Homeostasis Flashcards
Homeostasis (Definition)
A self-regulating process by which biological systems maintain stability while adjusting to changing external conditions.
Stimulus-response model
Stimulus => Receptor => CNS/ Endocrine system => Effector
=> Response
Stimulus
A stimulus is a change in the environment (either external or internal) that is detected by a receptor
Receptor
Receptors transform environmental stimuli into electrical nerve impulses
CNS/ Endocrine system
Electrical impulses sent from receptors are transmitted via neurons to the central nervous system where decision-making occurs and a response is selected consiously or unconsciously.
Effectors
Effectors are organs (either muscles or glands) that produce a response to a stimulus
Response
A response is a change in the organism resulting from the detection of a stimulus
Negative feedback
A cyclic process where responses counteract disturbances to keep concentrations of substances within narrow limits for optimal cell function.
Positive feedback
A cyclic process where responses reinforce and strengthen disturbances to normal cellular function. E.g. Ripening of fruit.
Chemoreceptor
Detects chemical stimuli such as pH, oxygen and concentrations.
Mechanoreceptor
Detects physical stimuli such as touch and sound.
Photoreceptor
Detects light
Nociceptor
Only detects intense (painful) chemical, thermal and mechanical stimulation.
Exteroceptor
Receives signals from outside the body like air, temperature, pressure, painful pressure or smells.
Interoceptors
Specifically receives signals from inside the body like body temperature, oxygen concentration or pH.
