B5: HOMEOSTASIS + THE REFLEX ARC Flashcards
What is homeostasis?
regulation of the internal conditions of a cell/organism to maintain optimum conditions for function; in response to internal and external changes
What are 3 conditions controlled in the human body?
-temp
-water levels
-glucose conc. in the blood
What organ systems are involved in automatic control systems?
-nervous system
-endocrine system
What are the 3 components of automatic control systems?
-receptors
-coordination centres
-effectors
Receptors
detect stimuli (eg: cells in sense organs)
Coordination centres
receive and process stimuli (eg: brain, spinal cord, pancreas)
Effectors
respond to stimuli (eg: muscles, glands)
What does the nervous system do?
-detects stimuli and coordinates an appropriate response for survival
-enables humans to react to their surroundings
Adaptations of nerve cells
-branched connections - connect to other neurones to form a network
-long body (axon) - helps transmit signals over long distances in the body
-myelin - insulates axon to help transmit electrical signals
What is the reflex arc?
sensory neurone –> relay neurone –> motor neurone
What is a synapse?
-a gap/junction where there is a connection between neurones
-the nerve signal is transferred by chemicals which diffuse across the gap
What are reflex actions?
rapid, automatic responses to certain stimuli (that don’t involve the conscious part of the brain)
