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
Bundles of axons in the CNS are called
tracts
Endoneurium:
Surrounds individual fibers within a nerve
Perineurium:
Surrounds a group (fascicle) of nerve fibers
Epineurium:
Surrounds the entire nerve
Definition of a nerve impulse
nerve impulse is a self-propagating wave of electrical disturbance that travels along the surface of a neuron’s plasma membrane.
Nerve impulses are also called
action potentials
The synapse:
a synapse is the place where impulsesare transmitted from one neuron, called the presynaptic neuron, to another neuron, called the postsynaptic neuron.
Synapse is made up of three structures
Synaptic knob, Synaptic cleft, Plasma membrane
Neurotransmitters
are chemicals by which neurons communicate.
The brain and the spinal cord are protected by three membranes called
meninges.
Consists of three parts of brain, named in ascending order
Medulla oblongata, Pons, Midbrain
Cerebellum
Second largest part of the human brain
Helps control muscle contractions to produce coordinated movements for maintaining balance, moving smoothly, and sustaining normal postures
Thalamus
Dumbbell-shaped mass of gray matter extending toward each cerebral hemisphere
Pineal gland (pineal body)
Small body resembling a pine nut behind the thalamus
Cerebrum
Largest and uppermost part of the brain .
