Senses

Sensory receptors based on stimulus origin

Sensory receptors = structures sensitive to stimuli from their surroundings and sends signal on to CNS via an axon of a neuron

Sensory receptors based on type of stimulus

General Senses = widespread touch (ex: proprioreceptors, interoceptors)


Special Senses = sight, smell, taste, hearing, equilibrium in head

Exteroceptors - sensitive to environmental stimuli (located on skin and special senses)

Interoceptors - sensitive to stimulus from internal organs

Proprioceptors - sensitive to stimuli from muscles, tendons, ligaments, joints (stretching), tells where body is in space/coordination, wrap around muscles/tendons (deep)

have free nerve endings (ex: hair follicle receptors)

have specialized sensory cells (ex: tactile epithelial cells)

all sensory receptors are different in structure and function

Thermoreceptors = sensitive to temperature (cold and warm ones)

Chemoreceptors = sensitive to chemicals (special senses, blood vessels)

Nociceptor = "noxious"/dangerous, sense pain

Mechanoreceptor = sense touch, pressure, vibration, stretch, sense physical/mechanical things

Photoreceptor = sensitive to light

Baroreceptor =specialized, measures blood pressure

Gross & Microscopic Anatomy of Eye

Fibrous layer

Sclera = "white" of eye, dense connective tissue, protective, anchor for extrinsic eye muscle, gives shape

Cornea =transparent, allows light to pass through into eye, helps focus light on retina

Vascular layer

Choroid = black in color, absorbs light and prevents light from scattering, nourishes retina and vascular layers

ruffled edges continuous w/ choroid, called the "ciliary body", made of smooth muscle, ciliary body can change shape of lens to help focus on distant or near objects

Inner layer

Retina = very thin, "tan color", location of photoreceptors, axons from retina converge to form optic nerve

Cones = sensitive to color (not good in dark, which is why you can't easily see colors in dark), need bright light to see best

Rods = most abundant, sensitive to light (good vision in dim lights because of rods)

Lens = focus light on the retina along with cornea

Iris = anterior to lens, continuous with ciliary body, smooth muscle/sphincter (dilates/constricts to allow more or less light into eye center), "color" of eye, "hole" in middle = pupil (allows light to center of eye)

Optic disc = posterior side of eye, no photoreceptors ("blind spot")

Macula lutea = posterior, fovea centralis is at center

Fovea centralis = at the center of macula lutea, light is focused here, clearest vision, only cones

Cavities of the eye

Posterior Segment = filled with vitreous humor (viscous liquid, gel-like), support retina and lens, maintains pressure in eye

Anterior Segment ( 2 parts)

Anterior chamber = from cornea to iris

Posterior chamber = from iris to lens

filled with aqueous humor (watery) that maintains eye pressure and nourishes lens and cornea because they're avascular