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Nervous System Aubrey Menchaca P : 5, : - Coggle Diagram
Nervous System Aubrey Menchaca P : 5
Spinal Nerves
12
pairs of
thoracic
nerves
5
pairs of
lumbar
nerves
8
pairs of
cervical
nerves
5
pairs of
sacral
nerves
31 pairs and supply all body part except head and part of neck
1
pair of tiny
coccygeal
nerves
each nerve connected to two roots
Ventral roots
- contain motor ( efferent ) fibers from ventral horn
Doral roots
- contain sensory ( afferent ) fibers from sensory neurons
BOTH
- branched medially as rootlets then join laterally to form spinal nerve
Cranial Nerves
V Trigeminal nerve
- Largest cranial nerve ; fibers extend from pons to face. supply motor fibers for mastication
IV Trochlear nerves
- primarily motor nerve that directs eyeball
VI Abducens nerves
- fibers from inferior pons enter orbits via superior orbital fissures
VII Facial nerves
- fibers from pons travel through internal acoustic meatuses and emerge through stylomastoid foramina to lateral aspect of face
VIII Vestibulocochlear nerve
- mostly sensory function ; small motor component for adjustment of sensitivity of receptors
Vagus nerves
- only cranial nerves that extend beyond head and neck region. fibers from medulla exit skull via jugular foramen.
III Oculomotor nerves
- fibers extend from ventral midbrain through superior orbital fissures to four of six extrinsic eye muscles
II Optic nerves
- Arise from retinas ; brain tract. pass through optic canals, converge, and partially cross over at
optic chiasma
I Olfactory nerves -
nerves of smell. fibers synapse in olfactory bulbs
XI Accessory nerves
- Formed from ventral rootlets from C1 to C5 region of spinal cord.
XII Hypoglossal nerve
- Fibers from medulla exit skull via Hypoglossal canal
IX Glossopharyngeal nerves
- fibers from medulla leave skull via jugular foramen and run to throat. innervate part of tongue
Reflex arc ( parts & functions )
integration
: processing and interpretation of sensory input
motor neuron
2
. sensory input :
information gathered by sensory receptors about internal and external changes
effector
1
. receptor
Disorders / Diseases
Anencephaly
- Cerebrum and parts of brain stem never develop because neural fold fails to fuse.
Causes
: death soon after birth
Cerebral Palsy
- neuromuscular disability involving poorly controlled or paralyzed voluntary muscles.
Cause
: brain damage or lack of oxygen during birth
Spina bifida
- incomplete formation of vertebral arches ; typically involving lumbosacral region
Multiple Sclerosis
- autoimmune disease that affects primarily young adults. Myelin sheaths in CNS destroyed.
Symptoms
: visual disturbances, weakness, loss of muscular control, speech disturbances
Phantom limb pain
- pain in limb after being amputated. Method : anethesia during surgery to reduce phantom pain
Meningitis
- inflammation of the meninges. May spread to CNS and lead to inflammation of the brain ( encephalitis )
Epileptic seizure
- electrical discharges by groups of neurons. prevent messages from getting through.
Symptoms
: loose consciousness, fall stiffly, and uncontrolled jerking.
Action potential & nerve impluses
Inside of cell is negative compared to outside
Generation of end plate potential
- membrane will open which leads to depolarization making Na+ causes channels to trigger Ap which leads to muscle fiber contractions
Resting sarcolemma is polarized ( voltage exists across membrane )
Depolarization
- generation and propaganda of an action potential
Repolarization
- restoration of resting conditions
Drugs of abuse
Methamphetamine
- dopamine vesicles force dopamine molecules of cell.
Affect
: Highly addictive and person feels intense pleasure and exhilaration
Alcohol
- Brain delivers double sedative punch.
Affect
: memory formation, decision making, and impulse control
Marijuana
- cannabinoid receptors turn off release of inhibitory neurotransmitters.
Affect
: slows down movement making person feel calm and relaxed
Cocaine
- Blocks transporters, dopamine trapped in synaptic cleft.
Affect
: abusers fidgety and unable to sit still
Ecstasy
- Mimics serotonin and interaction alters transporter ( works in reverse ).
Affect
: serotonin pathways responsible for mood, sleep, perception, and appetite
LSD
- may inhibit particular receptors and excite them.
Affect
: feeling of wakefulness and evoking a startle response to stimulus.
Heroine
- mimics natural opiates and binds to opiate receptors.
Affect
: used as painkiller and responsible for pain signals, stress, and emotional attachment
Neurotransmitters
Sterotonin
- made from the amino acid
tryptophan
Histamine
- made from the amino acid histidine
Biogenic amines - catecholamines, dopamine, nonrepinephrine, and indolamines
Ach
- released at neuromuscular junction.
