The brain, spinal cord and the nerves are the components of the human nervous system. Human nervous system can be divided into Central Peripheral AutonomicNervous System Nervous Nervous System System CNS PNS ANS
The CNS is a delicate structure composed of BRAIN and SPINAL CORD. Protective membranes called MENINGES are present in the space between soft CNS and the bone. CRANIUM or the SKULL is a bony structure which protects the brain. VERTEBRAL COLUMN or the BACK BONE protects the spinal cord.
Different parts of brain Spinal cord Ventricles, central canal and spaces between meninges are filled with CEREBROSPINAL FLUID(CSF), keeping CNS nourished. It protecting CNS by absorbing mechanical shock.
NERVES All the nerves are included in the peripheral system. Forms a network and spreads throughout the body. Instrumental in connecting all parts of the body in CNS. On the basis of function, they are categorized as: afferent and efferent nerves. Afferent Nerves carry impulse: Sensory organs Brain. Efferent Nerves carry impulses: Brain Sensory organs.
NEURONS Direction of impulse Nucleus Dendrite s Nerves are composed of specialized cells- neurons capable of Cyton creating & (cell body) transmitting electronic impulses & neuroglia- supportive cells assisting neurons in Axon their function. To next neuron Axon ending
Neuron In accordance to their functions, NEURONS are classified into: Neurons Sensory Motor Association neurons neurons neuronsConducts impulses from Conducts impulses from Brain Perform integrative functions ofsense organs to Brain &spinal cord to effector organs, nervous system.&Spinal cord. i.e. muscles and glands
Peripheral Nervous System.(PNS) Voluntary actions involve our muscles. Brain sends message to the muscles & muscles act accordingly. This communication between the CNS and other parts of body is brought about by the PNS. Composed of CRANIAL NERVES arising from brain & SPINAL NERVES arising from spinal cord. or Medulla oblongata Cerebrum or forebrain is main thinking part of brain. Involuntary actions are controlled by mid-brain and hind brain(medulla oblongata). Cerebrum has regions which receive the sensory impulses from various receptors.
AUTONOMIC NERVOUS SYSTEM It is called as ANS. It comprises of all nerve present in the involuntary organs like heart , stomach , lungs , etc. Conducts impulses from CNS to cardiac muscles, smooth muscles and glands.
Left hemisphere of brain has 186 million more neurons than the right hemisphere. 750-1000 ml of blood flows through brain every minute. Brain can stay alive 4-6 min without oxygen. Albert Einsteins brain weighed 1230 gm., less than avg., weight of human brain-1300 to 1400 gm.