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The Nervous System Britney Escalante Period 5 (Major Parts of the Brain…
The Nervous System Britney Escalante Period 5
Nervous System Divisions/Subdivisions
central nervous system- receive incoming sensory information, issue instruction
CN subdivision- brain, spinalcord
peripheral nervous system- spinal nerves carry impulses to & from spinal cord, cranial nerves, carry impulses & from cranium
PNS subdivision- all nerves that extend from brain & spinal cord
Major Parts of the Brain
gray matter- composes the outer surface of the brain
white matter- composes the deeper part of the brain
sulcus (sulci)- creases, shallow groves
fissures- deeper groves, usually separate large parts
gyrus (gyri)- bump, elevated ridges of tissues
longitudial fissure- divides the cerebrum into left and right
precentral gyrus- controls conscious movement of skeletal muscles
corpus collusum- connects left and right hemisphere allow them to communicate
basal ganglia- areas of gray matter deep in the cerebrum that helps regulate muscle movement
thalamus- relays sensory info, recognizes good vs bad sensation
hypothalamus- controls body temp., water balance metabolism & endocrine function
midbrain- reflex center for vision & hearing
pons- relay between cerebrum & cerebellum
medulla oblongata- reflex center for heart rate, breathing, vomiting & swallowing
cerebellum- receives information from the sensory systems, the spinal cord, & other parts of the brain
reticular formation- controls wake/sleep cycle
Lobes
temporal lobe- hearing, speech, memory, sequencing & organization
frontal lobe- personality, emotions, intelligence, attention, concentration, logic, and problem solving
parietal lobe- size, shape, color, pain, temperature, and speech
occipital lobe- processes, vision (visual cortex)
Spaces/Ventricles
cerebrospinal fluid- fills spaces (cerebral ventricles) in the brain between pia mater & arachnad in the brain
4 ventricles- two lateral ventricles, third, and fourth ventricle, communicating cavities in the brain
Tissues (structure/function) of neuron
nervous tissues- composed of neurons & supporting cells called neuroglia cells
neuron- nerve cells, relay electrical impulses through out the body
dendrite- portion of neuron that receives impulse & sends signal to the cell body
cell body- metabolic center
axon- portion that conducts signal away from the cellbody
myelin- fatty substance that insulates signal
node of ranvier- spaces between myelin/shawamm cells
Major Parts of Spinal Cord
gray matter- dentrites & cell bodies of neurons
white matter- made up of spinal tracts that are bundles of myelinated nerve fibers
ascending tracts- sends impulse up towards the brain
descending tracts- sends impulse down the cord from the brain
tracts- composed of axons that all serve the same function
spinothalamic tracts- sensory function produing sensations of crude touch, pain, & temperature
interneuron- transfers sensory impulses to outgoing motor impulses
spinal cord reflex- reflex that result from conduction over acrs in the spinal cord
Action Potential
strong enough stimulation/stimulus causes Na+ gates to open, Na+ rush into cells causing depolarization
If strong depolarization occurs, threshold potential is reached & impulse is sent down axon
K+ is rushout of neuron after Na+ rushes in, repolarizes membrane
Membrane is hyperpolarized too many K+ leaves the cell, membrane potential dips below resting potential
refractory period- the time during which no stimulus can cause another action potential
final step- resting membrane potential is restored graded potential
graded response- stronger the stimulus, the stronger the response will be
summation- if another stimulus of same type arrives before effect of the first stimulus wears off, additive effect of two or more stimuli
Coverings/Layers of Meninges
dura mater- tough outer layer lining the vertebral canal
pia mater- innermost membrane surroundings the actual spinal cord
arachnoid mater- membrane in between the dura mater & the pia mater
Functions
cerebrum- superior part of the brain composed of two hemisphere, largest mass of the brain
central nervous system- made of the brain and the spinal cord
peripheral nervous system- made up of nerves that branch off from the spinal cord
transmits signals between the brain and the rest of the body
fast communication,nerve cells, fibers that transmits nerve impulses between body parts
endocrine system- slow communication, glands in your body to make hormones, chemical messangers to make sure body work the way it should
organs- brain, spinalcord, nerves, eyes, ears,and skin
Reflex
spinal- signal travels through spine
cranial- signal travels through brain stem
reflex arc- pathway of a reflex response
Divisions of PNS
sensory (afferent) nerves- relay information from skin, muscle & glands
interneuron- nerves that connect sensory nerves to motor nerves
motor (effert) nerves- carry impulses from CNS to organ muscle
somatic motor neurons- conscious voluntary control, sense & respond to external enviroment
actonomic motor neurons- automatic, unconscious, involuntary control, respond to internal enviromental
Tissue (structure & function of neuron)
nervous tissues- composed of neurons & supporting cells called neuroglia cells
neuron- nerve cells, relay electrical impulses the body
dendrite- portion of neuron that receives impulses and send signals to the cell body
cell body- metabolic center
axon-portion that conducts signal away from cell body
myelin- fatty substance that insulates signal
node of ranvier- spaces between myelin/shwamm cells
Classification of Neurons
sensory (afferent) neurons- transmit impulses to the spinal cord & brain from all parts of the body
motor (efferent) neurons- transmit impulses away from the brain & spinal cord
interneurons (central or connecting neurons): transmit impulses from sensory neurons to motor neurons
Neutrotransmitters
chemical compounds released from axon terminals into a synaptic cleft
acetycholine- causes muscles to contract, activates pain responses
catecholamines- transmit signals from your blood to your organs & tissues
dopamine- send signals in between the nerve cells of the brain
sertatonin- help to regulate mood & social behavior, appetite, digestion, sleep and memory etc.
serotonin-help to regulate mood & social behavior, apetite, & digestion, sleep, and memory etc
Diseases of the Brain
concussion- shaking of the brain, no permanent damage, mostly result of swelling
contusion- causes tissue destruction, permanent damage, mostly result of swelling
intracranial hemorihage- bleeding in the skull, edema
dementra- forgetfulness, loss of brain function that occurs with certain diseases
CVA (cerebrovascular accident)- aka as stroke, blood flow to brain tissue is blocked causing cell death
hemorrhagic stroke- weaken/diseased blood vessels, blood leaks into brain tissue
Drugs affecting the Brain
heroine- influences over your opioid receptors leads to a rewiring o your brain and how it releases chemicals, can cause brain damage
ecstasy- affects herotonin pathways responsible formodd, sleep, perception & appetite
marijuana- anondomide known as to be involved in removing unnecessary short term memories it what makes you slow down movement, making us relaxed and calm
methamphetamine- addictive because it works directly on the brains reward pathway, making the user feel intense pleasure
alcohol- affects areas in the brain involved in memory formation decision making & control
cocaine- concentrates in the reward pathway, active in the part of the brain controlling voluntary movements, cocaine abusers are unable to be still
LSD- neuron from LC can branch to many different sensory areas of the brain, LS responsible for feeling of wakefulness & evoking a startle response to unexpected stimulus