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Nervous System P.5 Joseph Gonzales - Coggle Diagram
Nervous System P.5 Joseph Gonzales
Action potential & the Nerve Impulse
Action Potential happens or doesn't
occurs when charge reaches -55Mv
neurons are all the same strength
when reached cells respond by going back to their resting state (repolarization)
Impulse conduction
Continuous conduction
occurs in unmyelinated axons
conduct impulses over the entire length of their membrane
Saltatory conduction
occurs in myelinated axons
myelin sheath insulates axons from ion movement across the cell membrane
impulses 'jump' from one Node of Ranvier to the next, since sodium and potassium channels occur inly at the nodes
Classification of neurons
Bipolar neurons
dendrite and 1 axon
found in special senses (eyes, nose, lips)
2 processes extending from the cell body
Unipolar neurons
splits into 2 part function
1 axon
1 process extending from the cell body; outside cell
Multipolar neurons
Most neurons in cell bodies are multipolar
Many dendrites and 1 axon arising from body
Sensory neurons
usually unipolar
some are bipolar
impulses from peripheral receptors to CNS
afferent
Interneurons neurons
forms link between other neurons
multipolar neurons laying with CNS
cell bodies of some interneurons aggregate in nuclei
Motor neurons
conduct impulses from CNS to peripheral neurons
multipolar neurons
Tissues
Nueroglia
cells that support neurons
fills space, structurally support, protect and insulate neurons
does not generate or conduct nerve impulse
CNS
Microglia
small cells
function as phagocytes for bacterial cells, cellular debris, and produce scar tissue for injury
Oligodendrocytes
forms myelin sheath around axon in brain and spinal cord
Major Functions of the nervous system
integrative functions
processing infro is basis for decisions
coordination of sensory info in cns
thinking, movement internal process of physiology
sensory functions: provides sensory receptors
info travels from receptors to sensory neurons
transport info to cns
detect internal/ external changes
Motor functions
nerve impulses conducted along motor neurons to effectors
Effectors are muscles and glands that respond to decisions in the CNS
Neurotransmitters
more than 100 neurotransmitters
diffuse across the synaptic cleft and bind to receptors on the membrane of the postsynaptic neuron
include acetylcholine, amino acids, and neuropeptides
stores and released from synaptic cleft
action depends on type of receptors in a specific synapse
communication accomplished by a chemical
some neurons produce one type of transmitter and others produce 2 or more
released in response of a nerve impulse
Spinal nerves
contains a total of 31 pairs
control motor, sensory, and other functions
Pairs:
5 Sacral
1 coccygeal
5 Lumbar
12 Thoracic
8 Cervical nerves
All except the first pair are mixed nerves.
A ventral root and dorsal root unite to form a spinal nerve
Spinal Nerve Plexuses
Cervical Plexuses (C1-C4)
ie on either side of the neck;
upply muscles and
skin of the neck
Brachial Plexuses (C5 –T1)
supply muscles and skin of arms, forearms, and hands
arise from lower cervical and upper thoracic
nerves
lead into the
upper limbs
Lumbosacral Plexuses (L1-S4)
arise from the lower spinal cord
supply
muscles and skin of the lower abdomen, external genitalia, buttocks, and legs
the main branches of the spinal nerves, except the thoracic region are called plexuses
Major parts and functions of the spinal cord
cervical enlargement
thickened region at the top of the spinal cord
provides nerves to upper limbs
cauda equina (horse tails)
where spinal cord tapers to a point inferiorly
spinal nerves in lumbar and sacral areas
at the base of the brain
31 segments each connected to the spinal nerve
lumbar enlargement
thickened region near the bottom
rise to nerves for the lower limbs
bundles of myelinated nerve fibers
Dorsal root ganglia
outside the spinal cord
cell bodies of sensory neurons that enter the spinal cord
white matter
butterfly shaped core
houses interneurons and neuron cell bodies
Central canal
middle of gray matter contains csf
gray matter
lateral horn between
upper and lower wings of gray matter
Functions
descending tracts
carry motor info from brain to muscles and glands
Ascending Tracts
carry sensory info to the brain
spinal reflexes
passes through the spinal cord
controlled by reflex arc
transmits impulses to and from the brain
houses spinal reflexes
posterior and anterior horns
lateral horn between
upper and lower wings of gray matter
Connective Tissue Coverings
Arachnoid Mater
Has spiderweb-like structure that stands out
Thin, transparent, surrounding the spinal cord
protects the brain and spinal cord of sudden impact
middle layer
Pia Matter
aids in production of CSF
Protects from objects squishing/ pressuring the brain
innermost layer
Dura Mater
The first layer of the brain
Protects from disease meningitis
Tough connective tissue
Protects the brain, surrounds it
Perineurium
covering around fascicles of nerve fibers
bundles
Epineurium
outer covering of nerves
Endoneurium
covering around individual nerve fibers
axons
Reflex arc (major parts & functions)
central nervous syetem
motor/ efferent neurons
sensory or afferent neuron
effectors muscle /glands
Receptors
Pathway
Receptor-->Central Nervous System--> Effector
Reflex Behavior
automatic responses to stimuli (changes) on the inside and outside of body
Patella relfex
hit a knee to see if it responds
Withdrawal reflex
Occurs in response to touching something painful, such as
stepping on a tack
Cranial nerves
12 cranial nerves
VI Abducens
Primarily
motor
that move the eyes.
