The Senses and Their Related Anatomy

These flashcards cover key concepts and vocabulary related to the senses and their anatomical structures.

Adequate Stimulus

The specific type of stimulus that a sensory receptor is able to detect.

Receptive Field

The specific portion of the environment in which a sensory receptor can detect stimuli.

somatic (general) sense, special sense

receptors based on distribution

Somatic (general) Sense

General sensory receptors found throughout the body, signaling information to the primary somatosensory cortex.

Special Sense

Senses with specialized sensory organs located exclusively in the head, relaying signals to various sensory cortices.

interceptors, exteroceptors

receptors based on origin of stimulus

Ineroceptors

Receptors that detect stimuli originating within the body.

Exteroceptors

Receptors that detect stimuli originating external to the body.

tonic receptor, phasic receptors

receptors based activity pattern

Tonic Receptor

A receptor that produces a continuous pulsing signal to the central nervous system (CNS). Changes in stimulus are typically encoded as a change in the rate of impulse generation

Phasic Receptor

A receptor that is typically inactive until a stimulus is detected and loses sensitivity over time, a phenomenon known as adaptation.

Receptors based on stimulus

Chemoreceptor

Stimulus Modality; Receptor that detects the presence of specific chemicals in the environment.

Mechanoreceptor

Stimulus Modality: General name for receptors that respond to physical forces acting upon the receptor.

Proprioceptor

Stimulus Modality: Subtype of mechanoreceptor that detects muscle tension and joint position.

Baroreceptor

Stimulus Modality: Subtype of the above that is used to monitor internal pressures

Nociceptors

Stimulus Modality: Receptors that respond to a variety of stimuli associated with tissue damage.

Photoreceptors

Stimulus Modality: Receptors that detect light

Cones

Stimulus Modality: Subtype of the above that are only sensitive to relatively high intensity light of specific wavelengths (colors)

Rods

Stimulus Modality: Subtype of the above that are highly sensitive to even low intensity light making them less suitable for distinguishing wavelengths (colors)

Thermoreceptor

Stimulus Modality: General name for receptors that respond to changes in temperature within a relatively narrow range around body temperature.

Cool Thermoreceptor

Stimulus Modality: Receptor that responds to a decrease in body temperature.

Warm Thermoreceptor

Stimulus Modality: Receptor that responds to an increase in body temperature.

Acute pain

typically has a rapid onset and is often experienced a “burning” or “sharp” pain that will typically cease when the source of the tissue insult is removed

Chronic pain

typically has a more gradual onset and is often described as “duller” or “throbbing” pain that may persist after the precipitating tissue damage has healed.

Phantom Pain

Perception of pain originating from a body part that no longer exists.

Referred Pain

perception of pain originating from one part of the body, typically an internal organ, as originating from a surface region located elsewhere. This type of pain misperception is a result of the convergence of visceral and somatic pain pathways within the CNS.

Somatic senses

sensations of pressure, vibration, temperature, pain and itch.

Special senses

senses with specialized sensory organs located exclusively in the head.

Audition

Organ: Ear

Receptors: Hair cells

Olfaction

Organ: Nasal epithelium

Receptors: Olfactory cells

Equilibrium

Organ: Ear

Receptors: Hair cells

Gustation

Organ: Taste buds

Receptors: Taste receptor cells

Vision

Organ: Eyes

Receptors: Photoreceptors

Bitter

Chemical Detected: Alkyloid compounds (plant toxins)

Salty

Chemical Detected: Na+ ions

Sour

Chemical Detected: H+ ions (acids)

Sweet

Chemical Detected: Sugar molecules

Umami

Chemical Detected: Glutamate (amino acid / protein)

Taste receptors

located in taste buds, found on papillae located primarily on the tongue.

Filiform

Location / Distribution: Most common papillae found on the dorsum of the tongue

Tastebuds Present?: No

Foliate

Location / Distribution: Found on the lateral sides of tongue in children, absent in adults

Tastebuds Present?: Yes

Fungiform

Location / Distribution: Mushroom-shaped papillae found mostly on dorsum and sides of tongue

Tastebuds Present?: Yes

Vallate

Location / Distribution: Large papillae with a central body surrounded by a wall-like ring found in a line near base of tongue

Tastebuds Present?: Yes

Cornea

Location: Anterior 1/6 of eye

Description: Transparent, bubble-like dome

Function: Allows light to enter eye, minor focusing of incoming light

Sclera

Location: Posterior 5/6 of eye

Description: White, opaque outer layer

Function: Supports shape of eye and provides surface for muscle attachment

Iris

Location: Front of vascular tunic

Description: Variably pigmented ring of muscle

Function: Regulates amount of light allowed to enter eye

Pupil

Location: Center of iris

Description: Opening through the iris

Function: Allows light to pass the iris into the lens

Ciliary Body

Location: Vascular tunic surrounding the lens

Description: Ring of muscle and glandular tissue

Function: Muscles reshape the lens, glands secrete aqueous humor

Suspensory Ligaments

Location: Thin connective tissue strands

Description: Connects lens to ciliary body

Function: Transfers movements of ciliary muscles to lens

Lens

Location: Front of vascular tunic behind iris

Description: Flexible transparent structure, shape varies from spherical to disc-like

