Small and Large Intestine Flashcards
What happens in the small intestine?
majority of digestion and absorption occurs
Where does the cecum extend?
from the pyloris of the stomach to the first part of the large intestine
The duodenum is supported to the posterior abdominal wall of the…
mesentery
What does the lesser omentum attach?
Afoldofvisceral
peritoneum (serosa)
attaches it and the stomach
to the liver
Duodenum is about ___ inches in length.
12
Which part of the dudeonum has no attachments?
upper portion
What is the duodenum covered by?
peritoneum
What do the circular folds of the small intestine serve to do?
1) Permanent circular ridges in the mucosa to slow down flow of chyme
2) Enhance absorption by increasing the surface area and causing chyme to spiral as it passes through the S.I.
Are circular folds in the entire duodenum?
not in the first part
Where do the circular folds begin and end?
Begin in the duodenum and end gradually in the mid-portion of the ileum
What are the projections within/from the circular folds?
villi
What do villi of the mucosa do?
Greatly increase the surface area of the specialized epithelium available for absorption and digestion
Villi each contain a core of ________________.
lamina propria
Within each villus, there are 4 things. What are they?
an arteriole, a venule, a blood capillary and a lymph capillary
Explain where the nutrients go when they are absorbed by the epithelial cells.
Nutrients absorbed by the epithelial cells lining the villi pass through the wall of the capillary or central lacteal to enter the blood or lymph
Common Bile Duct joins the…
pancreatic duct
Pancreatic enters which papilla?
greater duodenal
What are the 2 types of movement in the small intestine?
Segmentation and migrating motility complex
What is segmentation?
Localized, mixing contractions that occur in portions occupied by large volumes of chyme
Mixes chyme with digestive juices
Brings food particles in contact with the mucosa for absorption
Explain the contraction that happens in segmentation.
Constricts intestine into segments
• Segments divide again with a second contraction of the muscle fibers lining each segment
• Finally, the muscles that initially contracted relax forming large segments again
Which muscle does the segmentation contract?
circular muscle
When does peristalsis begin?
After most of the meal is absorbed, segmentation stops and peristalsis begins.
What is migrating motility complex? (What happens)
Begins in lower portion of stomach
• Pushes chyme forward into the small intestine • The migrating motility complex (MMC) slowly
migrates down the S.I.
• MMC reaches the end of the ileum in 90-120 minutes
- Then another MMC begins
90% of absorption of food/nutrients happens where?
SI
10% of absorption of food/nutrients happens where?
Stomach and large intestine