Blood glucose concentration

What is the set point for blood glucose concentration

80-120mg/100cm³

What is hypoglycaemia

When blood glucose concentration falls below about 72mg/100cm³

What can hypoglycaemia lead to

Fainting, may lead to convulsions and coma

What is hyperglycaemia

When blood glucose concentration is abnormally high (approx 126mg/100cm³

What does hyperglycaemia lead to

• decrease in blood water potential causing water to be drawn by osmosis out of the cells, tissue and tissue fluid

• Causes blood volume to increase so kidney increases urine output to compensate

• Person deprived of fluid, dehydration occurs and blood pressure decreases

How is glucose absorbed into the liver

Glucose absorbed across the epithelial cells of the villi and carried straight to the liver via the hepatic portal vein

How does the liver store glucose absorbed from the blood

As glycogen

Why are there spikes in blood glucose concentration

Not all the glucose can be removed immediately so there is an increase in blood glucose concentration after a carbohydrate meal has been eaten.

What are the Islets of Langerhans

• Patches of cells found within the pancreas

• Endocrine glands

• Made up of two types of cells - alpha (α) and beta (β) cells

What happens when blood glucose concentration increases

• Detected by the beta cells of the islets of Langerhans

• Secrete hormone insulin into the blood

Which receptor cell is responsible for detecting falls in blood glucose concentration

Beta cells in the islets of langerhams in the pancreas

What are endocrine glands

Hormone secreting cells

How are the Islets of Langerhans adapted to their function

They have a rich capillary supply to carry their secretions away

What are insulins main target organs (where are insulin receptors)

Liver and skeletal muscle, also in adipose tissue

What does insulin cause

• increase uptake of glucose

• Increased glycogenesis

• Increases glucose to fatty acids and lipids in liver cells

• Increases lipid deposits around the body

What is the name for the conversion of glucose to glycogen

Glycogenesis

What receptors cells are responsible for detecting falls in blood glucose concentration

Alpha cells in islets of Langerhans of pancreas

What happens when the apha cells detect a decrease in blood glucose concentration

• Alpha cells stimulated to secrete a hormone called glucagon

• Beta cells stop secreting insulin

• Glucose isn’t taken up as fast by cells

Where are glucagon receptors located

Different receptors in the cell surface membrane of liver cells

What does glucagon do

Stimulated the hydrolysis of glycogen into glucose which can be released into the blood

What is the name for the break down of glycogen into glucose

Glycogenolysis

What is the name for the making of new glucose from amino acids and lipids

Gluconeogenesis