5. Vasculature & Innervation Of GI Tract

Question 1

Main branches that supply
1 foregut
2 midgut
3 hindgut
All come off (8) surface of abdominal (5)

Answer 1

1 coeliac trunk
2 superior mesenteric
3 inferior mesenteric
All come off anterior surf of abdominal aorta

Question 2

1 Foregut consists of
2 Midgut consists of
3 Hindgut consists of

Answer 2

1 oesophagus, stomach, proximal 3/8 of duodenum, liver, gallbladder, superior of pancreas, spleen
2 distal 5/8 of duodenum, jejunum, ileum, caecum, ascending colon, proximal 1/3 of transverse colon
3 distal 2/3 of transverse colon, descending colon, sigmoid colon, rectum
Note rectum blood supply comes from many other sources too (rectal, iliac arteries

Question 3

Draw branches of coeliac trunk

Answer 3

Check with lecture
Include:
Trunk>left gastric; splenic; common hepatic
Splenic has pancreatic branches
Common hep>right gastric branches off early then hepatic&gastroduodenal
Right gastric meets left gastric>oesophageal branches
Gastro duodenal split into superior pancreatoduodenal and right gastroepiploic. Later becomes left and joins splenic>short gastric arteries

Question 4

Branches of superior mesenteric

Answer 4

Check lecture slide

Question 5

Branches of inferior mesenteric

Answer 5

Slide

Question 6

Portal venous system:
Portal vein=?+?
Route of blood in this
Role of portal/portal hepatic vein

Answer 6

1 portal vein=splenic vein+sup mesenteric Vein
2 enter liver by portal vein; break into sinusoids; into hepatic veins; drain into IVC
3 uptake/metabolise/remove substances from nutrient rich blood that has just come from intestines

Question 7

Describe first pass effect

Answer 7

Drugs metabolised by liver before reaching systemic circulation>only small amount of active drug reaches

Alternative routes may be req for some drugs eg intramuscular or suppository (via rectum, urethra, vagina>dissolves/melts)

Question 8

Portal systemic anastomoses (4); describe

Reason they exist

Answer 8

1 oesophageal; tributaries of AZYGOS veins & of left gastric vein
2 rectal: middle, inferior, superior rectal veins; superficial veins of ant abdo wall
3 Paraumbilical goes from umbilical to liver
4 retroperitoneal/colic (descending colon)

If direct route blocked, this is alternative

Question 9

Describe oesophageal varices and caput medusaue

Answer 9

Varices: portal hypertension (cirrhosis)
Dilated vein in lower oesophagus
Can lead to haemorrhaging

Caput medusae
Engorged paraumbilical veins bc route to liver blocked; bypass goes via anastomose to systemic veins

Question 10

Sympathetic innervation of GIT

1. Role
2. Which
3. Synapses where

Answer 10

1. Blood flow regulation & PAIN
3. Prevertebral plexuses

Question 11

Innervation to GIT is
1 [autonomic or voluntary].
2 Name 3 systems involved in innervation and where their signal originate from
3 how they interact with each other (2 points)

Answer 11

1. Autonomic
2. Sympathetic comes from thoracolumbar areas
   Parasympathetic comes from craniosacral regions
   Enteric involving only GIT, has both para/sympathetic
   3 PNS increase ENT activity
   SNS inhibit GIT activity
   Note: PNS rest & digest; SNS=flight/fight

Question 12

Sympathetic innervation of GIT

1. Regulation of blood flow/pain
2. (Which splanchnic nerve+vert lvl; ganglia; viscera; region of referred pain)x4
3. Synapses are where?

Answer 12

1 Greater+T2-9; coeliac; foregut; epigastric
Lesser T10/11; sup mesenteric; midgut; paraumbilical
Least T12; aorticorenal; kidney; lessers thoracic
Lumbar L1/2; inf mesenteric; hindgut smooth muscles & glands & pelvic viscera; hypogastric

Question 13

Parasympathetic innervation of GIT

1. Role
2. Which nerve innervates
3. Distributes with (11) nerves via pre-(9) plexuses

Answer 13

1. Peristalsis
2. Cranial PS nerve fibres from CNX=foregut & midgut
   Sacral PS nerves via pelvic splanchnic nerves (S2-4); inf hypogastric plexus; hindgut viscera
   3.sympathetic, vertebral

Question 14

2 types of ganglia in ENS:

1. In which layer of GIT
2. PS or sympathetic input
3. Innervates what tissue
4. What nerve controls

Answer 14

Myenteric
1 Circular muscle
2 Sympathetic and PS
3 muscular layers of GIT wall
4 Control gut motility

Submucosal
1 Submucosa
2 Parasympathetic
3 Mucosa of GIT
4 secretomotor control

Question 15

1. Visceral abdo pain causes (3)
2. Pain usually referred to ? & why?
3. Visceral pain from stomach referred to ?; dermatomes involved =?
4. Visceral pain from appendix bc (2 things)
5. Appendix referred pain (travel via; vertebra ?; referred region)
6. If appendix inflammatory (8,10) involved; pain where?

Answer 15

1. Over-distension of organ; ischaemia (o2 blood restriction); chemical damage eg acid gastric juice
2. Midline bs GIT develops as midline structure with bilateral nerve supply
3. Epigastric; T5-9
4. Lumen distension or smooth muscle coat spasms
5. Lesser splanchnic nerve to T10 so umbilical region
6. Parietal peritoneum; pain in lower right quadrant

Question 16

Referred abdo pain diagram: causes incl

1. Gallbladder/diaphragm
2. Oesophagus
3. Heart
4. Gall bladder alone
5. Stomach
6. Appendix
7. Kidney
8. Ureter & bladder

Answer 16

Lecture 5 slide

Question 17

Lymph flow in GIT importance (3)

Name 3 important nodes/lymph structures in abdo aorta region

Answer 17

1. Lipid transportation
2. Mucosal immune func in acquired immunity >big GI absorption surf
3. More than 1/2 lymph formation in GIT

Cysterne chyli (start of thoracic duct)
Celiac nodes (around trunk)
Preaortic nodes, ant of abdo aorta