natremia The presence of sodium ions in the blood. Derived terms . dysnatremia; hypernatremia; hyponatremia; natremic; Translations
A reflex arc is a nerve pathway in the body of humans and some animals that connects certain muscle groups to others, without involving the brain. These sorts of pathways primarily control involuntary movements in response to some sort of stimulus.
Reflex arc. Reflex reactions in humans are controlled by the reflex arc. When the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neuron, via a relay neurone, to a motor neurone for instant, unthinking action. This is a reflex action.A reflex arc is the nerve pathway which makes such a fast, automatic response possible. It does not matter how brainy you are-you will always pull your hand away from a flame without thinking about it. It is in-built, or innate, behaviour, and we all behave in the same way.hen the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neuron, via a relay neurone, to a motor neurone for instant, unthinking action. This is a reflex action. A reflex arc is the nerve pathway which makes such a fast, automatic response possible.