mucins and mucus (lecture) Flashcards
What type of cells make the mucins that give mucus it’s properties ?
goblet cells in the epithelium
What is commensal bacteria ?
Bacteria that live in mucus and are harmless to a healthy human
= have a symbiotic relationship with humans
What is the ratio of human body cells to commensal bacteria in the body ?
1:10
(cells : bacteria)
= 10x more bacteria than cells in the body
Which diseases are associated with having ‘too little’ mucus ?
- gastric/duodenal ulcers
- ulcerative colitis
- crohn’s disease
- dry eye
- dry mouth (xerostomia)
Which diseases are associated with having ‘too much’ mucus ?
- asthma
- cystic fibrosis
- COPD
How many layers of mucus are there in the gut ? How do they differ?
2 layers
- firmly adherent layer = very sticky, sticks to epithelium
- loosely adherent layer = less sticky, “looser” allowing pathogens to live in it
Is the GI mucus barrier homogenous or heterogenous ?
heterogenous
In which mucus layer are commensal bacteria found ?
the outer loosely adherent layer
When can commensal bacteria become pathogenic ?
When the mucus barrier is broken down to the point where they can infiltrate the epithelium via the weakened firmly adherent mucus layer
Properties of the GI tract mucus …
- resistant barrier (physical + chemical)
- prevents dehydration (highly viscous)
- provides lubrication (highly viscous)
- porous to large molecules
- allows absorption/secretion to continue
What is mucus made up of ?
- water + ions (90%)
- glycoproteins (5-10%)
- mucins (1-5%)
What type of material is mucus classed as ?
a viscoelastic material
= viscous behaviour of a liquid, elastic properties of a solid
Are mucins made quickly on command or are they stored and released when necessary ?
stored in goblet cells
What are the family of ‘gel-forming’ mucins called ?
MUC proteins
(MUC 2, 5AC, 5B, 6, 19)
Name the 5 gel-forming mucin proteins …
- MUC 2
- MUC 5AC
- MUC 5B
- MUC 6
- MUC 19
