Post on 23-Feb-2016
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Lab 5
Nervous system and senses
Nervous System
Two primary divisions of the nervous system:
Central nervous system (CNS) - consists of the brain and spinal cord
Peripheral nervous system (PNS) - consists of all neural tissue outside of the CNS
The CNS contain both gray matter and white matter
gray matter - areas of CNS dominated by nerve cell bodies and unmyelinated axons
white matter - areas of CNS dominated by myelinated axons
The CNS is are covered by meninges (membranes) for protection and cushioning
dura mater - tough outer layerarachnoid mater - spider-like middle layerpia mater - transparent inner layer
CNS also contains cerebrospinal fluid - fluid bathing the surfaces of CNS
• fills ventricles and subarachnoid space•secreted by choroid plexus (complex interwoven network of peripheral nerves)
functions: -protection, drains unwanted substances away from brain – helps maintain homeostasis
Autonomic Nervous System – monitors and adjusts body systems to maintain homeostasis – involuntary (think automatic)
Sympathetic – stimulates metabolism, increased heartbeat, and elevates mental alertness to allow the body to cope with a stressful situation. Prepares body for “fight” or “flight” action. Widely distributed throughout the body.
Parasympathetic – conserves body by promoting sedentary activities, such as “rest and digest” functions. Limited to the head, neck, and selected viscera.
Relationships Between The Sympathetic And Parasympathetic Divisions
Dual Innervation – most organs are innervated by both divisions thru plexuses with opposing effects
Special Senses: Ear
Functions of ear: hearing and balance
•static equilibrium (linear acceleration)
•dynamic equilibrium (rotational acceleration)
Regions of the ear:
outer ear - pinna, external auditory canal/meatus, tympanic membrane (ear drum), captures sound
middle ear – ossicles: 3 bones - malleus/hammer, incus/anvil, stapes/stirrup, auditory/eustacian tube, amplifies sound
inner ear - network of canals (membranous labyrinth) with receptors, balance and sound detection
Regions of the eye:fibrous tunic - outermost region, epithelial tissue (integument) (NOT vascularized)
sclera - opaque white, function is support
cornea - transparent, function is protection
vascular tunic - middle region (vascularized)
iris - pigmented, contains smooth muscle that contract to change the diameter of the central opening of the iris pupil - regulates the amount of light entering the eye.
choroid - dark in color: many blood vessels, supplies nutrients + oxygen to retina
ciliary body - attached to lens and can change shape of lens to focus
neural tunic or retina - neural inner region with two primary layers
outer pigmented layer - absorbs light
inner neural layer – contains a photoreceptors layer
rods - b/w or dim lightcones – color or bright light bipolar layer - supporting cellsganglionic layer - neurons that perform preliminary processing and integration of visual information
macular zone - "yellow spot" - no rods in this section of photoreceptive layer, the highest concentration of cones is found in the center of the macular zone is the fovea
optic disc (blind spot) - axons from the ganglionic layer converge here and penetrate the wall of the eye and proceed toward the brain via the optic nerve.
Inner Ear