Chapter 7: Small Intestine - Anal Canal Flashcards
What are 3 general functions of the SI?
- Digestion
- Absorb Nutrients
- Produce Intestinal Hormones using DNES cells
IC: What are lacteals? Where are they found?
Lymphatic capillaries
Found in LP of SI villi
IC: Where are paneth cells found and what do they do?
Bases of crypts
produce lysozyme
IC: Where are Brunner’s Glands found? What do they do and why?
SM of duodenum
Secrete alkaline mucus to neutralize chyme
What 3 surface adaptations increase surface area by 400+?
Plicae Circulares (valves of Kerckring)
Villi
Microvilli (on luminal cell surface)
What permanent folds affecting the mucosa and submucosa are found in the duodenum, jejunum, and proximal ileum?
Plicae Circulares (valves of Kerckring)
What is the surface epithelium of the intestinal mucosa?
Simple columnar
What surface absorptive cells are found in the mucosa? What are their 2 main functions?
Enterocytes (with microvilli)
Fxns:
- Absorb water and nutrients
- Terminal digestion in glycocalyx (enterocytes produce the enzymes & absorb the monosaccharides and peptides created)
Where are goblet cells located in the SI?
Most in Ileum
Fewest in duodenum
How many types of DNES cells are found in the SI?
11
One DNES cell produces CCK… how does that effect the SI?
Stimulates gallbladder contraction & pancreatic secretion of enzymes from serous acini
One DNES cell produces GIP… how does that effect the SI?
Inhibits HCL release
One DNES cell produces secretin… how does that effect the SI?
Stimulates pancreas secretion of bicarbonate from the pancreatic ducts
Inhibits HCL release and the movement of chyme into small intestines.
What cells are found in the crypts of the SI?
Regenerative cells
Which cells are found at the base of the crypts of the SI? What is their function?
The long lived Paneth Cells - produce lysozyme
Where are M (microfold) cells located?
Ileum epithelium over Peyer’s Patches
IC: Name the surface epithelium lining the appendix.
Simple columnar
IC: Haustra in the ME of the colon form sacculations due to what?
Constant tonus of teniae coli (outer longitudinal muscle)
IC: Name the surface epithelium of the colon.
Simple columnar
IC: Name the extra thick outer longitudinal ms. layer in the colon?
Teniae coli
IC: Does the colon have villi? Crypts? Paneths?
No
Yes
No
Which cells contain large intracellular pockets that are fairly open to the LP?
M cells
What is the function of M cells?
Promote humoral immunity - plasma cells produce IgA which is transferred to enterocytes and released into gut lumen
Why are M cells important?
Maintain gut flora
What makes up the LP of the SI?
Loose areolar ct
What are the lymphatic capillaries found in the villus core?
Lacteals
What is the function of lacteals?
Lipid absorption
What is found in the villus core?
Lacteals
Vascular components (blood capillaries)
Longitudinal smooth muscle
How is the longitudinal smooth muscle of the LP affected if irritated?
The muscle will contract and the villus will shorten; can lead to nutritional deficiencies.
What does the LP of the SI border?
Intestinal glands (crypts of Lieberkuhn)
What connects to the MM of the SI?
The MM is thin but present
Connects to smooth muscle in villi
What kind of tissue makes up the Submucosa of the SI?
Dense fibroelastic ct with large blood vessels (highly vascular)
What are the glands found in the Duodenum?
Duodenal (Brunner) Glands - seromucous
What do Brunner Glands produce?
Alkaline Mucous (primary product; neutralizes chyme)
Urogastrone - inhibits HCL secretion; increases mitosis of epithelial cells
Where are Peyer’s Patches located?
Ileum
What are Peyer’s Patches?
Large lymph nodes
What is the function of Meissner’s Plexus?
Influences mucosa via parasympathetic innervations
What is the location of Meissner’s Plexus?
Close to the circular muscle in the ME (Ileum)
What is the function of the myenteric plexus?
Stimulates peristalsis in the ME
Where is the Auerbach Plexus found?
Between the circular & longitudinal layers of ME
Which parts of the SI contain serosa?
All of jejunum and Ileum
First and last 1-2 cm of duodenum
Which parts of the SI contain adventitia?
Descending (vertical) part of duodenum
T/F: The duodenum has both adventitia and serosa.
True
Where is the ileocecal valve?
Between the ileum and the cecum of the colon
What valve in the human body is a physiological and anatomical sphincter?
Ileocecal valve
What is the surface epithelium of the mucosa of the Appendix?
Simple columnar with surface absorptive cells, goblets, DNES, and regenerative cells
What is the MM of the appendix like?
Poorly developed
What special features does the Mucosa of the Appendix lack?
Paneth cells
Villi
What are the crypts like of the Appendix?
Short
What is the submucosa of the appendix like?
Thick with large blood vessels
What notable structures are found in the appendix?
numerous lymph nodules
T/F: The ME of the appendix is a normal pattern, but thick.
False - thin
What are the two functions of the appendix?
- Humoral immunity
2. Reservoir for good bacteria
What 4 parts make up the LI?
Cecum, colon, rectum, anus
What 4 parts make up the colon?
Ascending, Transverse, Descending, Sigmoid
What is the primary function of the colon?
Absorption of water
What are additional functions of the colon?
Compaction, lubrication, and elimination of feces
Vitamin production (B12, riboflavin, thiamin, K) as bacterial byproducts
What is the surface epithelium of the colon?
Simple columnar with many goblets and colonocytes, some regenerative cells, few DNES
What is the LP of the colon like?
Typical with intestinal glands (crypts)
What is lacking in the mucosa of the colon?
Villi
Paneth cells
T/F: The ME of the colon is a normal pattern.
FALSE
What 2 structures are unique to the colon?
- Teniae coli - outer longitudinal muscle that is gathered into discontinuous bands
- Haustra - sacculations formed by constant tonus of teniae coli
Does the colon have both adventitia and serosa?
Yes, it’s mixed
What’s present in the ascending and descending colon?
Adventitia posteriorly with some serosa
What’s present in the transverse and sigmoid colon?
Mostly serosa
