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141 terms

Nervous System MVCC BIO 181

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Alzheimer's Disease
loss of memory, judgment, loss of neurons in frontal
and temporal lobes due to neurofibrillary plaques and tangles blocking synaptic transmission
Epilepsy
seizures, due to uncontrolled activity in cerebral cortex
Multiple sclerosis
myelin in white matter of spine and brain is attacked by
immune system, loss of sensation and motor control; no cure
Polio
virus attacks CNS motor neurons, causing muscular paralysis; must be vaccinated
Sciatica
pain, numbness along sciatic nerve due to compression of roots by lumbar vertebrae (slipped disc)
Shingles
herpes zoster virus attacks dorsal roots, painful rash; temporary
Parkinson's disease
decrease in dopamine cause muscle rigidity and tremors, L-DOPA used to reduce symptoms
Meningitis
infection of the meninges by bacteria or virus; disrupts flow of CSF; headache, chills fever; must be immunized
ALS
(Lou Gerhig's disease): motor neurons are destroyed, lose muscular control, sensory remain OK
Huntington's disease
ACh and GABA neurons in cortex degenerate, loss of muscle control and intellectual abilities, genetic basis
Spina bifida
incomplete fusion of vertebrae; meninges and CSF protrude
Olfactory
Cranial nerve I smell/sensory
Cerebrum <------olfactory Tract <------olfactory Bulb <----nose
Optic
Cranial Nerve II smell/sensory
Occipital lobe <------ thalamus <---- optic chiasma <---- retina
Oculomotor
Cranial Nerve III Motor
Mid-brain ---> 4 eyeball muscles, iris, eyelids
Trochlear
Cranial Nerve IV Motor
Mid-brain ---> 1 eyeball muscle
Trigeminal
Cranial Nerve V mixed
3 branches, forehead, cheeks, jaw
<-----ophthalmic --- orbits, forehead, eyelids / brows
Pons<------maxillary -------- nose, gums, cheeks
<----- mandibular -----> tongue, lips, palate
Abducens
Cranial Nerve VI motor
Pons ---> 1 eyeball muscle
Facial
Cranial Nerve VII mixed
Pons -----> facial muscles, salivary & lacrimal glands
<----taste buds
Vestibulocochlear
Cranial Nerve VIII Sensory
2 Branches
Medulla<-------Cochlear ------- Organ of Corti (hearing)
Pons, cerebellum <-----Vestibular ----- Vestibular apparatus
Glossopharyngeal
Cranial Nerve IX Mixed
Medulla <-----> parotid gland taste buds, pharynx (swallowing)
Vagus
Cranial Nerve X Mixed
Medulla <---> lungs, heart, organs and muscles of GI tract
Accessory
Cranial Nerve XI Motor
Medulla -------> neck muscles, swallowing
Hypoglossal
Cranial Nerve XII Motor
Medulla -------> tongue muscles
Neurons
basic functional units of the nervous system of individual cells
Neuroglia
separate and protects the neuron, provides a supportive framework for neural tissue, act as phagocytes and helps regulate the composition of the interstitial fluid
Central Nervous System
consists of the spinal cord and brain. Responsible for integrating processing and coordinating sensory data and motor commands. Seat of higher function. Has both sensory and motor commands.
Peripheral Nervous System
all neural tissue outside the CNS. delivers sensory information to the CNS and carries motor commands to peripheral tissue and system.
Afferent division
brings sensory info to the CNS from receptors in peripheral tissue and organs.
Efferent division
carries motor commands from the CNS to nucleus, glands, and adipose tissue.
Somatic Nervous System (SNS)
controls skeletal muscle contractions, voluntary contractions
Autonomic Nervous System (ANS)
provides automatic regulations of smooth muscle, cardiac muscles and glandular secretions at the subconscious level.
Reflex
controlled at the subconscious level, outside your awareness.
Cell Body
contains a relatively large round nucleus with a prominent nucleolus.
Axon
long cytoplasmic process capable of propagating an electrical impulse conducts impulses away from cell bodies.
Axon Hillock
thicken region in a multipolar neuron, the portion of the cell body adjacent to the initial segment
The 2 major Efferent systems are
somatic nervous system and the autonomic nervous system.
collaterals
enable a single neuron to communicate with several other cells, side branches of Axon
Telodendria
fine extensions, terminal axonal branches that end in synaptic knobs.
