Week 1: Liver and Lymphatic drainage Flashcards
Direction of flow of lymphatics in the abdomen
lymphatic drainage follows the reverse path of the arteries as lymph flows from the regional nodes associated with the viscera to lymph nodes located on the abdominal aorta
lymph flows from the pre-aortic nodes to the cisterna chyli, the dilated proximal end of the thoracic duct to eventually enter the venous circulation
Naming of lymph nodes
These pre-aortic lymph nodes are named according to their associated artery
celiac nodes (foregut)
SMA nodes (midgut)
IMA nodes (hindgut)
Identify
Innervation of the abdominal viscera
innervation of the abdominal viscera has a similar pattern to the arterial supply but in addition, the enteric nervous system provides an “intrinsic” network of ganglia with connections to the autonomic nervous system which coordinates peristalsis (movement) and secretion
Location of the enteric ganglia and nerve plexus
are the myenteric plexus and the submucosal plexus within the layers of the bowel wall
Describe autonomic innervation of the gut
Describe innervation of the forgut
Describe innervation of the midgut and hindgut
Summary of the neurovascular supply of the gut
What is the largest solid organ in the body?
The liver
Anatomical divisions of the liver
right and left lobes
two smaller lobes (caudate and quadrate) are considered part of the left lobe
Liver receives venous drainage from?
the GI tract, accessory organs of the GI tract and the spleen via the portal vein
Liver storage
glycogen
fat
protein
vitamins
and iron
Liver produces and functions
fuels
plasma proteins
metabolizes toxins modifies hormones
produces bile acids
excretes substances (bilirubin) in bile via exocrine secretion
Liver vascular supply
supplied with oxygenated blood by the proper hepatic artery which is a branch of the common hepatic from the celiac trunk which runs within the hepatoduodenal ligament along with the portal vein and common bile duct anterior to the epiploic foramen
Describe the blood supply to the liver
Identify
Describe blood flow in the liver
blood enters the liver through the proper hepatic artery (30%) and portal vein (70%) and leaves via the hepatic veins which drain into the IVC before it enters the right atrium
Describe the biliary system
bile leaves the liver via the right and left hepatic ducts after draining the right and left lobes of the liver and enters the common hepatic duct
it enters the cystic duct and is stored and concentrated in the gallbladder
on stimulation, bile leaves the gallbladder, enters the cystic duct and passes down the common bile duct
it enters the hepatopancreatic ampulla (of Vater) which is surrounded by a smooth muscle sphincter (of Oddi) Bile then empties into the second part of the duodenum at the major duodenal papilla
What is the pancreas?
an exocrine and endocrine organ that lies posterior to the stomach in the posterior wall of the lesser sac
Pancreas location and shape
- It is retroperitoneal except for the distal tail which contacts the spleen
- the pancreas has a head, neck, body and tail with the head nestled in the C shaped curve of the duodenum
Pancreas ducts
In addition to the main pancreatic duct which joins the common bile duct at the hepatopancreatic ampulla, exocrine pancreatic secretions exit via the accessory pancreatic duct emptying into the duodenum at the minor duodenal papilla
What is the spleen?
A functionally larger lymph node
Spleen location
- that lies in the left upper quadrant (hypochondrium) posterolateral to the stomach and protected by the ribs
- It is connected to the stomach via gastrosplenic ligament and to the left kidney by the splenorenal ligament
Hepatic portal system function
carries blood from the abdominal viscera to the liver
Portal system features
in a portal system arterial blood flows into a capillary system (in GI viscera) then into veins (portal tributaries) and finally into more capillaries (liver sinusoids) before being collected by veins that return the blood to the heart (hepatic veins and IVC)
The tributaries of the portal system are named analogously to the veins
in contrast to the systemic circulation there are no valves in the portal system of veins
What are portosystemic anastomoses?
because of the lack of valves in the portal system, anastomoses (connections) between the portal and systemic veins called portosystemic anastomoses, allow blood to return to the heart via the systemic circulation when a major vein of the portal system is occluded or restricted
The most important portosystemic anastomoses
around the lower esophagus, rectum, umbilical region, retroperitoneal anastomoses
Portal blood flow restriction
backflows into the systemic circulation
engorged veins from this increased blood flow can result in esophageal varices, hemorrhoids, and cutaneous engorged veins around the umbilicus called caput medusae
cirrhosis of the liver and portal blood flow
cirrhosis of the liver leads to fibrosis and disrupts portal blood flow leading to portal hypertension and engorgement of the portosystemic anastomoses
Major cause of cirrhosis
alcoholic liver disease
Describe the portal system
Retroperitoneal structures
kidneys
suprarenal glands
ureters
abdominal aorta
inferior vena cava
Abdominal aortic aneurysm
localized abnormal dilation of the aorta that occurs when the structure of the aortic wall is compromised
Hypertension and atherosclerosis are major causes
Abdominal aortic aneurysm symptoms
Abdominal and back pain, nausea, early satiety but up to 75% are asymptomatic
Common causes of abdominal aortic aneurysm
Hypertension and atherosclerosis
Abdominal aortic aneurysms diagnosis
often discovered incidentally as an abdominal mass (often palpably pulsating)
Ruptured abdominal aortic aneurysm
A sharp tearing back pain accompanies rupture of an aortic aneurysm
Inferior Vena Cava
is part of the systemic or caval system of veins that drain blood from the body wall
At the pelvic brim, the common iliac vein is formed by the internal and external iliac arteries
Two common iliac veins join to form the IVC which receives drainage from the gonads, kidney, posterior abdominal wall, liver and diaphragm
The IVC drains into the right atrium of the heart
Describe the abdominal venous system
