college biology chapter 35

stimulus

a signal to which an organism responds

Mechanoreceptors

detect forms of mechanical energy (pressure, position, and acceleration)

Thermoreceptors

detect heat energy

pain receptors

(nociceptors) detect tissue damage

chemoreceptors

detect chemical energy in specific substances dissolved in fluid

osmoreceptors

detect changes in solute concentration (water volume)

photoreceptors

detect visible and UV light

sensory adaptation

the frequency of action potential decreases or stops even when the stimulus is maintained

free nerve endings

branched endings of sensory neurons in the skin that function as mechanoreceptors, thermoreceptors, and pain receptors

encapsulated receptors

A receptor in which the axon terminal is surrounded by a fluid-filled capsule formed of connective tissue

Meissner corpuscle

adapt slowly to vibrations of low frequencies

bulb of Krause

thermoreceptor; sensitive to temps below 10*C

Ruffini endings

sensitive to steady touching and pressure, and to temps above 45*C

Pacinian corpuscle

able to detect rapid pressure changes associated with touch and vibrations

visceral pain

pain that originates from organs or smooth muscles

referred pain

pain that is felt in a location other than where the pain originates

phantom pain

pain felt in a body part that is no longer there

olfactory receptors

nerve endings that act as the receptors for the sense of smell; detect water-soluble or volatile substances

pheromones

odorless chemicals that serve as social signals to members of one's species

equillibrium

A state of balance

vestibular apparatus

The receptive organs of the inner ear that contribute to balance and perception of head movement (semicircular canals)

utricle

fluid-filled chamber in the inner ear that detects changes in gravity

Amplitude

the loudness of a sound

frequency

pitch

outer ear

collects sound waves

pinna

the visible part of the ear

middle ear

picks up vibrations from the eardrum and passes them to three bones (hammer, anvil, stirrup), which amplify the sounds before transmittal to the inner ear

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

organ of Corti

tissue containing the hair cells necessary for hearing

hair cells

receptor cells for hearing found in the cochlea/organ of corti

eye lens

Focuses light onto retina

cornea

the transparent outer covering of the eye

retina

Light sensitive layer of the eye; contains rods and cones

iris

Colored part of the eye; adjusts the size of the pupil

pupil

The opening through which light enters the eye

sclera

white of the eye

aqueous humor

fluid in the eye, found between the cornea and the lens

vitreous body

helps to stabilize the eye and give physical support to the retina

ciliary muscle

controls the shape of the lens

rod cells

more sensitive to light and allow vision in dim light

cone cells

operate best in bright light; enable high-acuity, color vision

optic nerve

the nerve that carries neural impulses from the eye to the brain

fovea

the central focal point in the retina, around which the eye's cones cluster

myopia

nearsightedness; eyeball is too long, object focuses in front of the retina

hyperopia

farsightedness; eyeball is not long enough, object focuses behind the retina

cataract

clouding of the lens of the eye