Central Nervous System
What is a reflex arc (reflex circuit)?
pathway followed by action potential; has 5 components 1) Sensory receptor 2)Sensory neuron 3) Integration center 4) motor neuron 5) effector
What is the function of the visual association area?
complex processing of visual information Visual recognition and identification of objects. If damaged causes knowledge blindness (you can see what the object is but you have no idea what it is)
What are association fibers?
connect different parts of the same hemisphere (highways- connects states)
What is the ventral root?
contains axons of motor neurons- info from CNS to effectors
What is the dorsal root?
contains only sensory axons -info from receptors to CNS- (skin, muscles, internal organs); has dorsal root ganglion ->swelling which contains cell bodies of sensory neurons
What does the medulla oblongata contain? What is its function?
contains several important nuclei (clusters of neuronal cell bodies) nuclei ex. cardiovascular center, medullary respiratory center nuclei also control reflexes for vomiting, swallowing, sneezing coughing, hiccuping
What does the spinothalamic tract of the spinal cord do?
conveys action potential for pain, temp, itch, tickle
What does the dorsal column of the spinal cord do?
conveys action potentials for touch, pressure, vibration, propioception
What are the two cerebral hemispheres connected by?
corpus callosum
What are meninges?
membranes that surround the brain and spinal cord
What is the function of the limbic system?
plays primary role in rage of emotions and is involved in olfaction and memory involved in reactions and memories to odors extensively connected with hypothalamus= emotions associated with ANS and PNS extensively connected with frontal lobes= emotions associated with our thoughts
What is the arachnoid mater?
middle layer of the meninges web like extensions below is CSF
Where is the pons located?
middle of brain stem
What does the epidural space of the spinal cord contain?
soft padding of fat
What is right brain specialized at?
special patterns, mental images, intuition, art and music, creativity
Where is the cerebellum located?
located behind the brain stem "little brain"
What is the central canal of the spinal cord?
located in center of gray matter; extends entire length of cord and is filled with CSF
What are pyramidal cells?
main motor cells, send motor signals away from cerebrum
What are stellate cells?
main sensory interneurons within cerebrum
What is a somatic reflex?
most aware of these; contraction of skeletal muscles
What is white matter?
mostly myelinated axons (highways)
What is the reticular formation?
netlike region of interspersed gray/white matter that extends from upper part of spinal cord throughout brainstem and lower part of diencephalon -neurons within RF have ascending ad descending funcitons -sensory: RAS; reticular activating system -motor: help regulate posture and muscle tone filter 99% of stimuli
What is gray matter?
neuron cell bodies and non-myelinated axons (integration centers)
What are the 2 phases of sleep?
nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep
What is a autonomic/visceral reflex?
not consciously perceived; responses of cardiac smooth and glands
How many spinal nerves are there on each region?
o 8 (pairs) of cervical o 12 of thoracic o 5 of lumbar o 5 of sacral o 1 of coccygeal
What is hemisphere lateralization?
one side is stronger at something than the other
What is a spinal reflex?
when integration takes place in spinal cord gray matter ex. patellar reflex and flexor (away from pain) reflex
What is the purpose of the functional areas of the cerebrum?
where sensory, motor, and integrative signals are processed in certain regions
What is the function of superior colliculi?
reflex centers for visual activities; track moving images and scan stationary images; turn head and trunk in direction of sudden visual stimulus
What is the function of the auditory association area?
recognition and memories of sound
What is the function of the inferior cerebellar peduncle?
cerebellum receives information from proprioceptors and visual & equilibrium pathways cerebellar cortex determines best way to develop a smooth, coordinated movement
What is the function of the superior cerebellar peduncle?
cerebellum sends details to the cerebral areas that outline the coordinated movement
What are commissural fibers?
connect corresponding gray areas of both hemispheres -major commissure is the corpus callosum (us->canada)
What can diffuse across the blood brain barrier?
lipid soluble substances (O2, CO2, steroid hormones, alcohol, barbiturates, nicotine, caffeine) but not water soluble water soluble substances without a transport protein cannot cross glucose can cross
Where is the medulla oblongata located?
lower portion of the brain stem
What is the function of the pineal gland?
secretes the hormone melatonin considered part of endocrine system melatonin helps regulate circadian rhythms
What is the cranium?
skull
How many stages does REM have?
1
What is the purpose of the cerebrospinal fluid?
