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Flashcards in Anatomy Of The Intestines Deck (67)
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Microscopic structure of the small intestine?

Mucosa folded into villi
Villi separated by crypts

1

What happens when the cells of the small intestine epithelium reproduce and where do they do it?

Reproduce in the villi
Migrate towards the tips, maturing as they go
-acquire capacity to absorb

2

What do the microvilli do?

Massively increase the surface area to form a brush border

3

What does the brush border form?

An unstirred layer where nutrients meet and react with enzymes secreted by enterocytes (epithelial cells), completing digestion prior to absorption.

4

What are the main layers of the small intestine?

Mucosa
-epithelium
-lamina propria
-muscularis mucosae

Submucosa
-connective tissue
-with blood vessels, lymphatics and submucosal plexus

Muscularis externae
-2 smooth muscle layers, longitudinal and circular.
-Myenteric plexus lies between them

Adventitia
-loosely arranged fibroblasts
-collagen
-vessels and nerves pass through it

Covered by mesothelium, commonly called serosa

5

What are enterocytes?

Columnar cells which contain brush border enzymes for digestion

6

What are goblet cells?

Exocrine glands which secrete mucin

7

What cells do the crypts of Lieberkuhn contain?

Stem cells - produce new cells
Enteroendocrine cells - synthesise and secrete hormones
Paneth cells - secrete protective agents
Peyer's patches (only in ileum)
Brunner's glands - secrete alkaline fluid to neutralise chyme

8

What protective agents do Paneth cells secrete?

Defensins and lysosyme

9

What do Peyer's patches do?

Contain MALT which house white blood cells and lymphocytes
Produce antibodies to protect from infection

10

Over all function of the large intestine?

Receives digested food from small intestine, from which it absorbs water and sodium to form faeces

11

Tell me about the cecum

First part of the colon
Blind ended sac
Slightly inferior to ileocecal junction
Can be palpated in right iliac fossa if enlarged due to poo/gas

12

Where is the appendix?

Attached to the posteriomedial end of caecum
Contains lymphoid tissue

13

What is the blood supply to the cecum?

Arterial: SMA -> ileocolic artery
Venous: ileocolic vein -> IMA

14

Where does the ascending colon extend from and to?

Cecum to right lobe of liver
Right colic flexure/hepatic flexure

15

Where does the transverse colon extend from and to?

Right colic flexure -> left colic flexure/splenic flexure

16

Where does the descending colon extend from and to?

Left colic flexure to the sigmoid colon

17

Where in relation to the left kidney is the descending colon?

Passes anteriorly to it over its lateral border

18

What marks the beginning of the sigmoid colon?

Where the descending colon turns medially

19

What structures are just posterior to the sigmoid colon?

Left ureter
Left common iliac artery

20

What is lateral to the ascending and descending colon? Function?

Left and right paracolic gutters
Drain any fluid that leaks from the colon

21

Clinical relevance of the paracolic gutters?

Allow any potentially infectious material to circulate around the peritoneal cavity which can cause further infection
This is how a ruptured appendix can cause peritonitis

22

Arterial and venous supplies to the ascending colon?

Arterial - ileocolic and right colic branches of SMA
Venous - ileocolic and right colic tributaries of SMV

23

Blood supply of the transverse colon?

Arterial - middle colic of SMA
Venous - SMV

24

Blood supply of descending colon?

Arterial: Left colic and superior sigmoid - branches of IMA
Venous - IMV

25

Blood supply of sigmoidal colon?

Arterial: sigmoid arteries - branches of IMA
Venous: IMV

26

Which artery forms an anastamosis between the superior and inferior mesenteric arteries?

Marginal artery

27

Clinical relevance of the colonic blood supply?

It is collateral, so maintains blood supply in case of occlusion/stenosis of one of the major arteries.

28

Where is the rectus located?

Begins at S3
Retroperitoneal
Immediately anterior to sacrum

29

How does the extension of the peritoneal cavity in the pelvis differ between men and women?

Women: formed between posterior wall of uterus and colon - recto-uterine pouch / pouch of Douglas

Men: between posterior wall of bladder and the colon - retro-vesicle pouch