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Nervous System (Senses (Eye components and Visual Pathway
Fibrous…
Nervous System
Senses
Eye components and Visual Pathway
- Fibrous Layer = sclera & cornea
- Vascular Layer = choroid
- Inner Layer = retina
-Posterior Segment = largest segment in your eye, filled with clear vitreous humor, supports retina & lens, helps maintain normal pressure; location is iris to posterior segment but Iris is the border, not included
-Anterior Segment = has a posterior chamber and an anterior chamber, both are filled with aqueous humor to nourish the lens & cornea, maintains normal intraocular pressure; location is iris to corneaVisual Pathway
Cornea (focusing)>pupil>lens (focusing)>Posterior segment filled with vitreous humor>retina
Olfaction Components & Pathway
Location is the roof of nasal cavity (cribriform plates)
Olfactory epithelium is Pseudo-stratified Columnar Epithielium with Olfactory Sensory Neurons
Pathway
Olfactory receptors>Olfactory Sensory Neuron within the Olfactory bulb>Olfactory tract> travels to 2 locations: Limbic system (emotional brain) & Primary Olfactory Cortex in Temporal Lobe
Types of Receptors Based on Stimulus Type
- Thermoreceptor = cold & hot sensitive receptors
- Photoreceptor = light sensitive receptors
- Chemoreceptor = chemical sensitive receptors (chemicals such as air, saliva, chemicals in blood - calcium, potassium, sodium, CO2, etc.
- Nociceptor = pain sensitive receptors
- Mechanoreceptor = pressure/touch/vibration/stretch sensitive receptors
- Baroreceptor = special type of mechanoreceptor that measures blood pressure
Gustation Components & Pathway
Location is in the tongue, inner check, posterior wall of pharynx & epiglottis; taste buds are epithelial tissue
Pathway
Tongue>Facial Nerve (VII)>Glossopharyngeal Nerve (IX)>Vagus Nerve (X)>Medulla Oblongata>Thalamus>Gustatory Cortex in the Insula>Brain
Types of Receptors Based on Stimulus Origin
- Exterorecptors = stimulus that comes from environment; location: skin, special senses
- Interorecptors = stimulus comes from internal organs; location: stomach stretching
- Propriorecptors = stimulus comes from our muscles (tendons, ligaments, & joints)
location: within muscle, tendons, ligaments, joints
Ear Components & Pathway
Outer Ear
Auricle = outside of ear, gather sound waves-amplify
External Acoustic Meatus
Inner Ear
Tympanic Membrane = ear drum, border to the outer & middle ear
Auditory Ossicles = 3 bones in each ear = 6 bones total, continue to transmit vibrations
Cochlea (liquid filled)
Vestibulo nerve + Chochelear nerve = vestibulocochlear Nerve (VIII) this goes through the internal acoustic meatus
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Neurons
Structural types of Neurons
- Multipolar = lots of processes
- Bipolar = 2 extensions (processes, present in special senses (ex. retina)
- Unipolar = 1 process from cell body
Functional Types of Neurons
- Motor (Efferent) Neurons = multipolar neurons, cell bodies in CNS travel to muscle & glands
- Sensory (Afferent) Neurons = unipolar neurons (majority of general senses), bipolar in special sensory, cell bodies located in the ganglion of PNS near spinal cord
- Interneurons (Assosciation) Neurons = multipolar, between neurons, only in CNS, most numerous of all neurons in body - 99.98%
Major Components of a Neuron
- Cell body = the part of the cell that contains the nucleus and nucleoulus
- Nucleus =control center of a cell; contain genetic material; a cluster of neuron cell bodies in the brain
- Nucleolus = a small, dark-staining body in the cell nucleus
- Chromatophilic substance = the cytoplasm that contains all the usual cellular organelles
- Dendrites = processes that branch from the cell body like the limbs on a tree
- Axon Hillock = arises from a cone-shaped region of the cell body
- Axon = neuron process that carries impulses away from the cell body
- Axon Collaterals = branches extend from the axon at more or less right angles
- Terminal arborization = where it branches profusely at the end
- Terminal boutons or Axon terminals = ends in knobs
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