8.3 Senses Flashcards
Sensation definition
External stimuli trigger action potential
Sensation vs perception
Sensation occurs at receptor
Perception is interpretation of stimulus by CNS
40% of our cerebrum conscious mind associated with
Vision, 70% of sensory receptors in eye
Two types of sensory receptors
Tonic and Phasic
Phasic receptors
- quick acting, will pass, stop firing after continuous stimulation
Tonic receptors
- slow acting, continue firing, no adaptation
ex. Pain
Nociceptors are
Noxious/ Pain receptors
Mechanoreceptors
Mechanical stresses and movement
Hairs bent
Thermoreceptors
Changes in temperatures
Photoreceptors
Light
Chemoreceptors
Chemicals (tongue, CO2, O2)
Baroreceptors
Pressure (fluid)
Osmoreceptors
Osmolarity, concentration of solutes in solution
Eye surface visible
Anterior one-sixth
Eyes three tunics
Fibrous
Vascular
Sensory
Conjunctiva
Transparent mucous membrane
Lacrimal apparatus
Lacrimal gland, sac, fluid (empties into nasal cavity) tears
Fibrous tunic parts
Sclera - opaque, no light through, white
Cornea - anterior 1/6th translucent
Vascular tunic parts
Lens of the eye - accommodation (can change shape/curvature) to focus
Light rays converge on the retina at a single focal point
Iris - can change shape (smooth muscle), can constrict to reduce pupil size.
Sensory tunic aka
Retina
Rods: more sensitive to light, allow vision in dim light (blue gray)
Cones: operate best in bright light, enable high acuity, color vision (red green)
Macula lutae - little dense spot with most rods/cones
Optic disk - opening where all nerves and blood enter/leave eye.
