Lecture 3 Homeostasis and Control Systems

Question 1

Claude Bernard (1857) definition of homeostasis

Answer 1

“It is the constancy of the internal environment that is the condition of free and independent life”

Question 2

Homeostasis

Answer 2

maintenance of a constant internal environment

Question 3

aims of negative feedback control

Answer 3

aims to maintain a controlled variable at its set point

Question 4

controlled variable

Answer 4

some aspect of the internal environment e.g. blood pressure, plasma [glucose] etc

Question 5

set point

Answer 5

value at which the variable should be maintained

Question 6

6 steps of negative feedback

Answer 6

1. change in variable
2. sensor (sensory receptor cells)
3. afferent pathways
   4.Integrating centre e.g CNS, endocrine gland
   5.efferent pathways
4. effector (muscle cells, secretory cells)

Question 7

Integrating Centre

Answer 7

Processes information from sensor and causes change through effector

Question 8

afferent pathway

Answer 8

carry nerve impulses into the central nervous system

Question 9

efferent pathway

Answer 9

carry nerve impulses away from the central nervous system to effectors

Question 10

effector

Answer 10

mechanism that brings about change
usually a muscle or gland