Lab3: Glucose Homeostasis Flashcards
What is homeostasis?
Maintence of a dynamically-stable internal environment
What is a homeostatic control system?
A network of body components working to maintain a regulated variable relatively constant within an acceptable range around its setpoint.
What is the job of a sensor?
Alters its activity to report changes in the regulated variable
Which direction do afferent and efferent pathways go?
An afferent pathway is traveling towards the brain/intergrator, the efferent pathway is going towards the target
What is feedforward control?
Used for responses made in anticipation of change
What is negative feedback?
A change in a homeostatically-regulated variable triggers a response that acts to restore the regulated variable to its setpoint
What is positive feedback?
Acts to enhance or amplify the change so the regulated variable continues to move in the same direction of the inital change.
What is tonic control?
There is a single controller regulating a physiological parameter in an up-down fashion.
Like the volume control on a radio. The radio is always on, but you can make the sound level louder or softer
What is antagonistic control?
Uses 2 different controllers
For example, the sympathetic branch of the ANS incr. heart rate whereas the PNS decr. heart rate
What happens when blood glucose levels decrease?
Alpha cells in the pancrease sense this change and release the hormone glucagon. Glucagon binds to receptors in the liver and activates the breakdown of glycogen into glucose through glycogenolysis.
What happens when blood glucose levels increase?
Beta cells in the pancreas sense the change and release the hormone insulin. Insulin binds to receptors and causes GLUT transporter proteins to move to the membrane of cells and transport glucose from the blood.
How do the kidneys filter glucose?
Normally, all glucose that is filtered into the kidneys is reabsorbed via the sodium-glucose linked transporter. However, if the concentration of glucose saturates the transporter, excess glucose will be excreted in the urine and can cause dehydration.
What is stress hyperglycemia?
A temporary elevation of the blood glucose due to the stress of an illness.
