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Nervous System Concept Map Sarah Hernandez P.6 - Coggle Diagram
Nervous System Concept Map
Sarah Hernandez P.6
Major Functions of the Nervous System
major aspects: sensory input, integration + processing, motor input
functions: thinking, movements, internal physiology processes
Main Cell Types
neurons
: cells that communicate thru electrical impulses with other neurons/tissue
neuroglia
: cell that support, nourish, protect, and insulate neurons
neurotransmitters
: chemical messengers in synapse; conveys eletrical impulse from neuron to cells
FLOW OF INFO:
sensory receptors> brain/spinal cord> effector
(sensory input> integration> motor output)
general functions: sensory, integrative, motor
sensory
: by
sensory receptors
, detects internal/external changes
-infor travels : receptors> sensory neurons> cns
integrative
: coordinates sensory info in cns
-processing the info= basis of decision-making
motor function
: nerve impulses (of cns) are conducted along motor neurons to
effectors
effectors
: muscles/glands responding tot he decisions of cns
CNS and PNS
2 groups of organs in the nervous system:
central nervous system (CNS)
:
brain/spinal cord; for integration and decision-making
peripheral nervous system (PNS)
:
cranial/spinal nerves; connecting the cns to the rest of the body
contains
sensory (afferent) and motor (efferent)
divisions
motor
functions:
somatic nervous system
- controls voluntary skeletal muscles
autonomic nervous system
- controls involuntary effectors; smooth/cardiac muscles + glands
Major divisions and subdivisions of the nervous systems (+ CNS and PNS)
CNS
for integration of info/ decision making
made up of brain/spinal cord
PNS
connects cns to the rest of the body; made up of:
-
cranial nerves
: 12 pairs located underside of the brain- olfactory/ optic/ oculomotor/ trochlear/ trigeminal/ abducens/ facial/ vestivulocochlear/ glossopharyngeal/ vagus/ accessory/ hypoglossal
spinal nerves
: 31 spinal nerves- 8 cranial/ 12 sacral/ 5 thoracic/ 5 lumbar/ 1 coccygeal nerves
contains sensory (afferent) and motor (efferernt) divisions
motor functions
autonomic nervous system
: controls involuntary effectors- smooth/cardiac muscles +glands
somatic nervous system
: controls voluntary skeletal muscles
Tissues- structure and function of neurons and neuroglia
NEURON
STRUCTURE:
MYELIN SHEATH
myelinated fibers
large axons enclosed by
myelin sheaths
(increases condition speed of nerve impulses)
Node of Ranvier
: narrow gaps of myelinated sheath
FUNCTION:
sensory (afferent) neurons
: conduct impulses peripheral receptors to cns; unipolar/bipolar
interneurons (association/ internuncial neuron)
: multipolar neurons w/in cns forming links betw. other neurons
motor efferent neurons
: multipolar conduct impulses cns to peripheral effectors (muscles/glands)
NEUROGLIA: nerve glue, supports neurons: fill spaces, structural support, protect, insulate neurons
-no conduction/ generation of nerve impulses
-4 types in cns/ 2 types in pns
CNS NEUROGLIA
:
microglia
: small cells function as phagocytes for bacterial cells/cellular debris and produce scar tissue at injury sites
oligodendeocytes
: form myelin sheath around axons of brain/spinal cord
ependymal cells
: produces cerebrospinal fluids in cns
astrocytes
: between blood vessels/neurons
functions- structural support, form
blood-brain
barrier
PNS NEUROGLIA
:
schwann cells
: myelin-prod neuroglia of pns
satelite cells
: provide protective coating around cell bodies of pns neuron
NEURON GENERATION:
pns neurons: able to regenerate axons
cns axons= myelinated by digodendrocytes; do not regenerate
Classifications of Neurons
multipolar neurons
: many dendrites, one axon; most neurons with cell bodies in CNS (interneurons/ motor) are multipolar
bipolar neurons