1) Mechanical Protection (shock absorption) 2) Chemical Protection (ion homeostasis) 3) Circulation (nutrient, wastes, hormones)
How does the spinal nerve connect to spinal cord?
2 bundles of axons->roots
What is the total volume of CSF? how often is it replaced? where is it reabsorbed?
3-5 oz volume is replaced 3 times per day reabsorbed back into blood at arachnoid villi
How many spinal nerves are on the spinal cord?
31 pairs
How many stages does NREM have?
4
How does the spinal cord maintain homeostasis?
Action potential propagation and integration of information
What are the 4 major structures of the brain?
Cerebrum, Diencephalon, Cerebellum, and Brain stem
Where is the hypothalamus located?
Below the thalamus in the diencephalon
What does the subarachnoid space and central canal of the spinal cord contain?
CSF
What is the presentation of gray and white matter in the brain stem?
Central cavity surrounded by gray matter White matter all around with scattered gray matter nuclei
What is the presentation of gray and white matter in the spinal cord?
Central cavity surrounded by gray matter White matter along periphery
What is the function of the brain?
Control center Most of the weight of the nervous system and very energetically expensive
What is the purpose of the cranial nerve?
Cranial nerves link the brain to sensory receptors and effectors 12 pairs of cranial nerves part of PNS
What happens during NREM?
Heart/breathing rate and blood pressure decrease muscle tone and temperature decrease Minimal dreamin
What is the function of the pituitary gland?
It's the master gland. Controls everything.
What percent of body weight makes up the nervous system? Brain? Nerves+spinal cord?
Nervous system 3% Brain 2% nerves+spinal cord 1%
What is the dura mater?
Outermost layer of the meninges 2 mostly fused layers strongest
What are spinal nerves
PNS, connects spinal cord to sensory receptors and effectors
What are the sensory areas of the cerebrum?
Primary somatosensory cortex Primary visual cortex primary auditory cortex gustatory cortex olfactory cortex
What is the blood brain barrier?
Protects brain cells maintains brains stable environment Without BBB there would be constant neuronal firings, infections, etc Endothelial cells, basement membrane, astrocyte processes
What is the function of cerebral white matter?
Responsible for communication between cerebral areas, and between cerebral cortex and lower CNS Consists of myelinated axons bundled into large tracts
What are the cell types of the cerebrum?
Stellate cells and pyramidal cells (these are interneurons)
What are the grooves of the brain called?
Sulci
What is basal nuclei? What is its funciton?
They are several masses of gray matter (neuronal bodies) found in different parts of brain. deep in white matter help initiate body movements, suppress unwanted movements, and regulate muscle tone appear to influence learning, habitual behaviors, emotions and speaking if damaged (ex. parkinsons disease, huntingtons) muscle spasms
What is the pia mater?
This is the internal layer that clings to the surface of the brain (into sulci around gyri) rich vascularization delicate
How do gray and white matter differ with gender?
Women have ten times more white matter than men (women have more axons that send signals to and from the brain) Men have 6.5 times more gray matter then women (men have more integration centers)
What is a reflex
a fast, involuntary, unplanned sequence of actions that occurs in response to a particular stimulus some are inborn others are learned/acquired
How is cerebral white matter classified?
according to the direction they run 1) association fibers 2) commissural fibers 3) Projection fibers
What is the cerebral cortex role in sleep
active while awake and not so much when asleep
What is the indirect motor pathway of the spinal cord?
aka extrapyramidal pathways; include tectospinal, vestibulospinal, rubrospinal, lateral reticulospinal and medial reticulospinal tracts; convey action potentials from brain stem to cause involuntary movements that regulate posture, balance, muscle tone
What is the function of the prefrontal cortex?
aka frontal association area; makes up personality, intellect, complex learning abilities, recall info, initiative, judgement, foresight, reasoning...etc development depends heavily on feedback from environment, more interaction with environment means more growth and connection develops slow in children
What is the direct motor pathway of the spinal cord?
aka pyramidal pathways; include lateral corticospinal, ventral/anterior corticospinal and corticobulbar tracts; convey action potential that start in cortex and are destined to cause voluntary movement of skeletal muscles
What is the function of the facial recognition area?
allows to to recognize and identify familiar faces
What is the spinal cord?
cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull
What is the function of the premotor cortex?
deals with learned motor activities of complex and sequential nature as well as a memory bank for such movements
What is the function of motor tracts?
