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45 Cards in this Set
- Front
- Back
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About how long is the large intestines? |
4-5 feet |
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In what part of the colon do villi predominate? |
There are no villi in the colon. |
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What nerve provides PNS innervation to the colon from the cecum to the distal transverse colon? |
Vagus nerve |
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To what parts of the colon does the superior mesenteric ganglion contribute SNS innervation?
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Cecum, appendix, ascending, and transverse colon |
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What ganglia supply SNS innervation to the rectum and anus? |
Hypogastric ganglia |
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To what parts of the colon does the inferior mesenteric ganglion provide SNS innervation? |
Splenic flexure to the rectum: descending and sigmoid colon |
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What nerve allows voluntary control of the external anal sphincter? |
Pudendal nerve |
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What kind of muscle is the external anal sphincter? |
Skeletal muscle |
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What role does colonic bacteria play? (2) |
Digestion of cellulose and activation of Vitamin K |
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What volume of chyme comes to the colon daily? |
~1500 mL/day |
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What is the BER of the large intestines? |
3 osc/min |
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How long would a contraction in the colon last? |
>=1 minute |
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What are the mixing movements in the colons called? |
Haustrations |
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How is the longitudinal muscle in colon organized?
What are they called? |
3 non-overlapping bands called Teniae coli |
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How many times a day does mass movement occur? |
1-3 times per day |
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What hormone facilitates propulsion in the colon? |
Gastrin |
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What reflexes facilitate propulsion in the colon? (2) |
- Gastrocolic reflex - Duodenocolic reflex |
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What neurotransmitter decreases the BER of the large intestines? |
NE |
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What effect do pain, fear, and anxiety have on colonic motility?
What does this lead to? |
Slows it down.
Can lead to constipation (though diarrhea is possible too) |
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What can increased anger and resentment do to colonic motility?
What does this lead to? (3) |
increase motility
abdominal pain, flatulence, diarrhea (or constipation) |
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What does the colon secrete? (2) |
- Mucus - K+ |
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What functions does mucus secretion in the colon have? (3) |
- neutralization - lubrication - binds feces together |
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What is the primary source of neuronal regulation of the colon? |
Local intrinsic reflexes |
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What hormone helps retain sodium from the colon lumen? |
Aldosterone |
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What risk does too much dietary fiber have? |
Can leach minerals and vitamins |
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What has the greatest influence on water absorption in the colon? |
Rate of motility |
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What does the sodium gradient in colonic enterocytes help do for chlorine reabsorption? |
Create an electric gradient |
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How is chlorine absorbed by the colon? |
paracellularly |
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How is hydrogen excreted from colonic enterocytes? |
H+/K+ ATPase |
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What percentage of water is reabsorbed in the small intestines? |
90% |
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What is the transport maximum of water per day in the colon? |
4L/day |
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What NTs relax the internal anal sphincter? (2)
What controls its activity? |
NO & VIP
ENS (reflex of NT release from stretching) |
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What 2 controls does the external anal sphincter have? |
Voluntary and reflex control |
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What occurs when the rectum becomes distended? |
Mechanoreceptors cause enhanced contraction |
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Besides distention of rectum and anus, what else can relax the anal sphincters? |
Higher abdominal pressures |
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What muscle helps make a 90° angle to aid in prevention of inappropriate defecation? |
Puborectalis muscle |
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Why is defecation easier when squatting than standing up? |
Squatting removes the 90° angle that the puborectalis has on the rectum |
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What muscles coordinate passing gas? |
Relaxation of EAS while maintaining contraction of the puborectalis muscle |
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What part of the colon contracts most frequently? |
Rectum |
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What occurs after mass movement has caused distention of the rectum? |
Reflex causes IAS to open but EAS to close |
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How is EAS relaxed? |
Central control |
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Why does the urge to defecate go away if someone withholds the EAS shut? |
Rectum contracts contents back into sigmoid colon after mass movement |
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How is extra pressure generated for defecation? |
Valsalvic maneuvers (expiration against closed glottis) |
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Why does valsalva maneuver sometimes cause fainting? |
Increased abdominal pressure can occlude IVC and thus decrease afterload to brain |
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What term is used for extremely stiff fecal matter resulting from Hirschsprung disease? |
Fecolith |
