Flashcards in Liver Deck (30):
Where is the liver located?
The right upper quadra, against the diaphragm
Why is the liver brown in appearance?
High density of mitochondria
What is the name of the ligament that separates the two lobes of the liver?
The falciparum ligament
A fold in the peritoneum, attaching the liver to the anterior abdominal wall and diaphragm
Where does the liver get its blood from?
The gastro intestinal system
Describe the major vessels of the portal system
- Hepatic artery takes oxygenated blood from the aorta and spleen to the liver
- The portal vein takes deoxygenated blood from the small intestine (superior mesenteric vein) and from the large intestine (inferior m vein)
What are the two capillary systems in humans?
- Hepatic portal system
- Hypothalamo-hypophyseal portal system
How does the portal circulatory system differ from the typical circulatory route?
- Blood passes through TWO sets of smaller vessels before returning to the heart
- Blood from the first set of capillaries collects in portal vessels which then branch again to supply a capillary network to a second location before entering a series of veins to the heart.
What is the hypothalamo-hypophyseal portal system?
- System of blood vessels in the brain
- Connects hypothalamus with anterior pituitary
- Transport and exchange of hormones
- Fast communication between these two locations
How does the hepatic portal system function?
- First bed of capillaries in stomach and intestine
- Nutrients and toxins absorbed
- Hepatic portal vein
- Second capillary bed in the liver
- Nutrients and toxins leave to hepatocytes (liver cells)
- Hepatic vein
- Towards heart
What travels in the portal vein?
• Water soluble vitamins
• Electrolytes including sodium, potassium, chloride, bicarbonate, calcium, magnesium, iron etc
– Glucose, galactose and fructose
– Amino acids, dipeptides and tripeptides
• Intestinal hormones, particularly pancreatic hormones
• Toxins, including ammonia
Which toxic element does the liver destroy? How and why does it do this?
- Crosses the blood brain barrier
- Converts ammonia to urea
- Excreted as urine
What sort of toxins are found in water?
• Nematodes (Roundworms)
• Cestodes (Tapeworms)
• Trematodes (Flukes/ flatworms)
What doesn't travel in the portal vein? Why?
Lipids and fat soluble vitamins (A,D,E and K)
– Dietary lipid is mostly triglycerides, cholesterol and phospholipids
– Digested by lipases, this process needs bile acids to form micelles
– Lipids are taken into the cells in the smal intestine and processed into chylomicrons
– Chylomicrons are taken up by lymphatics, called lacteals. Lacteals contain chyle
What are the functions of the liver?
1. Metabolism (cat/anabolism)
- Fats (glycogen, lipoprotein, triglyceride)
3. Detoxification (decreases drug efficacy)
4. Bile production
What is stored in the liver?
• Vitamin A
• Vitamin B 12
• Vitamin D
• Vitamin K
What does the liver produce?
• Numerous coagulation factors
• Haematopoiesis in fetus (can be revived in adult if bone marrow failing)
How does the liver break down drugs?
- Cytochrome P450
- Breaks down drugs and other toxic compounds
Which compounds are catabolised in the liver?
• Drugs (cytochrome P450)
• Poisons (cytochrome P450)
• Can take over removal of aged red cells after splenectomy
How does the liver filter?
- Kupffer cells (stellate macrophages (vacuoles containing vitamin A))
- Specialised to the liver
- Line the sinusoids
- Recycle old blood vessels and injest pathogens
What is the livers exocrine function?
- Bile is secreted by the liver
How does the liver carry out its endocrine function ?
• It produces
– Insulin like growth factor 1 (IGF-1)
• It modifies to active forms
– Vitamin D
• It breaks down
– Oestrogen and progesterone
How do heaptocytes differ to other cells?
Compared to other cells contain
– Numerous mitochondria
– A lot of peroxisomes (organelles full of oxidising agents)
– Numerous free ribosomes
– A lot of rough endoplasmic reticulum
– A lot of smooth endoplasmic reticulum
– Numerous Golgi complexes
– Glycogen deposits
Where does the liver receive its blood from?
25% Hepatic artery
75% Portal vein (from GI)
What is a sinusoid?
A sinusoid is an irregular tubular space for the passage of blood, taking the place of capillaries and venules in the liver, spleen and bone marrow. Its endothelial cells gas large gaps
(wide capillary vessel)
Describe the shape of a liver lobule
- Hexagonal shaped (polyagonal ie not perfect )
- 6 sided
- Central vein
- Portal tried (hepatic artery, portal vein and bile duct)
- Bile flows outwards, blood towards central vein
- Kupffer cells dispersed throughout
How are lymphatics arranged in a liver lobule?
Lymphatics arise from the periportal space (space of Mall) and drain to the liver hilum and then onto the hepatic duct
What is a liver acinus?
Long axis between two central veins
Short axis between to portal triads
When toxins arrive = cells in this region get damaged
What occurs between hepatocytes?
- Bile canaliciuli
- Carry bile and get it back into bile duct
- Chicken wires around cells
What is the space of disse?
- Between hepatocytes and sinusoids
- Allows proteins and other plasma components to be absorbed by the hepatocytes