: 2 processes extending from cell body, 1 dendrite, 1 axon; location = special sense ( eyes, nose, ears)
unipolar neurons
: only 1 process extending from cell body (sensory nerves)
outside cell body= split into 2 parts, functions as 1 axon
peripheral process: dendrites near peripheral body part/ central process= CNS
^ cell bodies = in ganglia, outside CNS
Connective Tissue Coverings
epineurium
: outer covering of a nerve
perineurium
: covering of fascicles (bundles) of nerve fibers
endoneurium
: covering of individual nerve fibers (axons)
Major parts and functions of the brain
meninges
: between skull bones, vertebrae, soft CNS tissues; surrounds brain/ spinal cords
consists of dura mater, arachnoid mater, pia mater
dura mater
: outermost meninges layer
tough dense connective tissue
-sheath around spinal cord= separate from vertebra by
epidural
arachnoid mater
: middle meninges layer
-
subarachnoid space
contains
cerebrospinal fluid (CSF)
= between arachnoid and pia mater
pia mater
: innermost meninges layer
The Brain
gray matter: outside structure
white matter: inside structure
cerebral cortex
: thin layer of gray matter, is superficial, containing 75% of neuron cells w/in system
beneath cortex= white matter of myelinated nerves connecting cell bodies to the nervous system
4 main parts of the brain:
cerebrum, diencephalon, cerebellum, brainstem
cerebrum
: largest portion, associated with higher mental functions and sensory/motor functions
diencephalon
: processes sensory input and homeostatic control
cerebellum
: coordinates muscular activity
brainstem
: coordinates and regulates visceral activities and connects different parts of the nervous system
CEREBRUM Structure and Function
STRUCTURE
includes two mirrored
cerebral hemispheres (left and right cerebral hemispheres)
, contains 4 lobes:
frontal, parietal, temporal, occipital
corpus callosum
: flat nerve fiber bundle that connects hemispheres
surface of the brain
:
gyri
- ridges
sulci
- grooves
fissures
- deep grooves
FUNCTION
provides higher brain functions: intelligence, personality, sensory input, voluntary muscle movements
Functional Areas of the Cerebral Cortex
: sensory, association, motor areas
SENSORY AREAS
sensory areas
: several areas of the cerebrum, interpret sensory input, produces feelings/sensations
skin senses: anterior parietal lobe
visual area: posterior occipital lobe
auditory area: posterior temporal lobe
taste area: central sulcus base/ insula
smell area: deep temporal lobe
*sensory fibers of PNS cross over and sensory impulses are interpreted in centers of mirrored hemispheres
ASSOCIATION AREAS
association areas
: analyze/ interpret sensory impulses and function in reasoning, judgement, emotions, verbalizing ideas and strong memory
frontal lobe
: asso. areas= control # of higher intellectual processes
parietal lobe
: asso. areas= functions understanding speech/ choosing proper words
occipital lobe
: asso. areas= help analyze visual patterns/combine visual images with sensory information
MOTOR AREAS
primary motor cortex
(areas): located posterior frontal lobes, anterior of central sulcus= crossover of brainstem motor system; right side controls left half
Broca's motor speech area
: left side of frontal lobe; controls muscle movements of speech
VENTRICLES AND CEREBROSPINAL FLUID
ventricles
: series of connective cavities w/in cerebral hemispheres/ brainstem; cavities are filled with CSF
FLOW OF CSF
**2 lateral ventricles> interventricular foramina> third ventricle> cerebral aqueduct> fourth ventricle
choroid plexuses
- secretes CSF into ventricles, most csf is from lateral ventricles
DIENCEPHALON
: lies between midbrain and cerebral hemisphere
surrounds
3rd ventricle
; main parts=
thalamus/ hypothalamus
+limbic system
: generates feelings
FUNCTIONS OF THALAMUS
sorting sensory info (relay center)
channels all sensory impulses except smell