descending, axons that carry action potentials way from brain
During embryonic development, what part of the CNS experiences the most drastic changes?
diencephalon and telencephalon
What is the white matter of the spinal cord divided into?
dorsal white columns ventral white columns lateral white columns
What are the layers of the meninges?
dura mater, arachnoid mater, pia mater
Where is the limbic system located?
encircles upper part of brainstem and corpus callosum
Where is the site of CSF production?
from blood plasma by choroid plexus (ependymal cells)
What is the function of the orbitofrontal cortex?
gets input from olfactory cortex; allows you to discriminate among different colors
What is the function of the common integrative area?
gets input from somatosensory, visual and auditory association areas and forms thoughts in response
What does the CSF filtrate consist of?
glucose, oxygen, vitamins, and ions, (Na+, Cl-, Mg2+, etc) Less proteins, more Na+ and Cl-, less K+ and Ca2+ than blood plasma
What are the ridges of the brain called?
gyri
What is the dorsal gray horn?
have axons of incoming sensory neurons and cell bodies and axons of interneurons
What is the reticular activating system?
increase in activity of this region is responsible for transition between sleep and awake; when active many action potentials are transmitted all over cortex
What is meningitis?
inflammation of the meninges, caused by bacteria/virus; can be fatal
What is the function of Wernicke's area?
interprets meaning of words; translates words into thoughts; only in left hemisphere (the region of brocas and wernickes in the right hemisphere contribute to verbal communication by adding emotional content to spoken words)
What is the function of the substania nigra and red nucleus?
is a basal ganglia structure that help control body movements
What is the lateral gray horn?
present only in thoracic and upper lumbar segments (enlargements); have cell bodies of autonomic motor neurons that convey action potentials to cardiac, smooth muscles and glands
What are the motor areas of the cerebrum?
primary motor cortex brocas area
What are horns of the spinal cord?
projections of gray matter toward the outer surface of the spinal cord
What is the left brain specialized at?
reasoning, logic, analytical, meant and science, language
What is the function of the primary visual cortex?
receive and process visual information
What is the function of the somatosensory association area?
stores memories of past somatic sensory experiences so that you can identify objects just by touching it
What are the parts of the diencephalon?
thalamus, hypothalamus, and pineal gland
What is the subarachnoid space?
under the arachnoid mater contains CSF which functions as a shock absorber and suspension system
Where is the thalamus located?
upper part of diencephalon
Where is the midbrain/mesencephalon located?
upper portion of brain stem
What are the association areas of the cerebrum?
usually adjacent to primary sensory areas and receive input from both primary sensory areas and other brain regions -they integrate sensory experiences into meaningful patters of recognition and awareness
What is a cranial reflex?
when integration occurs in the brain stem ex. tracking movement of eyes when you read a sentench
What is arousal?
awakening from sleep; involves increased activity in the RAS -RAS must be stimulated for arousal to occur -RAS gets sensory input from lots of things that can cause stimulation and then arousal and then consciousness
Where is the pituitary gland located?
base of the brain
Where is the pineal gland located?
behind the thalamus pea sized gland
Where is the diencephalon located?
between brainstem and cerebrum
What does the CNS consist of?
brain and spinal cord -processes sensory info; generates thoughts, emotions, and memories; stimulates muscles to contract and glands to secrete
Where does the CSF circulate?
brain and spinal cord in subarachnoid space through central canal of cord, and through cavities in brain ventricles 2 lateral ventricles, 1 3rd and 1 4th
What cannot cross the blood-brain barrier?
cells and proteins
What are the 3 paired fiber tracts of the cerebellum?
cerebellar peduncles
What does the cerebrum include?
cerebral cortex(superficial gray matter), white matter, basal nuclei(islands of internal gray matter)
What is the hypothalamus composed of? what is its function?
composed of 12 nuclei -receives sensory input from receptors for vision, taste and smell -has several important connection w/ pituitary gland and produces hormones functions of medulla oblongata+hormones
What are projection fibers?
connect cerebral cortex to lower brain areas or spinal cord integration centers -sensory input enters the cerebral cortex through these, and motor output leaves through these
What is the predominant neuron of the cerebellum?
Purkinje fibers
What is the presentation of gray and white matter in the cerebrum?
central cavity surrounded by white matter, whit scattered gray matter nuclei Gray matter along periphery
What is cephalization?