Some sensory fibers conduct impulses associated with the condition of muscles.
VII Facial
Mixed
conduct impulses associated with taste receptors of the anterior tongue.
conduct impulses to muscles of facial expression, tear glands, and salivary glands.
V Trigeminal
Mixed
Maxillary division
conduct impulses from the upper teeth, upper gum, upper lip,
lining of the palate, and skin of the face.
Mandibular division
conduct impulses from the skin of the jaw, lower teeth, lower
gum, and lower lip.
Ophthalmic division
conduct impulses on the surface of the eyes, tear glands, scalp,
forehead, and upper eyelids.
VIII Vestibulocochlear
Sensory
Vestibular branch
conduct impulses associated with the sense of equilibrium.
Cochlear branch
conduct impulses associated with the sense of hearing.
IV Trochlear
Primarily
motor
move the eyes.
IX Glossopharyngeal
Mixed
conduct impulses from the pharynx, tonsils, posterior tongue, and carotid
arteries.
III Oculomotor
Primarily
motor
raise eyelids, move eyes, adjust
the amount of light entering the eyes, and focus lenses.
X Vagus
Mixed
conduct impulses to muscles associated with speech and swallowing;
autonomic motor fibers conduct impulses to the heart, smooth muscle, and glands in the thorax
and abdomen.
conduct impulses from the pharynx, larynx, esophagus, and viscera of the thorax
and abdomen.
II Optic
Sensory
sense of vision.
XI Accessory
Primarily
motor
Cranial branch
Motor fibers conduct impulses to muscles of the soft palate, pharynx, and larynx.
Spinal branch
Motor fibers conduct impulses to muscles of the neck and back
I Olfactory
Sensory
sense of smell.
XII Hypoglossal
Primarily
motor
Motor fibers conduct impulses to muscles that move the tongue.
Major divisions and subdivisions of the nervous system
CNS
made up of brain and spinal cord
responsible for integration of information and decision making
coordination of sensory info in the CNS
has 4 types of neuroglia
PNS
made up of cranial & spinal nerves that connect the CNS to the rest of the body
Contains sensory (afferent) & motor (efferent) divisions
Autonomic Nervous System
controls involuntary effectors (smooth & cardiac & cardiac muscles and glands.
Somatic Nervous System
controls voluntary skeletal muscles
Function: responsible for carrying out instructions from the CNS
2 type of neuroglia
Major parts and functions of the brain
4 main parts
Cerebrum
higher mental function and sensory with motor functions
largest portion of brain
Diencephalon
Controls homeostatic process
Process sensory input
Brainstem
coordinates and regulates activities
Connects to different parts of nervous system
Cerebellum
Coordinates muscle activity
smaller portion of the brain
4 lobes
Parietal
processes information about temperature, taste, touch and movement
integrate sensory input and process language
Occipital
responsible for vision
helps us see and understand what we are seeing
Frontal
cognitive functions and control of voluntary movement or activities
Responsible for: emotional expression. problem-solving. memory. language
Temporal
object recognition and interacts with other structures to create new and long term memories.
auditory responsibilities and helps us understand speech
major and most complex portion of the Nervous System
Compare & contrast autonomic nervous system
parasympathetic division
rest and digest
long preganglionic fibers arise from brainstem and sacral region
Pf extends outward in cranial or sacral nerves
synapse in terminal ganglia in or close to visceral effectors organs
sympathetic division
short preganglionic fibers arise from neurons in gray matter, in thoracic and lumbar regions
Axons exit spinal cord from the ventral roots
fight or flight response
axons leave spinal nerves, proceeds into sympathetic ganglia
synapse with postganglionic neurons, long axons return to spinal nerves and proceed to visceral effector