GIT Lec 3 Blood Vessels, Nerves, Lymph PDF

Lecture 3: Blood vessels, innervation, lymphatics Overview: Arterial supply  Blood supply Arterial supply The gut: Single unpaired branches Abdominal wall & other structures: Paired branches “Abdominal...

Lecture 3: Blood vessels, innervation, lymphatics Overview: Arterial supply  Blood supply Arterial supply The gut: Single unpaired branches Abdominal wall & other structures: Paired branches “Abdominal scarecrow”  Abdominal aorta aneurysms Diameter > 3cm Different types Back pain, pulsations in abdomen Associated with thoracic aorta and popliteal aneurysms Risk factors: Male, smoking, high blood pressure, family history  Foreg 1. ut Lower part of oesophagus, stomach, 2/3rds duodenum 2. Includes: Liver, spleen, gallbladder, pancreas 3. Supplied by coeliac trunk; drained by splenic artery 4. Note anastomosis around stomach: Left and right gastric arteries and left and right gastroomental* arteries Note: In older texts the gastroomental arteries are referred to as the gastroepiploic arteries  Coeliac 1. Left gastric trunk 3. Common hepatic artery artery Proper hepatic artery cystic artery; left and right 2. Splenic artery Left hepatic arteries gastroomental artery, short Right gastric artery gastric arteries Gastroduodenal artery Supraduodenal artery Right gastroomental artery Superior pancreaticoduodenal artery  Midg ut Superior mesenteric Last 1/3rd of duodenum, jejenum, ileum, artery cecum & appendix, ascending colon, 1st 1. Jejenual and ileal branches 2/3rd of tv colon 2. Ileocolic artery Supplied by superior mesenteric appendicular br artery; drained by superior mesenteric vein 3. Right colic artery 4. Middle colic artery  Hindg ut Last 1/3rd of tv colon, descending Inferior mesenteric colon, sigmoid colon, rectum artery 1 Left colic artery. Supplied by inferior mesenteric artery; Sigmoidal drained by inferior mesenteric vein 2 branches. Superior rectal 3. artery Superior rectal artery Anastomosis: Foregut - Midgut  Anastomosis: Midgut - Hindgut  Overview: Venous drainage…1 IVC: Caval system Drains the limbs, abdominal wall and paired structures Common iliac veins – from lower limbs and gluteal region Lumbar veins – from posterior abdominal wall Renal veins – from kidneys, left adrenal gland and left testis/ovary. Right testicular/ovarian vein from right testes or ovary Right suprarenal vein –  Overview: Venous drainage…2 IVC: Caval system (cont.) NOTE: Left testicular/ovarian vein drains into the left renal vein Left adrenal vein drains into left renal vein No tributaries from spleen, pancreas, gallbladder drain into portal system  Overview: Venous drainage…3 Portal hepatic vein: Portal system – Form GIT – Formed by union of splenic vein and inferior mesenteric vein – Posterior to head of pancreas on L2 – Tributaries: Inferior mesenteric vein Gastric veins Cystic veins  Comparis Portal system on Caval system Hepatic portal vein IVC Drains nutrient rich deoxygenated blood Drains nutrient poor deoxygenated blood From GIT From limbs, abdominal wall and paired structures Into IVC via hepatic veins inside liver Directly into the right atrium  Portocaval – anastomosis Butt (rectal) – Gut (Oesophageal & retroperitoneal) – Caput (paraumbilical) A: Oesophagal – Caval: azygos system – Portal: Left gastric v B: Rectal – Caval: Middle & Inferior rectal vv to internal iliac v – Portal: Superior rectal vein to IMV C: Paraumbilical – Caval: inferior epigastric vein – Portal: Paraumbilical vv D: Retroperitoneal – Caval: Lumbar vv – Portal: Inferior mesenteric Blockage of IVC below kidneys Portal hypertension Innervation: Abdominal wall Xiphistern um T6 Innervation: Autonomic involvement Foregut Midgut Hindgut Innervation: Peritoneum  Referred Pain perceived at pain a location other than the site of the painful stimulus Primarily due to convergence of sensory neurons in spinal cord Pain from injury, inflammation activate sensory neurons relaying info to spinal cord Due to convergence, pain signals may also activate sensory neurons from a different body region Brain is unable to differentiate between the two sources, perceives the pain as originating from the region represented by the activated sensory neurons Referred pain T 6  Exampl es 1. Gastric ulcers can cause referred pain to epigastric region Both stomach and epigastric region innervated by segments T6-T9 Pain signals from stomach misdirected to epigastric area due to convergence of sensory neurons in these spinal cord segments Perception of pain in epigastric region, which is located superior to umbilicus. T 6 2. Irritation of diaphragm refers pain to shoulder Same C3 and C4 roots: Phrenic and supraclavicular nerves