Nervous System Aubrey Menchaca P : 5

Spinal Nerves

Cranial Nerves

Reflex arc ( parts & functions )

Disorders / Diseases

Action potential & nerve impluses

Drugs of abuse

Neurotransmitters

ANS compare & contrast with SNS

Spinal cord ( parts & functions )

Connective tissue coverings

Brain ( parts & functions )

Neuron classifications

Tissues ( structures & functions of neurons and neuroglia )

Nervous system division and subdivisions ( CNS & PNS )

Nervous system functions

Reticular formation

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

governs brain arousal

control coarse limb movements

through central core of brain stem

regulate vasomotor, cardiac, and respiratory centers

Mental functions

Memory - storage and retain information

protection- mengines cover and protect cns

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

Short-term-memory : temporary in holding information

Long-term-memory : limitless capacity

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

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

Methamphetamine - dopamine vesicles force dopamine molecules of cell. Affect : Highly addictive and person feels intense pleasure and exhilaration

Inside of cell is negative compared to outside

  1. 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 )

  1. Depolarization - generation and propaganda of an action potential

Motor output - Activation of effector organs produces a response

Two principal parts

Integration - processing and interpretation of sensory input

Neuroglia - Nervous tissue histology

Sensory input - information gathered by sensory receptor through internal and external changes

CNS - brain and spinal cord of dorsal body cavity

PNS - outsides of CNS and has many nerves extending from brain and spinal cord

Neuroglia (glial cells) - surround and wrap neurons

Neurons (nerve cells) - excitable cells transmit electrical signals

Unipolar - one t like process ( aka - pesudounipolar )

Neurons grouped by direction where nerve impulses travels to CNS

Bipolar - Two processes

Multipolar - three or more processes

Sensory - transmit impulses from sensory receptors towards cns

Motor - carry impulses from cns to effectors

Interneurons - ( aka association neurons ) shuttle signals through cns pathways

Somatic

Autonomic

Pathway uses a two-neuron chain

innervates cardiac muscle, smooth muscle, and glands

Cell body is in CNS and a single, thick myelinated group extends in spinal or cranial nerves directly to skeletal muscle

innervates skeletal muscles

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

Sympathetic 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 "

Mobilizes body during activity

exercise, excitement, emergency, embarrassment activates

innervates more organs than parasympathetic

" fight - or - flight "

Form lateral horns of spinal cord

blood pressure, heart rate, and respiratory rates are low

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

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.

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

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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

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

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

PNS

CNS

Integration and control center

interprets sensory input and dictates motor output

Brain and spinal cord of dorsal body cavity

consists mainly of nerves that extend from brain and spinal cord

has two functional divisions

Part of nervous system outside of the CNS

( 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

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

  1. integration : processing and interpretation of sensory input
  1. motor neuron

2. sensory input : information gathered by sensory receptors about internal and external changes

  1. effector

1. receptor

  1. Repolarization - restoration of resting conditions

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.

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