Nervous System I Flashcards
What are the functions of the nervous system?
receives environmental stimuli from receptors, transmits information to effectors, regulates internal environment, storage site for information
What are the two subdivisions of the nervous system?
central nervous system, peripheral nervous system
what two systems is the peripheral nervous system divided into?
the somatic nervous system, and autonomic nervous system
what does the CNS contain?
brain and spinal cord, enclosed by bone
what does the PNS contain?
cranial nerves and spinal nerves
what is a neuron?
the basic functional unit of the nervous system
What is the soma? what does it contain?
the cell body of a neuron, contains nucleus and metabolic machinery
What is the function of dendrites?
receive neurotransmitters from other neurons at synapses, transmits information to cell body via graded potentials
what is an axon?
long cytoplasmic process that transmits action potentials over long distances (up to one meter)
what are telodendria?
terminal branches of axon (ending in terminal button) that release at synapses
what are action potentials?
nerve impulses
What are the three types of neurons?
bipolar, unipolar, multipolar
What is the structure of bipolar neurons? give an example.
soma located near the middle of the axon.
e.x. retinal neurons
What is the structure of unipolar neurons? give an example.
soma lies off to one side of the axon
e.x. sensory neurons
What is the structure of multipolar neurons? give an example.
soma lies very close to dendrites (e.x. motor neurons)
What is the function of afferent (sensory) neurons?
carry impulses from receptor cells to the CNS (pain or thermal receptors etc.)
what is the function of efferent (motor) neurons?
carry impulses from the CNS to effectors (muscles or glands)
what is a nerve?
cord like structure containing many axons within the PNS
Nerves are surrounded by _________
epineurium (connective tissue layer)
bundles of axons are surrounded by ________
perineurium (connective tissue layer)
axons are surrounded by _________
endoneurium (connective tissue layer)
what is a tract?
bundle of axons connecting different parts of the CNS
what is a ganglion? give an example
a cluster of neural cell bodies of the PNS (dorsal root ganglion)
what is the nucleus? give an example
a cluster of neural cell bodies of the CNS (thalamus)
The spinal cord occupies the ____________ canal of vertebrae
vertebral (neural)
Where does the spinal cord begin?
foramen magnum of the skull
where does the spinal cord end in humans?
lumbar region (L1-L2) continues as collection of spinal nerves
__________ and _________ rootlets emerge from spinal cord
dorsal and ventral
spinal nerves exit the spinal cord via the ___________ foramina then divide into the_________ and ________ rami
intervertebral, dorsal, ventral
what is metamerism?
segmentation
Spinal nerves exhibit _________. a specific spinal nerve innervates specific __________ and __________
metamerism, myotomes, dermatomes
What does gray matter consist of?
neuronal cell bodies
what does white matter consist of?
myelinated axons that form ascending (sensory) and descending (motor) fiber tracts
what is the spinothalamic tract?
one of many ascending tracts originating the the spinal cord and extending to the brain
what is the function of the spinothalamic tract?
transmits information to the brain about pain, temperature, pressure, and crude touch
axons of the spinothalamic tract ______ to the other side of the spinal cord
decussate
1st order sensory neuron axons from skin receptors enter the ________ of the spinal cord and synapse with 2nd order sensory neurons (spinothalamic tract cells) in the ________
dorsal root, dorsal horn
axons travel up the brainstem as ___________ tract to the thalamus
spinothalamic
what is the corticospinal tract?
one of many descending tracts originating in brain and extending to the spinal cord
neuronal cell bodies in the motor cortex of the corticospinal tract send axons _______ through the _______ and ________
down, brain stem, spinal cord
most axons of the corticospinal tract ________ to the opposite side in the __________
decussate, medulla
upper motor axons of the corticospinal tract synapse with the lower motor neurons in the ________ of spinal cord
ventral horn
axons of lower motor neurons of the corticospinal tract innervate ________ muscles
voluntary
what is the function of somatic motor nerves?
motor to skeletal muscles
what is the function of somatic sensory nerves?
sensory from general cutaneous receptors and proprioceptors of skeletal muscles, tendons, joints, vision, and hearing
what is the function of visceral motor nerves?
motor to smooth muscle, cardiac muscle, and glands
what is the function of visceral sensory nerves?
sensory from receptors in viscera, taste, and olfaction
T/F? Lampreys have both dorsal and ventral roots that do not unite to from the spinal nerve
true
_________ rami from multiple adjacent spinal nerves combine to form _________ in gnathostomes
ventral, plexuses
_________ rami of C __, __, __, form the _______ nerve that innervates the diapraghm
ventral, 3, 4, 5, phrenic
what is a meninx?
single layer of meninges
what are the meninges?
protective layer surrounding the brain and spinal cord
fishes have ________ meninx
primitive
amphibians, reptiles, and birds have 2 meninx layers the _________ and _________
dura mater, pia mater