Dendrites
slender, sensitive processes that extend out from the cell bodies, receives stimulus
Synapse
specialized site where the neuron communicates with other cells. Involves two cells-presynaptic cells and postsynaptic cells. Gaps between neuron and next cell
Presynaptic cells
includes synaptic terminal and sends a message
Post-synaptic cells
receives the message
Synaptic terminals
release neurotransmitters
Neurotransmitter
chemical compound released by one neuron to affect the transmembrane potential of another
Structural Classification of Neurons
1. Bipolar
2. unipolar
3.multipolar
Bipolar
2 distinct process-one dendritic process that branches extensively at its distal and one axon. are rare but occur in special sense organs-are small and uncommon.
unipolar
dendrites and axon are continuous cell body lies off to one side. most sensory neurons of the peripheral nervous system. 1 process usually sensory
Multipolar
have 2 or more dendrite and a single axon. most common neurons in the CNS. controls skeletal muscle. longest carry motor commands from the spinal cord to small muscles that moves the toes
Functional Classification of Neurons
1. Sensory
2. Motor
3. Interneurons
Sensory
from afferent division. delivers info from sensory receptors to the CNS. located in peripheral sensory ganglia are unipolar
Motor
from the efferent division, carry instructions from the CNS
Interneurons
outnumber all other cells types of neurons. the more complex the response to a given stimulus, the more they are involved. common in brain, memory, and reasoning. Responsible for both the distribution of sensory information and the coordination of motor activity.
Interneurons have 2 primary cells
1. Purkinje
2. pyramid cells
The central nervous system has 4 types of Neuroglia
1. Ependymal
2. Astrocytes
3. Oligodendrocytes
4. Microglia
Ependymal
lines the central canal and ventricles, have slender processes that branch extensively and make direct contact with neuroglia in the surrounding neural tissue. Produce CSF in Ventricles.
Astrocytes
maintain Blood-Brain Barrier, create a 3D framework for the CNS, repair damage neural tissue, guide neuron development, and control the interstitial environment. Control Brain environment.
Oligodendrocytes
possess slender cytoplasmic extensions. Cell bodies are smaller and have fewer processes that astrocytes myelinated CNS axon
Microglia
many fine branches, capable of migrating through neural tissue appear early in embryonic development act as wondering police force and janitorial service by engulfing cellular debris, waste, products and pathogens.
Two types of Neuroglia in the PNS
1. Satellite cells
2. Schwaan cells
Schwaan Cells
form a sheath around peripheral axon. Most axons in the PNS whether myelinated or unmyelinated are shield from contact with interstitial fluids. Insulate axon, prevent destruction faster, impulse. Myelinate PNS axon
Satellite Cells
surround neurons cell bodies in ganglia, they regulate the environment around the neurons
Node of Ranvier
the small gaps of a few micrometers that separate adjacent internodes. Unmyelinated areas are sites of impulse.
Myelin
the membranous wrapping of electrical insulation- increase the speed at which an action potential travels along the axon
Resting Membrane Potential
all neural activities begins with a change in the resting membrane potential of a neuron
Neuron Activity
most action occurs in a axon
How many steps in an neuron activity
6 steps total
1. resting membrane potential
2. action potential
3. Propagation along axon
4. synaptic terminal
5. across the synapse
6. Post synaptic cell
Step one in Neuron activity
resting membrane potential
1.axal plasma-inside neuron its more negative than outside (-70)
2. Na+/K+ pumps move 3 Na+ to outside and 2 K+ to inside, uses ATP
3. Large neg. proteins stuck inside.
4. Na+ and K+ channels are closed during this process.
Step two in Neuron activity
Action Potential
1. all or none event-once threshold is reached action potential starts. Depolarization occurs. 1st Na channels open causing Na+ to defuse into cells. Inside cell reaches +30mv, K+ channels stay closed
2.Repolarization-K+ channels open and defuses out. Inside cell reaches -70mv again. Na+ channels are now closed
3. Refractory period
Step three in Neuron activity
Propagation along axon.
1.continuous conduction or
2. salutatory conduction can occur
Step four in Neuron activity
Synaptic Terminal
1. action potential arrives and depolarizes the synaptic knob
2. Ca++ channels open an d Ca++ diffuses causing enzymes to activate the NT into synapse by exocytosis.
Step five in Neuron activity
Across the synapse
1. NT diffuses across the synapse
2.binds to receptors on post synaptic cell
3. degranders breaks down excess NT to prevent "echoes"
Step six in Neuron activity
Post-synaptic cell
1.NT binds the receptors
2.one of two things can happen: 1.IPSP or 2. EPSP
Depolarization
any shift from the resting potential towards a more positive potential.
