4/29: Colon Flashcards
What does pressure and chemical irritation do?
Relax sphincter and excite peristalsis
What does fluidity of contents promote?
Emptying
What does pressure or chemical irritation in cecum do?
Inhibits peristalsis of ileum and excites sphincter
Where is the absorbing colon?
Proximal 1/2
What is the function of the absorbing colon?
Absorption of water and electrolytes from chyme to form solid feces
Where is the storage colon?
Distal 1/2
What is the function of the storage colon?
Storage of fecal matter until it can be expelled
What does poor motility cause?
Greater absorption and hard feces in transverse colon cause constipation
What does excess motility cause?
Less absorption and diarrhea or loose feces
What is the longitudinal muscle?
Teniae coli
How long does it take to move contents from ileocecal valve to anus?
8-15 hours
What are mixing movements?
Haustrations
Describe haustrations
- Fecal material slowly dug into and rolled over
- All fecal material gradually exposed to mucosal surface
- Facilitates absorption of water and dissolved substances
- Movement of material from cecum through ascending colon
What are propulsive movements?
Mass movements
Descrive propulsive movements
- 1-3x each day
- Transverse to Sigmoid
- Occurs throughout colon for 10 min.
- Force feces into rectum
- Gastrocolic and Duodenocolic Reflexes
- Irritation can stimulate
What promotes growth of colon bacteria?
Slow motility
What valve keeps bacteria in colon?
Ileocecal valve
What do colon bacteria ferment?
Undigested carbs to short chain fatty acids
Describe short chain fatty acids that are fermented
– Soluble and easily absorbed.
– Nutrient salvage
– Evidence obesity associated with biasing microbes to species efficient at nutrient salvage
What do colon bacteria produce?
Vitamin K (vital since amount in diet not sufficient)
What do colon bacteria increase risistence of?
the intestinal mucosa to colonization with pathogenic microorganism
What does colon bacteria produce?
Flatus
What is the defecation reflex?
Muscles from the colon move stool towards the rectum
What is the function of the pudendal nerve?
controls the movement of your: Anal sphincter muscles, which help you hold in or release feces (poop)
What nerves control the descending and sigmoid colon?
Parasympathetic nerve fibers (pelvic nerves)
What nerves control the rectum?
Afferent nerve fibers
What nervces control the internal anal sphincter?
Parasympathetic nerve fibers
What nerves control the external anal sphincter?
Skeletal motor nerves from conscious cortex
