THE NERVOUS SYSTEM
• The nervous system is the master controlling and communicating system of body
• Cells communicate via electrical and chemical signals
o Rapid and specific
o Usually cause almost immediate responses
• The nervous system has three overlapping functions:
1. Sensory input
▪ Information gathered by sensory receptors about internal and external changes
2. Integration
▪ Processing and interpretation of sensory input
3. Motor output
▪ Activation of effector organs (muscles and glands) produces a response
• The nervous system is divided into two principal parts:
o Central nervous system
▪ Brain and spinal cord of dorsal body cavity
▪ Integration and control center
• Interprets sensory input and dictates motor output
o Peripheral nervous system (PNS)
▪ The portion of nervous system outside CNS
▪ Consists mainly of nerves that extend from brain and spinal cord
• Spinal nerves to and from spinal cord
• Cranial nerves to and from brain
• The peripheral nervous system (PNS) has two functional divisions
o Sensory (afferent) division
▪ Somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints to CNS
▪ Visceral sensory fibers: convey impulses from visceral organs to CNS
• The nervous system is the master controlling and communicating system of body
• Cells communicate via electrical and chemical signals
o Rapid and specific
o Usually cause almost immediate responses
• The nervous system has three overlapping functions:
1. Sensory input
▪ Information gathered by sensory receptors about internal and external changes
2. Integration
▪ Processing and interpretation of sensory input
3. Motor output
▪ Activation of effector organs (muscles and glands) produces a response
• The nervous system is divided into two principal parts:
o Central nervous system
▪ Brain and spinal cord of dorsal body cavity
▪ Integration and control center
• Interprets sensory input and dictates motor output
o Peripheral nervous system (PNS)
▪ The portion of nervous system outside CNS
▪ Consists mainly of nerves that extend from brain and spinal cord
• Spinal nerves to and from spinal cord
• Cranial nerves to and from brain
• The peripheral nervous system (PNS) has two functional divisions
o Sensory (afferent) division
▪ Somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints to CNS
▪ Visceral sensory fibers: convey impulses from visceral organs to CNS
