Controlling our internal environment

Homeostasis - maintenance of a stable internal environment

Living cells can function within a narrow range of conditions of nutrient availability, temperature, pH and Ion conc.

Claude Bernard stated the body is constantly striving to maintain a stable, well balanced internal environment that is not affected a lot by outside influences

stable - conditions in our body fluctuate within a narrow range around an average called a set point.

negative feedback- maintains homeostasis by the body sensing a change and activates mechanisms to reverse that change. this involves a receptor, effector and efficient communication.

continuous monitoring of the factor being controlled produces adjustments of the output resulting in oscillations around the set point.

Claude Bernard conclueded the bosy must be under the control of one dtronf regulating control.

this is called the hypothalamus and contains receptors that monitor the blood and receives impulses from other body receptors.

ANS = autonomic nervous system

Two branches of the ans called sympathetic and parasympathetic and have opposite effects on the body. E.G....

• an impulse travelling along a sympathatic nerve to the liver would cause glucose to be released
• impulse along a parasympathetic branch would cause the liver to produce glucose slightly working with the endocrine system mo maintain blood glucose levels

Hypothalamus contains many receptors that monitor water potential and blood temperature.

the hypothalamus can control every endocrine gland in the body and alter blood pressure, body temperature, metabolism and adrenaline levels.