Day 9 Histology and Function of Small Intestine and Colon

What are the components of the small intestine?

duodenum, jejunum, ileum

The small intestine is the primary site for what?

.digestion and absorption

The absorptive capacity of the small intestine is enhanced by what three features?

mucosal folds, villi, microvilli

Small intestine epithelial cells, or enterocytes, have abundant organelles in the apical region for what?

processing of nutrients absorbed from the lumen

The microvilli are the location of enzymes and termed the ____________________

brush border

Goblet cells contain large vacuoles with mucinogen and increase in number from where?

duodenum to ileum to colon

How does oxygen diffuse in the villus?

from arteriole to venule at base of villus to top

When there is decreased blood flow and poor perfusion, why do villus tips necrose first?

villus tip is normally hypoxic

Absorption occurring at the villus tips results in high ____________ that will lead to increased blood flow.

osmolarity

The crypts of intestinal glands are lined by what epithelial cell type?

columnar

What is found at the base of the crypts?

stem cells

The columnar epithelial cells of crypts are variably secretory and __________________.

undifferentiated

The stem cells at the base of the crypts replicate to produce the undifferentiated cells that migrate where?

up sides of villus and differentiate into enterocytes, goblet cells, paneth cells, or enteroendocrine cells

Other than stem cells, what else is found at the base of crypts?

paneth cells

Are paneth cells identifiable in veterinary species?

no

What cells, in H&E, contain bright eosinophilic granules in the apical portion of the cell?

paneth

What is released by paneth cells?

antimicrobial peptides

A special lymphatic vessel exists in the center of each villus and is called the _____________.

lacteal

The lacteals and lymphatic vessels in the deeper mucosa of the SI and beyond are import for transport of what?

absorbed triglycerides

In the submucosa of the small intestine, and particularly in the duodenum, submucosal glands are found that are called what?

brunners glands

Brunners glands are serous, mucous, or seromucous depending on what?

species

Submucosal GALT is also found in the small intestine and the most prominent aggregates are called peyer's patches. true/false

true

Where are peyer's patches likely to be found in the small intestine?

ileum

The large intestine is separated into what components?

cecum, colon, rectum

Do the ascending, transverse, and descending components of the colon differ microscopically?

no

What is the main difference in the microscopic composition of the large intestine compared to the small intestine?

no villi, flatter mucosa due to absence of villi, more goblet cells

The epithelium of the colon is of what cell type?

cuboidal

At the _________ region of the colon, the glandular mucosa transitions to nonkeratinized stratified squamous epithelium.

anorectal

What parts of the intestine provide a barrier?

mucus, microbiota, GALT

How do crypts facilitate secretion?

chloride channels (CFTR) on liminal surface

Where are brush borders found in the small intestine?

villi

In the crypts, active secretion of _______ and _________occurs through channels via activation by signaling pathways.

Cl- and HCO3-

The lumen is _________ charged.

negatively