produces general sensation awareness- pain, touch, temperature
FUNCTIONS OF HYPOTHALAMUS
maintains homeostasis by regulating visceral activities and linking endocrine system with nervous system
regulates heart rate, body temp, water/ electrolyte balance, hunger, controls movement, reg, sleep/ wakefullness
of pituitary gland
simulate> posterior> secrete hormones
produce> anterior> secrete hormones
BRAINSTEM
: lies at base of cerebrum, connecting cerebrum, diencephalon+ cerebellum to spinal cord
MIDBRAIN:
contains main motor pathways between cerebrum and lower portions of nerv.sys
location: between diencephalon/pons
PONS:
contains centers that regulate rate/depth of breathing
location: between midbrain and medulla oblongata
MEDULLA OBLONGATA:
transmits all ascending/ descending impulses between brain/spinal cord
controls visceral functions:
cardiac center: alters heart rate
vasomotor center: controls vasoconstriction/ vasodilation of blood vessels, controls blood pressure
respiratory center: controls rate/depth of breathing
*contains nuclei that controls reflexes: coughing, sneezing, swallowing, vomiting
CEREBELLUM
: located beneath the occipital lobes of cerebrum
cerebellar cortex
: thin layer of gray matter; lies outside of
arbor vitae
, the core of white matter
cerebellum communicates with the cns by 3 tract pairs; **cerebellar penduncles
FUNCTIONS:
integrates sensory info of body part position
coordinates skeletal muscle activity
maintains posture
ensure desired movements occur
Major parts and functions of the spinal cord
SPINAL CORD STRUCTURE AND FUNCTION
cervical enlargement
: thickened area near top of spinal cord, provides nerves to upper limbs
lumbar enlargement
: thickened region near bottom of spinal cord, gives nerves serving lower limbs
couda equina (horse tail)
: structure formed where spinal cord tapers to point inferiorly
-consists of spinal nerves in lumbar/sacral areas
STRUCTURE:
31 segments, each connects to pair of spinal nerves
-
white matter
: bundles of myelinated nerve fibers (nerve tracts), surrounds gray matter
gray matter
: surrounded by white matter, houses interneurons/ neuron cell bodies
sensory neuron cell bodies enter spinal cord through
dorsal root ganglia
central canal
: middle of gray matter, contains csf
FUNCTIONS:
transmits impulses to/from brain, houses spinal reflexes
ascending tracts
: carry sensory info to brain
descending tracts
: carry motor info from brain to muscles/glands (effectors)
spinal reflexes
: controlled by reflex arcs that pass through spinal cord
Action potential and Nerve Impulse
polarized
: charge inside membrane is different from charge outside membrane
inside is
more negative
than outside
membrane potential
: charge inside a cell
resting membrane potential
: cell charge at rest= about -70mV (neurons)
sodium ions
: greater concentration
outside
cell
potassium ions
: greater concentration
inside
cell
negatively charged ions/ proteins also found inside of cell
threshold stimulus
: strong stimulus to cause Na ions to enter neurons, potential changes from
-70mV to -55mV
(threshold potential)
depolarization
: change from negative to positive charge inside neuron
action potential = all or nothing response; occurs at -55mV charge
repolarization
: action returns to resting potential; -70mV
hyperpolarization
: potential dips below resting potential
refractory period
: period during/after an action potential; threshold stimulus cannot cause another action potential
ION CHANNELS + ACTION POTENTIAL
1. Resting Membrane Potential
Na+ ions and some K+ channels are closed. The outside of the cell membrane is positively charged compared to the inside
2. Depolarization
Na+ channels open, K+ channels begin to open. Depolarization results due to inward movement of Na+, thus a positive internal membrane
3. Repolarization
