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Anatomy and Function of the Small Intestine: Structure, Absorption, and Secretion, Study notes of Anatomy

An in-depth exploration of the small intestine, its division into three parts (duodenum, jejunum, and ileum), and its functions in digestion, absorption, and secretion. Key features include plicae circulares, intestinal villi, microvilli, and various types of cells (goblet, absorptive, Paneth, and endocrine) in the small intestinal gland. The document also discusses the muscularis, serosa/adventitia, and regional differences in the small intestine.

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

oliver97
oliver97 🇺🇸

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Small intestine
Divided into three parts:
duodenum
jejunum
ileum
Function:
*digestion
*absorption
*secreted certain hormones
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Small intestine

Divided into three parts:

duodenumjejunumileum

Function:

digestionabsorption *secreted certain hormones

*small finger- or leaf-like projection of the mucosa,

found only in the small intestine; varying in the form and height in different regionbeing covered by epith.*having a core of lamina propria withcapillary network, a central lacteal andfew smooth muscle fibers.

Intestinal villi

microvilli:

the minute projections (1 μm long

and about 0.1 μm wide) of cell membranes

The inner surface of small intestine can be greatly enlarged by:* plicae circularesX 3.* villiX 10.* microvilliX 20.

gland

villus

Core of villusepithelium

Artery Lacteal

vein

Longitudinal section of small intestine

H.E. staining

Smooth muscle

5.1.2 lamina propria

* C.T. containing lymphatictissue, solitary lymphaticnodule, intestinal glands.* protrudes into the lumentogether with epithelium toform villi.

5.1.1 Epithelium* Simple columnar epith.

Small intestinal gland

*infolding the epithelium to the lamina propria

at the base of villus

*types of cells:

Goblet c.Absorptive c.Paneth cStem c.Endocrine c.

absorptive cells

  • a tall columnar cell with ovoid nucleus

located toward the base.

striated border

formed by closely

packed, parallel microvilli

goblet cells

EM of goblet cells

{

The RER is present mainly in the basalportion of the cell

{

the cell apex is filled with light secretorygranules (SG) some of which are beingdischarged.

{

The Golgi complex (G) lies just above thenucleus.

function:secrete mucus.

Paneth cells

EM of paneth cell

5.3 muscularis5.4 serosa/adventitia

glial cell

Nerve cell

Lymphatictissue

duodenum

jejunum

ileum

Glands insubmucosa

Present

none

none

Goblet C.

leaf-like

Villi shape

finger-like

becoming smaller

Regional differences in the small intestine

aggregated lymphatic nodule

scattered lymphacytes,solitary lymphaticnodule

Same as induodenum