Efferent Function of Sensory Nerves

Maggi. C.A. (1991) The pharmacology of the efferent function of sensory nerves./ Auton. Pharmacol.. 11,173 208. 

Fox AJ, Barnes PJ, Urban L, Dray A (1993) An in vitro study of the properties of single vagal afferents innervating guinea-pig airways. J Physiol (Lond) 469 21-35 Fox AJ, Barnes PJ, Venkatesan P, Belvisi MG (1997) Activation of large conductance potassium channels inhibits the afferent and efferent function of airway sensory nerves in the Guinea pig. JChn Invest 99 513-519... 

The somatic nervous system is composed of sensory afferents and motor efferents and serves to perceive external states and to modulate appropriate body responses. The autonomic nervous system (ANS), together with the endocrine system, controls the milieu interieur. It adjusts internal organ functions to the changing needs of the organism. The ANS operates largely autonomously, beyond voluntary control, at the subconscious level. Its central components reside in the hypothalamus, brain stem, and spinal cord. The ANS has sympathetic and parasympathetic branches. Both are made up of afferent, mainly in the vagus nerve, and efferent fibers. 

The nervous system can be divided into three parts the central nervous system (CNS), the peripheral nervous system (PNS), and the autonomic nervous system (ANS) (Dawson et al. 2003). The CNS consists of the brain and spinal cord. The PNS resides outside the CNS and forms a network to collect information from sensory responses. The ANS is identified by primary ganglia of the head and neck, sympathetic chain and adrenal gland (Gabella and Larry 2009). The primary function of the nervous system is to receive input from the environment and innervate muscle tissues in response. To accomplish this task, neurons, which are the basic unit of the functional nervous system (Dawson et al. 2003), form a highly specific interconnecting network from the brain to the spinal cord. There are 12 paired cranial nerve and 31 paired spinal nerve connections between the CNS and the PNS, which result in motor/ efferent, sensory/afferent, or mixed function. Furthermore, internal environments such as cardiorespiratory activities, glandular secretions, vasodilatation and genital erectile tissue responses are monitored by an array of visceral receptors, chemoreceptors, and stretch receptors via autonomic nerves from the CNS (Keller et al. 2009). 

The nervous system is divided into two parts the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists of all afferent (sensory) neurons, which carry nerve impulses into the CNS from sensory end organs in peripheral tissues, and all efferent (motor) neurons, which carry nerve impulses from the CNS to effector cells in peripheral tissues. The peripheral efferent system is further divided into the somatic nervous system and the autonomic nervous system. The effector cells innervated by the somatic nervous system are skeletal muscle cells. The autonomic nervous system innervates three types of effector cells (1) smooth muscle, (2) cardiac muscle, and (3) exocrine glands. While the somatic nervous system can function on a reflex basis, voluntary control of skeletal muscle is of primary importance. In contrast, in the autonomic nervous system voluntary control can be exerted, but reflex control is paramount. 

The nervous system (Fig. 1) consists of the central nervous system (CNS with brain and spinal cord) and the peripheral system (with afferent sensory and efferent motor nerves), which regulate all aspects of bodily function and is staggering in its complexicity. Another distinction is between the somatic (sensoric system, innervation of skeletal muscles) and the autonomic nervous system (heart and blood circulation respiration motility of the gastrointestinal tract, smooth muscles of gall and urinary bladder, ureter, uterus, secretion of glands). The autonomic nervous system is further divided into a sympathetic and... 

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