Anatomy and function of the pancreas and liver Flashcards
(11 cards)
Endocrine function of the pancreas
Secretes hormones directly into the blood to control blood sugar levels
Islets of Langerhans secrete insulin and glucagon
Insulin is secreted by beta cells and lowers blood sugar by promoting glucose uptake and storage
Glucagon is secreted by alpha cells and raises blood sugar by stimulating glycogen breakdown
Somatostatin is secreted by delta cells and inhibits both insulin and glucagon secretion
Anabolic definition
A type of metabolic pathway that utilises energy to build up complex molecules from smaller ones
Insulin key points
Insulin is secreted from the B-cells of the Islets of Langerhans in response to high blood glucose
Glucose uptake via Glut transporters
Anabolic reactions with target cells (liver, skeletal muscle and adipose tissue)
Promotes the synthesis of protein and glycogen
Glucagon key points
Low blood glucose is detected by the alpha cells in the Islets of Langerhans
Glucagon release
Targets the brain, pancreas, liver, fat and heart
Leads to the breakdown of substrates (catabolism)
Produces energy
Exocrine function of the pancreas
Secretes digestive juices and enzymes into a duct to digest food directly
Acini cells produce and release digestive enzymes and juices into ducts leading to the duodenum
Key pancreatic enzymes and their roles
Amylase breaks down carbohydrate into sugars
Proteases (trypsin and chymotrypsin) break down proteins and protect against pathogens
Lipases work with bile to break down fats enabling the absorption of fat-soluble vitamins
Waters & salts help dissolve and transport enzymes
Regulation of exocrine pancreatic function
Parasympathetic nervous system stimulates enzyme release during digestion, this aligns with the cephalic and gastric phases
Hormonal regulation via secretin which stimulates bicarbonate rich juice
Cholecystokinin (CCK) which stimulates enzyme rich juice for fat and protein digestion
Secretin and CCK release in response to chyme entering the duodenum, released from enteroendocrine cells (EECs)
Functions of the liver
Metabolism of carbohydrates to store and release glucose for blood sugar balance
Metabolises fatty acids for energy and produces lipids
Processes amino acids, converting ammonia to urea for excretion
Production of bilirubin for bile formation to emulsify fats
Storage of vitamins, iron, copper, retains fatty acids from triglycerides
Detoxification - filters toxins to prevent entry to the blood stream, metabolises drugs into inactive forms, removes excess hormones from circulation
What happens in diabetes?
Insulin deficiency increases protein breakdown, more amino acids in plasma, loss through urination resulting in dehydration and acidosis and in extreme cases coma and death
Decreased glucose uptake increases glucose plasma concentrations which can result in glycosuria, osmotic diuresis and electrolyte loss
Also increase in fat breakdown so increase in plasma fatty acid concentration which can result is ketosis (where the body uses fat for fuel instead of carbohydrates, causes dehydration, nutrient deficiencies, constipation/diarrhoea and potential cardiovascular problems)
Types of diabetes
Type 1 - from birth, a lack of insulin
Type 2 - mature onset, insulin resistance
Net result of both is that no glucose can enter cells resulting in high blood sugar
Glucagon and insulin are antagonistic hormones
Interplay between diabetes and liver function
The liver is a primary target of insulin
In type 2 diabetes where there’s insulin resistance, hepatocytes become resistant to insulin leading to high blood pressure
The liver overproduces glucose contributing to hyperglycaemia
Non-alcoholic fatty liver disease (NAFLD) is caused by fat build up in the liver due to insulin resistance
It can progress to severe conditions like non-alcoholic steatohepatitis (NASH), cirrhosis and liver failure
