THE NERVOUS SYSTEM
• Definition: A network of billions of nerve cells linked together to form the rapid control center of the body.
• Main function: Integrating center for homeostasis, movement, and almost all other body functions.
BASIC FUNCTIONS OF THE NERVOUS SYSTEM
1. Sensation• Monitors changes/events occurring in and outside the body. Such changes
are known as stimuli and the cells that monitor them are receptors.
2. Integration• Parallel processing and interpretation of sensory information to determine the
appropriate response
3. Reaction• Activation of muscles or glands (typically via the release of neurotransmitters
(NTs))
ORGANIZATION OF THE NERVOUS SYSTEM
1. Central Nervous System• The brain + the spinal cord• The center of integration and control
2. Peripheral Nervous System• Spinal nerves + Cranial nerves • The nervous system outside of the brain
and spinal cord
PERIPHERAL NERVOUS SYSTEM
• Responsible for communication between the CNS and the rest of the body.
• Can be divided into:• Sensory Division: Conducts impulses from receptors
to the CNS • Motor Division: Conducts impulses from CNS to
effectors (muscles/glands)
Can be divided further:• Somatic nervous system
• Autonomic nervous system
MOTOR DIVISION
• Somatic nervous system• VOLUNTARY (generally): Conducts impulses from the
CNS to skeletal muscles
• Autonomic nervous system• INVOLUNTARY (generally): Conducts impulses from the
CNS to smooth muscle, cardiac muscle, and glands.
NERVOUS TISSUE
2 cell types1. Neurons
• Functional, signal conducting cells
2. Neuroglia• Supporting cells
1.
2.
SENSORY NEURONS
Carries impulses from receptors e.g pain receptors in skin to the CNS (brain or spinal cord)
MOTOR NEURON
Carries impulses from CNS to effector e.g. muscle to bring about movement or gland to bring about secretion of hormone e.g LH
http://tle.westone.wa.gov.au/content/file/969144ed-0d3b-fa04-2e88-8b23de2a630c/1/human_bio_science_3b.zip/content/002_nervous_control/page_03.htm
The axon is only 10µm in diameter but can be up to 4m in length in a large animal!}
And in humans up to 1m large!
http://www.tokresource.org/tok_classes/biobiobio/biomenu/metathink/required_drawings/index.htm