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Angela Luna P.2 Nervous System - Coggle Diagram
Angela Luna P.2 Nervous System
Disorders/Diseases
Cerebrovascular accident (stroke): occurs when blood flow to a portion of brain is halted
Autism: brain disorder that makes it difficult to communicate
Alzheimer's disease: a form of dementia associated with age (60+)
Spinal cord injury: damage to spinal cord
Meningitis: infection in the meninges surrounding the brain
Multiple sclerosis: autoimmune disease that damages the myelin sheath
Hypertension (high blood pressure): overactive sympathetic vasoconstrictor response to stress
Raynaud's disease: painful, exaggerated vasoconstriction in fingers/toes
Autonomic dysreflexia: life-threatening, uncontrolled activation of autonomic neurons in quadriplegias/ people with spinal cord injuries
Parkinson's disease: degeneration of dopamine-releasing neurons of substantia nigra
Huntington's disease: fatal hereditary disorder caused by accumulation of protein huntingtin in brain cells
Tissues
Neurologia
CNS
Astrocytes: most abundant, versatile, highly branched of glial cells
function: support/ brace neurons, play role in exchanges between capillaries/neurons, guide migration of young neurons, control chemical environment around neurons
Microglial cells: small, ovoid cells with thorny processes that tough/ monitory neurons
function: regulate brain development, maintenance of neuronal networks, and injury repair
Ependymal cells: range in shape from squamous to columnar, may be ciliated
function: form permeable barrier between CSF in cavities & tissue fluid bathing CNS cells
Oligodendrocytes: branched cells
function: processes wrap CNS nerve fibers, forming insulating myeline sheaths in thicker nerve fibers
PNS
satellite cells: surround neuron cell bodies in PNS
function: similar to astrocytes
Schwann cells (neurolemmocytes): surround all peripheral nerve fibers & form myelin sheaths in thicker nerve fibers
function: similar to oligodendrocytes
Neurons
dendrites
motor neurons that contain short, tapering, diffusely branched processes
receptive region of neuron
convey incoming messages toward cell body as graded potentials (short) distance signals)
axon
STRUCTURE
axon starts at axon hillock
in some neurons axons are short/absent; in others axon compromises almost entire length of cell
long axons= nerve fibers
branch profusely at end
distal endings= axon terminals/ terminal beutons
FUNCTION
conducting region of neuron
generates nerve impulses & transmits them along axolemma to axon terminal
myelin sheath
composed of myelin: whitish, protein lipid substance
function: protect & electrically insulate axon, increase speed of nerve impulse transmission
myelination in PNS
formed by Schwann cells
wraps around axon in jelly roll fashion
one cell forms one segment of myelin sheath
myelin sheaths in CNS
formed by processes of oligodendrocytes, not whole cells
each cell can wrap up to 60 axons at once
myelin sheath gap present
Major parts and functions of the spinal cord
dorsal horns: interneurons that receive somatic & visceral sensory input
ventral horns: some interneurons; somatic motor neurons
lateral horns: only in thoracic/superior lumbar regions; sympathetic neurons
ventral roots: bundle of motor neuron axons which exit spinal cord
dorsal roots: sensory input to cord
dorsal root (spinal) ganglia: cell bodies of sensory neurons
gray commisure: bridge of gray matter that connects masses of gray matter on either side
spinal nerves: formed by fusion of dorsal/ventral roots
spinal cord is enclosed in vertebral column
FUNCTIONS: provide 2 way communication to/from brain and body, major reflex center: reflexes initiated/completed at spinal cord
gray matter is located in core, white matter is located outside
Neurotransmitters
Chemical structure
acetylcholine (ACh)- used by ANS/ CNS neurons
biogenetic amines- catecholamines: dopamine, norepinephrine(NE), epinephrine
indolamines: serotonin, histamine
amino acids- make up all protein
peptides (neuropeptides)- beta endorphin, dynorphin, enkephalins= natural opiates
purines- monomers (effect in both CNS & PNS)
gases & lipids
endocannabinoids
Function
EFFECTS
excitatory neurotransmitter effects= depolarizing
