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Nervous System Fundamentals Isabel Blackwood (Senses (Eye Components and…
Nervous System Fundamentals Isabel Blackwood
Senses
Receptors: Stimulus Origin
Exteroceptors
Origin is environment
Located in skin and special senses
Interoceptors
Origin and location is internal organs
Proprioceptors
Origin and Location is muscles, tendons, ligaments and joints
Senses where the body parts are
Receptors: Stimulus Type
Thermoreceptor
Sensitive to temperature
Photoreceptor
Sensitive to light
Chemoreceptor
Sensitive to chemicals
Nociceptor
Sensitive to pain
Mechanoreceptor
Baroreceptor
Sensitive to blood pressure
Sensitive to touch, pressure, stretch, and vibration
Eye Components and Visual Pathway
Fibrous Layer (tunic 1)
Sclera
Dense irregular connective tissue
protective, gives shape, anchor for eye muscles
Cornea
allows light into the eye, helps focus light on retina
transparent
Vascular Layer, Choroid (tunic 2)
deeply pigmented to absorb light and prevent scattering
nourishes other layers with blood supply
continuous with ciliary body
muscle that changes shape of lens
Inner Layer, Retina (tunic 3)
photoreceptors present
axons converge to form optic nerve
Rods and Cones
quantity: rods > cones
rods sensitive to light
cones allow color vision, work best in bright light
Lens and Iris
Iris is anterior to lens
involved in focusing light on retina
Optic disc
"blind spot" no photo receptors
Macula Lutea
precise posterior pole, directly opposite pupil
fovea centralis
center of macula lutea, location of clearest vision
Posterior segment
posterior to lens and ciliary body
filled with vitreous humor
clear, transmits light
supports retina and lens
gel like, keeps retina in place
maintains normal pressure in the eye
Anterior segment
filled with aqueous humor (watery)
posterior chamber
from iris to posterior segment
Anterior chamber
from iris to cornea
nourishes lens and cornea
maintains normal intraocular pressure
Visual Pathway
Cornea
pupil
lens
posterior segment
retina
optic nerve
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Olfaction Components and Pathway
location; roof of nasal cavity
structure; pseudostratified columnar epithelium and sensory nerves
`pathway
olfactory receptors
olfactory sensory neuron in olfactory bulb
olfactory tract
limbic system
primary olfactory cortex in temporal lobe
Gustation Components and Pathway
location; tongue, inner cheeks, posterior wall of pharynx, epiglottis
structure; epithelial tissue, gustatory epithelial cells
pathway
cranial nerves VII, IX, X
medulla oblongata
thalamus
gustatory cortex in the insula
Ear Components and Pathway
outer ear
aurical
gathers sound waves and amplifies
middle ear
tympanic membrane
ear drum
auditory ossicles
3 small bones
cochlea
liquid filled
pathway
cranial nerve VIII
medulla oblongata
pons
midbrain
thalamus
primary auditory cortex in temporal lobe
Nervous System Organization
CNS (Central Nervous System) Structures and Functions
function; receive, process and respond to incoming signals
structure; brain and spinal cord
PNS (Peripheral Nervous System) Structures and Functions
structure; cranial nerves, spinal nerves, ganglia
Somatic Division
output to skeletal muscle
Autonomic Division
output to contents of ventral body cavity
output to smooth muscle, skin, glands, blood vessel walls, and cardiac muscles
Anatomy of Nervous System
Nerve Components
contains sensory and motor neurons
some are myelinated
axons protected by endoneurium
bundle of axons is an axon fascicle
which is covered in perineurium
a group of fascicles with some blood vessels is a nerve
which is covered in epineurium
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Glial Cells
Astrocytes
CNS, most numerous
many processes that connect to capillaries
structurally supports neuron, maintains proper chemical environment
Microgila
CNS, phagocytes
removes microbes and damaged nerve tissue
Ependymal cells
CNS, lines spaces with cerebrospinal fluid
fluid protects and floats brain
contains cilia that moves fluid
Satellite cells
PNS, structurally supportive
supports neurons, regulates trade in and out of cell body
Neurons
Major Components
cell body
nucleus, and nucleolus
chromatophilic substance
renew plasma membrane and proteins in cytosol
dendrites
axon hillock
axon
axon collaterals
terminal arborization
axon terminals
Structural Types
Multipolar
most abundant
Bipolar
special senses
Unipolar
Functional Types
motor
always multipolar, cell bodies in CNS
sensory
unipolar
bipolar for special senses
cell bodies in ganglia of PNS
interneurons
between neurons in CNS
multipolar, most abundant