Homeostasis Flashcards
What is a set point?
A value at which a variable must be maintained to maintain homeostasis
What is the set point for temperature?
37 degrees
What is the set point for pH?
7.4
What is the set point for plasma glucose?
5.5mM
What is the set point for blood pressure?
120/80mmHg
What is the set point for plasma osmolality?
300osmoles/kg
What are the set points for PO2 and PCO2?
PO2 = 100mmHg PCO2 = 40mmHg
What happens when a variable deviates from the set point?
There is an error signal that activates a homeostatic mechanism to apply compensation
What is a closed loop system?
When the change from the set point causes an error signal which activates a homeostatic mechanism which applies compensation and makes the variable back to set point and the changing of the variable back to set point then causes a negative feedback mechanism on the error signal and homeostatic mechanism
What part of the brain is known as the homeostatic centre?
The hypothalamus
What 4 things does the hypothalamus control?
- Body temperature
- Plasma osmolality
- Appetite/thirst
- Hormone release
How does the ANS control homeostasis?
Through autonomic reflexes and hormones
What two hormones are involved in regulating plasma glucose levels?
Insulin and glucagon
What happens when plasma glucose exceeds 5.5mM?
Increased insulin secretion leads to an increased uptake of glucose into the tissue particullary by the liver in order to lower it back down to 5.5mM
What happens when plasma glucose drops below 5.5mM?
Increase glucagon secretion leads to an increased release of glucose from the tissues espiecally the liver to raise plasma glucose back to 5.5mM
What is low plasma glucose called?
Hypoglycemia
What is high plasma glucose called?
Hyperglycemia