ANS compare & contrast with SNS
Somatic
Cell body is in CNS and a single, thick myelinated group extends in spinal or cranial nerves directly to skeletal muscle
innervates skeletal muscles
Autonomic
Pathway uses a two-neuron chain
innervates cardiac muscle, smooth muscle, and glands
Both
effectors
Efferent pathways and ganglia
have motor fibers
contained in most spinal and many cranial nerves
Higher brain centers regulate and coordinate both systems
Two arms of ANS
Parasympathetic divison
directs digestion, diuresis, and defecation
fibers originate from brain stem regions or cord
keeps body energy use as low as possible
" rest - and - digest "
blood pressure, heart rate, and respiratory rates are low
Sympathetic divison
Mobilizes body during activity
exercise, excitement, emergency, embarrassment activates
innervates more organs than parasympathetic
" fight - or - flight "
Form lateral horns of spinal cord
Spinal cord ( parts & functions )
Epidural space
- cushion of fat and network of veins in space between vertebrae and spinal dura mater
Filum terminate
- extends to coccyx. Fibrous extension of conus covered with pia mater
Provides two-way communication to and from brain and body
Denticulate ligaments
- cervical and lumbar enlargements : are where nerves servicing upper and lower limbs arise from spinal cord
Enclosed in vertebral column and begins at the foramen magnum.
Trauma and disorders
parethesias
- caused by damage to dorsal roots or sensory tracts. leads to sensory function loss
paralysis
- causes by damage to ventral roots or ventral horn cells. Leads to motor function loss
trauma
- localized injury to spinal cord or its roots lead to functional losses
paraplegia
- transection between T1 and L1
spinal shock
- transient period of functional loss caudal to lesion
Quadriplegia
- transection in cervical region
Lou Gehrig's disease
- destruction of ventral horn motors neurons and fibers of pyramidal tract.
Symptoms
: loss of ability to speak, swallow, and breath.
Death
: within 5 years
Neuronal pathways
Relay
- consist of chain of two or three neurons
Somatotopy
- precise spatial relationship in CNS correspond to spatial relationship in body
Decussation
- most pathways cross from one side of CNS to other at some point
Symmetry
- pathways are paired symmetrically ( right and left )
Major spinal tracts are part of multineuron pathways. four key points
Connective tissue coverings
meninges
cover and protect CNS. Protects blood vessels and encloses venous sinuses. consists of
three layers
Pia mater
- Delicate connective tissue that clings tightly to the brain, following every convolution
CSF
- Forms a liquid cushion of constant volume around brain.
Function
: gives buoyancy to CNS structures
Arachnoid mater
- middle layer with spider web-like extensions. separated from dura mater by subdural space
Choroid plexus
- cluster of capillaries that hang from roof of each ventricle, enclosed by Pia mater and surrounding layer of ependymal
Dura mater
- strongest meninx
Blood brain barrier
- helps maintain stable environment
Brain ( parts & functions )
Reticular formation
governs brain arousal
control coarse limb movements
through central core of brain stem
regulate vasomotor, cardiac, and respiratory centers
Limbic system
fornix :
fiber tract linking limbic system regions
large part of emotional & affective brain
medial aspects of cerebral hemispheres and diecephalon
put emotional responses to odors
Mental functions
Memory - storage and retain information
Short-term-memory :
temporary in holding information
Long-term-memory :
limitless capacity
protection- mengines cover and protect cns
Dura mater
is the top and strongest, next is
arachnoid
which is in the middle, and last is
pia mater
which is delicate
CSF :
gives buoyancy to cns structures and protects it from trauma
Language - cortex of left hemisphere
Broca's area :
speech production. people w lesions understand words but cannot speak
Wernicke's area :
understanding spoken and written words. people w lesions can speak but not understand words
Neuron classifications
Unipolar - one t like process ( aka - pesudounipolar )
Neurons grouped by direction where nerve impulses travels to CNS
Sensory - transmit impulses from sensory receptors towards cns
Motor - carry impulses from cns to effectors
Interneurons - ( aka association neurons ) shuttle signals through cns pathways
Bipolar - Two processes
Multipolar - three or more processes
Tissues ( structures & functions of neurons and neuroglia )
Astrocytes
- cling to neurons, synaptic endings, and capillaries
Oligodendrocytes
- branched cells
Neuroglia - nervous tissue histology and consists of two cell types
Neuroglia ( glial cells )
- small cells that surround and wrap delicate neurons
Neurons ( nerve cells )
- excitable cell that transmit electrical signals
Nervous system division and subdivisions ( CNS & PNS )
PNS
consists mainly of nerves that extend from brain and spinal cord
has two functional divisions
( efferent ) motor divison. Visceral sensory fibers
- convey impulses from visceral organs to CNS
( afferent ) somatic sensory fibers
- convey impulses from skin, skeletal muscles, and joints to CNS
Part of nervous system outside of the CNS
Voluntary SNS
- somatic nerve fibers conduct impulses from CNS to skeletal muscle
Involuntary ANS
- Consists of visceral motor nerve fibers and regulates smooth muscle, cardiac muscle, and glands
CNS
Integration and control center
interprets sensory input and dictates motor output
Brain and spinal cord of dorsal body cavity
Nervous system functions
Motor output - Activation of effector organs produces a response
Two principal parts
CNS - brain and spinal cord of dorsal body cavity
PNS - outsides of CNS and has many nerves extending from brain and spinal cord
Integration - processing and interpretation of sensory input
Neuroglia - Nervous tissue histology
Neuroglia (glial cells) - surround and wrap neurons
Neurons (nerve cells) - excitable cells transmit electrical signals
Sensory input - information gathered by sensory receptor through internal and external changes
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