the Human Nervous System

the human
NERVOUS SYSTEM



ROLE → CNS = central nervous system
• receives, transmits and integrates internal
and external information based on which
it develops appropriate answers
• controls the body’s actions and sensations
• coordinates thinking, emotions, memory


SYSTEMS
• Central Nervous System (CNS)
- Structure: Brain & Spinal Cord
• Peripheral Nervous System (PNS)
- Structure: Nerves




the NEURON




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, STRUCTURE
➢ Cell Body
- cell membrane + cytoplasm
 Forms the gray substance of the NS in which the nerve cells are located
➢ Neural Extensions
- dendrite + axon (it ends with the terminal buttons)
 forms the white substance of the NS in which the nerve impulse
conduction
 pathways are located


PROPERTIES

A. Excitability
 The property of the neuron to respond through
specific manifestations (nerve impulses) DENDRITE
when stimulated
CELL BODY
B. Conductibility
 The property of the neuron to conduct nerve AXON
impulses. They are unidirectional due to the synapses


TYPES OF NEURONS
According to the functions they perform, neurons can be:
▪ SENSORY – they take the impulses from
the sense organs and transmit them to
the nervous centers

▪ MOTOR – they transmit commands to
effectors (muscles and glands)

▪ INTERNEURONS – they connect the sensory
neurons to the motor neurons
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