Nervous System Flashcards
structural classification of nervous system
CNS and PNS
Functional classification of nervous system
sensory (afferent) division and motor (efferent) division
CNS
- brain and spinal cord
- act as integration and command center of nervous system
- interprets incoming sensory information & issues instructions based on past experiences and current conditions
PNS
- spinal nerves and cranial nerves
- serve as communication lines, linking all parts of body
spinal nerves
impulses to and from spinal cord
cranial nerves
impulses to and from brain
sensory division
- aka afferent division
- nerves that convey impulses to CNS
- skin, skeletal muscle, and joints: somatic sensory fibers
- visceral organs: visceral sensory fibers
motor division
- aka efferent division
- carries impulses from cns to effector organs, muscles, and glands
- brings about a motor response
- divided into somatic nervous system and autonomic nervous system
somatic nervous system
- allows for the conscious control of skeletal muscle
- voluntary nervous system
autonomic nervous system
- regulates involuntary events, such as cardiac muscles, smooth muscles, and glands
- involuntary nervous system
- contains sympathetic and parasympathetic divisions
2 types of cells nervous system is made up of
supporting cells and neurons
supporting cells
aka neuroglia
- includes many types of glia that provide support, insulate, and protect neurons
- don’t transmit impulses
- never lose ability to divide
neurons
- transmit impulses
- can not divide
astrocytes
- in CNS
- contains numerous projections that anchor them between capillaries and neurons, exchanging materials between them
- protects and controls chemical environment of brain
microglia
- In CNS
- spiderlike phagocytes that dispose of debris
ependymal cells
- in CNS
- line cavities of brain and spinal cord using cilia to circulate cerebral spinal fluid and to form a protective cushion around cns
oligodendrocytes
in CNS
- contains flat extensions to wrap tightly around nerve fibers
- fatty insulation covers
schwann cells
in PNS
-form from myelin sheaths around nerve fibers
satellite cells
-act as protective cushioning cells
neuron anatomy
cell body
at least one process extending from body
myelin
cell body
contains nucleus
acts as metabolic center
lots of ER and neurofibrils
processes
used in messaging
- dendrites
- axons
dendrites
convey message toward cell body
axons
conduct impulse away from cell body
sensory neurons
carry impulses to cns
aka afferent neurons
cutaneous sense receptors
proprioreceptors
cutaneous sense receptors
detect pain with heat, cold, or pressure
proprioreceptors
receptors of muscles and tendons
detect amount of stretch/tension
motor neurons
efferent neurons
carry impulse to muscle or gland
association neurons
aka interneurons
connect motor and sensory neurons
multipolar neuron
neuron with several processes
motor and association neurons
bipolar neuron
2 processes
have one axon, one dendrite
receptors in only adult eye and ear
unipolar neuron
one process (very short) process divides into proximal and distal fibers (conducts impulse towards and away from cell body) sensory neurons in pns ganglia
2 types of impulses
irritability and conductivity
irritability
neurons use sodium-potassium pump inside cells to create difference in charges
conductivity
ability to transmit impulse to other neurons, muscles, or glands
reflexes
- rapid, predictable, involuntary response to stimuli
- occur over neural pathways called reflex arcs
- autonomic and somatic
reflex arcs
contain sensory receptor, effector organ, afferent and efferent neurons, and integration center
autonomic reflex
regulate activity of smooth muscles, heart, and glands
-ex: salivary and pupillary reflex
somatic
stimulate skeletal muscles
-ex: pull hand away from hot surface
cranial nerves
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
olfactory nerve function
sensory; sense of smell
optic nerve function
vision
oculomotor nerve function
supplies motor fibers to 4 of the 6 muscles that move the eyeball
trochlear nerve function
supplies motor fibers for superior oblique eye muscle
trigeminal nerve function
conducts sensory impulses from skin of face, mucosa of nose, mouth
-activates chewing
abducens nerve function
supplies motor fibers to lateral rectus muscle
facial nerve function
activates muscles of facial expression, lacrimal & salivary glands, sensory impulse from taste buds of anterior tongue
