First, the CNS consists of only the brain and the spinal cord, while the PNS consists of the network of nerves located outside the CNS.
The PNS performs both an afferent and an efferent function.
The afferent (sensory) function means providing the CNS with information about the external world and the body's internal environment.
The efferent (motor) function means conveying information from the CNS to the muscles, organs and glands of the body.
So how do the two nervous systems work together?
Imagine that heat-sensing receptors in the skin have detected a cool change in your external environment (a cold wind has just picked, it has started raining, a dark cloud has moved over the sun). Information in the form of nerve impulses is conveyed to the CNS via afferent (sensory) neurons, which are part of the PNS, to alert the brain to a drop in temperature of the cells of the body. Nerve impulses are then sent from the CNS to skeletal muscles (via the efferent function of the PNS) to activate the shivering mechanism. Shivering generates heat, and body temperature rises, all as a result of the interaction between the CNS and the PNS!
The PNS performs both an afferent and an efferent function.
The afferent (sensory) function means providing the CNS with information about the external world and the body's internal environment.
The efferent (motor) function means conveying information from the CNS to the muscles, organs and glands of the body.
So how do the two nervous systems work together?
Imagine that heat-sensing receptors in the skin have detected a cool change in your external environment (a cold wind has just picked, it has started raining, a dark cloud has moved over the sun). Information in the form of nerve impulses is conveyed to the CNS via afferent (sensory) neurons, which are part of the PNS, to alert the brain to a drop in temperature of the cells of the body. Nerve impulses are then sent from the CNS to skeletal muscles (via the efferent function of the PNS) to activate the shivering mechanism. Shivering generates heat, and body temperature rises, all as a result of the interaction between the CNS and the PNS!
