small intestine pancreas Flashcards
Three main segments of the small intestine:
duodenum, jejunum and ileum
The surface area of the small intestine are covered by VILLI, the villi are covered by the intestinal epithelial cells which are called ___
enterocytes
The enterocytes further increase the surface area through the presence of ___ —- provides a great advantage for fast absorption of nutrients
microvilli
There are also invaginations called ___, which function as a nursery and they contain the stem cells which constantly divide and differentiate.
they then travel up to the tip of the villus before they undergo programmed cell death or apoptosis, and shed to the lumen to be replaced by the newly differentiated epithelial cells. This takes about __ days.
crypts
3
In the epithelial we have several cell types :
Absorptive epithelial cell
Enteroendocrine cells
Goblet cells
enterocytes which specialize to absorb the nutrients
Absorptive epithelial cell
this epithelial cell secrete various hormones into the blood
Enteroendocrine cell
produce mucous, which has very important protective functions.
Goblet cells
___ cells do not migrate up to the vilus but after differentiation they stay at the bottom of the crypt and it has been suggested that they function to protect the stem cells in the cypts against various bacterial toxins and viral factors
Paneth
Each vilus is supplied by a arteriole which in turn branches in the vilus pore into capillary network. And then capillaries join to form the venules, which is away from the vilus. In addition, in each vilus pore we have lymphatic vessels which is called the ___ ___
central lacteal
Most of the absorbed nutrients enter the capillary network and they enter blood circulation directly. However, the fats are too large to be absorbed directly into the capillary network, instead they first go into the ______ so the fats 1st enter the lymphatic circulation and then they join the venus circulation through the thoracic duct
lymphatic lacteal
____ cells produce a large amount of mucous. The mucous covers the intestinal epithelium and protects it against shear stress and microbial damage
goblet cells
one of the most important glycoproteins produced by the goblet cells is ____
Mucins MUC
____ can bind to the potential pathogenic bacteria and it prevents the colonization of the intestinal lumen by the dangerous bacteria.
Mucin MUC
____ ___ seal the space between epithelial cells and prevent the passage of substance via paracellular pathways between the cells
Most agents enter by crossing the epithelial cell membrane using the specialized membrane transporters
Tight junction
refers to the collection of disorders and conditions idiopathic associated with chronic gastrointestinal tract inflammation.
Inflammatory Bowel Disease (IBD)
The two major forms of inflammatory bowel disease are:
Ulcerative colitis
Crohn’s disease
___ is confined to the colon. The inflammation is diffused and only affects the mucosal layer
____ can affect any area of the digestive tract; inflammation is also discontinuous, so we can have skipped lesion where one area has inflammation and the next to it there isn’t any inflammation–
. Inflammation is also more severe bc it not only affects the mucosal layer but the sub-mucosal layer
Ulcerative colitis
Crohn’s disease
Common symptoms inflammatory bowel disease include:
abdominal pain, rectal bleeding, diarrhea, various nutritional deficiencies such as iron deficiency and weight loss
Patients can also have inflammation of the bile ducts (cholangitis) or arthritis or inflammatory conditions of the eyes
When tight junctions are leaky some bacteria products and dietary antigen in the lumen can pass through the tight junctions and enter the \_\_\_\_ \_\_\_. ---- which initiates an immune respnse The APC (antigen presenting cells)and dendritic cells can pick up various antigens which cause the differentiation of t cells and production of various pro-inflammatory \_\_\_
lamina propria
cytokines
are two pro-inflammatory cytokines which have been suggested to be involved in the pathogenesis of IBD
Interferon gamma and TNF-alpha
Signaling events triggered by IFNy and TNFa they cause further opening of the ___ ___, so they further compromise the tight junction barrier. As a result there’s more flux of the bacteria and various antigen from the lumen to the lamina propia which further amplifies the inflammatory response. (chronic inflammation is established)
tight junctions
the disruption of the gastrointestinal barrier leads to the over aggressive immune response of ___ —happens mostly in individuals that are genetically pre-dispose
Tcells
the combination of 3 factors are necessary for chronic inflammation in IBD
Genetic predisposition
Environmental triggers
Over aggressive immune response
therapeutic options for IBD
Aminosalicylates Corticoidsteroid Immunomodulator Biologic agents Antibiotics
1st line therapy for mild to moderate ulceraliphilits ; sometimes used to treat crohn’s disease; the exact mechanism of action is not well understood
Aminosalicylates
been used to treat patients with IBD, however, they are not used to maintain remission bc corticoidsteroids are associated with severe side effects.
Corticoidsteroid
were originally developed as immunosuppressant’s for organ transplant therapy, and has been used as cytotoxic agent in cancer therapy, but are also being used to manage IBD; mostly used with patients that don’t respond to aminosalicylates
Immunomodulator
specific pro-inflammatory cytokines which have been shown to be involved in IBD pathogenesis.
targets are TNFa agent and a4 integrins
Biologic agents
used for the manipulation of colonial bacteria seem to be beneficial for some patients.
are mostly used to treat crohn’s disease in patients with mild and moderate symptoms
Antibiotics
is the 1st line therapy for patients with mild to moderate ulcerative colitis as well as for management of patients with crohn’s disease.
Mesalamine (5ASA) (amino salicylate acid)
agent of 5ASA which showed improvements of the gastrointestinal symptoms in the patients who also had ulcerative colitis
Sulfasalazine
a good example oral administer drugs which is absorbed only in the distal gastrointestinal tract in the colon. it happens bc the chemical link between sulfapyridne and mesalamine prevents the absorption of ___ in the gastrointestinal tract, but then the colonic bacteria can breakdown this chemical link and then both components can be absorbed
Sulfasalazine
sulfasalazine
there are delayed released mesalamine capsules called ___ , which importantly, it is released and absorbed at the whole length of the digestive tract starting in the stomach.
PENTASA
There’s also the pH sensitive release tablet called _____, which is released and absorbed in the ileum
ASACOL / LIALDA
