Digestive System- Histology Flashcards
The digestive system consists of ______ _____ and ____ _____ _____
- alimentary canal (GI tract)
- accessory digestive organs
The organs of the GI tract (alimentary canal) include ___, _____, ____, ____, _____ ____ and ____ ____
- mouth
- most of pharynx
- esophagus
- stomach
- small intestine
- large intestine
The Accessory Digestive Organs include ___, ____, ___ ____, ___, ___, _____
- tongue (PB)
- teeth (PB)
- salivary glands (S)
- pancreas (S)
- liver (S)
- gallbladder (S)
During _____ _____ organs come in direct contact with food and help to physically break it down
physical breakdown
What accessory digestive organs are involved in physical breakdown?
- Tongue
- Teeth
During ___ ____ organs produce or store secretions that will reach the digestive tract via ducts; organs never come into direct contact w/ food
chemical breakdown
What accessory organs are involved in the chemical breakdown of food by producing or storing secretions?
- salivary glands
- pancreas
- liver
- gallbladder
Anything inside the lumen of the GI tract “outside the body” must cross the ____ ____ to be considered “inside” the body
epithelial lining
The structural organization of the wall of the alimentary canal from the proximal part of the esophagus to the distal part of the anal canal is the ___, although some specializations based on functional needs will be present
same
What are the 4 layers of the GI tract from the lumen outward?
- Mucosa
- Submucosa
- Muscularis externa
- Serosa or Adventitia
What are the 3 layers of the mucosa?
- lining epithlium
- lamina propria
- muscularis mucosae
What layer of the mucosa must you cross to be “inside” the body?
lining epithelium
What are the functions of the the mucosa?
- protection
- absorption
- secretion
What are the three parts of the mucosa?
- Lining epithelium (barrier)
- lamina propria ( loose (areolar) connective tissue)
- muscularis mucosae (smooth muscle tissue)
What are the two types of lining epithelium and where are they found?
- Nonkeratinized stratified squamos epithelium; mouth, pharynx, esophagus, anus
- Simple columnar epithelium; stomach, S. intestine, L. intestine
What type of lining epithelium is for protection?
Nonkeratinized stratified squamos epithelium
What type of lining epithelium is better for secretion/absorption and has tight junctions to stop leakage?
simple columnar epithelium
What is the lamina propria made of ____ ____ ___ and is associated with the mucus membrane
loose (areolar) connective tissue
The muscularis mucosae consists of ______ muscle tissue and has 2 layers that create folds
smooth
This layer of the mucosa contains blood vessels, lymphatic vessels, glands, macrophages, GALT (gut associated lymphatic tissue)
lamina propria
What layer isfound between the muscularis mucosae and muscularis externa?
submucosa
The submucosa is made up of _____ _____ _____ tissue and contains ________ plexus which contains unmyelinated nerves/ganglia that control _______
- dense irregular connective
- meissner’s
- secretion
The upper 1/3 of the esophagus contains _______ muscle, middle 1/3 ______ muscle,
distal 1/3 _______
- skeletal
- mix (skeletal/smooth)
- smooth
The muscularis externa contains ____ _____ tissue and ____ ____ plexus
- smooth muscle tissue
- myenteric nerve
What are the two layers of smooth muscle tissue (involunatary m) that is found in the muscularis externa?
- inner circular layer
- outer longitudinal layer
The inner circular layer can be thickened to form ________ or valves
sphincters
The outer longitudinal layer is found along the length of _____ _____
- GI tract
The outer longitudinal layer dilates the _______ and ____ the GI tract when they ____
- lumen
- shortens
- contract
The inner circular layer _____ the lumen and _____ the length of the GI tract
- closes
- extend
The alternating contraction/relaxation of between the inner circular layer and outer longitudinal layer produces _______
peristalsis
The myenteric nerve plexus (Auerbach’s plexus) controls the movement of ______ ____ in muscularis externa
smooth muscle
The serosa (visceral peritoneum) is a serous epithelial membrane made up of _______ on top of ______ and is found on __________
- mesothelium ( simple squamos epithelium)
- loose (areolar) connective tissue
- organs of peritoneal cavity
The adventitia is made up of ____ ____ tissue and is found ________
- loose (areolar) connective
- not in the peritoneal cavity
This is a collapsible muscular tube, that connects the laryngopharynx to the stomach at T12 to transport food to the stomach and produce mucus
esophagus
The esophagus is made up of what type of lining epithelium?
nonkeratinized stratified squamos epithelium
The esophagus has what type of muscularis externa
proximal 1/3- skeletal muscle
middle 1/3- mix of smooth and skeletal
Distal 1/3- smooth muscle
Serosa is found in the _____ esophagus and adventitia is found in the _____ esophagus
- distal
- proximal
What are the two types of mucous glands found in the esophagus that secrete mucus to reduce friction?
