Lecture 1

Question 1

What are some functions of the Liver?

Answer 1

Liver Functions:

1. FILTRATION and STORAGE of blood
   - Can store 500 ml of blood
   - With SNS can cause blood to go into circulation
2. Carbohydrate metabolism
   - Storage and production glycogen
3. Metabolism of protein and fat
4. Metabolism and Elimination of Hormones and foreign substance processing
5. Production of clotting factors/ coagulation factors
6. Storage of IRON and vitamins
7. BILE formation

Question 2

Describe the Organ of the Liver.

Answer 2

- Largest organ in the body

- 2% of body weight

- 1.5 kg (average adult)

Location: RUQ Inferior to diaphragm

• Diaphragm separates it form pleura, lungs and heart

Question 3

Describe the anatomy of the Liver.

Answer 3

1. Diaphragmatic Surface - (anterior, superior and some posterior)
2. Visceral Surface - (posterior, infererior)
3. Portal lobes
   - The liver has functionally independent right & left lobes.
   - Equal in size, has its own blood supply from hepatic artery and portal vein, and own venous and biliary drainage
4. Portal Hepatis (“hepatic portal”; “Portal Fissure”) is a Transverse fissure on visceral surface of liver, between CAUDATE and QUADRATE lobes
   - This is where Portal Vein and Heptaic Artery enter the liver and where Heptatic Ducts leave
   - Gives passage to the portal vein, the hepatic artery, hepatic nerve plexus, hepatic ducts, and lymphatics
5. Portal Triad

Portal vein

Hepatic artery

Bile passages

Question 4

Describe the blood flow through the liver.

Answer 4

The liver is divided into FOUR lobes consisting of 50,000 to 100,000 individual hepatic lobules.

1. Oxygenated blood flows from the AORTA to the left & right HEPATIC ARTERIES to the liver. - 25% of blood supply
2. DEOXYGENATED blood flows from the GI tract to the liver via the PORTAL VEIN - 75% of blood supply
   - The Portal Vein, Hepatic Arteries, and Bile ducts all form PORTAL TRIADS
3. Blood flows past hepatocytes from the portal triads, via sinusoids, to the CENTRAL VEIN.
   - There is usually only one layer of hepatocytes (Liver Cell Plate) between sinusoids so the total area of contact with plasma is great.
4. Central veins join to form hepatic veins, which drain into the IVC.

Question 5

What is the functional unit of the liver?

Answer 5

Functional unit = LIVER LOBULES

Lobules have Central Vein that drains into Hepatic Veins then drains into IVC

Question 6

Describe hepatic cellular plates.

Answer 6

Hepatic cellular plates (extend out from central vein)

• Two cells thick
• Between adjacent cells are BILE CANULICULI that drain into bile ducts in the Fibrosepta that separate the lobules

Question 7

Describe the flow of Bile.

Answer 7

1. Bile drains into Right and Left hepatic ducts, from the liver
2. From the Gallbladder, bile is directed into the CYSTIC DUCT, which joins heptaic ducts, from the liver, to form the COMMON HEPTIC DUCT
3. The Common hepatic Duct then joints the PANCREATIC DUCT, which then travels to the DUODENUM via an opening called THE SPHINCTER OF ODDI

Question 8

Where is bile stored?

Where is bile manufactured?

Answer 8

Stored: GALLBLADDER

Manufactured: LIVER

Question 9

What is the function of the gallbladder?

Answer 9

Function of gallbladder:

CONCENTRATE BILE by absorbing water and salts and deliver the concentrated bile when food is in duodenum

Bile sent via the COMMON BILE DUCT and CYSTIC DUCT to duodenum when food is present

Question 10

Describe the Venous Sinusoids.

Answer 10

Venous sinusoids

• Extend out from the CENTRAL VEIN

Venous Sinusoids contain:

1. Hepatic cells
2. Endothelial cells
   - Endothelial layer has large pores between endothelia lining
   - Below the endothelial lining are the Spaces of DISSE or “Parasinusoidal Spaces”. These connect with lymphatics, since pores are so large even plasma proteins move between the spaces.
3. Kuffer cells (RE cells)
   - Large macrophages that act as phagocyte
   - Deal with bacteria and other foreign things in hepatic sinus blood
   - “Reticular Endolelial Ccells”

Question 11

What is NORMAL hepatic blood flow?

Answer 11

l00 ml/ min/ l00 gm tissue

Question 12

What percentage of CO is hepatic blood flow?

Answer 12

25% CO

Question 13

How much of the liver’s blood supply comes from the portal vein? Hepatic artery?

Answer 13

Blood Supply:

75% from portal vein

25 - 30% from hepatic artery

Low vascular resistance

Question 14

Describe the portal vein.

Answer 14

PORTAL VEIN

1. DELIVERS 70 - 75% of blood supply to the liver
2. Portal vein is SHORT and WIDE and formed by the superior mesenteric and splenic veins posterior to the neck of the pancreas.
   - It then ascends anterior to the IVC and divides at the right end of the Porta Hepatis into the right and left branches
3. Carries Poorly oxygenated but nutrient rich blood from GI tract travels to the liver sinusoids
4. Carries toxins to the liver
5. Mean Arterial Pressure = < 10 mmHg
   - Blood is deoxygenated in the preportal tissues: stomach, spleen, pancreas, small intestine, and colon
6. Even though blood in portal vein is partially deoxygenated, it still carries 50-55% of liver’s oxygen supply
7. Also has alpha l and dopamine receptors

Question 15

Describe the Heptatic Artery.

Answer 15

HEPATIC ARTERY

1. Branch of celiac trunk carrying well oxygenated blood from the aorta supplying 45 - 50% of oxygen supply to liver
2. Dilates when portal vein flow decreases which is called: RECIPROCITY OF FLOW
3. Contains Alpha l receptor, dopamine, and cholinergic receptors
4. Hepatic veins formed by the union of the central veins of the liver and open into the IVC just inferior to the diaphragm
5. Portal venous system communicates with the systemic venous system in a number of areas
   - Most significantly is the communication between the esophageal veins draining into the azygous veins of the systemic system or the left gastric vein of the portal system
   - When dilated, these veins become ESOPHAGEAL VARICES
6. 25 - 30% of Hepatic blood flow
7. Mean pressure = 90 - 100 mmHg