test 3: Digestive pt 1 Flashcards
what are the structures that make up the digestive tract?
- oral cavity
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
what are the accessory organs to the digestive system?
- teeth, tongue, salivary glands
- liver
- gallbladder
- pancreas
what are the 7 main functions of the digestive tract?
1) ingestion
2) mechanical processing
3) absorption
4) secretion
5) excretion
6) compaction
7) digestion
what are the 4 general layers of the digestive tract from superficial to deep?
1) mucosa
2) submucosa
3) muscular layer
4) serosa (or adventitia)
what are the 3 layers of the mucosa?
1) epithelium
2) lamina propria
3) muscular mucosa
mucosal epithelium
- most superficial layer of mucosa
- stratified
- moves to simple in stomach and small and large intestine
lamina propria
- middle layer of mucosa
- CT where BV, nerve endings, lymphatic vessels reside
muscular mucosa
- deepest layer of mucosa
- 2 thin concentric layers of muscle (internal circular and external longitudinal); alter diameter of lumen, move epithelial plates and folds around (folds are transverse or longitudinal in digestive tract - allows extension of area; increases surface are for more secretion and absorption)
what are the components of the submucosa
1) large blood and lymphatic vessels
2) exocrine glands
3) neural plexuses
- sensation to digestive tract
what are the components of the muscular layer?
1) inner circular layer (contains myenteric plexus; parasympathetic and sympathetic stimulation occurs here to dilate or constrict)
2) outer longitudinal layer
3) sphincters
where is the 4th layer of the digestive tract an adventitia rather than a serosa?
- pharynx
- esophagus
- rectum
mesentery - def
fused double layer of the peritoneal membrane
which structures make up the mesentery?
1) falciform ligament
- runs between liver and diaphragm
2) lesser omentum
- between liver and stomach (lesser curvature)
3) greater omentum
- greater curvature of stomach to transverse colon
which parts of the small intestine are supported by the mesentery proper?
-jejunum and ilium (these are inter peritoneal)
peritoneum - def
bilayer of serous membrane
which organs are retroperitoneal?
- pancreas
- duodenum
- ascending and descending colon
- middle third of rectum
- kidneys
- adrenal glands
- proximal ureters
- renal vessels
the uvula is an extension of the _____ palate
soft
what is the function of the uvula?
prevents food from entering pharynx too soon
what is the function of the tongue?
- mechanical processing: helps teeth chew
- helps in swallowing
- provides sensory analysis of foods (touch, temp, taste)
- chemical processing (secretion of mucins and lingual lipase)
salivary glands are located in the oral cavity
true or false?
false
what are the 3 salivary glands and their location?
1) parotid gland (largest)
- deep to mandible, inferior to zygomatic arch
2) sublingual gland
- floor of mouth
3) submandibular gland
- floor of mouth (medial mandible)
where do the parotid glands release their contents?
-duct empties into oral vestibule around second upper molar
where do the submandibular glands release their contents?
- ducts empty on either side of the frenulum (base of tongue)
- posterior to teeth
what percentage does each salivary gland contribute to the formation of saliva?
- 70% from submandibular glands
- 25% parotid salivary glands
- 5% from sublingual salivary glands
where do the sublingual glands empty?
numerous ducts open along either side of frenulum
what is the location of the esophagus?
runs in the mediastinum posterior to the trachea
-starts at C6 (cricoid cartilage) and goes to T7
esophageal hiatus - def
hole in the diaphragm where the esophagus passes
describe the mucosal layer of the esophagus
- folds; run the length of the esophagus
- muscular mucosa: thin or absent in pharynx; single layer of longitudinal smooth muscle in esophagus
describe the submucosa of the esophagus
- esophageal glands - lubricate bolus, protect mucosal layers as food passes
- only other place we find mucus is large intestine
describe the muscular layer of the esophagus
- inner circular and outer longitudinal layer
- changes as you run down tract (superior = skeletal, middle = mix, inferior = smooth)
- even though there is skeletal muscle, there is no voluntary movement in the esophagus at all
describe the adventitia of the esophagus
-connects esophagus to posterior aspect of the body wall so it stays in place
what are the three functions of the stomach
1) temporary food storage
2) mechanical digestion
3) chemical digestion (acid, enzymes)
what is the location of the stomach
- sits around T7/L3 region
- occupies 4 regions (left hypochondriac, left lumbar, umbilical, epigastric)
- this varies
what is the fundus of the stomach
superior (above esophagus)
-contacts diaphragm
what is the cardia of the stomach?
where the esophagus ends and the stomach begins
what is the pylorus of the stomach?
lower portion
describe the histology of the stomach: gastric folds
- the surface epithelium of the gastric mucosa is a simple columnar epithelium
- gastric pits open to gastric surface (these are temporary, not present when stomach is full)
describe the histology of the stomach: muscular layer and mucosal layer
- creates esophageal and pyloric sphincters
- contains extra layers of smooth muscle in addition to circular and longitudinal (extra oblique layer) - strengthen the stomach wall and assist in mixing and churning
what are the 4 secretory cells found in the stomach?
1) mucous neck cells
2) parietal cells
3) enteroendocrine cells
4) chief cells
function of mucous neck cells
water soluble stomach lubricant
- found in all regions of the stomach
- in gastric pits (shallow depression)
function of parietal cells
- intrinsic factor (vitamin B12 absorption)
- HCl (lowers pH, kills microorganisms, breaks down CT and protein)
-found in proximal portion of gland (base of pit, beginning of gland)
function of enteroendocrine cells
-gastrin (hormone) that stimulates parietal and chief cells and promotes muscle contraction (activates smooth muscle)
what is the function of chief cells
- pepsinogen (converted to pepsin; activated by acid of stomach) - breaks down proteins
- found primarily in fundus of stomach
where does 90% of the absorption of material occur
small intestine
what are the 3 portions of the small intestine?
- duodenum
- jejunum
- ileum
duodenum
- closely associated with pancreas (sits in curvature) and liver (bile secretion)
- shortest and widest section
- majority is retroperitoneal
- receives chyme from stomach
jejunum
- interperitoneal
- supported by mesentery proper
- bulk of absorption
- thicker wall than ileum
- umbilical region
ileum
- longest section
- interperitoneal
- hypogastric region
- mesentery thicker, more fatty tissue than jejunum
what structures are found in the small intestine to increase surface area?
1) circular folds
- permanent folds
2) villi
- simple columnar epithelium
- project into lumen diameter
3) microvilli
What is the name of the lymphatic vessel found within the intestinal villi
lacteals (found in lamina propria)
-material that can’t be absorbed by capillaries will be picked up here to enter venous circulation by thoracic duct
which cells in the small intestine are responsible for creating our good gut bacteria?
paneth cells
what are the regional differences between the 3 regions of the small intestine?
Duodenum:
- contains mucus producing glands to protect from acidic chyme
- contains duodenal ampulla (receives bile from pancreas)
Jejunum:
- circular folds and villi prominent in proximal half
- most nutrient absorption
ileum
- distal portion lacks circular folds
- lamina propria contains aggregated lymphoid nodules (Peters patch)
