Exam 1 - LI

Question 1

started slide 8 of module 3A

Answer 1

started slide 8 of module 3A

Question 2

Where does the Large Intestine (LI) begin and end? Total length?

Answer 2

Begins at Ileocecal Valve, ends at anus. 1.5m long.

Question 3

What are the five regions on the LI and 4 regions of the colon?

Answer 3

LI: Cecum, Appendix, Colon, Rectum, Anus

Colon: Ascending, Transverse, Descending, Sigmoid Colon

Question 4

What are the two directional muscles unique to the LI?

Answer 4

Circular and Longitudional muscles

Question 5

What are the 3 longitudional bands of muscle along length of colon called?

Answer 5

Teniae Coli

Question 6

What are Haustra and what are they formed from?

Answer 6

Pouches formed from circular muscle of the LI

Question 7

Which sphincter controls passage of chyme from Sigmoid Colon to Rectum?

Answer 7

O’Bierne Sphincter

Question 8

What are the two motility patterns of the LI?

Answer 8

1. Segmental

2. Peristalsis

Question 9

When do Segmental Contractions occur in the LI? What are the two called?

Answer 9

While fasting.

1. Haustral segmental contractions
2. Multihaustral segmental contractions

Question 10

How do Haustral and Multihaustral segment movements compare and contrast?

Answer 10

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.

Question 11

What is the function of single Haustral segmental movements?

Answer 11

To maximize absorption of water and electrolytes in LI

Question 12

What is the function of Mass Movement Peristalsis?

Answer 12

Promote emptying of intestine into Sigmoid Colon and Rectum.

Question 13

What are the two intestinal reflexes of the colon?

Answer 13

1. Orthocolic Reflex

2. Gastrocolic Reflex

Question 14

What is the stimulus and action of the Orthocolic Reflex?

Answer 14

Stimulated by standing first thing in morning which activates LI peristalsis.

Action is to propel fecal mass into Sigmoid Colon and Rectum

Question 15

What is the stimulus and action of the Gastrocolic Reflex?

Answer 15

Stimulated during or immediately after ingesting food.

Activates peristalsis to propel fecal mass into Sigmoid Colon and Rectum.

Question 16

The Gastrocolic Reflex is a “continuation” of what other reflex?

Answer 16

Gastroileal Reflex, which increases motility of stomach to promote motility of SI

Question 17

What is the last reflex of the GI system?

Answer 17

Rectal Reflex

Question 18

What is the simulus and action of the Rectal Reflex?

Answer 18

Stimulated by stretch of rectal wall.

Action is relaxation of Internal Anal Sphincter and urge to go poop.

Question 19

The Rectal Reflex can be inhibited by what sort of control?

Answer 19

Voluntary control by contracting the External Anal Sphincter.

Question 20

What can cause loss of bowel control?

Answer 20

Cauda Equina Syndrome. Damage to nerve roots below T12.

Question 21

What is the range of total water ingested/secreted into the GI tract in one day?

Answer 21

7.5 to 8L/day

Question 22

Where is most water absorbed and sent to?

Answer 22

90% absorbed in SI and sent to blood stream.

Question 23

What drives the absorption of fluid from the LI? What does the LI do to fluids and electrolytes?

Answer 23

Driven by electrolyte balance. LI “fine tunes” fluid and electrolyte homeostasis.

Question 24

How much fluid is normally excreted in stool and how much by kidneys in a normal day?

Answer 24

Stool=100mL/day

Kidneys=1-2L/day