A. Gross
Anatomy of Small Intestine
1. It extends
from the pyloric sphincter to the ileocecal valve where it joins the
large intestine. It has three subdivisions: the duodenum, the jejunum, and the ileum.
B.
Microscopic Anatomy of Small Intestine
1. Modifications for absorption
a. It is
highly adapted for absorption with three microscopic modifications: plicae
circulares,
villi, and microvilli [brush border]
2. Histology of the wall
a. Simple columnar epithelial tissue with
tight junctions and goblet cells
b. Theintestinal crypts, or the crypts of
Lieberkühn, secrete intestinal juice that
serves as a carrier fluid for absorbing nutrients from
chyme.
c. Enteroendocrine
cells and the enterogastrones secretin and cholecystokinin
d. Intraepithelial
lymphocytes [IELs]
e. Paneth
cells: defensins and lysozyme
f. Peyer's patches: part of GALT
C. The liver
1. Functions [more than 200 functions!]
a.
Metabolic regulation: regulation of
blood composition, removes and stores nutrients, mobilizes stored
reserves, performs synthetic activities, plays a role in carbohydrate, lipid &
protein metabolism, waste removal, vitamin [A, D, E, K & B12]
and mineral [converts iron reserves to ferritin], drug inactivation
b.
Hematological regulation:
phagocytosis and antigen presentation [Kupffer
cells], synthesis of plasma proteins, removal of
circulating hormones, removal of antibodies, removal or storage of toxins
c.
Synthesis and secretion of bile [mostly
water, with minor amounts of ions, bilirubin, cholesterol and an assortment of
lipids known as bile salts, that
function in the emulsification
of lipids
2. Gross Anatomy
a. Hepatic portal vein
3. Microscopic Anatomy
a. Hepatocytes, liver sinusoids, Kupffer cells
1. Stores
and concentrates bile
E. Pancreas
1. Functions:
secretion of a watery buffer solution of a pH of 7.5-8.8 and a "bucket
full
of
enzymes" [pancreatic amylase, lipase, nucleases and proteases]
F. Regulation
of Bile and Pancreatic Secretion and Entry into the Small Intestine
A. Functions
1.Absorption of water, bile salts, and
bacterial-generatedvitamins K, biotin [glucose metabolism] & vitamin B5
(pantothenic acid) [manufacture of steroids and some neurotransmitters]
B. Gross Anatomy
1.
Teniae coli, haustra, &epiploic
appendages
2. Subdivisions: cecum,
appendix, colon, rectum, anal canal
3. Colon:
ascending, transverse, descending, sigmoid