- concentration of sensory organs and nervous system at the anterior end of the body - formation of the head and brain
What are the important functions of the hypothalamus?
-Control of autonomic nervous system -Production of hormones (produces ADH and oxytocin) -Regulation of emotional and behavioral patterns -regulation of eating and drinking -control of body temperature -regulation of circadian rhythms Four F's (fighting, fleeting, feeding, mating)
What is the function of the primary motor cortex?
controls voluntary contractions of specific muscle groups/muscles; electrical stimulation of any point in this cortex causes contraction of specific skeletal muscle on opposite side of the body
What is the brain protected by?
cranium, meninges, blood brain barrier, and cerebrospinal fluid
What happens during REM sleep?
heart/breathing rate and blood pressure increases inhibited skeletal muscle activity high brain and neuron activity dreaming can be very vivid hardest to wake someone compared to nrem
What are the white matter tracts on the spinal cord?
highways for action potential propagation sensory information travels along those tracts toward brain and motor output travels from brain along those tracts toward effectors
What is the function of the olfactory cortex?
perception of odors
What is the function of the cerebellum?
-evaluates how well movements initiated by motor areas in cerebrum are actually being carried out -coordinates skilled movements -main region that regulates posture and balance -think of dancers and athletes
What does the midbrain/mesencephalon contain? What is its function?
-has nuclei and tracts -nuclei include (substantia nigra and red nucleus-> both help control body movements) -back surfaces has superior colliculi and inferior colliculi
What does the pons contain? What is its function?
-has nuclei and tracts -signals for voluntary movement from motor areas of cerebral cortex are relayed through several pontine nuclei into cerebellum -has pontine respiratory center; works with medullary respiratory center to control breathing
How does the Wernicke's area function (steps)
1. Info about the word is conveyed in wernikes area 2. translation of word into appropriate though 3. Wernikes area transmits info about word to brocas area 4. development of motor pattern for speech muscle activation 5. Motor pattern sent to primary motor cortex which activates speech muscle
What is the functional component of the blood brain barrier?
consists of membrane transport proteins (carriers and ion channels) in endothelial cell plasma membranes that selectively move some water-soluble substances across brain capillary walls
What is the function of brocas area?
articulation of speech (coverts thoughts into speech); in most people it is present in the left hemisphere
Where does the CNS begin embryonically?
as a neural tube
What is the function of sensory tracts?
ascending, axons that conduct action potentials toward brain
What role do astrocytes play in the blood brain barrier?
astrocytes maintain the tightness of the tight junction and the tightness of the blood brain barrier
What is the ventral gray horn?
have cell bodies of somatic motor neurons that convey action potential to skeletal muscles
how are the gustatory and olfactory cortex related?
have high association with eachother 80% of taste is smell sends signals and communication with frontal cortex
What does the thalamus composed of and what is its function?
masses of gray matter organized into nuclei w/interspersed tracts of white matter -relay center for most sensory input from spinal cord and brain stem -relay motor information from cerebellum and basal nuclei -relays inputs from hypothalamus regarding emotional visceral responses
What does the brain stem contain?
medulla oblongata, pons, midbrain
What is the function of the middle cerebellar peduncle?
motor areas of the cerebral cortex send signals, notifying the cerebellum of planned skeletal muscle contractions
What continuous supply does the brain depend on?
oxygen and glucose by the blood neurons synthesize AT almost exclusively from glucose via rxs that use O2 When the activity of the brain region increases, blood flow also increases Virtually no glucose is stored in the brain so it must continuously circulate
What is the function of the inferior colliculi?
part of auditory pathway; makes startle reflex; turns head/trunk in direction of sudden auditory stimulus
What is the function of the gustatory cortex?
perception of taste
What is the function of the gray matter on the spinal cord?
receives and integrates incoming/outgoing information
What is the function of the primary auditory cortex?
receives auditory input, if damaged you are deaf
What is the function of the primary somatosensory cortex?
receives sensory info for touch, pressure, vibration, temp, pain, propioception, and the perceptions of those somatic sensations; sensory info from one side of the body are conveyed to opposite side
What is the function of the cerebrum?
· Bc of it we can read, write, speak, make calculations, compose music, remember past, plan future, imagine things · Has outer ring of cortex, inner region of white matter and nuclei embedded in white matter -contains billions of neurons arranged into 6 layers
