L46: Large Intestine Flashcards

1
Q

What are the three components of the large intestine?

A
  • Caecum;
  • Colon;
  • Rectum.
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2
Q

What are the two colic flexures (curvatures)?

A
  • Hepatic (right);

- Splenic (left).

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3
Q

What are haustrae?

A

Sacculation of the large intestine- give rise to segmented appearance

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4
Q

What are appendices epiploicae?

A

Fatty tags

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5
Q

What are the two sphincters of the anal canal?

A
  • Internal (involuntary);

- External (voluntary).

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6
Q

Where does the caecum end and colon begin?

A

Ileo-caecal junction

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7
Q

Where does chyme pass through into the large intestine?

A

Ileo-caecal valve

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8
Q

What prevents back flow from L.I. to S.I.?

A

A fold of mucosa

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9
Q

Where is the appendix located?

A

Off of the caecum

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10
Q

What epithelium lines the large intestine?

A

Simple, columnar with goblet cells

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11
Q

What are intestinal crypts (of Leiberkuhn)?

A

Intestinal glands found along the epithelium lining (invaginations), secrete intestinal juice

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12
Q

What are the main differences of structure between the S.I. and L.I.?

A
  • Villi in small intestine ONLY;
  • In L.I., incomplete layer of longitudinal muscle (taenia coli);
  • In circular muscle, ring-like arrangement of circular muscle (haustrae);
  • Fatty tags.
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13
Q

Why is the recto-anal junction at higher risk of cancer?

A

Change of epithelium from simple columnar to stratified squamous

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14
Q

What is the primary function of the large intestine?

A

Fluid and electrolyte absorption

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15
Q

What is the primary site of absorption in the large intestine?

A

Colon

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16
Q

How is the colon subdivided?

A
  • Ascending;
  • Transverse;
  • Descending;
  • Sigmoid.
17
Q

What are the roles of intestinal flora?

A
  • Ferment dietary fibre (cellulose) and lipid;
  • Gas production (‘flatus’);
  • Synthesis some vitamins;
  • Vitamin B complex (cell metabolism);
  • Vitamin K (blood clotting).
18
Q

Describe the motility of the large intestine.

A

Caecum and ascending colon:

  • Mixing movements;
  • Similar segmentation to S.I.;
  • Contraction of circular muscles, shortening of longitudinal muscles.

Transverse and descending colon:

  • Local peristalsis (faecal matter towards rectum);
  • Mass movements (moves chyme/faeces from proximal to distal colon).
19
Q

What movements of the large intestine are infrequent?

A

Mass movements

20
Q

What type of muscle is in the internal anal sphincter?

A

Smooth (controlled by ANS)

21
Q

What type of muscle is in the external anal sphincter?

A

Skeletal (striated)

22
Q

What is diarrhoea?

A
  • Excessively watery stools;
  • Failure of fluid absorption
  • Leads to dehydration and electrolyte imbalance.
23
Q

What is constipation?

A
  • Hard faeces, difficult to pass;
  • Due to increased fluid absorption;
  • Side effect of some drugs, excess fibre (>70g).