6C: Regulation of blood glucose Flashcards
- Define the following: • Alpha cells • Beta cells • Islets of Langerhans • Glucose • Glycogen • Glycogenesis • Glycogenolysis • Insulin • Glucagon - Describe the homeostatic mechanisms used when blood glucose is high. -Describe the homeostatic mechanisms used when blood glucose is low.
When talking about glucose levels we are usually referring to
Blood glucose
Glucose from food
carbohydrates are broken down into glucose–>glucose in the small intestine–>transported in blood via glucose transporters
Glucose–>Skeletal muscle
burned immediately, stored as glycogen
Glucose–>liver
burned immediately, stored as glycogen
Glucose–>Adipose tissue
stored as fat (adipose tissue)(glucose will need to be converted into triglycerides in order to become fat)
Glycogenesis
glucose–>glycogen
Glycogenolysis
Glycogen–>glucose
Hyperglycaemia
high blood sugar/glucose
Normal levels of blood glucose
normal levels of blood glucose (optimal)
Hypoglycemia
low levels of blood sugar/glucose
Pancreas is made up of a clump of cells called
The islet of Langerhans
Two types of cells inside the islet of Langerhans are
Beta cells and Alpha cells
Alpha and Beta cells control
blood glucose
-gallbladder is connected to the pancreas (not relevant to topic above)
K
Insulin
secreted by beta cells in the pancreas when blood glucose is elevated
Glucagon
secreted by alpha cells in the pancreas when blood glucose is low
Stimulus response model for increased blood glucose levels
-Normal glucose levels (blood glucose)–>increase of glucose–>hyperglycemia–>pancreas (pancreatic beta cells release insulin)–>cells (insulin stimulates glucose uptake by cells) AND Liver (insulin stimulates glycogenesis (glucose–>glycogen) in the liver)–>Plasma glucose returns to normal levels
Increased blood glucose can be due to
increased carbs/sugars from eating food, etc
Stimulus response model for decreased blood glucose levels
-Normal glucose levels (blood/0 glucose)–>decreased glucose–>Hypoglycemia–>pancreas (pancreatic alpha cells release glucagon)–>liver (glucagon stimulates gluconeogenesis and glycogenolysis (glycogen–>glucose) in liver and release of glucose to plasma)–>plasma glucose returns to normal levels
Stimulus response overview
)stimulus (increase or decrease of glucose)
)receptor (pancreas)
)modulator (pancrease)
)effector (liver and cells (cells only for increase of glucose (hyperglycemia)))
)response (glycogenolysis or glycogenesis)
)feedback (negative –> increase/decrease of blood glucose to normal levels)
Paragraph on when blood sugar is high
-The increase of blood glucose results in hyperglycemia. In order to counteract this stimulus via homeostasis we require a receptor that is the pancreas. From the pancrease (also the modulator) pancreatic beta cells release insulin that proceed to two location. One of which being cells to which insulin stimulates glucose uptake by cells, the other being the liver to which insulin glycogenesis (the process of which glucose in turned into glycogen) within the liver. This results in the plasma glucose levels returning to an optimal/normal level.
Paragraph of when blood sugar is low
-The decrease of blood glucose results in hypoglycemia. In order to counteract this stimulus via homeostasis we require a receptor that is the pancreas. From the pancrease (also the modulator) pancreatic alpha cells release glucagon. This proceeds to the liver in which glucagon stimulates gluconeogenesis and glycogenolysis (glycogen–>glucose) in liver and release of glucose to plasma. This results in plasma glucose returning to a normal level.