Na+ channels close and K+ channels open. Na+ movement into the cell stops, K+ movement out of the cell increases, causing repolarization
IMPULSE CONDUCTION
Neuron membrane maintains resting potential
Threshold stimulus is received
Sodium channels in the trigger zone of the axon open
Sodium ions diffuse inward, depolarizing the axon membrane
Potassium channels in the axon membrane open
Potassium ions diffuse outward, repolarizing axon membrane
Resulting action potential causes local electric current that stimulates the adjacent portions of the axon membrane
A series of action potentials occur along the axon
Neurotransmitters
Nuerotransmitters
: chemical messengers in the synapse, conveys electrical impulse from neuron to cells
more than 100+ neurotransmitters
neurotransmitters= acetylcholine/ amino acid/ neuropeptides
action: depends on type of receptors in specific synapse
-neurons produce one/multiple types of neurotransmitters
synapse
: junction between 2 communicating cells
gap between neurons=
synaptic cleft
; impulse must be conveyed across the cleft
presynaptic neuron
: neuron sending the impulse
postsynaptic neuron
: neuron receiving the impulse
communication complete= neurotransmitter stored/released un
synaptic vesicle
NEURONTRANSMITTERS: released in response to nerve impulse> diffuse across cleft> bind to membrane receptors on postsynaptic neuron
RELEASE OF NEUROTRANSMITTERS
Action potential passes along an axon and over the surface of its synaptic knob
Synaptic knob membrane becomes permeable to calcium ions, diffuses inward
With calcium ions, synaptic vesicles fuse to synaptic knob membrane
Synaptic vesicles release their neurotransmitter into synaptic cleft
Cranial Nerves
I- OLFACTORY
sensory: sensory fibers conduct impulses in relation to sense of smell
II- OPTIC
sensory: sensory fibers conduct impulses in relation to sense of vision
III- OCULOMOTOR
primarily motor: motor fibers conduct impulses to muscles of eyelids, move eyes, adjusts light+ focuses lenses for the eyes
IV- TROCHLEAR
primarily motor: motor fibers impulses for muscles that move the eyes
V- TRIGEMINAL: ophthalmic/maxillary/mandibular divisions
mixed nerves:
ophthalamic division
= sensory fibers conduct impulses from eye surface, tear glands, scalp, forehead, upper eyelids
maxillary division
= sensory fibers conduct impulses from upper teeth, gums, lip, skin of face
mandibular division
= sensory fibers conduct impulses from skin of jaw, lower teeth, gum, lip
VI- ABDUCENS
primarily motor: (some sensory with condition of muscles) motor fibers conduct impulses that move eyes
VII- FACIAL
mixed:
sensory fibers: impulses in relation to taste receptors of anterior tongue
motor fibers: impulses to muscles for facial expressions, tear glands, salivary glands
VIII- VESTIBULOCOCHLEAR
: sensory vestibular/cochlear branches
vestibular branch
= sensory fibers to asso. with sense of equilibrium
cochlear branch
= sensory fibers to asso. with sense of hearing
IX- GLOSSOPHARYNGEAL
mixed:
sensory fiber impulse= from pharynx, tonsils, posterior tongue, carotid arteries
motor fiber impulse= muscles of pharynx for swallowing/ salivary glands
X- VAGUS
: mixed
somatic motor fibers impulse= muscles of speech, swallowing
automatic motor nerve fiber impulse= heart, smooth muscle, thorax glands, abdomen
sensory fibers impulse= pharnyx, larynx, esophagus, viscera of thorax, abdomen
XI- ACCESSORY: cranial/ spinal branch
primarily motor:
cranial
= motor fibers impulses to muscle of soft palate, pharynx, larynx
-
spinal
= motor fiber impulses of neck/back muscles
XII- HYPOGLOSSAL
primarily motor:
motor fibers conduct impulses to tongue muscles
12 pairs of cranial nerves, underside of the brain
first pair= in cerebrum/ second pair= thalamus/ most pairs= from the brain stem
*cranial nerves are primarily motor nerves so long as they are part motor control
Spinal Nerves