Repolarization
restoring the normal resting potential after depolarization
Refractory period
from the time an action potential has stabilized the membrane will not respond normally to additional depolarized stimuli.
Continuous conduction
basic mechanism by which an action potential is propagated along an unmyelinated axon occurs more slowly
Saltatory conduction
carries nerve impulse along an axon much more rapidly. Myelinated axon jump from node to node rather than moving along the axon in a series of tiny steps. Occurs along white matter tracts.
Identify 2 different types of postsynaptic potential
1. EPSP
2.IPSP
Hyperpolarization
the loss of positive ions produces an increase in the negativity of the resting potential.
EPSP
is a graded depolarization caused by the arrival of a neurotransmitter at the postsynaptic membrane. Results from the opening of chemically gated membrane channel that leads to depolarization of the plasma membrane. Na+ channels open
IPSP
a grated hyperpolarization of the postsynaptic membrane. May result from the opening of chemically gated K+ channels
Norepinephrine
a neurotransmitter that is widely distribution in the brain and in portions of the ANS. Typically has an excitatory depolarizing effect on the postsynaptic membrane. Excreted at smooth and cardiac muscle, glands. Also a hormone.
Dopamine
a CNS neurotransmitter may have either inhibitory or excitory effects release in one portion of the brain prevents the over stimulation of neurons that control skeletal muscle tone. Excitatory in pleasure centers of brain, reward mechanism. Inhibitory in subconscious motor function.
Serotonin
inadequate production can have widespread effects on a person's attention and emotional states and may be responsible for many cases of severe chronic depression: mood elevator.
Gaba
has an inhibitory effect roughly 20% of the synapses in the brain release, release appears to reduce anxiety
3 different types of postsynaptic cells
can turn on another neuron, a gland, or a muscle
Endorphins
inhibits pain
Brain stem contains
medulla oblongata, olives, pyramids, pons, mid brain and reticular formation
Medulla Oblongata
relays sensory info to thalamus and to other portions of the brain stem. Autonomic centers for regulations of visceral function (cardiovascular, respiratory and digestive system)
Nuclei
clusters of cell bodies in CNS, consists of gray matter, integrate info. located everywhere in the body.
Gyrus
elevated ridges that server to increase the surface area of the cerebral cortex
Sulcus
separate the gyri by shallow depressions
Postsynaptic potential
are graded potentials that develop in the postsynaptic membrane in response to a neurotransmitter.
name the neurotransmitter found n neuromuscular junctions
acetylocholine
Pons
relay sensory information to cerebellum and thalamus. Somatic and visceral motor center connects the cerebellum to the brain stem. Cranial nerve 5-8 located here. Included asc. desc. and transverse tracts.
Tracts
bundles of myelinated axon, transport impulses and is info highway. There are ascending (sensory) and descending(motor)
Mid brain/ Mesencephalon
processing of visual and auditory data. Generation of reflexive somatic motor responses. Maintenance of colliculus and inferior colliculus
Superior Colliculus
receives visual inputs from the lateral nucleus of the thalamus. Controls the reflex movement of the eyes, head, and neck in response to visual stimuli.
