B10 Nervous System Flashcards
Examples of controlled human internal conditions
Blood pressure
Body temperature
Water balance
Homeostasis
Process when body maintains stable internal environment
Internal conditions need to be maintained
To allow enzymes to function efficiently
If internal environment isn’t maintained enzymes become denatured
Pathway of control system
Receptor ——> coordination centre —–> effector
Receptor
Detects change in the environment (temperature)
Coordination centre
Processes information from receptor and sends instructions
Effector
Responds to instructions and brings about a change to restore balance
e.g. sweat glands produce sweat to cool body
Enzymes are essential
For metabolism
Drugs which effect homeostasis
Stimulants, depressants, diuretics
Stimulants
(Caffeine) can increase heart rate and blood pressure disrupting homeostasis
Depressants
Alcohol - can slow down nervous system affect coordination and reaction times
Diuretics
Cause increased urine production, disrupting water balance in the body
Stimuli, receptors, coordination centres and effectors in examples of nervous and chemical responses
Example (hot object)
Stimulus - heat
Receptors - thermorereceptors in skin
Coordination centre - brain or spinal cord
Effector - muscles
Differences between nervous and chemical responses
Nervous responses are fast and involve electrical impulses traveling through neurons
Chemical responses are slower and involve chemicals released in bloodstream
Nose and tongue
Chemicals (smell, taste)
Pathway of impulses from receptor to effector
Receptor - detects stimulus
Sensory neuron - transmits impulse to central nervous system (CNS)
CNS process information and sends impulse through motor neuron to effector
How the nervous system coordinates a response
Nervous system detects a stimulus through receptors and sends electrical impulses by neurons
CNS process information and sends insturctions to effectors
Neurone
Single nerve cell that transmits electrical impulses
Nerve
A bundle of neurons that transmit signals between the central nervous system and rest of the body
How information is passed along neurones
In the form of electrical impulses
These impulses travel along axon of neurone and passed to next neurone or effector across synapse
Reflex reactions
Automatic responses to stimuli
(Blinking, pull hand away from something hot)
How reflex actions are fast and automatic
They involve spinal cord (not brain) reducing time taken to process infromation
How impulses travel across a synapse
At a synapse, the electrical impulse triggers release of chemicals (neurotransmitters) from the end of one neuron
These chemicals diffuse across synaptic gap and bind to receptors on next neurone, triggering new electrical impulse
Why reflex actions are important
They protect body from danger by quick, automatic responses without conscious thought
Apply knowledge of synapses to explain the effects of drugs
Certain drugs can increase or decrease the activity of neurotransmitters at synapses
stimulants may increase neurotransmitter release, speeding up synaptic transmission, while depressants slow down the transmission by reducing neurotransmitter release.
order the events involved in a reflex action
Stimulus detected by receptor
Sensory neuron transmits impulse to spinal cord
Impulse travels through a relay neuron
Motor neuron transmits impulse to effector
Effector (e.g., muscle) carries out the response.
describe the function of synapses
to allow electrical impulses to be passed between neurons
They also ensure that impulses travel in one direction only and enable integration
