Final answer:
Cephalization refers to the development of nervous structures and functions in an organism's head region, which is seen as an evolutionary trend to improve sensory and neural functions. The term is related to the study of the central nervous system, comprising the brain and spinal cord, which coordinate sensory information, voluntary actions, and reflexes. The correct option is (5)
Step-by-step explanation:
The term that refers to the concentration of nervous structures and functions in the head region is cephalization. This biological concept is particularly relevant to the study of animal evolution and development, where it indicates the trend in the evolution of the nervous system where the head end of an organism contains the central nerve organs, enhancing sensory and neural functions.
The central nervous system (CNS) consists of two main structures: the brain and the spinal cord. The brain is responsible for integrating most sensory information and coordinating body function, both consciously and unconsciously. It is protected by the skull as well as three membranes called meninges, and it is further cushioned by cerebrospinal fluid. Within the brain, we find different regions with specific functions. The cerebrum, which is the largest part, controls voluntary actions and is divided into lobes, each with its task, like the frontal lobe that is associated with reasoning and planning. Other significant regions of the brain include the diencephalon, the brain stem, and the cerebellum.
The spinal cord is another major part of the CNS housed within the vertebral column. It acts as an information superhighway between the brain and the body, transmitting sensory and motor signals. It is also responsible for coordinating reflexes. The spinal cord retains a tubular structure from its embryonic development, with the central canal filled with cerebrospinal fluid.