chapter 9 nervous system Flashcards
The nervous system is divided into two principal divisions
central nervous system (CNS) and peripheral nervous system (PNS).
Central nervous system (CNS) include the
brain and spinal cord
peripheral nervous system (PNS) includes all
nerves
Autonomic nervous system (ANS)
consists of structures that regulate the body’s automatic or involuntary functions
Two major types of cells are found in nervous tissue:
neurons or nerve cells and glia, which are support cells. Neurons conduct impulses, whereas glia support neurons.
Dendrites:
Branching projections that conduct impulses to cell body of neuron
Axon:
Elongated projection that conducts impulses away from cell body of neuron.
Axon is surrounded by a segmented wrapping of a material called
myelin
Sensory (afferent) neurons:
carry impulses to the spinal cord and brain from all parts of the body. Sensory neurons are also called afferent neurons.
Motor (efferent) neurons:
Conduct impulses away from brain and spinal cord to muscles and glands. Motor neurons are also called efferent neurons.
interneurons:
Conduct impulses from sensory neurons to motor neurons or among a network of interneurons; also known as central or connecting neurons
Glia (neuroglia)
One function of glial cells is to hold the functioning neurons together and protect them.
Astrocytes:
Star-shaped cells that anchor small blood vessels to neurons
Microglia:
Small cells that move in inflamed brain tissue carrying on phagocytosis
Oligodendrocytes:
Form myelin sheaths on axons in the CNS