from spinal cord: sensory fibers connecting PNS receptors to CNS
31 pairs of spinal nerves; all but first pair= mixed nerves
each arise from two roots:
sensory
dorsal root
(contains dorsal root ganglion; bases cell bodies in sensory neurons entering spinal cord)
motor
ventral root
spinal nerves
8 pairs= cranial nerves
12 pairs= sacral nerves
5 pairs= thoracic nerves
5 pairs= lumbar nerves
1 pair= coccygeal nerves
spinal nerve plexuses
: main branches of spinal nerves (except thoracic) form plexus networks
cervical plexus C1-C4
: either side of neck, supplies muscles/skin of neck, controls diaphragm
brachial plexus C5-T1
: lower cervical to upper thoracic nerves; muscle/skin of arms, forearms, hands, upper limbs
lumbrosacral plexuses L1- S4
: lower spinal cord; supply muscle/skin of lower abdomen, external gentalia, buttocks, legs
thoracic spinal nerves are not plexuses, but
intercostal nerves
Compare/contrast automatic nervous system
ANS: portion of PNS that functions constantly w/o conscious effort
controls:
visceral motor functions
of smooth/ cardiac muscles + glands; maintians homeostasis, responds to emotional stress, prepares body for strenous activity
controls heart rate, blood pressure, breathing rate, body temp
mainly controlled by
control centers** of brain/ spinal cord,
AUTONOMIC NEURONS:
all motor neurons
preganglionic neuron
: leaves cns, synapses with one/more neurons; has cell bodies in autonomic ganglion of PNS
postganglionic neuron
: fiber (axon) leaves automatic ganglion and supplies visceral effector with nerves
ANS CHARACTERISTICS:
autonomic activities= regulated by
reflexes
with sensory receptors in viscera/skin
impulses are conducted to the brain/spinal cord; motor impulses through cranial/spinal nerves to gonglia to effectors (muscles/glands)
sympathetic division
: active in stress/ emergency conditions (flight or flight)
parasympathetic divisions
: active under normal, restful states (restful and digest)
SYMPATHETIC DIVISION
short preganglionic fibers
in sym. division= from neurons in gray matter in the thoracic/ lumbar regions of the spinal cord (T1- L2)
axons exit the spinal cord by ventral roots of spinal nerves
axons leave into
sym. (paravertebral) ganglia
; chain of sym. ganglia close to vertebral column per side
synapse with
postgonglionic neurons
; whose long axons return to spinal nerves to visceral effectors
PARASYMPATHEIC DIVISION
long preganglionic fibers
in parasym. divisions= from brainstem/ sacral regions of the spinal cord
preganglionic fibers extend outward in cranial/sacral nerves and synapse in
terminal ganglia
close/in visceral effector organs
short postganglionic fibers
continue to effector organs (muscle/ glands)
Reflex Arc (major parts/functions)
reflexes
: autonomic response to changes (stimuli) inside/outside of body, maintains homeostasis
withdrawal reflex
: occurs in response to touching something painful
involves: interneurons, sensory/motor neurons
sensory receptors send pain messages on sensory neurons to spinal cord
sensory neurons send impulses to interneurons; info is coordinated
interneurons issue motor commands
motor neurons signal to flexor muscles to contract
REFLEX ARC PARTS AND FUNCTION
receptor
: receptor end of a dendrite/ specialized receptor cell in a sensory organ
function: senses specific type of internal/external change
sensory neuron
: dendrite, cell body, and axon of a sensory neuron
function: carries info from receptor into brain/ spinal cord
interneuron
: dendrite, cell body, and axon of a neuron w/in the brain or spinal cord
function: carries info from sensory neuron to motor neuron
motor neuron
: dendrite, cell body, axon of a motor neuron
function: carries instructions from brain/spinal cord out to effector
effector
: muscle/gland
responds to stimulation by motor neuron and produces reflex/behavioral action