Lecture 22: Abdominal Viscera II Flashcards
What are the major functions of the Liver?
Largest internal organ
- metabolism of carbohydrates, protein and fat (endocrine)
- modification of exogenous substances (endocrine)
- Formation and secretion of bile (exocrine)
What is the superior / anterior surface of the liver called?
- Convex diaphragmatic (anterior, superior, and partly posterior) surface
- Contacts with the thoracoabdominal diaphragm and the anterior body wall
What is the lower / posterior surface of the liver?
It has a relatively flat visceral (postero-inferior) surface
What are the four lobes of the liver?
- Right Lobe
- Left Lobe
- Quadrate Lobe
- Caudate Lobe
Liver: What ligament separates the left lobe from the right lobe?
The falciform ligament
Describe location of caudate and quadrate lobes.
Quadrate (anterior and inferior) and caudate lobes (posterior and superior) are visible on the visceral (inferior) aspect, demarcated by the sagittal fissures
What is the porta hepatis?
- A transverse fissure in the middle visceral surface of the liver
- Is the entrance and exit for many vessels
What enters liver through porta hepatis?
- Proper Hepatic Artery
- Nerve Supply (autonomic)
- Portal Vein
- Hepatic ducts
Where does venous drainage leave the liver? What do they empty into?
- Through hepatic veins on the posterior aspect of liver
- Empty into inferior vena cava
What type of blood enters the liver through hepatic portal vein?
- Brings oxygen poor blood from GI tract
- Contains nutrients and toxins from intestines
- Blood cells and their breakdown products from spleen
- Endocrine secretions from pancreas and intestines
How much of the liver blood supply is provided by hepatic artery?
20 % oxygenated blood
Describe the structre of liver tissue.
Parenchymatous organ
80% parenchyma consisting of hepatocytes arranged into thin plates separated by blood sinusoids
20% is connective tissue stroma
What is the morpho-functional unit of the liver? How many?
- Classic lobule
- Liver contains about 1 million
Describe the structure of the classic lobule:
* Shape
* Central vessel
* What’s located at peripheral angles?
- Hexagonal
- Central vein: Large venule at center - largest tribuatry to hepatic vein
- Portal areas (loose stromal connective tissue) / portal triads
What three vessels does the portal triad consist of?
Terminal branches of:
1. Hepatic portal vein
2. Hepatic Artery
3. Bile Ductule
What connects the portal area to the central vein?
An anastomotic system of sinusoids that are radially arranged.
What type of blood do sinusoids receive, and where do they send it?
- Receive mixed blood from hepatic artery and vein
- Sinusoids perfuse the cells with mixed blood while hepatocytes exercise their endocrine and exocrine roles
- After hepatocyte modification, the blood is sent to central vein
Describe the structure of the hepatocyte.
- 2 surface face sinusoids
- Other 4 face neighboring hepatocyte
- Bile canaliculus is present between adjacent cell membranes
- Network of bile canaliculi continue through the plates of hepatocytes
What is the function of liver hepatocytes?
*Metabolism of carbohydrates, proteins and fats (endocrine)
*Modification of exogenous substances like drugs and alcohol
Describe the bile flow system:
* direction of flow
* order of drainage
- Centrifugal, from the region of the central vein toward the portal area (opposite to blood)
- Bile canaliculus drains into bile ductules in portal triads
- Bile ductules carry bile to the interlobular (intrahepatic) bile duct which drains into** right and left hepatic ducts** the common hepatic duct and then the duodenum via common bile duct
Identify indicated structures
Identify indicated structures.
Identify indicated structures.
Identify indicated structures
What are circled areas?
Portal triad area
Identify indicated structure
Classic Lobule
What are the colored channels?
Sinusoids
Identify tissue type and indicated cells.
Where is the gall bladder and what is its function?
- Located on visceral surface of liver
- Stores and concentrates bile that is produced in the liver
- Releases bile into duodenum to aide in emulsification and breakdown of fat
What are the four parts of the gallbladder?
- Fundus - wide blunt end
- Body
- Infundibulm - narrowing opposite fundus
- Neck - ends in cystic duct, which joins bile duct
What are the 3 layers to the gall bladder tissue?
What is not present?
- Mucosa
- Muscularis externa
- Adventitia / peritoneum
What cell type composes the mucosa of the gall bladder and what is their function?
Simple columnar with microvilli to allow absorption of water (and concentration of the bile) into capillaries in the lamina propria
What is the function of the cystic duct?
- Cystic duct carries the unconcentrated bile from the
common hepatic duct into the gall bladder - concentrated bile out of the gall bladder into the bile duct
Trace the course of the bile duct to the duodenum.
- bile duct joins the main pancreatic duct from the pancreas
- opens into the descending part of the duodenum through the major duodenal papilla
What tissue sample is this from and what are the names of the layers?
Identify the following tissue sample. What cell types are present?
Identify indicated structures
What is the pancreas and where is it located?
- Posterior abdominal wall between duodenum and spleen
- Accessory digestive gland that serves both exocrine
(ducts) and endocrine (blood) functions
What is the main pancreatic duct?
- carries digestive enzymes from most of the pancreas
- it joins the bile duct and opens into the duodenum at the major duodenal papilla
What is the main function of the accessory pancreatic duct?
- (sometimes absent) drains the superior portion of the head
- It empties into the duodenum just superior to the major duodenal papilla
What are the 4 sections of the pancreas?
Describe structure of the pancreas
What kind of cells compose the serous secretory acini tissue, and what do they secrete?
Where is the endocrine tissue of the pancreas? What does it secrete?
Which organ is this tissue located?
Pancreas
Where is this gland located, what kind is it?
What tissue / cell-type?
Indicated structures?
What is the tissue type, and indicated structure?
What is the spleen? Is it essential for life?
- Large lymphoid organ
- It filters blood
- Responsible for hematopoiesis in fetus
- Responsible for lymphopoiesis
- Splenic artery
- Splenic vein
- Spleen is not essential for life
What is the hilus of the spleen?
Portion of spleen, not covered by peritoneum, where blood vessels (splenic artery and veins) enter and exit.
The hilum is often in contact with the tail of the pancreas.
What provides innervation to the gastrointestinal tract?
- Enteric nervous system
- Axons of extrinsic parasympathetic and sympathetic, and visceral afferent neurons
What are the 2 plexi of the enteric nervous system, and their fuctions?
- Submucosal (Meissner’s) plexus - Coordinates secretion, absorption, and motility of mucosa
- Myenteric (Auerbach’s) plexus - initiates and controls peristalsis