Inferior Colliculus
receives auditory data from nuclei in the medulla oblongata and pons. Controls the reflex movement of the head, neck, and trunk in response to auditory stimuli
Diencephalon
consists of the thalamus and hypothalamus
Thalamus
relay and processing centers for sensory information, filters out irrelevant. Visceral, occipital lobe, auditory temporal. Relay important info to appropriate parts of the brain
Hypothalamus
centers controlling emotion autonomic functions and hormone production. Regulates homeostasis
Cerebellum
partially hidden by cerebral hemisphere second largest part of the brain. Has hemispheres that are covered by a layer of gray matter it adjust outgoing movements by comparing arriving sensations with previously experienced sensations allowing you to perform same movement over and over. Contains a cortex with purkinje cells
Cranial Meninges
are continuous have distinct anatomical and functional characteristics. Made up of dura mater, arachnoid mater, and pia mater. Protect membrane around brain and spine
Dura Mater
consists of outer and inner fibrous layer. Outer layer is fused to the peritoneum of the cranial bone. Typically separated by a slender gap that contains tissue and blood. Contains 2 layers sinus drain blood into vein and folds secure brain into cranial cavity 3 large folds, falx cerbri, falx cerebelli and tenterium
Falx Cerebri
fold of dura mater that projects between the cerebral hemispheres in the longitudinal fissure
Tentorium Cerebeli
protects the cerebellar hemisphere and separates them from those of the cerebrum. Extends across the cranium at right angle to the falx cerebri
Falx cerebelli
divides the two cerebellar hemispheres along the midsagittal line inferior to the tentorium cerebelli
Trabeculae
webbing
Sub Trabeculae
space where CSF flows
Arachnoid villi
reabsorbs old CSF, penetrate the meningeal layer of the dura mater and extend into the superior sagittae sinus
Pia Mater
sticks to the surface of the brain, extends into every fold and accompanies the branches of the cerebral blood vessels as they penetrate the surface of the brain to reach internal structures. Its thin and wraps around cortex
Cerebrospinal fluid
its function is to cushion delicate neural structures, support the brain, transport nutrients. Flows through the ventricles. Produced by ependymal cells in the Choroid Plexus and reabsorbed by arachnoid villi
Choroid Plexus
consists of a combination of specialized ependymal cells and permeable capillaries involved in the production of CSF. Two extensive folds: found roof of 3rd vent. Cover floor of the 4th vent.
Circulation of CSF
circulates from the choroid plexus through the ventricles and fills the central canal of the spinal cord. Diffusion between it and the interstitial fluid of the CNS is unrestricted between and across the ependymal cells. Reaches sub arachnoid space through two lateral apertures and single median aperture. Flows through the sub arachnoid space surrounding the brain, spinal cord and cauda equina. Arachnoid villi penetrate the meningeal layer of the dura mater. It absorbs into the venous circulation at the arachnoid grandulations.
Excitatory neurotransmitter
causes depolarization and promote the generation of action potentials
Inhibitory Neurotransmitter
causes hyperpolarization and suppresses the generation o action potential
Acetyichoine ACh
a chemical neurotransmitter in the brain and PNS releases at neuromuscular junction and synapses of the parasympathetic division
achetylchinesterase AChE
an enzyme found in the synaptic cleft, bound to postsynaptic membrane in tissue, fluids breaks down and activates ACh molecules its a degrader
Olives
relay info to the cerebellar cortex about somatic motor commands as they are issued by motor centers at higher levels bulges along the vent. surface of the medulla. Coordination and balance
Cerebellar cortex
involuntary coordination and control of ongoing body movement
Arbor Vitae
white mater of the cerebellum forms a branching array that in sectional view resembles a tree. connects cerebellar cortex and nuclei with cerebellar peduncles
Vermis
separates the cerebellar hemispheres
Superior peduncle
link the cerebrum with nuclei in mid brain diencephalon and cerebellum
middle peduncle
connected to a broad band of fibers that cross the ventral surface of the pons. connect hemi. with sensory and motor nuclei of the pons
inferior peduncle
permit communication between the cerebellum and nuclei in the medulla and carry ascending and descending tracts from spinal cord
Pineal Gland
an endocrine structure that secretes the hormone melatonin. Regulates day-night cycles
Mamillary bodies
process sensory information including olfactory sensations contains motor nuclei that control reflex movements associated with eating
Limbic system
functions included establishing emotional states linking conscious with unconscious functions of the brain stem facilitating memory group of tracts and nuclei
Fornix
is a tract of white mater that connects the hippocampus with the hypothalamus
Pituitary gland
component of the endocrine system responsible for the integration of the nervous and endocrine system. releases hormone
cerebral peduncles
contains desc. fibers that go to the cerebellum by way of the pons and desc. fibers that carry voluntary motor commands issued by the cerebral hemisphere
central sulcus
deep groove divides the anterior frontal lobe from the more posterior parietal lobe
Frontal lobe
site of judgment, predictions, logical and abstract thought
Precentral gyrus
voluntary motor control over skeletal. located in frontal lobe
parietal lobe
interpret info regarding touch pressure and taste
temporal lobe
auditory, olfactory input
occipital lobe
visual interpret
cerebellum
coordinates complex somatic motor patterns adjusts output of other somatic motor centers in brain and spinal cord
insula
lies medial to lateral sulcus, interprets taste
association fibers
interconnect areas of neural cortex within a single cerebral hemisphere, contains white mater tracts