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Nervous System (Senses (the eye components and visual pathway, (Fibrous…
Nervous System
Senses
the eye components and visual pathway,
Cones
allow us to see color, fewer, work best in bright light
Lens
posterior to iris, focuses light on retina
Rods
sensitive to light, many, allow us to see black and white and dim light
Iris
color part of the eye ; anterior to lens ; intrinsic muscle- sphincter muscle ; can dilate/constrict
Inner Layer/ Neuro Layer
Retina
photoreceptors, axons converge to form optic nerve
Optic Disc
no photoreceptors
Vascular Layer
Choroid
nourishes other layers, deeply pigmented, absorbs light and prevents scattering, continuous with ciliary body (muscle that changes shape of lens)
Macula Lutea
precise posterior pole (clearest vision here) ; opposite from pupil
Fibrous Layer
Sclera
(the white of the eye) Dense C.T., protective anchor for muscle, gives shape
Cornea
(clear) allows light into the eye, involved with focusing light on the retina
Fovea Centralis
at center of macula lutea- is fovea centralis ; location of our clearest vision
Visual Pathway
cornea--->pupil--->lens--->posterior segment--->retina--->optic nerve--->optic chiasm--->optic tract--->midbrain--->thalamus--->primary visual cortex in occipital lobe
anterior segment
posterior chamber (from iris to posterior chamber) ; anterior chamber (from iris to cornea) ; filled with aqueous humor (nourishes the lens and cornea and maintains normal intraocular pressure
posterior segment
filled with vitreous humor ; supports retina and lens ; gel like ; maintain normal pressure in eye
olfaction components and pathway
Olfactory Pathway
olfactory receptors--->olfactory sensory neuron within the olfactory bulb--->olfactory tract--->limbic system--->primary olfactory cortex in temporal lobe
Olfactory Epithelium
roots of nasal cavity, pseudostrat. collepi. , with olfactory sensory nerves
the types of receptors based on stimulus type
Nociceptor
sensitive to pain
Chemoreceptor
sensitive to chemicals
Photoreceptor
light sensitive
Thermoreceptor
cold and warm receptors/sensitive
Baroreceptor
measures blood pressure
Mechanoreceptor
sensitive to pressure, touch, vibration, stretch
gustation components and pathway
taste buds
tongue, inner cheeks, posterior wall of pharynx (throat)
three cranial nerves
facial nerve (VII), glossopharyngeal nerve (IX), vagus nerve (X) ; connected to the brain, do not go through spinal cord
Gustatory Pathway
medulla oblongata--->thalamus--->gustatory cortex in the insula
the types of receptors based on stimulus origin
Interoceptors
stimulus origin is internal organs
Propriocepptors
Stimulus from our muscles (including our tendons, ligaments and joints)
Exteroceptors
stimulus comes from environment (located in skin and special senses
ear components and pathway
Auricle
gather sound waves-amplify
Tympanic Membrane
eardrum
External Acoustic Meatus
passageway that leads from outside of head to tympanic membrane
Auditory Ossicles
continue t transmit vibrations
Ear Pathway
auricle--->tympanic membrane--->auditory ossicles--->cochlea (liquid filled)
Nervous System Organization
PNS main structures and functions
cranial nerves, spinal nerves and ganglia
be sensitive to stimuli and send that information towards the CNS
somatic division
output to skeletal muscle
skin and eyes
CNS main structures and functions
brain and spinal cord
receive, process incoming signals and respond
autonomic division
(visceral) mainly to contents of ventral body cavity; smooth muscle, glands, blood vessel walls, digesttive sys, resp sys, urinary sys, arrector pillis muscle of skin, sweat glands
stomach and tongue
Neurons
major components of a neuron
Dendrites
Axon Hillock
Chromatophilic Substance
Axon
Nucleus and nucleolus
Axon Collaterals
Cell Body
Terminal Boutons (axon terminals)
Terminal Arborization
functional types of neurons
Sensory
(afferent) unipolar (majority) ; bipolar (special senses)cell bodies located on ganglia of PNS
Interneurons
(association neurons) between neurons in CNS ; multipolar ; 99.984 % of all neurons in body
Motor
(efferent) multipolar ; cell bodies in CNS--->muscle glands
structural types of neurons
Bipolar
Unipolar
Multipolar
Anatomy of Nervous System
nerve components
Perineurium
fibrous connective tissue that covers each fascicle
Endoneurium
tough fibrous connective tissue that surrounds entire nerve
Nerve
bundle of fascicles
Axon
part of neuron that carries a signal
Myelin Sheath
insulation that covers some axons
fascicle
bundle of axons
glial cells, location and brief description
Ependymal Cells
simple cuboidal/columnar epithelium ; bring spaces filled with cerebral spinal fluid ; with cilia ; keeps CFS moving (CNS)
Satellite Cells
structurally supportive ; regulates exchange of materials in fat of neuron cell body (neurons in the ganglia)
Microglia
phagocytes ; remove microbes or damaged nerve tissues (CNS)
Oligodendrocytes
bind the CNS neurons together and insulate the axons ; (form myelin in CNS)
Astrocytes
most numerous ; many processes that contact neurons and capillaries ; supports neurons ; help maintain appropriate chemical environment (CNS)
schwann cells
insulate PNS axons (PNS nerve fibers)