Structure of the Vertebrate Nervous System Flashcards
central nervous system (CNS)
the brain and the spinal cord
peripheral nervous system (PNS)
connects the brain and spinal cord to the rest of the body
Planes of the Brain
somatic nervous system
consists of the axons con- veying messages from the sense organs to the CNS and from the CNS to the muscles
Controls voluntary muscles and conveys sensory information to the central nervous system
autonomic nervous system
part of the PNS, controls the heart, intestines, and other organs
made up of sympathetic and parasympathetic nervous systemns
Controls involuntary muscles
Sympathetic: Expends energy Parasympathetic:
Conserves energy
Anatomical Terms Referring to Directions
spinal cord
part of the CNS within the spinal column. The spinal cord communicates with all the sense organs and muscles except those of the head.
dorsal root ganglia
clusters of neurons outside the spinal cord, these are the cell bodies of the sensory neurons;
receive sensory input
gray matter
H-shaped gray matter in the center of the cord is densely packed with cell bodies and dendrites.
send axons to the brain or to other parts of the spinal cord through the white matter
sympathetic nervous system,
network of nerves that pre- pare the organs for a burst of vigorous activity, consists of chains of ganglia just to the left and right of the spinal cord’s central regions (the thoracic and lumbar areas)
prepare the organs for “fight or flight,” such as by increasing breathing and heart rate and decreasing digestive activity
parasympathetic nervous system
sometimes called the “rest and digest” system, facilitates vegetative, nonemer- gency responses.
the sympa- thetic nervous system increases heart rate, and the parasym- pathetic nervous system decreases it. The parasympathetic nervous system increases digestive activity, whereas the sym- pathetic nervous system decreases it. The parasympathetic system also promotes sexual arousal, including erection in males
three major divisions of the brain
hindbrain, the mid- brain, and the forebrain or hombenceph- alon (hindbrain), mesencephalon (midbrain), and prosen- cephalon (forebrain)
hindbrain
posterior part of the brain, consists of the medulla, the pons, and the cerebellum
medulla
enlarged extension of the spinal chord; cranial nerves originating in the medulla control vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezin
pons
lies anterior and ventral to the medulla; axons from each half of the brain cross to the opposite side of the spinal cord so that the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side
brain stem
medulla and pons, the midbrain, and certain central structures of the fore- brain
cerebellum
large hindbrain structure with many deep folds; control of movement, and many older text- books describe the cerebellum as important for “balance and coordination.”; but also attention shifting, judgment of timing, etc
midbrain
middle of the brain, although in adult mammals it is dwarfed and surrounded by the forebrain;
tectum - roof of the midbrain
superior colliculus and the inferior colliculus - swellings on each side of the tectum; mportant for sensory processing—the inferior colliculus for hearing and the su- perior colliculus for vision
tegmentum - intermediate level of the midbraon
substantia nigra - gives rise to a dopamine-containing pathway that facilitates readiness for movement.
forebrain
most prominent part of the mammalian brain, consists of two cerebral hemispheres, one on the left and one on the right;
cerebral cortex
outer portion of the forebrain
limbic system
located in the forebrain under the cerebral cortex forming a border around the brain stem; includes:
olfactory bulb
hypothalamus
hippocampus
amygdala
cingulate gyrus of the cerebral cortex
thalamus
pair of structures (left and right) in the center of the forebrain;
sensory in- formation goes first to the thalamus, which processes it and sends output to the cerebral cortex (except olfactory, which go directly to the cerebral cortex
hypothalamus
small area near the base of the brain just ventral to the thalamus;
hypothalamus conveys messages to the pituitary gland, altering its release of hormones
pituitary gland
docrine (hormone-producing) gland attached to the base of the hypothalamus
synthesizes hormones that the blood carries to organs through- out the body.
basal ganglia
group of subcortical structures lateral to the thalamus
include three major structures: the caudate nucleus, the putamen, and the globus pallidus
integrate motivational and emotional behavior to increase the vigor of selected actions
critical for learned skills and habits, as well as other types of learning that develop gradually with extended experience
damage to the basal gan- glia impairs movement, as in conditions such as Parkinson’s disease and Huntington’s disease
nucleus basalis
One of the structures on the ventral surface of the forebrain
receives input from the hypothalamus and basal ganglia and sends axons that release acetylcholine to widespread areas in the cerebral cortex
key part of the brain’s system for arousal, wakefulness, and attention,
Hippocampus
large structure between the thalamus and the cerebral cortex, mostly toward the posterior of the forebrain
critical for certain types of memories, especially memories for individual events. It is also essential for monitoring where you are and where you are going
ventricles
four fluid-filled cavities within the brain. Each hemisphere contains one of the two large lateral ventricles
Toward their posterior, they connect to the third ventricle, positioned at the midline, separating the left thalamus from the right thalamus
Cells called the choroid plexus along the walls of the four ventricles produce cerebrospinal fluid (CSF) -
cerebrospinal fluid
a clear fluid similar to blood plasma.
