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NervousSystem.LanPham.pdf (Senses (Base on stimulus type (Photoreceptor:…
NervousSystem.LanPham.pdf
Neurons
Major components: cell body, dendrites, axon, axon terminals
Structure types
Bipolar: have 2 process that extend from opposite sides of cell body
Unipolar: short, single process engage from the cell body and divide tow long branches
Multipolar: has more than 2 process, numerous of dendrites and single axons
Function
Sensory or afferent neurons: conduct impulse toward the CNS
Motor or efferent neurons: conduct away from CNS
Interneurons or association neurons: lies in the CNS between sensory and motor neurons.
Senses
Base on stimulus orgin
Interoceptors: internal organs
Proprioceptors: muscle, tendons, ligaments, joints
Exteroceptors: environment (skin, special sense)-- hearing, olfaction smell, sight, taste, equilibrium
Base on stimulus type
Photoreceptor: light
Chemoreceptor: chemicals ( in nose, tongue)
Thermoreceptor: cold and warmth receptors
Nociceptor: pian
Mechanoreceptor: touch, vibration, stretch (proprioreceptors), pressure (baroceptor--sensitive to blood pressure).
Olfaction component and pathway
Root of nasal cavity
Pseudostratified columnar epithelium with olfactory
Sensory neurons---> olfactory bulb---> olfactory tract (limbic region: emotional barin, primary olfactory cortex in temporal lobe)
Gustation component and pathway
Taste buds with receptor cells (tongue, epiglottis, pharynx, palate) ---> 3 cranial nerves---> medullar oblongata---> thalamus---> primary gustatory cortex in the insula
3 cranial nerves: fascial nerve central nervous VII, glossopharynael central nervous IX, Vagus central nervous
Ear component and pathway
Auricle (pinna) collect sound waves---> tympanic membrane (ear drum) vibrate---> transmits vibrations---> middle ear---> auditory ossicles---> transmit vibrations to cochlea---> cochlear nerve and vestibular nerve = vestibuloc ochlear ( equilibrium) ---> medulla oblongata---> pons---> mid brain---> thalamus---> primary auditory cortex in the temporal lobe.
Eye component and pathway
Component
Fibrous layer
Sclera: white ( dense C.T, anchor for extrinsic eye muscle, protective, give shape)
Cornea: transparent, allow light into eyes, focus light
Vascular layer
Choroid: nourish other layers, pigment absorbs light prevents scattering. Choroid continuous with the ciliary body muscle that change shape of the lens.
Inner layer
Retina--photoreceptors: converge to from optic nerve
Rods: most abundant, dim vision
Cones: color vision, work best in bright light
Lens: focus light in retina, surround by cililary body
Iris: anterior the lens, posterior the cornea, colored part of the eye--intrinsic muscle for dilation or constriction of pupil
Optic disc: blind spot, no photoreceptors
Macula lutea: clearest vision
Fovea centralis: within the lutea
Pathway
Cornea--->lens--->retina--->optic nerve--->optic chiasm--->optic tracts--->midbrain--->thalamus--->primary visual cortex in occipital lobe.
Nervous system organization
CNS: ( brain and spinal cord) receive process and respond to sensory input
PNS: (ganglia, spinal nerves, cranial nerves) gather sensory information from all receptors and passes it on to the CNS
Somatic: mainly to the skin, body wall, skeletal muscle, except ventral body cavity contents.
Autonomic: mainly ventral body cavity contents, include smooth muscle, cardiac muscle, glands, goosebump (arrectorpili muscle), sweat gland, smooth muscle of blood vessels.
Anatomy of nervous system
Ganglia cells: non-nervous supporting cells, act to support, protect, nourish, insulate neurons
Ganglia in CNS (astrocytes, microglia, ependymal cells). In PNS ( satellite cells, schwann cells)
Nerve is bundle of axons, each axon is surrounded by Schwann cells, bundle of axon called fascicle