14 - Intestines Flashcards
What are the divisions of the small intestine
duodenum
jejunum
ileum
What are the divisions of the large intestine
caecum
colon
rectum
anal canal
What structures does the celiac trunk supply
stomach
pancreas
duodenum
liver
What does the superior mesenteric artery supply
SI and 1/3 large intestine
What does the inferior mesenteric artery supply
distal 2/3 of the large intestine
Which structures drain through the hepatic portal vein
stomach, spleen, intestines (everything)
What structures of the SI pass through the mesentery
Nerves, BV, lymphatics
What are the layers of the SI
muscularis
submucosa
mucosa –> plicae circularis –> villi –> microvilli
What are the features of the duodenum
densest plicae circularis
major site for calcium and iron absorption
contains duodenal glands –> at the first 10cm of the duodenum and secrete bicarb rich mucus
contains hepatopancreatic ampulla
- accepts digestive juices from pancreas and bile from the liver to aid with digestion
What are the features of the jejunum
long vasa recta –> straight rods that come off anastamoses
glucose, aa, water absorption
What are the features of the ileum
contain lymphatic nodules and prominent lacteals
only site for B12 absorption
plicae circularis taper out
ileum ends at the ileocacecal valve
What is the gastroileal reflex
clears residual matter from the SI and serves ot limit the excessive growth of bacteriA
What does pancreatic juice do
contains digestive enzymes for digestion
What does CCK induce
secretion of enzyme rich juice
What does secretin induce
secretion of bicarb rich juice
What are the two patterns of intestinal contractions
fed pattern
- during feeding, irregular contractions to mix contents with digestive juices
fasting pattern
- migrating motility complex (perstalisis) begins at the duodenum and propels residual materiaal into the proximal colon (prevents vacterial overgrowth)
Which strctures release enzymes to digest carbs
salivary amylase
pancreatic juice
microvili at brush border of intestinal absorptive cells
What structures release enzymes to digest lipids
liver –> bile salts
sublingual gland of oral cavity
pancreas
stomach
What structures release enzymes to digest proteins
stomach
pancrease
brush border enzymes
What structures release enzymes to digest nucleic acids
pancreas
absorptive cells in brush border
What prevents the digestion of the pancreas
pancreatic enzymes are secreted in an inactive form
enteropeptidase (brush border enzyme) begins the process by converting inactive trypsinogen into trypsin
How is glucose transported into the intestine and then to blood
SAT to the brush border –> with sodium
facilitated diffusion into the capillaries
How are amino acids transported into the intestine and then to blood
SAT to the brush border –> with sodium
simple diffusion into blood stream
How are fats transported into the intestine and then to blood
short chain FA –> diffuse directly into blood
long chain FA –> transported as micelles and seperated into FA and monoglyceride
@ apical brush border, put back as triglyceride and delivered as a chylomicron to the blood
How much is ingested and secreted
How much is absorbed
How much is excreted
9.3
9.2
0.1
What are the layers of the large intestine
serosa
muscularis
submucosa
mucosa
What are the functions of the large intestine
producing vit B and vit K
absorbing some water and vitamins
forming feces
emptying the rectum
What is the gastrocolic reflex
encourages matter in the large intestine to migrate toward the rectum
What do intesintal glands do
secrete mucus that helps to aid the passage of feces
What cells are found in the intestine
absorptive cell –> absorb water
goblet cell –> secretes mucus
What are alterations in the LI
smoother mucosa
teniae coli
thinner circular muscle
pouches (haustra) –> haustral contractions help to mix geces and facilitate water reabsorption
Describe the defecation reflex
- Stretched rectal wall –> mass movement of reflex (gastrocolic reflex)
- sends afferent signals to the spinal cord - afferent signals –> parasympathetic relfex
- contraction of the rectal wall and relaxation of the internal anal sphincter - external anal sphincter is under volutnary control –> if appropriate, may defecate conscioucly relaxing the external anal sphincter
