Exam 1 - LI Flashcards
started slide 8 of module 3A
started slide 8 of module 3A
Where does the Large Intestine (LI) begin and end? Total length?
Begins at Ileocecal Valve, ends at anus. 1.5m long.
What are the five regions on the LI and 4 regions of the colon?
LI: Cecum, Appendix, Colon, Rectum, Anus
Colon: Ascending, Transverse, Descending, Sigmoid Colon
What are the two directional muscles unique to the LI?
Circular and Longitudional muscles
What are the 3 longitudional bands of muscle along length of colon called?
Teniae Coli
What are Haustra and what are they formed from?
Pouches formed from circular muscle of the LI
Which sphincter controls passage of chyme from Sigmoid Colon to Rectum?
O’Bierne Sphincter
What are the two motility patterns of the LI?
- Segmental
2. Peristalsis
When do Segmental Contractions occur in the LI? What are the two called?
While fasting.
- Haustral segmental contractions
- Multihaustral segmental contractions
How do Haustral and Multihaustral segment movements compare and contrast?
Haustral=Single segments move feces back and forth. Majority of the time.
Multihaustral=several segmenets contract and relax as a unit, push feces short distance forward. 10% of the time.
What is the function of single Haustral segmental movements?
To maximize absorption of water and electrolytes in LI
What is the function of Mass Movement Peristalsis?
Promote emptying of intestine into Sigmoid Colon and Rectum.
What are the two intestinal reflexes of the colon?
- Orthocolic Reflex
2. Gastrocolic Reflex
What is the stimulus and action of the Orthocolic Reflex?
Stimulated by standing first thing in morning which activates LI peristalsis.
Action is to propel fecal mass into Sigmoid Colon and Rectum
What is the stimulus and action of the Gastrocolic Reflex?
Stimulated during or immediately after ingesting food.
Activates peristalsis to propel fecal mass into Sigmoid Colon and Rectum.
The Gastrocolic Reflex is a “continuation” of what other reflex?
Gastroileal Reflex, which increases motility of stomach to promote motility of SI
What is the last reflex of the GI system?
Rectal Reflex
What is the simulus and action of the Rectal Reflex?
Stimulated by stretch of rectal wall.
Action is relaxation of Internal Anal Sphincter and urge to go poop.
The Rectal Reflex can be inhibited by what sort of control?
Voluntary control by contracting the External Anal Sphincter.
What can cause loss of bowel control?
Cauda Equina Syndrome. Damage to nerve roots below T12.
What is the range of total water ingested/secreted into the GI tract in one day?
7.5 to 8L/day
Where is most water absorbed and sent to?
90% absorbed in SI and sent to blood stream.
What drives the absorption of fluid from the LI? What does the LI do to fluids and electrolytes?
Driven by electrolyte balance. LI “fine tunes” fluid and electrolyte homeostasis.
How much fluid is normally excreted in stool and how much by kidneys in a normal day?
Stool=100mL/day
Kidneys=1-2L/day
