Digestive System Overview Flashcards
How long does an AA chain have to be in order to be absorbed
<3 AA’s in length
How many AA’s are essential
9
How many AA’s are conditionally essential
7
How many AA’s are non essential
4
Once inside the enterocyte what happens to the FFA’s and monoglycerols
They are turned back to TAGs in the ER
From the ER they go to the Golgi to be packaged w/ cholesterol and lipoproteins as a chylomicron
From the Golgi the chylomicron in dumped into a lacteal (lymph duct) where it then enter the blood stream via the thoracic duct
Where do LDL’s come from and what do they do
When VLDLs are stripped of their TAGs thet get remodeled in the liver to LDL
the function of LDL is to deliver cholesterol to body cells
What is the role of HDLs
to deliver excess cholesterol to the liver
What organs/tissues are considered to be accessory in the digestive system
Teeth, tongue, salivary glands, liver, gallbladder, spleen, pancreas, aorta bifurcation and superior mesenteric vein
What are the 6 basic processes of the digestive system
- ingestion
- secretion
- mixing and propulsion
- digestion (mechanical and chemical)
- absorption
- defection
What are the 4 tissue layers of the digestive system
- serosa (aka visceral peritoneum) = covers all the GI tract except the esophagus, composed of areolar connective tissue and squamous epithelium (mesothelium)
- adventitia= covers esophagus
- muscularis= muscular portion that also contains the myenteric plexus
- submucosa= areolar connective tissue that binds mucosa and muscularis, contains many blood and lymph vessels for absorption, and submucosal plexus
- mucosa= inner layer of the GI tract
What is the myenteric plexus also known as, where is it found, and what does it control
- aka Auerbach plexus
- found between muscle layers of the muscularis
- controls GI tract motility
What is the submucosal plexus also known as and what does it control
- aka Meissner plexus
- found between the submucosal and muscularis
- controls secretion in the GI tract
Name the the 3 layers of the mucosa from outer to inner and describe them
- muscularis mucosae= thin layer of smooth muscle that causes the mucosa to have a folded appearance and increase surface area
- Lamina propria= areolar connective tissue, with many blood vessels and lymph that connect to submucosa, contains MALT
- Epithelial layer
What type of epithelial cells line the mucosa layer of the mouth, pharynx, esophagus, and anus
nonkeratinized squamous epithelium
What type of epithelial cells line the mucosa layer of the stomach and intestines
simple columnar
What arises from the embryonic foregut
Everything from salivary glands to proximal doudenum
salivary gland, esophagus, stomach, liver, gallbladder, pancreas, proximal duodenum
supplied by branches of the celiac artery
What arises from the embryonic midgut
Everything from middle duodenum to the proximal 2/3 transverse colon
middle and distal duodenum, jejunum, ileum, cecum, appendix, ascending colon and 2/3 transverse colon
supplied by superior mesentery artery
What arises from the embryonic hindgut
Everything from the distal 1/3 transverse colon to the anus
distal 1/3 transverse colon, descending colon, sigmoid colon, rectum, and proximal anal colon
supplied by inferior mesentery artery
What is visceral somatic convergence and why do we care
abdominal organs lack a dedicated sensory pathway so pain in these organs is “referred” to skin or muscle
Where is foregut pain referred
epigastric area via the greater splanchnic nerves (T5-T9)
Where is midgut pain referred
peri-umbilical area via lesser splanchnic nerves (T10-T11)
Where is the hindgut referred
suprapubic area via least splanchnic nerves T12
What connects the myenteric and submucosal plexuses
interneurons
Where are sensory neurons of the GI tract located and what are some of their functions
mucosal epithelium
fxns= chemoreceptors (activated by chemicals from food), baroreceptors
What nerves supplies the parasympathetic fibers to most of the GI tract
The Vagus nerve
When the parasympathetic nerves of the GI tract what happens
increases GI secretion, and motility
Where do the sympathetic nerves of the GI tract arise from
the thoracic and upper lumbar regions of the spinal cord
What is the largest serous membrane in the body
the peritoneum
What is the peritoneum made of
simple squamous epithelium and areolar connective tissue
What are the 2 layers of the peritoneum and where are they located
- parietal peritoneum= lines wall of abdominopelvic cavity
2. visceral peritoneum= serosa
What GI organs are retroperitoneal
- ascending and descending colon
- proximal duodenum
- head and body of the pancreas
Name the 5 major folds of the peritoneum and and describe them
- Greater omentum=largest fold, attaches to duodenum and stomach then travels downward and turns upward to attach to the transverse colon. Has lots of adipose tissue, and lymph nodes
- Falciform omentum= fold that divides the liver into its 2 lobes and attaches it to the anterior abdominal wall
- Lesser omentum= connects stomach and distal duodenum to the liver, it is a pathway for blood vessels entering the liver
- Mesentery= fan shaped fold the wraps around the jejunum and ileum it arises from and returns to the posterior peritoneal wall. It contains blood and lymph vessels that supply the small intestines
- Mesocolon= 2 folds that bind the large intestine to the posterior wall, 1st fold binds to transverse colon, 2nd fold binds to the sigmoid colon
What ligament arise from the free border of the falciform ligament and what is it a remnant of
the ligament of teres, (aka round ligament)
remnant of umbilical vein
True or False the mesentery and mesocolon hold the small intestine in place
True
