Human Anatomy and Physiology Laboratory Manual, Cat Version: 6. Digestive System - Large Intestine Flashcards


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1

Location and size of large intestine

  • Attached to the posterior abdominal wall by the mesocolon
  • 5 ft in length
2

Parts of the large intestine

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  • Cecum
  • Colon
  • Rectum
  • Anal canal
3

Parts of the colon

  • Ascending
  • Transverse
  • Descending
  • Sigmoid
4

Layers of large intesting

  • Mucosa
  • Submucosa
  • Muscularis
  • Serosa
5

What is missing from large intestine that is present in the layers of the small intestine

  • Circular folds
  • Villi
  • Digestive enzyme secretion
6

Mucosa - Large intestine

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  • Absorptive cells (mainly for water)
  • Microvilli are plentiful
  • Interspersed goblet cells produce mucous
7

Teniae coli

  • Present in the muscularis
  • 3 separate longitudinal ribbons of smooth muscle that run the length of the colon
  • Shorter than colon, causing it to become sacculated into haustra
8

Haustra

  • Small pouches caused by sacculation, which give the colon its segmented appearance.
  • When one distends it simulates muscles to contract, pushing the contents to the next one.
9

Cecum

  • Hangs inferior to the ileocecal valve
  • Small pouch, 2.5 in long
  • Attached to appendix
10

Appendix

  • Attached to cecum
  • 3 in coiled tube
11

Colon

Long tube that merges with the open end of the cecum

12

Rectum

  • The last 8 inches of the GI tract
  • Lies anterior to the sacrum and coccyx
13

Anal Canal

  • Final inch of the rectum
  • Opening to the exterior is called the anus
14

Anus

Opening of the anal canal to the exterior.

  • Internal Anal Sphincter (Involuntary)
  • External Anal sphincter (voluntary)
15

Feces

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  • Wastes left over after digesting and absorbing all the nutrients from eaten material
  • Brown coloration comes from a combination of bile and bilirubin
  • Odor due to bacterial action - aerobic and anaerobic
16

Defecation reflex

Activated by stretch receptors stimulated by filling of the rectum

17

What leads to defecation

  • Food in stomach stimulates mass peristalsis
  • Food moves through intestines into the rectum
  • Rectal receptors respond to distention and longitudinal muscles shorten the rectum
  • ANS releases the internal anal sphincter and gives a conscious awareness of distention
  • Release of external sphincter is under conscious control
18

Mechanical digestion in large intestine

  • Ilocecal valve is normally closed so chime cannot enter large intestine
  • Gastroileal reflex is triggered when food enters and distends the stomach
  • Migrating motility complexes are intensified by this reflex, forcing chime through the ileocecal valve into the cecum