The Nervous System:
Neural Tissue
Introduction
Nervous vs Endocrine systems
Shared characteristics:
Chemical communication with targeted tissues
Nervous system:
Relatively swift but brief responses
Endocrine:
Slower but they often last much longer
An Overview of the Nervous System
Two anatomical subdivisions:
Central nervous system
(CNS)Brain and spinal cord
Integrating, processing, and coordinating
Intelligence, memory, learning, and emotion
Peripheral nervous system
(PNS)Neural tissue outside the CNS
Provides sensory information to the CNS
Carries motor commands to peripheral tissues
Subdivisions of the PNS
The PNS is subdivided into two divisions.
Afferent division
Somatic nervous system (SNS)
Autonomic nervous system (ANS)
Efferent division
Somatic nervous system (SNS)
Autonomic nervous system (ANS)
Nervous System Subdivisions Review
Cellular Organization in Neural Tissue
Neural tissue contains two distinct cell types:
Nerve cells, or neurons:
Are responsible for the transfer and processing of information in the nervous system.
Supporting cells, or neuroglia:
Isolate the neurons.
Typical Neuron
Neuroglia
Neuroglia of the CNS
Neuroglia of the PNS: Satellite Cells
Neuroglia of the PNS: Schwann Cells
Neuron Structure
Neuron Classification: Anatomical
Neuron Classification: Functional
Neurons have three functional groups:
Sensory neurons:
Most are pseudounipolar neurons.
Motor neurons:
Most are multipolar neurons.
Interneurons or association neurons:
Most are multipolar neurons.
Neuron Classification: Receptors
Receptors are monitored by the sensory neurons:
Exteroceptors = external environment:
Touch, temperature, and pressure sensations
Special senses of sight, smell, and hearing
Proprioceptors = internal environment:
Position and movement of skeletal muscles and joints
Information carried in somatic sensory neurons
Neuron Classification: Receptors
Interoceptors = internal environment:
Digestive, respiratory, cardiovascular, urinary, and reproductive systems
Sensations of deep pressure and pain
Neuron Classification: Functional
Types of Synapses
The Chemical Synapse
Neuronal Impulses
Action Potentials
Threshold stimulus
Sodium & Potassium
Speed of impulse
Myelinated neurons
Diameter of axon
Synapses
Axodendritic
Axosomatic
Axoaxonic
Neuroeffector – neuromuscular
Chemical vs Electrical
Neuron Organization and Processing
Anatomical Organization
of the Nervous System