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Jessie Castro P.2 Nervous System - Coggle Diagram
Jessie Castro P.2 Nervous System
Drug 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
Eustasy
neurotransmitters: serotonin
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
Marihuana
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
highly addictive, pleasure and exhilaration
causes transporters to work in reverse- pumping dopamine out of cell and into
synapse; excess dopamine binds over and over, overstimulating the cell
neurotransmitters: dopamine
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
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)
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
Reflex Arc
receptor: site of stimulus action
sensory neuron: transmits afferent impulses to CNS
motor neuron: conducts efferent impulses from integration center to effector organ
integration center: monosynaptic/polysynaptic region within CNS
effector: muscle fiber/ gland cell- responds to efferent impulses by contracting/secreting
Major Functions Of 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
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 and 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
Major Parts and Functions of 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
Major Functions and Parts of the Brain
Cerebral Hemisphere
left hemisphere: controls language, math, logic
visual-spatial skills, intuition, emotion, artistic/musical skills
5 lobes: frontal, parietal, temporal, occipital, insula
Surface Marking
,
transverse cerebral fissure: separates cerebrum & cerebellum
longitudinal fissure: separates 2 hemispheres
fissures: deep grooves
sulci: shallow grooves
gyri: ridges
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
.
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
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)
Cranial Nerves
.
I. Olfactory nerves: sensory nerves of smell
II. Optic nerves: sensory (visual) function
III. Oculomotor nerves: function in raising eyelid
IV. Trochlear nerves: motor nerve- directs eyeball
V. Trigeminal nerves: convey sensory impulses from areas
VI. Abducens nerves: motor, innervating lateral rectus muscle
.
VII. Facial nerves: facial expression
VIII. Vestibulocochlear nerves: vestibular nerve handles balance
IX. Glossopharyngeal nerves: provides motor and sensory
information
X. Vagus nerves: regulate activities of heart and lungs
.
XI. Accessory Nerves: exit skull to innervate trapezius
XII. Hypoglossal nerves: innervate extrinsic/intrinsic muscles
Disorders and Diseases
.
Cerebrovascular accident (stroke): occurs when blood flow to is stopped
Autism: brain disorder that makes it difficult to communicate
Alzheimer's disease: a form of dementia associated with age (60+)
Meningitis: infection in the meninges surrounding the brain
Multiple sclerosis: autoimmune disease that damages the myelin sheath
Hypertension (high blood pressure): overactive sympathetic vasoconstrictor
Raynaud's disease: painful, exaggerated vasoconstriction in fingers
Autonomic dysreflexia: life-threatening, uncontrolled activation of neurons
.
Parkinson's disease: degeneration of dopamine-releasing
neurons
Huntington's disease: fatal hereditary disorder caused by
accumulation of protein huntingtin in brain cells
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
Functions
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
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
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, defalcation
Sympathetic division (flight or flight system): mobilizes body during activity; exercise, excitement, emergency, embarrassment activates system
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
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 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
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
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
ANS- preganglionic neuron: cell body in CNS with myelinated preganglionic axon extending to ganglion
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