- esophageal glands (proper)- submucosa
- esophageal cardiac glands (lamina propria)
What gland is found in the distal esophagus and is involved with gastric reflux?
esophageal cardiac glands; protects against stomach acid
What gland is associated with the length of the esophagus but is concentrated in the upper half?
esophageal glands (proper)- submucosa
Where does nonkeratinized stratified squamos epithelium change to simple columnar epithelium?
esophagogastric junction
What is the J shaped enlargement of the GI tract that connects the esophagus to the duodenum?
Stomach
What are the 4 gross anatomical subdivisions of the stomach?
- Cardia
- Fundus
- Body
- Pylorus
What re the functions of the stomach?
- hold and mix food (chemical and physical breakdown)
- protein, lipid, and carbs degredation
10% of absorption occurs in the ______ and ___ _____ while 90% occcurs in the ____ ______
- stomach, L intestine
- S intestine
These are muscosa and submucosa folds that accommodate expansion of the stomach (empty stomach collapses on itself)
Rugae
Food is referred to ______ from the esophagus to the stomach
bolus
Food is referred to ____ when it leaves the stomach and enters the S intestine
chyme (low pH) - fluid like
The pH of chyme must be _____ to go into the duodenum
increased
What is the thickened circular smooth muscle found at the distal part of the stomach that controls chyme secretion to the duodenum
pyloric sphincter
What are the histological subdivisions of the stomach?
- cardia
- fundus/body
- pylorus
In the cardia of the stomach cardiac glands produce primarily ______
mucous
In the fundus/body of the stomach gastric (fundic) glands contain cells that secrete _____ and _____
- HCL
- pepsin
In the pylorus region of the stomach, the pyloric glands produce primarily _______
mucous
Mucous glands are found near the ______ and _____ of the stomach
- entrance
- exit
Glands are invaginations of this layer?
lamina propria
Secretions from glands enter ______ and then go to the ______
- pits
- surface
What type of lining is found in the stomach and what can be formed from by the invagination of the lamina propria?
- simple columbar epithelium with surface mucous cells
- gastric pits- which lead to glands (simple branched tubular glands)
The submucosa of the stomach contains ______ glands
no
What is the third layer of the muscularis externa of the stomach that is not found in other parts of the digestive system?
Inner oblique layer
The third layer of the muscularis externa of the stomach; inner oblique allows for the ______ breakdown of food
physical
The _____ is found on the whole length of the stomach?
Serosa
The _________ junction is where epithelial cells change from stratified columnar to simple columnar epithelium
esophagogastric
What is one way to determine a pyloric from a cardiac gland?
pyloric glands have longer pits
The fundic glands are found in the fundus/body subdivision of the stomach and contain what three parts?
- Isthmus
- Neck
- Base
Stems cells regenerate cells every 3-5 days and are found in which part of the fundic glands?
isthmus
What are the five different types of cells found in the fundic gland?
- surface mucous cell
- mucous neck cell
- parietal cell
- chief cell
- G cell (enteroendocrine cell)
What are the cells found in the neck of the fundic gland?
- mucous neck cell
- parietal cell
The ______ cells secrete HCl and intrinsic factor and stain eosinophilic bc they contain numerous mitochondria for ion pumps and a central nucleus
parietal cell
What cells are found in the base of the fundic gland?
- chief cell
- G cell (enterendocrine cell)
_____ cells have granules and secrete pepsinogen (proteins) and gastric lipase (lipids)
chief
____ cells are enteroendocrine cell that secretes the hormone gastrin
G
Parietal cells secrete _____ that converts pepsinogen to pepsin and intrinsic factor needed for the absorption of vitamin ____
- HCl
- B12
G cells secrete ____ that stimulates parietal cells to secrete HCl and chief cells to secrete pepsinogen
gastrin
The muscularis allows for _____ _____ which mixes food with gastric juice to form chyme and peristalsis which forces ____ through the pyloric sphincter
- mixing waves
- chyme
What macromolecule is digested from beginning to end in the small intestine?
Nucleic Acid
____ % of absorption occurs in the small intestine
90
What are the three parts of the small intestine?
- Duodenum
- Jejunum
- Ileum
The small intestine has a ______ surface area available for absorption and is ______ ft long
- large (200m^2)
- 10
What are the permanent transverse circular folds with a submucosa core that are found in the small intestine; inc surface area for digestion and absorption?
plicae circulares
What are the fingerlike projections of mucosa found in the small intestine?
villi
What are the projections of apical membrane of intestinal absorptive cells (folds of villi); striated border; inc surface area for digestion and absorption
microvilli
What are the two types of cells found in the simple columnar epithelium of the small intestine?
