Chapter 3 - Anatomy of the Nervous System Flashcards
central nervous system (CNS)
division of the nervous system located within the skull and the spine; composed of two divisions –> the brain (skull) and the spinal cord (located in the spine)
peripheral nervous system (PNS)
division located outside the skull and the spine,
composed of two divisions: somatic nervous system (SNS) and automatic nervous system (ANS)
afferent nerves
carry sensory signals from the skin, skeletal muscles, joints, eyes, ear to the CNS
efferent nerves
carry motor signals from the CNS to the skeletal muscles
somatic nervous system (SNS)
part of the PNS that interacts with the external environment, composed of the afferent nerves and the efferent nerves
automatic nervous system (ANS)
part of the PNS that regulates the body’s internal environment
sympathetic nerves
automatic motor nerves that project from the CNS in the lumbar (small back) and the thoracic (chest area) regions of the spinal chord
parasympathetic nerves
automatic motor nerves that project from the brain and sacral (lower back) region of the spinal chord
cranial nerves
12 pairs of nerves extending from the brain (optic nerves, olfactory nerves, and vague nerves)
meninges
three protective membranes that cover the brain and the spinal cord
dura mater
outer meninx, though membrane
arachnoid membrane (spider web membrane)
immediately inside the dura mater
subarachnoid space
beneath the arachnoid membrane, contains many large blood vessels and cerebrospinal fluid
pia mater
innermost meninx, really delicate, adheres o the surface of the CNS
cerebrospinal fluid (CSF)
protects the CNS, fills the subarachnoid space, the central Canal of the spinal cord and the cerebral ventricles of the brain
central canal:
small central channel that runs the length of the spinal cord
cerebral ventricals
four large internal chambers of the brain: two lateral ventricles, the third ventricle and the fourth one
choroid plexuses
network of capillaries or small blood vessels that protrude into the ventricles from the Pia mater; produces CSF, the excess CSF is continuously absorbed from the subarachnoid space into large blood-filled spaces or dural sinuses
blood-brain barrier
a mechanism that impedes the passage of many toxic substances from the blood into the brain
neurons
cells that are specialized for reception, conduction and transmission of electrochemical signals; they come in an incredible variety of shapes and sizes
Neuron cell membrane
composed of a lipid bilayer, or two layers of fat molecules
external features of a neuron
cell body, myelin, cell membrane, dendrites, axon hillock, axon, nodes of ranvier, buttons, synapses
dendrites
the short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons
axon hillock
the cone shaped region at the junction between the axon and the cell body
Myelin
the fatty insulation around many axons
axon
the long, narrow process that projects from the cell body
Nodes of Ranvier
the gaps between sections of myelin
buttons
the button like endings of the axon branches, which release chemicals into synapses
synapses
the gaps between adjacent neurons across which chemical signals are transmitted
major internal features of a neuron
endoplasmatic reticulum, cytoplasm, ribosomes, Golgi complex, nucleus, mitochondria, microtubules, synaptic ventricles, neurotransmitter
endoplasmatic reticulum
system of folded membranes in the cell body, rough portions (those with ribosomes) play a role in the synthesis of proteins; smooth portions (those without ribosomes) play a role in synthesis of fats
cytoplasm
the clear internal fluid of the cell
ribosomes
internal cellular structures on which proteins are synthesized; they are located on the endoplasmatic reticulum
Golgi complex
a connected system of membranes that packages molecules in vesicles
nucleus
the spherical DNA-containing structure of the cell body
mitochondria
sites of aerobic (oxygen-consuming) energy releases
> powerhouse of the cell
mircotubules
Tubules responsible for the rapid transport of material throughout neurons
Synaptic vesicles
Spherical membrane packages that store neurotransmitter molecules ready for release near synapses
neurotransmitter
Molecules that are released from active neurons and influence the activity of other cells
multipolar neuron
a neuron with more than two processes extending from its cell body, most neurons are multipolar
unipolar neurons
neuron with one process extending from its cell body
bipolar neuron
a neuron with two processes tending from its cell body
interneurons:
they only have a short or no axons at all, They integrate neural activity within a single brain structure; not to conduct signals from brain structures to another
nuclei
clusters of cell bodies in the CNS
ganglia
clusters of cell bodies in the PNS
tracts
bundles of axons in the CNS
nerves
bundles of axons in the PNS
glia cells
several classes of nonneural cells of the nervous system
oligodendocytes
