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Spinal cord and Peripheral nervous system
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Spinal cord - FunctionsSensory and motor pathway
Reflex arc (spinal cord)Reflex center –
Sensory receptor Sensory neuron Interneuron (association neuron) Motor neuron (effector) An effector organ
Spinal Cord Anatomy Association neuron Motor
http://www.bayareapainmedical.com/wspinecrd.html
Gray Matter – “butterfly” interneuronsWhite Matter – myelinated
Spinal cord Anatomy
Spinal Cord tractsSensory 1. Dorsal column
2. SpinothalamicAscending tracts
temperature, pressure, pain, light, touch
Spinal cord tracts continued
Motor tracts
1. Corticospinal Decending Skeletal tone, voluntary muscle movement
Nerves attached to Sp. Cord Dorsal Root Ganglia
– bundle of sensory nerves
Ventral Root Ganglia – bundle of motor fibers
Peripheral Nervous system
P e rip he ra l N ervo u s S ys tem
S o m a tic
sym p ath tic N e rvo ussys tem
p a rasym p a the tic n e rvo ussys tem
A u ton o m ic N ervo ussys tye m
P N S
Somatic Nervous System Includes all nerves in the
musculoskeletal system, sense organsReceptor (receives impulse) to Effector
(muscle fiber)
Autonomic Nervous SystemMotor neurons that control internal
organs (involuntary) Innervate all organs Two divisions of
Autonomic Nervous System Sympathetic
“Fight or flight response”
Inhibits digestion Pupils dilate Accelerates heart
rate Increase breathing
rate.
Parasympathetic Normal state Promotes digestion Pupils constrict Normal heartbeat “feed and breed”
The Eye: Photoreceptor Lens – refraction and
focusing Iris – controls entrance
of light into eye Pupil – window into the
eye Choroid – blood
vessels, absorbs stray light
Eye anatomy continued Sclera – white
fiborous layer, protection
Humors – Aqueous humor –
between the cornea an lens
Viterous humor – fills large cavity, gelatinous material
Eye Anatomy continued Ciliary body – holds
lens in place Retina – contains
receptors Cones – color vision Rods – black and
white vision Optic Nerve
Rods and Cones Illustration
Eye Anatomy Continued Optic Nerve – picks up
impulse Ciliary muscles –
controls the shape of the lens
Accommodation – Additional focusing
power Near object – ciliary
muscle contracts, lens becomes round
Physiology of sight Focusing – light rays
bent by cornea, focus on the retina, refraction and inverted
Fields of Vision Illustration
Refer to Lab on eye dissection
Cross section of head
Normal Vision 20/20at a distance of 20 feet, you can read a
certain line (labeled 20) on the chart and that your vision is normal.
20/40 -
Nearsightedness (myopic)Farsightedness (hyperopia)
Disorders of the Eye:
Glaucoma – built up pressure in the eye due to lack of aqueous humor drainage
Vision of a person with Glaucoma
Cataracts- clouding of the lens