lesson controls and conditions notes for board exam
Answers
A living being does not live in isolation. It has to constantly interact with its external environment and has to respond properly for its survival. For example; when a hungry lion spots a deer, the lion has to quickly make a move so that it can have its food. On the other hand, the deer needs to quickly make a move to run for its life. The responses which a living being makes in relation to external stimuli are controlled and coordinated by a system; especially in complex animals.
Human brain is a highly complex organ; which is mainly composed of the nervous tissue. The tissues are highly folded to accommodate a larger surface area in less space. The brain is covered by a three layered system of membranes; called meninges. Cerebrospinal fluid is filled between the meninges. The CSF provides cushion to the brain against mechanical shocks. Furthermore, the brain is housed inside the skull for optimum protection. The human brain can be divided into three regions, viz. forebrain, midbrain and hindbrain.