glia cells with the extension that wrap around axons of some neurons of the CNS
Schwann Cells
second class of glial; each Schwann cell constitutes one myelin segment
microglia
this class of glia; they are smaller than other glia, they respond to injury or disease by multiplying, engulfing cellular debris or even entire cells
Astrocytes
forth class of glia; largest glia cells; they are star shaped, some extensions of some astrocytes cover the outer surface of blood vessels that course through the brain
cranial nerves
olfactory, optic, Oculomotor, Trochlear, Abducens, Trigeminal, facial, auditory, Glossopharyngeal, Vagus, Spinal accessory, Hypoglossal
Golgi Stain
a neural stain that completely darkens. few of the neurons in each slice of tissue, thereby revealing their silhouettes
Nissl Stain
a neural stain that has a an affinity for structures in neuron cell bodies
electron microscopy
a microscopy technique used to study the fine details of cellular structures
anterior
toward the nose end (anterior end)
posterior
toward the tail end
dorsal
toward the surface of the back/ top head
ventral toward the surface of the chest/ bottom of the head
toward the surface of the chest/ bottom of the head
medial
toward the midline of the body
lateral
away from the midline of the body
gray matter
composed largely of cell bodies and unmyelinated interneurons
dorsal horns
the two dorsal arms of the gray matter
ventral horns
the two ventral arms
white arms
composed largely of myelinated axons
five major divisions of the brain
- telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
reticular foundation
complex network of 100 tiny nuclei that occupies the central core of the brain stem from the posterior boundary of the myelencepalon to the anterior boundary of the midbrain
pons
major division of the mesencephalon; the other is the cerebellum
cerebellum
large, convoluted structure on the brain stem’s dorsal surface; important sensorimotor structure;
> cerebellar damage also produces a variety of cognitive deficits
mesencephalon
two divisions: tectum, tegmentum
tectum (roof)
dorsal surface of the midbrain; in mammals, the tectum is composed of two pairs of bumps, the colliculi
inferior colliculi
they have an auditory function
anterior colliculi
visual-moor function, specifically directed to the body’s orientation toward / away from particular visual stimuli
tegmentum
division of the mesencephalon ventral to the tectum, Contains three structures: periaqueductal gray, substantia nigra, red nucleus
periaqueductal gray
gray matter situated around the cerebral aqueduct
diencephalon
composed of two structures: the thalamus and the hypothalamus
thalamus
large, two-lobed structure that constitutes the top of the brain stem. One lobe sits on each side of the third ventricle, and the two lobes are joined by the massa intermedia, which runs through the ventricle
sensory relay nuclei
nuclei that receive signals from sensory receptors, process them, and then transmit them to the ap- propriate areas of sensory cortex
lateral geniculate nuclei, the medial geniculate nuclei, ventral posterior nuclei
important relay stations in the visual, auditory, and somatosensory systems, respectively
hypothalamus
located just below the anterior thalamus (hypo means “below”), plays an important role in the regulation of several motivated behaviors (e.g., eating, sleep, and sexual behavior)
pituitary gland
dangles from it on the ventral surface of the brain, the hypothalamus exerts its effects in part by regulating the release of hormones from the pituitary gland
optic chiasm
point at which the optic nerves from each eye come together
cerebral cortex
the layer of neural tissue covering the cerebral hemispheres of humans and other mammals
> mainly composed of small, unmyelinated neurons, it is gray and is often referred to as the gray matter
telencephalon
largest division of the human brain; mediates the brain’s most complex functions
> initiates voluntary movement, interprets sensory input, and mediates complex cognitive processes such as learning, speaking, and problem solving
limbic system
circuit of midline structures that circle the thalamus; involved in the regulation of motivated behaviors (including the 4 Fs of motivation: fleeing, fighting, feeding, sexual behavior)
> major structures of the limbic system: amygdala, fornix, cingulate cortex, septum
amygdala
almond-shaped nucleus in the anterior temporal lobe
cingulate cortex
large strip of cortex in the cingulate gyrus on the medial surface of the cerebral hemispheres, just superior to the corpus collosum, it encircles the dorsal thalamus
fornix
major tract of the limbic system encircles the dorsal thalamus, it leaves the dorsal end. of the hippocampus and sweeps forward in an arc coursing along the superior surface of the third ventricle & terminating
septum
mideline nucleus located at the anterior top of the cingulate cortex
basal ganglia
a collection of subcortical nuclei
