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

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