12- The roles of the Liver Flashcards
How many lobes does the liver contain
4
Where is the liver located
Located in the upper right hand part of the abdomen behind lower ribs.
What are the 3 main functions of the liver
Metabolism- Control of synthesis and utilisation of carbohydrates, lipids and proteins
Secretory and Excretory Functions- synthesis and secretion of bile and detoxification
Vascular Function- formation of lymph and hepatic phagocytic system
What processes does the liver carry out to maintain blood glucose levels
Glycogenesis
Glycogenolysis
Gluconeogenesis
What is glycogenesis
When excess glucose is taken up by the liver and stored by glycogen
What is gluconeogensis
When hepatic glycogen reserves are depleted, glucose is synthesised from amino acids and non-hexose carbs
What is glycogenolysis
When blood glucose levels decline there is depolymerisation of glycogen to glucose
What does the liver do in terms of lipid metabolism
Convert products of carb metabolism to fatty acids and lipids that can be stored in adipose tissues
Synthesise large quantities of cholesterol and phospholipids.
What happens to protein in the liver.
The amine group is first converted into ammonia which is toxic and then converted to urea.
Urea is non toxic and excreted from the body by the kidneys (a component of urine)
What is transamination
Amine group can also be transferred via transamination to make new amino acids
What is the one protein in plasma that isn’t metabolised by the liver
Immunoglobulins
Where is the majority of liver blood supply received from
Venous- via hepatic portal vein
What do hepatocytes have to remove substances from blood
An array of transporters
What are the 2 main functions of bile
Important for digestion and absorption of fats and fat-soluble vitamins
Many waste products, including bilirubin are secreted into bile and excreted in the faeces
What does amphipathic mean and what does this mean for bile
Contains both hydrophilic and hydrophobic faces
Lipid centre with a hydrophilic outer layer.
How is bilirubin excreted.
Red blood cells are phagocytosed and haem is converted to bilirubin
Free bilirubin (stripped of albumin) is absorbed by hepatocytes and conjugated with glucuronic acid or sultanate
Conjugated bilirubin is secreted into bile and metabolised by bacteria in the intestine for elimination in faeces
How do secretions from the liver reach the small intestine
Through the sphincter of oddi
Functions of Exocrine pancreas
Digestive enzymes- protease, lipase and amylase
From exocrine acinar cells
Bicarbonate- From epithelial cells in pancreatic ducts
What 3 hormones control exocrine secretion
Cholecystokinin- from enteric endocrine cells in the proximal small intestine
Secretin- from endocrine cells in the epithelium of the proximal small intestine. Stimulates duct cells to secrete water and bicarbonate.
Gastrin – secreted by the stomach and stimulates pancreatic acinar cells to secrete enzymes
What innervates the pancreas
Sympathetic fibres from the splanchnic nerves
Parasympathetic fibres from the vagus
Function of alpha cells
Secrete glucagon
Function of Beta cells
Secrete insulin
Function fo Delta Cells
Secrete somatostatin
Function of PP cells
Secrete pancreatic polypeptide
How are alpha and beta cells arranged in the islet of langerhans
Alpha cells on the outside and Beta cells on the inside
What is the anatomy of the gallbladder
Fundus
Body
Neck
Bile duct
What innervates the gallbladder
The vagus nerve delivers parasympathetic innervation
The celiac plexus carries sympathetic and sensory fibres
What are the two types of gallstones
Cholesterol Stones- Yellow green
Pigment Stones- Smaller and darker
What are the innate immunity involvement of the liver
Production of acute phase proteins
Nonspecific phagocytosis
Nonspecific cell killing
Disposal of waste molecules
What is the adaptive immunity involvement of the liver.
Deletion of activated T cells
Induction of tolerance to ingested and self antigens
Extrathymic proliferation of T cells
Disposal of waste molecules
