5.1 Communication And Homeostasis Flashcards
Define cell signalling
The way in which cells communicate with each other
Define effector
A cell, tissue or organ that brings about a response
Define homeostasis
Maintaining a constant internal environment despite changes in external and internal factors
Define negative feedback
The mechanism that reverses a change, bringing the system back to optimum
Define positive feedback
The mechanism that increases a change, taking the system further away from the optimum
Define sensory receptors
Cells/sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials
Define ectotherm
An organism that relies on external sources of heat to maintain body temperature
What does homeostasis control?
Body temp Blood glucose Blood salt Water potential of blood Blood pressure Carbon dioxide concentration
Examples of positive feedback
Activity of neurons
oxytocin and cervical dilation
Advantages of ectotherms
less food is used in respiration
more energy and nutrients for growth
need to find less food
can survive for long periods without food
Disadvantages of ectotherms
Less active in cooler temperatures
Define hypothalamus
the part of the brain that coordinates homeostatic responses