From the fourth ventricle, some of it flows into the central canal of the spinal cord, but more goes into the narrow spaces between the brain and the thin meninges, membranes that surround the brain and spinal cord
Cerebrospinal fluid cushions the brain against mechanical shock when the head moves. It also provides buoyancy.
meninges
membranes that surround the brain and spinal cord
he brain has no pain receptors, the meninges do, and meningitis—inflammation of the meninges—is painful. Swollen blood vessels in the me- ninges are responsible for the pain of a migraine headache
corpus callosum and anterior commissure
Neurons in each hemi- sphere communicate with neurons in the corresponding part of the other hemisphere through two bundles of axons, the corpus callosum and the smaller anterior commissure
laminae
A row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites
layers of cell bodies that are parallel to the surface of the cortex and separated from each other by layers of fibers
cerebral cortex contains up to six distinct laminae, some areas are missing certain levels
cells of the cortex are also organized into columns of cells perpendicular to the laminae
occipital lobeposterior (caudal) end of the cortex
posterior (caudal) end of the cortex
main target for visual information
posterior pole of the occipital lobe is known as the primary vi- sual cortex, or striate cortex,
parietal lobe
between the occipital lobe and the central sulcus
area just posterior to the central sulcus, the postcentral gyrus, or primary somatosensory cortex, receives sensations from touch receptors, muscle-stretch receptors, and joint receptors.
monitors all the information about eye, head, and body positions and passes it on to brain areas that control movement
essential not only for spatial information but also numerical information
central sulcus
deep groove in the surface of the cortex
postcentral gyrus
area just posterior to the central sulcus
temporal lobe
lateral portion of each hemi- sphere, near the temples
primary cortical target for auditory information
in most cases, the left temporal lobe—is essen- tial for understanding spoken language
also contributes to complex aspects of vision, including perception of movement and recognition of faces
also important for emotional and motivational behaviors.
Klüver-Bucy syndrome
Previously wild and aggressive monkeys fail to display normal fears and anxieties after temporal lobe damage
frontal lobe
containing the primary motor cortex and the prefrontal cortex, extends from the central sulcus to the anterior limit of the brain
posterior por- tion of the frontal lobe, the precentral gyrus, is specialized for the control of fine movements, such as moving a finger
Separate areas are responsible for different parts of the body, mostly on the contralateral (opposite) side but also with slight control of the ipsilateral (same) side
primary motor cortex
precentral gyrus, also known as the primary motor cortex.
No area in the motor cortex controls just a single muscle. If two muscles usually move together, such as the muscles controlling your little finger and your ring finger, then the brain areas that control one of them largely overlap those that control the other one
prefrontal cortex
most anterior portion of the frontal lobe
Neurons in the prefrontal cortex have huge numbers of synapses and integrate an enormous amount of information.
three major regions of pre-frontal cortex
posterior portion is as- sociated mostly with movement
middle zone pertains to working memory, cognitive control, and emotional reactions
anterior zone of the prefrontal cortex is important for making decisions, evaluating which of several courses of action is likely to achieve the best outcome
binding problem
large-scale integration problem
question of how various brain areas produce a per- ception of a single object
Major Solci/Fissures
Interhemispheric Fissure
Sylvian Fissure (separates temporal from parieatal)
Parieto-occipital Fissure and Calcarine Sulcus (y shaped from temporal, splitting parietal, occipital and temporal)
Central, Postcentral and Precentral Sulci
Number of neurons
cerebral cortex: 12 to 15 billion
spinal cord: 1 billion
cerebellum 70 billion
cranial nerves
postcentral gyrus
primary somatosensory cortex
Primary target for touch sensations and information from muscle-stretch receptors and joint receptors
precentral grrus
just posterior to central sulcus
contains the primary motor cortex
STRUCTURAL ASYMMETRY
the brain is not symmetrical
The right protrudes in front
The left protrude in back
The right has more volume
The left is larger posteriorly in occipital region
The planum temporale at Wernicke’s area is larger in L hemispehere in 65% of the brains;
11% had a larger surface area in R hemisphere
columns
A set of cells perpendicular to the surface of the cortex, with similar properties
Tract
A set of axons within the CNS, also known as a projection. If axons extend from cell bodies in structure A to synapses onto B, we say that the fibers “project” from A onto B.
Nerve
A set of axons in the periphery, either from the CNS to a muscle or gland or from a sensory organ to the CNS
Nucleus
A cluster of neuron cell bodies within the CNS
Ganglion
A cluster of neuron cell bodies, usually outside the CNS (as in the sympathetic nervous system)
cingulate gyrus
part of limboc system
highly influential in linking motivational outcomes to behavior (e.g. a certain action induced a positive emotional response, which results in learning
