Lecture 22: The Gastrointestinal Tract Flashcards Preview

CHI 280: Human Anatomy I > Lecture 22: The Gastrointestinal Tract > Flashcards

Flashcards in Lecture 22: The Gastrointestinal Tract Deck (16):
0

Adult hindgut derivatives

Slide 5
Supplied by inferior mesenteric artery
-distal portion of transverse colon
-descending colon
-sigmoid colon
-rectum
Be able to label slide 5
-anal canal
-epithelial of urinary bladder
-most of uretha

1

Localisation of pain and embryological origin
-Pain arising from the foregut derivatives localised in the ____
-pain arising from midgut localises in the _____
-pain arising from hindgut derivatives localises in the ___

Localisation of pain and embryological origin
-Pain arising from the foregut derivatives localised in the __(epigastric region)
-pain arising from midgut localises in the ___(periumbilical region)
-pain arising from hindgut derivatives localises in the ___(hypo gastric region)

2

Large intestine

1.5m long
-absorbs water and important ions from faeces
-compacts faeces for delivery to rectum

Features:
Teniae coli: 3 longitudinal bands of smooth muscle on colon surface
Haustra: sacculations of colon created by contracting taeniae coli
Omental appendices: small fat accumulations that hang from colon
-greater luminal diameter

Look at slide 9- memorise

3

Tell me about the teniae coli

-3 longitudinal bands of smooth muscle
-originate at base of appendix
-broaden and terminate as a continuous layers around rectum
-tonic contraction causes sacculations known as "haustra"

4

Caecum

7.5 x 7.5
-receives terminal portion of ileum
-inferior to ileocaecal junction
-continuous with ascending colon
-right iliac fossa > greater pelvis provides protection

5

Ascending colon

-retroperitoneal
-ascends on right flank to reach liver
-bends into right colic (hepatic) flexure
-site of most of water reabsorption in large intestine
Slide 12

6

Transverse colon

-runs transversely from right to left hypochondrium
-attachement to posterior abdominal wall by transverse mesocolon
-bends to form the left colic (splenic) flexure.
Slide 13

7

Descending colon

-Secondarily retroperitoneal
-commences at left colic (splenic flexure)
-descends along left flank to join sigmoid colon in left iliac fossa
Slide 14

8

Sigmoid colon

-between descending colon and rectum
-extends from left iliac fossa to S3 vertebrae
-suspended by sigmoid mesocolon
15 slide

9

Rectum slide 16
Function:

-accumulates and temporarily stores faeces
-primary retroperitoneal and sub peritoneal
-extends from S3 vertebrae to anal canal
-ends anteroinferior to tip of coccyx as GIT pierces the pelvic diaphragm
-anterior and lateral reflections of peritoneum create
-anterior and lateral reflections of peritoneum create recto vesical pouch in males and rectouterine pouch in females.
-arterial perfusion via branches of inferior mesenteric artery and internal iliac artery

Venous drainage:
-anastomosis between portal and systemic veins in wall of anal canal.
-superior rectal vein drains back to the inferior mesenteric vein (➡splenic➡ portal vein)
-middle rectal veins drains back to internal iliac veins
-anastomosis between rectal veins

10

How is the rectum innervated?

Sympathetic: lumbar splanchnic nerves
Parasympathetic: pelvic splanchnic nerves
Visceral afferent: rectum inferior to pelvic pain line so all visceral afferent fibres follow pelvic splanchnic nerves retrogradely back to S2-S4 spinal sensory ganglia.

11

Male rectum exam.
In males the following structures can be palpate through the walls of the rectum:

-prostate gland
-seminal vesicles
-pelvic surface of coccyx and sacrum

12

Female rectal examination.
What structures can be palpate a through wall of the rectum?

-cervix
-pelvic surface of sacrum and coccyx

13

Anus

2.5-3.5cm long.
-internal anal sphincter: smooth involuntary (contraction stimulated by sympathetic fibres; parasympathetic fibres from pelvic splanchnic nerves inhibit sympathetic contraction and evoke peristaltic contraction for defaecation.
Importance of tonic contraction?

External anal sphincter: large voluntary sphincter innervated by inferior anal nerve- branch do pudendal nerve
-external haemorrhoids (piles)
-anal fissures
➡Distal anal canal is sensitive to touch, pain and temperature

All visceral afferent fibres travel retrogradely with parasympathetic fibres to S2-S4 spinal sensory ganglia.
Anal canal perforates levator ani muscle

14

Puborectalis muscle. Slide 26

Has a major role to play maintaining faecal continence

15

Haven't finished..only 3 more slides, couldn't do it. Piece out negro