Exam 2: week 2 Sensory organs core

Define stimulus

what is detected

List the four steps by which a stimulus becomes a sensation

reception, transduction, transmission, perception

Define transduction

converting a stimulus into an electrical signal in a sensory receptor

where perception actually happens

the brain/cerebral cortex

Define receptor

what detects a stimulus

Name the receptor types by stimulus

chemoreceptors, mechanoreceptors, photoreceptors, thermoreceptors, nociceptors

Define and example of chemoreceptors

receptors that detect chemicals

Define and example of mechanoreceptors

receptors that detect physical forces

Define and example of photoreceptors

receptors that detect light

Define and example of thermoreceptors

receptors that detect changes in temperature

Define and example of nociceptors

receptors that detect potentially harmful stimuli that can cause pain

Define sensory adaptation

a decreased response to a stimulus when it stays constant for a long time

Define tonic receptors

slowly adapting

Define phasic receptors

rapidly adapting

List the cutaneous senses

touch, pressure, temperature, pain

Match the major skin receptors to their stimuli: Free nerve endings

pain, temperature, itch

Match the major skin receptors to their stimuli: Meissner's

Light touch

Match the major skin receptors to their stimuli: Pacinian

Deep pressure and vibration

Match the major skin receptors to their stimuli: Merkel

Light touch, pressure, texture

Match the major skin receptors to their stimuli: Ruffini

Skin stretch

Label the eye structures involved in focusing light

cornea, iris/pupil, lens, retina

Define refraction

the bending of light as it passes from one material into another

Explain how the cornea and lens bend light onto the retina

the cornea and lens bend and focus incoming light onto the retina so the eye can detect an image

Define accommodation

how the ciliary muscle changes lens shape to focus on near vs. far objects

Locate the photoreceptors in the retina

located in the retina, at the back of the eye

Distinguish rods by function

dim light, no color

Distinguish cones by function

bright light, color, sharp vision

Explain in general terms how light striking a visual pigment changes a photoreceptor's signal

Light changes visual pigments, which changes the photoreceptor's electrical signal

3 cone types in retina

S cones, M cones, L cones

S cones

short wavelengths of light, blue

M cones

medium wavelengths of light, green

L cones

detect long wavelengths of light, red

Explain how three types of cones produce color vision

three cone types detect different wavelengths of light, and the brain compares their signals to produce color vision

Trace the path of sound:

outer ear → tympanic membrane → ossicles (malleus, incus, stapes) → oval window → cochlea

Explain how vibrations become fluid waves that bend cochlear hair cells to generate a signal

sound vibrations → cochlear fluid waves → hair cells bend → electrical signal → brain

Define pitch

how high or low a sound seems, frequency (Hz)

Define loudness

how loud or soft a sound seems, amplitude (dB)

Identify the vestibular apparatus (semicircular canals plus utricle and saccule)

the organ of equilibrium

Define semicircular canals

inner-ear structures that detect rotational head movements and help maintain balance

Semicircle canals detect

rational movement

utricle and saccule detect

linear acceleration and head position

Explain how hair cells convert movement into a neural signal

movement bends hair cells → changes their electrical activity → creates a neural signal sent to the brain

Identify taste and smell as the chemical senses

both use chemoreceptors

Name the five basic tastes

sweet, sour, salty, bitter, umami

Explain in general terms how a dissolved chemical triggers a taste or smell receptor

Dissolved chemical → binds to receptor → changes electrical activity → neural signal → brain

How many cranial nerves are there

12 pairs

Define sensory

receives information from the body to the CNS

Define motor

sends commands from the CNS to muscles or glands

Define i olfactory

Sensory nerve responsible for smell

Define ii optic

Sensory nerve responsible for vision

Define VII vestibulocochlear

Sensory nerve responsible for hearing and balance