- Absorptive cells (enterocytes)
- Goblet cells
These cells of the S. intestine have their nucleus at the base and can produce enzymes
absorptive cells (enterocytes)
These cells increase in number as you go through the S. intestine to the L. intestine
goblet cells
These glands are tubular glands that consist of paneth cells, enteroendocrine cells and stem cells?
Crypts of Lieberkuhn (Intestinal Glands)
These cells are found near the base of the crypts, stain eosinophilic, secrete lysozymes and regulate the bacteria flora of the S. intestine
paneth cells
Paneth cells secrete lysozymes that _______
are bacterial enzymes that digest bacterial cell walls
The submucosa of the small intestine (duodenum) contains what specialized glands?
Brunner’s glands
Brunner’s glands produce _________
alkaline mucous that neutralize the pH of chyme with the bicarbonate form the pancreas
The majority of the stomach contains serosa
Ture; except for the retroperitoneal duodenum
In the ileum, groups of _____ _____ are present in the lamina propria and submucosa
lymphatic nodules ( Peyer’s patches)
What are the specialized epithelial cells in the ileum that overlie Peyer’s patches and have an antigen presenting role?
M (microfold cells)
T/F The large intestine contains plicae circulares and villi
False; does not contain these
These are found in the large intestine, this is an outer muscularis externa layer that is gathered into bands
teniae coli
What are the pouches and sacks found in the large intestine?
haustra
What are the fatty projections of serosa that are found in the large intestine?
omental appendages
What is the mucous membrane w/ longitudinal folds that is found in the large intestine?
anal columns
What are the functions of the large intestine?
- absorption of H2O
- formation and elimination of feces
- bacteria synthesize vitamins (B + K)
- bacterial fermentation of carbs which releases gases
________ ________ epithelium lines the small and large intestines
simple columnar
The small intestine and the large intestine contain crypts of Lieberkuhn; what are the differences in the large intestine?
- absorptive cells are colonocytes (have microvilli)
- Goblet cells are increased
- no paneth cells bc lots of bacteria
Where does the epithelium change from stratified squamous to nonkeratinized to keratinized at the surface?
recto-anal junction (conversion back to skin)
What are the three parts of the pancreas?
- head
- body
- tail
The pancreas is 98-99% an ______ gland and 1-2% _______ gland
- exocrine (compund acinar gland)
- endocrine (islets of langerhans)
What is the function of the exocrine gland part of the pancreas?
- secretes pancreatic juices (enzymes, bicarbonate) to surface of duodenum
What role does the bicarbonate that is produced by the exocrine part of the pancreas play?
- neutralizes chyme secreted into duodenum
What is the function of the endocrine gland (islet of langerhans) of the pancreas?
- secretes hormones (insulin + glucagon)
The exocrine portion of the pancreas stains ________ than the endocrine portion
darker
The liver receives blood from what two sources?
- hepatic artery
- hepatic portal vein
The hepatic artery supplies _______ blood to the liver
oxygenated
The hepatic portal vein carries ________ blood with newly absorbed nutrients, drugs, and possible microbes and toxins from the GI tract
deoxygenated
Where is oxygen, most of the nutrients, and certain toxic substances taken up by hepatocytes; also where hepatocytes’ products and stored nutrients are secreted back into the blood
liver sinusoids
What is the progression of blood from the liver to the heart?
- oxygenated blood (hepatic artery) + nutrient rich, deoxygenated blood (hepatic portal vein)
- Liver sinusoids
- Central vein
- Hepatic vein
- Inferior vena cava
- Right atrium of heart
These are the six-sided structures consisting of specialized cells (hepatocytes) in plates surrounded a central vein
hepatic lobules
Stacks of plates of hepatocytes one cell thick are surrounded by __________
anastomosing sinusoids lined w/ discontinuous endothelium
What is the space that microvilli of the hepatocytes extend into?
perisinusoidal space (space of Disse) - btw endothelial cells and hepatocytes
What are the largest cells lining the sinusoids that are phagocytotic (breakdown old or damaged RBCs from spleen)
Kupffer cells
What are found on each corner of the hexagonal hepatic lobules?
portal triad (bile duct, portal vein, hepatic artery)
The bile duct is lined with what type of epithelium?
simple cuboidal
Hepatocytes produce ____ that goes into caniliculi in the heaptic lobules
bile
What is used for the storage of bile and the release of it when it is needed for fast breakdown?
gallbladder
T/F The gallbladder contains no submucosa and no lymphatic vessels in the lamina propria
true
What is very large in the gallbladder that is used for squirting out bile?
muscularis externa
Bile contains _____ which is a byproduct of breaking down hemoglobin
bilirubin
H2O, electrolytes, and bile salts are important for the digestion of ______
fats (emulsification)
