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JamiThompsonNervousSystem (Senses (Receptors Based on Stimulus Type…
JamiThompsonNervousSystem
Senses
Eye
Components
Inner Layer
Retina
Pigmented Layer
Melanocytes
Neural Layer
Photoreceptors (rods and cones)
Regional Specializations
Fovea Centralis
see most clearly at this point
Optic Disc (blind spot)
axons of ganglion cells, no photoreceptors
Macula Lutea
Optic Nerve
runs from the eye to the brain
Photoreceptor
Rods
sensitive to light, permit vision in dim light, gray and fuzzy
Cones
bright light, high-acuity color vision
Vascular Layer
Ciliary Body
striated, connected to lens by suspensory ligaments
Iris (controls size of pupil)
colored, sphincter
Choroid
vascular, darkly pigmented membrane
Chambers/Fluids
Posterior Segment
Vitreous Humor
jellylike fluid, transmits lights, holds retina firmly against pigmented layer, helps maintain intraocular pressure
Anterior Segment
Anterior Chamber
between cornea and iris
Posterior Chamber
between iris and lens
Aqueous Humor
clear fluid, renews continuously, helps maintain intraocular pressure, supplies nutrients and oxygen to lens and cornea
Fibrous Layer
Cornea
transparent
Sclera
thick, tough, white
Lens
thick, transparent, biconvex disc that changes shape to allow focusing of light on the retina
Visual Pathway
Optic Nerve
Optic Chiasma
Optic Tract
Lateral Geniculate Nucleus of the Thalamus
Optic Radiation
Primary Visual Cortex
Olfaction (Smell)
Components
Olfactory Epithelium
Supporting Epithelial Cells
surround olfactory sensory neurons, columnar
Olfactory Stem Cells
continually form new olfactory sensory neurons
Olfactory Sensory Neurons
bipolar neurons, one of the few neurons that undergo replacement in adult life
Olfactory Cilia
radiate at the apical surface of epithelium, part of olfactory sensory neurons
Lamina Propria (connective tissue)
Filaments of the Olfactory Nerve
Forebrain
Olfactory Bulb
Mitral Cells (Neurons)
Glomeruli (complex clusters of mitral cells)
Pathway
Cilia of Olfactory Sensory Neuron
Dendrite of olfactory sensory neuron (through epithelium)
Axon of olfactory sensory neuron (through lamina propria)
Filaments of the Olfactory Nerve (through cribriform plate)
Olfactory Bulb (forebrain); synapse with mitral cells in clusters called glomeruli
Mitral cells relay olfactory information to other parts of the brain
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Receptors Based on Stimulus Type
Baroreceptor
monitors blood pressure, type of mechanoreceptor
Thermoreceptors
respond to temperature changes
Mechanoreceptors
mechanical forces: touch, pressure, stretch, vibrations
Chemoreceptors
respond to chemicals in solution and changes in blood chemistry
Photoreceptors
respond to light (located in the eye)
Nociceptors
respond to harmful stimuli that result in pain
Gustation (Taste)
Components
Taste Buds
Gustatory Epithelial Cells
gustatory hairs project and extend through a taste pore to surface of epithelium
Basal Epithelial Cells
divide and replace gustatory epithelial cells every 7-10 days
Papillae
Vallate Papillae
arranged in an inverted "V" near the back of the tongue
Foliate Papillae
posterolateral surface of the tongue
Fungiform Papillae
scattered over entire surface of tongue
Pathway
Taste Buds
facial nerve, glossopharyngeal nerve, vagus nerve
solitary nucleus in the medulla of the brain
thalamus
gustatory area of the cerebral cortex
Receptors Based on Stimulus Origin
Smell
patch of epithelium on the roof of the nasal cavity
Sight
eye; specifically the retina (rods and cones or photoreceptors)
Taste
mucosa of the mouth and pharynx (most located on tongue)
Hearing
ear: cochlear duct in the cochlea of internal ear
Peripheral Sensory Receptors
Interoceptors (visceroceptors)
internal viscera (digestive tube, urinary bladder, lungs)
visceral pain, nausea, hunger, fullness
Proprioceptors
skeletal muscles, tendons, joints, ligaments
monitor degree of stretch and send input to CNS
Exteroceptors
outside the body, at/near the body surface
touch/pressure/pain/temperature in the skin, most special sense organ receptors (more detailed locations below)
Equilibrium
semicircular ducts inside each semicircular canal; utricle and saccule of the vestibule
Ear (Hearing)
Components
Middle Ear
Tympanic Membrane
eardrum, shaped like a flattened cone, boundary between external and middle ear
Auditory Ossicles
transmit vibrations of the eardrum across the cavity to a fluid in the internal ear, includes: malleus, incus, and stapes
Internal Ear
External Ear
Auricle (Pinna)
gathers and funnels sound waves
External Acoustic Meatus
canal lined with hairs and glands leading to eardrum
Pathway
Cochlear Nerve
Cochlear Nuclei in Medulla
Information passes through several nuclei in the brain stem
Medial Geniculate Nucleus of Thalamus
Cerebral Auditory Cortex
Nervous System Organization
Peripheral Nervous System (PNS)
Spinal Nerves
Ganglia
Cranial Nerves
Communication lines between the CNS and the rest of the body
Somatic Nervous System
voluntary, conducts impulses from the CNS to skeletal muscles
Central Nervous System (CNS)
Brain
Spinal Cord
Integrative and Control Centers
Autonomic Nervous System
involuntary, conducts impulses from the CNS to the cardiac and smooth muscles, and glands
Anatomy of Nervous System
Nerve Components
Consist of many axons arranged in parallel bundles
Schwann cells surround each axon
covered in a layer of loose connective tissue called endoneurium
groups of axons bound into bundles called fascicles
covered in connective tissue called perineurium
whole nerve surrounded by tough fibrous sheath called epineurium
Glial Cells
6 Types: 4 in CNS, 2 in PNS, surround neurons
provide scaffolding support for neurons, cover nonsynaptic parts of neurons creating insulation that prevents electrical activities of adjacent neurons from interfering with each other
Neurons
Structural Types
Bipolar Neurons
two processes on either side of cell body, occur in some special sensory organs
Unipolar Neurons
short, single process
Multipolar Neurons
99% of neurons, >2 processes
Functional Types
Motor Neurons
motor division of PNS
Interneurons
lie between motor and sensory neurons, exclusive to CNS
Sensory Neurons
sensory division of PNS
Major Components
Dendrites
Axons
Neuron Processes
Synapses
Cell Body