Lecture 3- Mucosal membranes Flashcards
mucosal memerbanes line
most hollow internal organs of the body
mucosal membranes are continues with skin at openings e.g.
lips vagina anus ears nose mouth
mucus membranes secrete mucus which contains
- mucins (proteins)
- electrolyte
- antiseptic enzymes (lysozyme)
- immunoglobulins
mucus membranes function
- Stops pathogens and dirt from entering the body
- Prevent bodily tissues from becoming dehydrated
- Lubricate surface
examples of systems with mucosal membranes
- GI tract
- Urinary tract
- Respiratory tract.
simple structure of mucosal membrane
- epithelium
- lamina propria
+ muscular mucosa (ELM)
basement membrane
- thin acellular layer where epithelial cells are anchored
function of the mucosa
1) absorb substances from the lumen (microvilli)
2) Prevent ingress of pathogens
3) move content and expel waste (peristaltic action)
layers of theGI tract
1) Mucosa (ELM)
2) Submucosa
3) Musculares externa (inner circular and outer longitudinal)
4) serosa
mucosa
epithelial cells
lamina propria
muscularis mucosa
mucosa in gI of
o Epithelial cell lining and supporting mesenchymal layer
muscularis mucosae in the GI
o A thin discontinuous smooth muscle layer
Submucosa
a connective tissue layer that contains artery sand veins
muscularis externa in the GI
o A smooth muscle layer that has muscle fibres going in different directions
An inner circular muscle
Outer longitudinal
the serosa of the GI
o Another connective tissue layer
Contains collagen and elastin fibres with some smaller arteries and veins and some nerve fibre
in the stomach the surface are is increased by invagination called
gastric glands
no villi in
l. intestinal
- has intestinal crypts
order of GI tract
1) Mouth
2) Oesophagus
3) Stomach
4) Liver
5) Gallbladder
6) Pancreas
7) Small intestine
a. Duedenum
b. Jejunum
c. Ileum
8) Large intestine
a. Cecum
b. Ascending colon
c. Transverse colon
d. Descending colon
e. Sigmoid colon
f. Rectum
g. Anal canal
oesophageal structure-function relationship
- Epithelium- stratified squamous non-keratinised (withstands abrasion)
- Submucosa- layer of connective tissue containing mucus-secreting glands
- Muscularis externa- smooth muscle layers
- Inner- circular
- Outer- longitudinal
o Moves bolus of food by peristalsis
stomach layers
M= gastric mucosa secretes acid, digestive enzymes and hormone gastrin (epithelium) MM= muscularis mucosae SM= submucosa (connective tissue) ME= Musucalaris externa (3 layers of s.muscle in stomach- oblique, circular, longitudinal) R= Rugae folds of gastric mucosa forming longitudinal ridges in empty stomach
jejunum layers
M= Jejunal mucosa (simple columnar epithelium (absorbtion) and lamina propria)
MM= Muscularis mucosae
SM= Submucosa (connective)
ME= muscularis externa (2 layers)
Pilcae circulares= circular folds of mucosa and submucosa projecting into gut lumen
colon
The muscularis mucosae is indistinct at this magnification
- Simple columnar epithelium of the crypts produces mucus and supplies cells to the surface
- Surface epithelial cells absorb water and electrolytes
function of the mucosa in the urinary tract
- To absorption of essential nutrients in the kidney
- Prevent entry of pathogens
- Removal of waste products e.g. urea
structural unit of the kidney
the nephron
cells which line the corpuscle
squamous epithelium
lining of the collecting duct is
cuboidal epithelium
proximal contains
ciliated surfaces (movement)
basal lamina in the kidney
around each tubule
where does the muscle layer first appear in the urinary system
the ureter and bladder
cells in the bladder
transitional epithelium (can contract and relax) - urothelium
what acts as a shock absorber in an expanding bladder
fat
rounded transitional cells
relaxed state
flattened transitional cells
distended state
function of mucosal layer in the urinary tract
- Epithelial cells produce mucus
- Protects bladder from damage by acidic urine
- Tight junctions prevent leakage to inner cell layers
urethra structura
Structure similar to bladder (except epithelial cells change from transitional epithelium to squamous and then keratinised squamous epithelium).
Large number of mucous glands present
( produce sticky mucus to prevent ingress of pathogens)
order of the respiratory tract
o Nasal cavity o Nasopharynx o Oropharynx o Larynx o Trachea o Bronchi o Bronchioles o Respiratory bronchioles o Alveoli Alveolar sacs and ducts o Diaphragm
respiratory tract is divided into two part
conducting protion
respiratory protion
conduction portion
nasal cavity to bronchioles
respiratory portion
respiratory bronchioles to alveoli (gas exchange)
how long and wide is a trachea
10cm: 2.5cm
trachea divides into
two primary bronchi at the mid thorax
how does the structure of the primary bronchi differ to that of the trachea
cartilage rings and spiral muscles completely encircle the lumen
(in the trachea its a horseshoe shape)
layers of the trachea
- mucosa
- submucosa
- C-shape hyaline cartilage
mucosa in the trachea
o Epithelial layer is several cells deep and covered in cilia (moves debris, dust, bacteria etc towards the mouth)
submucosa in the trachea
o Connective tissue layer contains mainly collagen and elastin fibres and many fibroblasts
Contains seromucous glands- produce water mucus that thickens during infection
C-shaped Hyaline cartilage in the trachea can be palpated externally and is made of two layers
o Perichondrium- fibroblasts that lay down collagen fibres
o Chrondrogenic layer- from which cartilage is formed
Cells present can interconvert from chrondroblasts to chondrocytes- so can make both hyaline and elastic cartilage
the trachea has no
outer layer of smooth muscle
Secretions from the epithelium and submucosal glands of the trachea and bronchi contain:
- Mucins and water- sticky mucous
- Serum proteins- lubricates
- Lysozyme- destroy bacteria
- Anti-proteases- inactivate bacterial enzymes
Mucocilliary escalator’
Together with a ‘cilia wave’ mucus moves material to the oral cavity where the material can be swallowed
- - Cilia beat at 12Hz
secondary and tertiary bronchi histology
histology similar to primary bronchi EXCEPT cartilage no longer in full circle of rings
layers of secondary and tertiary bronchi
- Epithelium (E) – pseudostratified and ciliated
- Bound by smooth muscle (M)
- Supported by seromucous glands in the submucosa
- Airways kept open with crescent shaped cartilage
- NO OUTER LAYER OF SMOOTH MUSCLE
alveolus capillaries
lined with endothelium
- fused to basal lamina with even thinner epithelial cells of the alveoli (optimum gas exchange)
folds of the basal lamina in the alveolus
allow for expansion of the air sacs when air is drawn into the lungs
collagen and elastic in alveoli allow
recoil to empty sacs when exhaling