inhibitory neurotransmitter effects= hyperpolarizing
ACTIONS
direct action: neurotransmitter binds directly to/ opens ion channels
indirect action: acts through intracellular 2nd messengers
Compare & contrast the autonomic nervous system
EFFECTORS
SNS- innovates skeletal muscle
ANS- innervates cardiac/smooth muscle, gland
EFFERENT PATHWAYS & GANGLIA
SNS- cell body in CNS, single thick myelinated group A axon extends in spinal/cranial nerves to skeletal muscle
ANS- preganglionic neuron: cell body in CNS with myelinated preganglionic axon extending to ganglion
postganglionic neuron (outside CNS): cell body synapses with preganglionic axon in autonomic ganglion with nonmyelinated postganglionic axon extending to effector organ
TARGET ORGAN RESPONSES TO NEUROTRANSMITTERS
SNS- all somatic motor neurons release ACh; effect= always stimulatory
ANS- preganglionic fibers release ACh, postganglionic fibers release NE/ ACh at effectors; effect= stimulatory/inhibitory depending on type of receptor
Major functions of the nervous system
master controlling/communicating system
sensory input: info gathered by sensory receptors about internal/ external changes
integration: processing and interpretation of sensory input
motor output: activation of effector organs (muscles and glands) produces a response
Cranial nerves
I. Olfactory nerves: sensory nerves of smell
II. Optic nerves: sensory (visual) function
III. Oculomotor nerves: function in raising eyelid, directing eyeball, constricting iris, controlling lens shape
IV. Trochlear nerves: motor nerve- directs eyeball
V. Trigeminal nerves: convey sensory impulses from areas of face, supply motor fibers for mastication
VI. Abducens nerves: motor, innervating lateral rectus muscle
VII. Facial nerves:
motor function-
facial expression, parasympathetic impulses (lacrimal/ salivary glands),
sensory function-
(taste) from anterior 2/3 of tongue
VIII. Vestibulocochlear nerves: vestibular nerve handles balance and equilibrium, cochlear nerve is responsible for hearing
IX. Glossopharyngeal nerves: provides motor and sensory information to mouth and throat; helps raise part of your throat, enabling swallowing
X. Vagus nerves:
motor fibers-
regulate activities of heart, lungs, abdominal viscera;
sensory fibers-
carry impulses from thoracic & abdominal viscera, baroreceptors, chemoreceptors, tastebuds of posterior tongue/pharynx
XI. Accessory Nerves: exit skull to innervate trapezius & sternocleidomastoid nucleus
XII. Hypoglossal nerves: innervate extrinsic/intrinsic muscles of tongue that contribute to swallowing/speech
Spinal nerves
supply all body parts except hand/ neck
8 pairs: cervical nerves (C1-C8)
12 pairs: thoracic nerves (T1-T12)
5 pairs: lumbar nerves (L1-L5
5 pairs: sacral nerves (S1-S5)
1 pair: coccygeal nerves (C0)
Major divisions and subdivisions of the nervous system
Central nervous system (CNS)
brain/spinal cord of dorsal body cavity
integration & control center: interprets sensory input and dictates motor output
Peripheral nervous system (PNS)
portion of nervous system outside CNS
consists mainly of nerves that extend from brain/spinal cord
spinal nerves= to/from spinal cord
cranial nerves= to/from brain
Sensory (afferent) division
somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints TO CNS
visceral sensory fibers: convey impulses from visceral organs TO CNS
Motor (efferent) division
transmits impulses from CNS to effector organs (muscles & glands)
somatic nervous system (voluntary): somatic motor nerve fibers conduct impulses from CNS to skeletal muscle
autonomic nervous system (involuntary): consists visceral motor nerve fibers, regulates smooth/ cardiac muscles, glands
Parasympathetic division (rest & digest system): keeps body energy use low; directs digestion, diuresis, defacation
Sympathetic division (flight or flight system): mobilizes body during activity; exercise, excitement, emergency, embarrassment activates system
Reflex arc
receptor: site of stimulus action
sensory neuron: transmits afferent impulses to CNS
integration center: monosynaptic/polysynaptic region within CNS
motor neuron: conducts efferent impulses from integration center to effector organ
effector: muscle fiber/ gland cell- responds to efferent impulses by contracting/secreting
Connective Tissue Coverings
