6. NERVOUS SYSTEM
The nervous system is the body’s control center, coordinating all activities by transmitting signals between different body parts. It consists of the central nervous system (CNS) and the peripheral nervous system (PNS).
| Central Nervous System (CNS): | The CNS comprises the brain and spinal cord. The brain processes and interprets sensory information, directs responses, and is responsible for higher cognitive functions like thinking, memory, and emotion. The spinal cord is a conduit for signals between the brain and the rest of the body and coordinates reflexes. |
| Peripheral Nervous System (PNS): | The PNS includes all the nerves outside the CNS. It is divided into the somatic nervous system, which controls voluntary movements and transmits sensory information, and the autonomic nervous system, which regulates involuntary functions such as heart rate, digestion, and respiration. The autonomic nervous system is further subdivided into the sympathetic and parasympathetic nervous systems, which have opposing effects on the body’s organs. |
| Neurons and Synapses: | Neurons are the basic functional units of the nervous system, responsible for transmitting signals throughout the body. They consist of a cell body, dendrites (which receive signals), and an axon (which sends signals). Synapses are the junctions between neurons where neurotransmitters are released to pass the signal from one neuron to another. |