lntestinal Gland

Human lntestinal  Gland

The  mucosa of  small intestine  possesses  numerous finger-like  projections  called villi (sing.villus). At the base of  the  villi  the epithelium  folds  in places  to form  narrow  tubes.  These tubes are called  crypts  of Lieberkuhn  (fig.  3.5). In  the crypts  of Lieberkuhn  there present  a kind  of cell called Paneth  cetl.  In  the  duodenum there  in  addition  rounded  Brunner's  gland.

Cells  of  the  intestinal  mucosa, are subjected to  considerable wear  and are constantly undergoing replacement.  Cells  deep  in  the crlpt of  Lieberkuhn  divide  rapidly and  migrate up the villus.  The cells reach  the tip  of the villus  in  about two days.  there they  shed,  along with their  membrane enzymes, into the  lumen  at the  rate  of some  17 billion  a day  along length  of the intestine. Before they  are  shed, however, these  cells  differentiate into absorptive  cells  that  transports nutrients into  the network  of  blood and  lymph  vessels, once  digestion is  completed.  The  average  life  of these  cells  is  about 5 days.

Functions:

i. The  epithelial  cells  of villi produce  membrane enzyme which  helps in  digestion.

ii. The  cells  of  the  crypts secrete  intestinal  juice,  a slightly  alkaline  fluid  which contains

water  and  mucus and  helps to  increase  the volume  of fluid  in  the  gut.

iii. Paneth  cells  secrete  lysozyme,  the  bacterial  enzyme  which  kills  bacteria.

iv. Goblet cells  secrete  mucus.  which  protects  the  intestinal  wall.

v. Bru,,ner's  glands  secrete mucus which  als, r'oiects  the  intestinal  rvall.