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ShelbyBenkofskeNervousSystem (Neurons (Structural types of Neurons…
ShelbyBenkofskeNervousSystem
Senses
Receptor Types based on stimulus origin
Exteroreceptors
stimulus from the environment (skin and special senses)
Interoreceptors
stimulus from internal organs
Proprioreceptors
stimulus from muscles, ligaments, tendons, and joints, allows body to be properly oriented in it's environment
General vs Special Senses
General Senses
Widely spread throughout the body (skin and internal organs)
Typically interoreceptors and exteroreceptors
Special Senses
Located in the head region and include many different types of stimuli
Sight, hearing, taste, olfaction, smell, equilibrium
Types of receptors based on stimulus type
Thermoreceptors
sensitive to temperature (warm and cold) and found in the skin
Photoreceptors
sensitive to light and found in the eye
Chemoreceptors
sensitive to chemicals and found in the nose, tongue, and blood
Nociceptors
sensitive to dangerous things/pain and found in the skin but also a lot of areas of the body to keep protected
Mechanoreceptors
sensitive to tough, pressure, vibration, and stretch and found in skin
Baroreceptor
a type of mechanoreceptor that is sensitive to blood pressure and found in the blood vessels/arteries
Eye Components of the Visual Pathway
2 layers
fibrous layer: sclera and cornea
vascular layer: choroid
anatomy
sclera: white part of the eye, dense connective tissue, anchor for muscles, protective
cornea: anterior part of eye that is translucent and allows light into the eye, focuses light
choroid: deep to sclera, nourish the other layers, black, absorbs light to prevent scattering
ciliary body: muscle that changes the shape of the lens, intrinsic muscle
retina: photoreceptors present, posterior region of the eye where all light is focused
optic disc: where all the photoreceptors converge, blind spot, no photoreception here
optic nerve: all of the photoreceptors of the eye converged into one, takes signals/senses onto the brain
lens: anterior region that is surrounded by ciliary bodies, is pulled and relaxed to see different distances and focus on certain things
iris: anterior to the lens and posterior to cornea, the color part of the eye, a muscle (intrinsic muscle), dilate or constrict the pupil
macula lutea: part of the retina that is exactly opposite of the pupil, clearest vision
fovea centralis: the spot that gives the clear vision in the macula lutea
pathway
cornea--> lens--> retina--> optic nerve--> optic chiasma--> optic tract--> midbrain--> thalamus--> primary visual cortex
Olfaction Components and Pathway
pathway: olfactory sensory neurons--> olfactory bulb--> factory tract--> limbic system AND primary olfactory cortex
location: roof of the nasal cavity (pseudo stratified columnar epithelium) in the inferior nasal concha
Ear Components and Pathway
pathway: tympanic membrane--> middle ear--> auditory ossicles-->cochlea--> cochlear fluids--> cochlear nerve--> vestibular nerve--> medulla oblongata--> pons--> midbrain--> thalamus--> primary auditory cortex
anatomy
tympanic membrane: vibrates and transmits to the middle ear
auditory ossicles: transmits vibrations to the cochlea
cochlea: shell shaped, fluid filled, vibrates
cochlear nerve: stimulus from cochlea and joins tubular nerve
pinna: outer ear part that funnels all of the sound into the ear, amplify sound
vestibular nerve: responsible for equilibrium
Gustation Components and Pathway
locations
tongue
pharynx
inner cheek
palate
epiglottis
Cranial nerves that transmit taste
facial nerve (VII)
glossopharyngeal (IX)
vagus nerve (X)
pathway: taste buds--> 3 cranial nerves--> medulla oblongata--> thalamus--> primary gustatory cortex
Nervous System Organization
Central Nervous System
structure
brain
spinal cord
function
receive to sensory input
process to sensory input
respond to sensory input
Peripheral Nervous System
structure
cranial nerves
spinal nerves
ganglion
function
gather sensory information from all receptors and funnel it to the central nervous system
Motor (efferent) Nervous System
signals moving AWAY from the CNS
somatic motor system (SNS)
goes to the skin, skeletal muscles, torso/trunk
autonomic motor system (ANS)
going to the ventral body (organs/guts), smooth muscle and cardiac muscles
Sensory (afferent) Nervous System
signals moving TOWARD the CNS
somatic sensory system
get input from skin, skeletal muscles, joints, hearing, equilibrium, and vision
autonomic (visceral) sensory system
get input from ventral body cavity (organs), taste/gustation and olfaction
Anatomy of Nervous System
CNS
glial cells
astrocytes: most abundant, supportive cells, help maintain proper chemical environment
microglia: phagocytes, eat damaged or foreign cells/pathogens
Ependymal: simple cuboidal/columnar epithelium that has cilia and microvilli, located in ventricles of the brain
oligodendrocytes: create the myelin sheath, does multiple axon at one time, use lipids to create myelin sheath
gray vs white matter
gray matter
outer region of brain/cortex, cell bodies in brain
white matter
inner part of the brain, bundles of axons in brain
nucleus: similar to ganglion in the PNS but found in the CNS (not the exact same as the ganglion in the PNS), cluster of neuron cell bodies
tract: similar to a nerve in the PNS but found in the CNS (not the exact same as the ganglion in the PNS), bundle of axons
main components of CNS
brain
spinal cord
PNS
glia cells
satellite cells: found in ganglia and surrounds cells bodies, regulate what goes in/out of neuron cell bodies
Schwann cells: wrap around part of the axon to create the myelin sheath, can wrap around many times
ganglion: cluster of cell bodies
nerve: bundle of axons where signals are traveling
main components of PNS
cranial nerves
spinal nerves
ganglion
Neurons
chromatophilic substance: dense region of ER, free ribosomes
nucleolus: found inside the nucleus and responsible for ribosome synthesis
nucleus: contain the genetic information of the neuron cell
cell body: contain the nucleus
dendrites: the region where signals are received from another neuron to be process and transmitted
axon hillock: where the axon leaves the cell body
axon: conduct signals away from the axon body
axon collaterals: branch of axon from the main axon
terminal arborization: the multiple branching at the end of a nerve fiber
terminal boutons: the region where neurotransmitters are transferred to another neurons dendrites to transmit the signal further
myelin sheath: a layer of lipid over the axon that speeds up the transmission rate and insulates the axon
Structural types of Neurons
multipolar: many dendrites but 1 axon
bipolar: 2 processes coming from a central cell body
unipolar: one process that is branched to two processes off the cell body
Functional types of Neurons
motor/efferent neurons: away from the CNS (multipolar)
sensory/afferent neurons: signals toward the CNS (unipolar)
interneurons/association neurons: in the CNS only, between neurons (multipolar)