Somatic nervous system

Sensory receptors

specialized structures that detect changes in environment

Cutaneous sensory receptors

Thermo receptors and mechanoreceptors

Thermoreceptors

respond to temperature changes

Mechanoreceptors

respond to touch, pressure and vibrations

Visceral sensory receptors

Chemoreceptors, irritant receptros, baroreceptors and stretch receptors

Chemoreceptors

respond to chemical changes in blood

irritant receptors

respond to pollutants in airway

Baroreceptors

respond to blood pressure changes

strecth receptors

decect stretch in wall of bladder

Special sneses

gustation (taste), Olfaction (smell), vision, hearing and equilibrium

The olfactory system

receptor neurons are within the olfactory epithelium of the nasal cavity; azons project through the cribriform plate of the ethmoid bone and synapse with the neurons of the olfactory bulb

Nasal conchae

Ol

olfactory bulb

olfactory tract

olfactory epithelium

Cribriform plate of the ethmoid bone

Fibrous tunic

The outermost layer of the eye wall; contains sclera and cornea

Sclera

attatchment of muscles

Cornea

Transparent, admits light

Vascular tunic (Uvea layer)

the middle layer of the eye wall; contains the chorid, cillary body and iris

Chorid

Vascular

Cillary body

secretes aqueous humor and suspends lens

Iris

Color, changes size of pupil

Sensory tunic

inner layer of the eye wall; contians a pigmented layer and a neural layer

Neural layer

becomes the optic nerve

Iris sizing

changes the size of the pupil depending on the intensity of light

Cataract

clouding of the lens, induced by diabetes, uv radiation, becoming opaque with age

Glaucoma

eleveted pressure within the eye, due to improper drainage of aqueous humor and may lead to blindness

Pathway of light in the eye

cornea—— awueous humor in anterior chamber —— pupil —— aqueous humor in posterior chamber —— lens —— virteous humor —— retina —— optic nerve

Pathway of light in retina

Pigmented layer of retina —— photoreceptors —— bipolar cells —— ganglion cells

Retina

where the conversion of light energy to action potential occurs

Steps of light energy

Photoreceptro cells absorb light and generate signals to the bipolar cells which go to the ganglion cells; Axons for me optic nerve to primary visual cortex in the occipital lobe of cerebrum

Optic nerve and chiasm

extents from posterior aspect of eye with some fibers crossing at the chiasm; tract propogates signals to occipital lobe

Rods

activated by dim light, no clor vision, requires vitamin a to function due to rhodopsin, only has photoreceptors, produces fuzzy images

Cones

Activated by bright ligt, less in numper only photoreceptors in fovea centralis, color vision, sharp images

Outer ear

Auricle, external auditory canal, tympanic membrane

Auricle, external auditory canal

guard hairs and cerumen

Middle ear