The neural system of all animals is composed of highly specialized cells called neurons which can detect, receive and transmit different kinds of stimuli.
HUMAN NEURAL SYSTEM
The human neural system is divided into two parts:
- Central Nervous System (CNS): Includes the brain and the spinal cord and is the site of information processing and control.
- Peripheral Nervous System (PNS): Comprises of all the enrves of the body associated with the CNS.
The nerves of the PNS are of two types:
- Afferent fibres: Transmit impulses from tissues/organs to the CNS
- Efferent fibres: Transmit regulatory impulses from the CNS to the concerned peripheral tissues/organs.
The PNS is divided into:
- Somatic neural system: Relays impulses from the CNS to skeletal muscles
- Autonomic neural system: Transmits impulses from the CNS to the involuntary organs and the smooth muscles of the body. The autonomous neural system is further classified into sympathetic neural system and parasympathetic neural system.
The brain can be divided into three major parts:
- Forebrain: Consists of cerebrum, thalamus and hypothalamus. The cerebrum is longitudinally divided into halves that are connected by the corpus callosum. Hypothalamus controls the body temperature, eating and drinking. Inner parts of the cerebral hemispheres and a group of associated deep structures form a complex structure called limbic system which is concerned with olfaction, autonomic responses, regulation of sexual behaviour, expression of emotional reactions, and motivation.
- Midbrain: It receives and integrates visual, tactile and auditory inputs.
- Hindbrain: It comprises of pons, cerebellum and medulla. The cerebellum integrates information received from the semicircular canals of the ear and the auditory system. The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions. Pons consists of fibre tracts that interconnect different regions of the brain. The entire process of involuntary response to a peripheral nervous stimulation is called reflex action.
Information regarding changes in the environment is received by the CNS through the sensory organs which are processed and analyzed. Signals are then sent for the necessary adjustments.