PERIPHERAL NERVOUS SYSTEM
• The spinal cord is a long bundle of neurons that serves two vital functions
the nervous system. Look at the cross-section of the spinal cord in fig
spinal cord
• a long bundle of neurons that carries messages between the body and
brain and is responsible for very fast, life saving reflexes.
• Notice that it seems to be divided into two areas, a lighter outer section a
darker inner section. If it were a real spinal cord, the outer section wo
appear to be white and the inner section would seem gray. That’s because
outer section is composed mainly of myelinated axons and nerves, w
appear white, whereas the inner section is mainly composed of cell bodie
neurons, which appear gray. The purpose of the outer section is to c
messages from the body up to the brain and from the brain down to the b
In some ways, it serves as a message “pipeline.”
,CROSS SECTION OF SPINAL CORD
, • This part of the spinal cord is responsible for certain reflexes—very fast
lifesaving reflexes.
• To understand how the spinal cord reflexes work, it is important to know
there are
• three basic types of neurons: afferent (sensory) neurons that carry
messages from the senses to the spinal cord,
• efferent (motor) neurons that carry messages from the spinal cord to t
muscles and glands, and
• interneurons that connect the afferent neurons to the efferent neurons
(and make up the inside of the spinal cord and much of the brain itself)
• The spinal cord is a long bundle of neurons that serves two vital functions
the nervous system. Look at the cross-section of the spinal cord in fig
spinal cord
• a long bundle of neurons that carries messages between the body and
brain and is responsible for very fast, life saving reflexes.
• Notice that it seems to be divided into two areas, a lighter outer section a
darker inner section. If it were a real spinal cord, the outer section wo
appear to be white and the inner section would seem gray. That’s because
outer section is composed mainly of myelinated axons and nerves, w
appear white, whereas the inner section is mainly composed of cell bodie
neurons, which appear gray. The purpose of the outer section is to c
messages from the body up to the brain and from the brain down to the b
In some ways, it serves as a message “pipeline.”
,CROSS SECTION OF SPINAL CORD
, • This part of the spinal cord is responsible for certain reflexes—very fast
lifesaving reflexes.
• To understand how the spinal cord reflexes work, it is important to know
there are
• three basic types of neurons: afferent (sensory) neurons that carry
messages from the senses to the spinal cord,
• efferent (motor) neurons that carry messages from the spinal cord to t
muscles and glands, and
• interneurons that connect the afferent neurons to the efferent neurons
(and make up the inside of the spinal cord and much of the brain itself)
