Chapter 13: Organization and Control of Neural Function

Organization and Control of Neural Function comprehensively details the organization and control mechanisms of neural function, beginning with the cellular basis of the nervous system: highly excitable neurons, responsible for signaling, and supportive neuroglial cells (including oligodendrocytes in the CNS and Schwann cells in the PNS, which form myelin). Nervous tissue is metabolically demanding, requiring high rates of oxygen consumption and relying primarily on circulating glucose for fuel. Neural communication is achieved through action potentials, which involve rapid changes in membrane potential driven by ion channel activity, moving sequentially through resting potential, depolarization (sodium influx), and repolarization (potassium efflux). Synapses allow communication between neurons, relying on chemical messengers called neurotransmitters; the net effect on the postsynaptic neuron is determined by the integration (spatial and temporal summation) of opposing excitatory (EPSPs) and inhibitory (IPSPs) graded potentials. Structurally, the central nervous system (CNS) develops from the embryonic neural tube, forming the spinal cord (organized into dorsal and ventral horns for afferent and efferent pathways, respectively) and the three major brain divisions: the hindbrain (medulla, pons, cerebellum), midbrain, and forebrain (diencephalon and cerebral hemispheres). Protection is afforded by the meninges and cerebrospinal fluid (CSF), which is circulated through the ventricular system and maintained by the blood-brain barrier. Finally, the Autonomic Nervous System (ANS) manages visceral homeostasis through two opposing systems: the sympathetic (fight-or-flight, utilizing norepinephrine) and the parasympathetic (rest-and-digest, utilizing acetylcholine). These neurotransmitters exert their effects by binding to specific receptor classes, such as cholinergic (nicotinic and muscarinic) or adrenergic (alpha and beta) receptors.