8- Histology of Small & Large Intestines Flashcards
The small intestine is the principal site for digestion of food and absorption of digestion products. What are the components of the small intestine?
Duodenum
Jejunum
Ileum
These are transverse folds with a submucosal core that lie within the small intestine. They cannot lay flat if distended, and are visible in the jejunum but less so in the ileum.
Plicae Circulares
These are mucosal folds that project into the lumen and cover the surface of small intestine. They are covered with a simple columnar epithelium of enterocytes and goblet cells.
Intestinal Villi
Intestinal Villi have a core of loose CT with microvasculature and a ________.
Lacteal
***This is lymphatic vessel of small intestine that absorbs digested fats!
In Intestinal Villi, _________ produce enzymes for digestion and absorption.
Enterocytes
In Intestinal Villi, ________ ________ provide mucus coating to shield from abrasion and bacterial invasion.
Goblet Cells
Intestinal Villi are covered with _________ to increase absorptive surface area.
Microvilli
This layer of the small intestine is composed of simple columnar epithelium with tubular intestinal glands. It contains the lamina propria and muscularis mucosae.
Mucosa
This layer of the small intestine is composed of dense irregular CT. It contains neurovasculature, lymphatics, and glands may be present.
Submucosa
This layer of the small intestine has inner circular and outer longitudinal layers of muscle.
Muscularis
This layer of the small intestine has loose CT covered by visceral peritoneum.
Serosa
Motility of the SI and LI is innervated by the…
ANS
The ENS (intrinsic) consists of the…
Submucosal (Meissner) Plexus
Myenteric (Auberbach) Plexus
Extrinsic innervation for the SI and LI are preganglionic parasympathetics via _______ and _______ nerves, and postganglionic sympathetics.
Vagus
Pelvic
Intestinal Glands are simple tubular glands lined by simple columnar epithelium. What cells do they contain?
Enteroendocrine Cells
Paneth Cells
M (Microfold) Cells
Intestinal Stem Cells
Intestinal Glands are continuous with the simple columnar epithelium that covers the…
Intestinal Villi
Intestinal Glands open onto the luminal surface of the intestine at the base of the _______.
Villi
These cells are found throughout the intestinal glands. They secrete peptide hormones to control gut motility, regulate secretion of enzymes, HCl, bile, and other components for digestion.
Enteroendocrine Cells
What do Enteroendocrine Cells secrete?
Gastrin Secretin GIP (Gastric Inhibitory Polypeptide) Motilin CCK (Cholecystokinin)
These are pyramidal-shaped cells at the base of intestinal glands. There are large, eosinophilic secretory granules in their apical cytoplasm.
Paneth Cells
These cells function in innate immunity by secreting antimicrobial substances (lysozyme, alpha-defensins). They regulate normal bacterial flora via antibacterial action and phagocytosis.
Paneth Cells
These cells reside in a niche at the crypt base near Paneth Cells. They repopulate the epithelial lining by daughter cells moving out of the crypts. They differentiate into Goblet Cells, Enterocytes, and Enteroendocrine Cells.
Intestinal Stem Cells (ISCs)
These are epithelial cells specialized for transepithelial transport of particles and microorganisms. They are located in the ileal mucosa, overlying Peyer patches.
M (Microfold) Cells
M (Microfold) Cells have a pocket formed by deeply invaginated membrane and containing…
Lymphocytes
Macrophages
The apical surface of the M Cells express receptors that bind specific macromolecules and Gram-negative bacteria (i.e., E. Coli). These are then internalized and transferred to immune cells. M Cells function as highly specialized…
Antigen-Transporting Cells