Chapter 18 — Neural Control and Coordination

Neural Control and Coordination covers how the neural system coordinates body functions through neurons, nerve impulses, and synapses. The brain controls voluntary movements, vital organs, and integrates sensory information through three major divisions: forebrain, midbrain, and hindbrain.

Chapter 18 explains the neural system's role in coordinating organ functions to maintain homeostasis. The human neural system divides into the central nervous system (brain and spinal cord) and peripheral nervous system (nerves). Neurons, the functional units, transmit impulses through the generation of action potentials caused by ion concentration gradients. The brain, protected by skull and meninges, controls voluntary movement, vital organ function, thermoregulation, sensory processing, memory, and behavior through three major regions: the forebrain (cerebrum, thalamus, hypothalamus), midbrain, and hindbrain (pons, cerebellum, medulla).

1. 01The neural system maintains homeostasis through coordination of organ systems via neurons that detect, receive, and transmit stimuli.
2. 02Neurons have three parts: cell body (with Nissl's granules), dendrites (transmit impulses toward cell body), and axon (transmit impulses away from cell body).
3. 03Nerve impulses are generated by ion channel permeability changes — Na⁺ influx depolarizes the membrane, while K⁺ efflux restores resting potential.
4. 04Synapses are junctions between neurons; chemical synapses use neurotransmitters released from synaptic vesicles to transmit impulses across the synaptic cleft.
5. 05The brain divides into forebrain (controls sensory/motor functions, temperature, eating, emotions), midbrain, and hindbrain (controls respiration, heart rate, balance).
6. 06Myelinated axons conduct impulses faster than unmyelinated axons due to myelin sheath insulation and nodes of Ranvier.