6.4.1 Principles of Homeostasis and Feedback Mechanisms Flashcards
Define homeostasis
Maintenance of constant internal environment within restricted limits
What does homeostasis ensure? Give two reasons this is important.
Ensures tissue fluid is kept at optimum conditions which enables normal cell function and prevents cell damage
What is dynamic equilibrium?
Small fluctuations about optimum level
What causes dynamic equilibrium?
Due to activity in cells, the environment constantly changing so homeostasis needs to make adjustments continually to bring back all factors to correct level
Give three examples of things homeostasis controls.
Blood pH
Blood glucose conc
Body temperature
Define endotherm
Organism that can use internal sources of heat to maintain body temp, also uses behavioural mechanisms as well as physiological ones
Define ectotherm
Organism that relies on external sources of heat to regulate body temp, uses behavioural mechanisms for heat absorption
Define negative feedback
Reversal of a change to a steady state or optimum position
Describe the process of negative feedback (3)
Change to internal environment detected by receptors
Change signalled to other cells by communication system (usually different parts of the brain)
Effector responds to reverses change
Define positive feedback
Continuing in the direction of change
How can the process of positive feedback be both beneficial and harmful to the body?
Hypothermia- body temp falls below 35°C, normal negative feedback falls as molecules have less kinetic energy and metabolic reactions slow down, respiration slows so less heat energy generated and body temp falls further
Blood vessel repair- Damage to blood vessels, clotting by platelets that release chemicals, more platelets arrive
What is the main difference between negative and positive feedback?
Negative reduces change so less product, positive ampifies change so more product
