Reflex arcs Flashcards
What is a stimulus?
A detectable change in the internal of external environment of an organism
Stimuli are detected by …
Receptors
Name the structure labelled B on the diagram

Spinal cord
A response is produced by an ….
Effector
Give two examples of an effector
Gland or muscle
Name the type of neurone ahown on the diagram

Motor neurone
Name the strucutre labelled D on the diagram

Effector (in this case a muscle)
Give the sequence of events that lead from a stimulus to a response
Stimulus –> Receptor –> Coordinator–> Effector –> Response
The simplest type of nervous response is called a …
Reflex
The central nervous system consists of …
Brain and spinal cord
What is the function of a sensory neurone?
Carry electrical impulses from receptors to central nervous system
Name the neurone labelled C on the diagram

Motor neurone
What is the function of a motor neurone?
Carry electrical impulses from central nervous system to effectors.
Why are reflexes important?
Protect from danger
Maintain posture
Give two features of a reflex arc
Immediate - only 3 neurones involved. Minimum number of synapses
Specific - one stimulus leads to one response
Involuntary - happens without conscious though
Innate - present from birth
Name three receptors
Pacinian corpuscel
Rod cell
Cone cell
Thermoreceptor
Osmosreceptor
Chemoreceptor
Name the neurone labelled A on the diagram

Sensory neurone
When does the heart rate need to increase?
Exercise/increased muscle contraction
Fight or flight response
Name the receptors that detect and increase in carbon dioxide in the blood,.
Chemoreceptors
Where in the body are the chemoreceptors that detect an increase in carbon dioxide in the blood
Carotid arteries
Aortic arch
What effect does the sympathetic nervous system have on the rate rate?
Increases heart rate and stroke volume
What effect does noradrenaline have on the heart rate?
Increases heart rate
What effect does the parasympathetic system have on the heart rate?
Decreases heart rate
Name the neurotransmitters released by the sympathetic and parasympathetic system on the SAN
Sympathetic - noradrenaline
Parasympathetic - acetylcholine



