cells
Release hormones
* increase pancreatic & gallbladder activity
* initiates gastric & intestinal motility
* stimulates insulin release
* paracrine (local) effects also
Paneth cells
o secrete lysozyme for antimicrobial affect to regulate
normal flora of small intestine
Submucosa of the small intestine : regional variations (duodenum)
Duodenum
Brunner’s Glands
Sero-mucous secretion
pH 8.5 – 9.3
Submucosa of the small intestine : regional variations (jejunum)
Dense irregular CT
Vessels, fibroblasts
Submucosa of the small intestine : regional variations (ileum)
Peyer’s Patches
Lymphatic nodules
Small Intestine
distinguishing histological features
- Plicae circularis
- Villi
- Paneth cells
- Brunner’s glands in submucosa of Duodenum
- Peyer’s patches of lymphoid tissue in Ileum