vestibulocochlear nerve function
balance and hearing
glossopharyngeal nerve function
promote swallowing and saliva production
carries impulse from taste buds (posterior tongue) and pressure receptors of carotid artery
vagus nerve function
impulses to and from pharynx, larynx, and viscera
accessory nerve function
activate sternocleidomastoid and trapezius
hypoglossal nerve function
control tongue movements
4 major nerve plexi
cervical
brachial
lumbar
sacral
major nerve within cervical plexus
phrenic
major nerve within brachial plexus
axillary radial median musculocutaneous ulnar
major nerve within lumbar plexus
femoral
obturator
major nerve within sacral plexus
sciatic
superior
inferior gluteal
distribution of cervical nerve plexus
diaphragm and muscles of shoulder and neck
distribution of brachial nerve plexus
deltoid triceps forearm extensor hand muscles arm flexors wrist muscles
distribution of lumbar nerve plexus
lower abdomen buttocks anterior thighs skin of antermedial leg and thigh adductor muscles of medial thigh small hip muscles skin of medial thigh hip joint
distribution of sacral nerve plexus
lower trunk posterior surface of thigh lateral leg and foot posterior leg and foot gluteus muscles of hip
function of sympathetic division of ANS
mobilizes body during extreme situations fight or flight heart rate/blood pressure increase lung bronchioles dilate blood vessels dilate withdrawal of blood from digestive organs
function of parasympathetic division
most active when body is at rest
bp and heart rate regulated at normal level
factors that may harm brain development
smoking/alcohol/drugs
why does our brain decline as we age
neurons can’t regenerate so as they die, the sympathetic nervous system becomes less efficient. shrinking can be quickened by alcoholism or boxing, which leads to senility
how does cns develop from embryonic to adult form
- first appears as neural tube
- begins to form during first month of embryonic development
- hypothalamus matures the latest
- brain reaches max weight in young adulthood
- then begins to disintegrate
four major regions of brain
cerebral hemisphere
cerebellum
brain stem
diencephalon
gyri
elevated rides of tissue (brain wrinkles)
sulci
shallow groves of tissue (brain wrinkles)
fissures
deep grooves of tissue (brain wrinkles)
four lobes of cerebral hemisphere
frontal
parietal
occipital
temporal
frontal lobe function
skeletal muscle movement
decision making
parietal lobe function
recognize pain, cold, light touch
temporal lobe function
auditory
occipital lobe function
vision
broca’s area
- found on anterior portion of frontal lobe (precentral gyrus)
- helps us speak
corpus callosum
- large fiber tract that connects the cerebral hemispheres
- allows them to communicate with one another
3 major structures of diencephalon
- thalamus
- hypothalamus
- epithalamus
thalamus function
relay station for sensory impulses passing upward to sensory cortex
hypothalamus function
plays a role in regulating body temp, water balance, and metabolism
epithalamus function
forms cerebral spinal fluid and aids in parts of endocrine system
regulates emotions/drives secretion of melatonin
what are the three structures of the brain stem
midbrain
pons
medulla oblongata
midbrain function
vision and hearing
pons
control breathing
medulla oblongata
regulates visceral activities, heart rate, blood pressure, breathing, swallowing, swallowing, vomiting
reticular formation
extends entire length of brain stem.
involved in motor control of visceral organs
damage can cause permanent unconsciousness
cerebellum function
- provides precise timing for skeletal muscle activity
- controls balance and equilibrium
cranial bones
encase brain to prevent severe damage
meninges
made up of dura mater, arachnoid mater, and pia mater
dura mater
double-layered membrane that surrounds brain
arachnoid mater
threadlike extensions that span subarachnoid space to attach to pia mater
pia mater
clings to brain surface and spinal cord
cerebrospinal fluid
‘broth’ made up of protein, vitamin c, ions
formed from blood that continuously circulates throughout brain
blood-brain barrier
composed of least permeable capillaries prevents metabolic waste from entering brain tissue
four spinal nerve regions
cervical
thoracic
lumbar
sacral
what is the cauda equina
collection of spinal nerves at inferior end of the vertebral canal
