GI Tract Flashcards
Structure of GI in small intestine
With glands and villi
Structure of GI in Colon
Glands only
Mucosa in Esophagus
- Stratified squamous Non-Keratinized Epithelium
- Muscularis Mucosa (smooth muscle)
- Esophageal glands in sub-mucosa secrete mucous
Muscularis Externa in Esophagus
- Proximal (toward middle of body) (upper) third of muscularis externa is skeletal muscle
- Middle third of muscularis externa is both skeletal and smooth muscle
- Distal (lower) third of muscularis externa is only smooth muscle
Mucous esophageal glands are in the…
Submucosa
Striated Skeletal muscle is in the…
Musclularis
Esophago-gastric Junction
At the junction of the esophagus and the cardiac region of the stomach there is an abrupt change in the lining mucosa from stratified squamous epithelium to simple columnar epithelium which invaginates as gastric pits
Cardiac Stomach
The cardiac stomach is no more than 3 cm wide. From the gastric pits extend cardiac glands. the cardiac glands are coiled, tubular, branched lines by mucous columnar cells
(Gastric pits and cardiac glands. Secretes mostly mucus)
Body and Fundus Stomach
Gastric pits and gastric glands. The glands are branched tubular. Each gastric gland has an isthmus, neck, and base. The isthmus has mucous cells and a few parietal cells. The neck has mucous neck cells and parietal cells. The base has parietal cells and chief cells. Large mucosa and submucosa folds (rugae)
Rugae
Large mucosa and submucosa folds
Pyloric Stomach
Deeper gastric pits and short pyloric glands which are coiled tubular branched, Secretes mostly mucous.
Surface mucous cells in the Stomach Fundus & Body
Secrete protective mucous
Mucous Neck cells in the Stomach Fundus & Body
Mucous secretion
Parietal cells in the Stomach Fundus & Body
Secrete HCL and intrinsic factor
stain lightly
CHIEF OR ZYMOGENIC CELLS in the Stomach Fundus & Body
Secrete gastric lipase and precursor pepsinogen that is converted in the acid environment of the stomach to proteolytically active pepsin (stain darkly)
G Cells in the Stomach Fundus & Body
secrete the hormone gastrin
Enteroendocrine (argentaffin Cells) in the Stomach Fundus & Body
Secrete serotonin
Duodenum Characteristics
- Villi on surface
- Short Crypts of Lieberkuhn (intestinal galnds)
- Long duodenal glands (Brunner’s glands; branched tubular) extend through submucosa
Jejunum
Only Surface Villi and Crypts of Lieberkuhn
Ileum
Surface Villi with crypts of Lieberkuhn, Lympathic nodules (peyers patches)
Peyers Patches
Formed by Lymphatic Nodules
Large Intestine (colon) Characteristics
- Cecum with evaginated appendix
- Ascending, transverse, descending colon
- Sigmoid (pelvic colon)
- Rectum
- NO VILLI
- Intestinal glands (tubular) goblet and absorptive cells
- Taeniae Coli
Taeniae Coli
Three outer longitudinal bands of smooth muscle
Recto-Anal Junction
(PICS) Rectum lined by simple columnar epithelium and tubular glands changes to stratified squamous epithelium of anus
What organs are in small intestine?
- Dudenum
- Jejunum
- Ileum
General Structure of the GI Tract
half resembles the small intestine and the other half resembles the colon.
Regions of the Stomach
Cardiac Stomach, Body and Fundus Stomach, Pyloric Stomach
In Body and Fundus of the stomach, Gastric glands are ___
Branched tubular
Each Gastric Gland has…
An
- Isthmus-Has mucous cells and a few parietal cells
- Neck- Has Mucous neck cells and parietal cells
- Base-Has Parietal cells and chief cells
Body & Fundus VS. Pyloric Stomach Glands
Body & Fundus Glands: Short gastric pits and long branched tubular glands
Pyloric Stomach Glands: Deeper gastric pits and short pyloric glands which are coiled tubular branched
Stomach Parietal RESTING VS ACTIVE CELLS
In Resting- Tubulovesicles in the cytoplasm are seperate bu tin Active, they fuse together to form microvilli that fill up the inctracellular canaliculli
Transition from the stomach to the intestine
Mucosa changes from gastric pits to intestinal villi. At the Junction, The thickened smooth muscle of the pyloric sphincter can be seen
Small Intestine Structure
PICS
- Glands
- Vili
- Crypts of Lieberluhn:
- Goblet cells (musucs gland)
- Renewal of cells
- Smooth Muscle
- Lymphocytes
- Panneth Cells (has to do with lymphocytes)
- Mitosis of vili needs to occur since number of cells are leaving
- Stem cells at bottom of Gastric Pits are going to be moving upward as they reproduce.
Stem Cell of Small Intestine can turn into…
Paneth Cell-Exocrine Cell
Goblet Cell-Protective Cell
Enteroendocrine Cell- Endocrine Cell
Enterocyte- Absorptive Cell
Structure of Microvili in Small Intestine
PIC
- Actin Filament
- Fibrin
Structure of Small Intestine Vessels & Nerves
Blood circulation, Lympathic Circulation, Innervation & Muscle System
Intestinal Glands are also called
Crypts of Liekerkuhn
Small VS Large Intestine
PIC
Large: Intestinal Crypts have no Villi (IMPORTANT), tenai colit
The Appendix is invaginated in…
Large Intestine
In large colon- why do the segments turn?
because of the positioning of liver and spleen- which cause they colon to turn
The stomach deals w/ several harsh conditions that pass it and need to renew cells
Remember: theyre actively reniewing and non-keratinized so not as tough as skin- stem cells are located on surface levels and renewal is based on organ
