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.
Gland
An organ that secretes chemicals or proteins within the body or externally.
Motor neuron
A cell that transmits nerve impulses from the CNS to an effector.
Endocrine gland
A gland that secretes substances directly into the bloodstream.
Exocrine gland
A gland that secretes substances onto an external surface or body tract.
Metabolism
A sum of all chemical reactions that maintain life within an organism.
Catabolic reactions
A reaction that involves the breakdown of complex molecules into simpler products.
Anabolic reactions
A reaction that builds complex molecules from simple molecules.
Tolerance limits
Range/ limit an organism can function in.