endoneurium: loose CT- encloses axons and their myelin sheaths
perineurium: coarse CT- bundles of fiber into fascicles
epineurium: tough fibrous sheath around fascicles to form nerve
Action potential & nerve impulse
Resting state: all gates Na+/K+ channels closed
Depolarization: depolarizing local currents open voltage-gated Na+ channels= Na+ rushes into cell
Na+ influx= more depolarization= more Na+ channels open
Repolarization: Na+ channels inactivating, K+ channels open
K+ exits down electrochemical gradient
Hyperpolarization: some K+ channels remain open, Na+ channels reset
Drugs of abuse
Heroine
neurotransmitters: inhibitory, dopamine
mimics natural opiates and binds to opiate receptors, turning off dopamine inhibition
dopamine is allowed to flood the synapse, producing feelings of sedation and well-being
Ecstasy
neurotransmitters: seratonin
mimics serotonin and is taken up by serotonin transporters; transporter becomes confused; transports serotonin out of cell causing it to bind to the receptors over and over, overstimulating the cell
affects serotonin pathways responsible for mood, sleep, perception, appetite
Marijuana
neurotransmitters: inhibitory, dopamine
THC mimics anandamide and binds to cannabinoid receptors; inhibition turned off and dopamine is allowed to squirt into synapse
anandamide is responsible for slowing down movement- relaxed and calm; unlike THC, anandamide breaks down quickly in the body
Methamphetamine
neurotransmitters: dopamine
causes transporters to work in reverse- pumping dopamine out of cell and into synapse; excess dopamine binds over and over, overstimulating the cell
highly addictive, pleasure and exhilaration
Alcohol
neurotransmitters: GABA inhibitory, glutamate
interacts with GABA receptors to make them even more inhibitory; binds to glutamate receptors preventing glutamate from exciting the cell
affects areas of brain involved in memory formation, decision making, impulse control
Cocaine
neurotransmitters: dopamine
blocks dopamine transporters leaving dopamine trapped in synaptic cleft; binds over and over, overstimulating the cell
fidgety and unable to stay still
LSD
neurotransmitters: serotonin
either inhibit/ excite receptors; has complex sensory effects
excites locus coeruleus (responsible for wakefulness and evoking a startle response to unexpected stimulus)
Major parts and functions of the brain
surface markings
transverse cerebral fissure: separates cerebrum & cerebellum
longitudinal fissure: separates 2 hemispheres
fissures: deep grooves
sulci: shallow grooves
gyri: ridges
5 lobes: frontal, parietal, temporal, occipital, insula
cerebral hemispheres
left hemisphere: controls language, math, logic
visual-spatial skills, intuition, emotion, artistic/musical skills
thalamus: act as relay station for info coming into cortex
hypothalamus: below thalamus; main visceral control & regulating center vital to homeostasis
epithalamus: extends from posterior border, secretes melatonin that helps regulate sleep-wake cycle
brain stem: controls automatic behaviors necessary for survival
midbrain: associated with vision, hearing, motor control, sleep/wake, alertness, and temperature regulation, acting as a sort of relay station for auditory and visual info
pons: handles unconscious processes and jobs, such as sleep-wake cycle and breathing
medulla oblongata: helps control vital processes like heartbeat, breathing and blood pressure; regulate vomiting, hiccupping, swallowing, coughing, sneezing
cerebellum
processes input from cortex, brain stem, sensory receptors to provide precise coordinated movements of skeletal muscle
plays role in thinking, language, emotion
balance & coordination
Classification of neurons
Number of processes
Multipolar: 3 or more processes (1 axon, others dendrites), most common, major neuron type in CNS
Bipolar: 2 processes (1 axon, 1 dendrite), rare
Unipolar: one T-like process (2 axons), aka pseudounipolar
Direction
Sensory: transmit impulses from sensory receptors toward CNS, unipolar, cell bodies located in ganglia in PNS
Motor: carry impulses from CNS to effectors, multipolar, cell bodies located in CNS
Interneurons: lie between motor & sensory neurons, shuttle signals through CNS pathways, most within CNS, 99% body neurons