Function: Focus light on the surface of the retina

Retina

Location: Inner layer of tissue

Description: Multilayer structure (see below)

Function: Photoreception

Retinal Pigmented Epithelium

Location: Outermost layer of retina

Description: Darkly pigmented simple cuboidal epithelium

Function: Non-sensory, absorbs excess light, provides physiological support to photoreceptors

Photoreceptor Layer

Location: Layer internal to the retinal pigmented epithelium

Description: Composed of rod and cone photoreceptors

Function: Detect light to create an image

Bipolar Cell Layer

Location: Layer internal to the photoreceptor layer

Description: Composed primarily of short bipolar neurons

Function: Relay signals from photoreceptors to ganglion cells

Ganglion Cell Layer

Location: Innermost layer of the retina

Description: Composed of bipolar neurons whose axons will form optic nerve

Function: Relay signals from the bipolar cells to the brain via optic nerve

Ora Serrata

Location: Back, outer edge of ciliary body

Description: Saw-toothed border

Function: Represents anterior edge of the neural retina (inner 3 layers)

Optic Disc

Location: Posterior retinal surface about 20° medial to the visual axis

Description: Circular spot on the surface of retina, lacks photoreceptors

Function: Point at which the ganglion cell axons pass back through the wall of the eye as the optic nerve; blind spot

Macula Lutea

Location: Center of the retina (on visual axis)

Description: Yellowish spot of surface of retina; composed almost exclusively of cone photoreceptors

Function: Reception of light; produces a high resolution color image

Fovea Centralis

Location: Center of the macula lutea

Description: Indentation created by displacement of inner layers of retina

Function: Produces the highest quality image

Anterior Cavity

Location: Space between cornea and lens

Description: Aqueous humor-filled space; transparent

Function: Fluid pressure helps maintain shape of anterior eye and provide nutrients to internal structures

Anterior Chamber

Location: Between cornea and iris

Description: Aqueous humor-filled space; transparent

Function: Fluid pressure helps maintain shape of anterior eye and provide nutrients to internal structures

Posterior Chamber

Location: Between iris and lens

Description: Aqueous humor-filled space; transparent

Function: Fluid pressure helps maintain shape of anterior eye and provide nutrients to internal structures

Posterior Cavity (Vitreous Chamber)

Location: Space posterior to the lens and ciliary body

Description: Large space filled by vitreous body

Function: Helps maintain shape of eye and allows nutrients from aqueous humor to diffuse to the retinal surface

Vitreous Body

Location: Fills posterior cavity

Description: Large, gelatinous, transparent structure

Function: Helps maintain shape of eye and allows nutrients from aqueous humor to diffuse to the retinal surface

Rod

Distribution: Most numerous in periphery of retina (away from visual axis)

Outer Segment Shape: Long and narrow

Sensitivity (Intensity): Low

Sensitivity (Color): None

Image Resolution: Low

Cone

Distribution: Primarily in center of retina near visual axis

Outer Segment Shape: Tapered

Sensitivity (Intensity): High

Sensitivity (Color): Red, green, and blue

Image Resolution: High

two senses of the ear

audition, which refers to the detection of sound, and equilibrium, which is the sensation of movement and gravity.

External (Outer) ear

Function: Capture sound waves from the environment

Middle ear

Function: Transfer and amplify vibrations via small bones

Inner ear

Function: Sensation of pressure waves or movement in fluid

Auricle (Pinna)

Location: Outer ear

Description: Funnel-like structure supported by cartilage

Function: Capture and direct sound into ear canal

External Acoustic Canal

Location: Outer ear

Description: Tubular structure leading to middle ear

Function: Conducts sound to tympanic membrane

Tympanic Membrane

Location: Outer ear

Description: Flexible membrane covering opening to middle ear

Function: Vibrates when struck by sound waves

Tympanic Cavity

Location: Middle ear

Description: Air filled space

Function: Houses the structures of the middle ear

Auditory Ossicles

Location: Middle ear

Description: Set of three tiny bones

Function: Transfer vibrations of tympanic membrane to inner ear

Malleus

Location: Middle ear

Description: Hammer-shaped bone

Function: Transfers vibration of tympanic membrane to incus

Incus

Location: Middle ear

Description: Anvil-shaped bone

Function: Transfers vibration of malleus to stapes

Stapes

Location: Middle ear

Description: Stirrup-shaped bone

Function: Transfers vibration of incus to the inner ear

Tensor Tympani

Location: Middle ear

Description: Muscle attached to the malleus bone

Function: Contracts to limit magnitude of the ossicles in response to loud noise

Pharyngotympanic Tube

Location: Middle ear

Description: Long tubular passage connecting middle ear to nasopharynx

Function: Allows air to flow in or out of the middle ear to equalize pressure on either side of tympanic membrane

Vestibular Complex

Location: Inner ear

Description: Large central body with three loop-like passages

Function: Sensation of equilibrium

Vestibule

Location: Inner ear

Description: Central body of vestibular complex with two internal sac-like spaces

Function: Sensation of gravity and linear motion

Semicircular Canals

Location: Inner ear

Description: Loop-like passages attached to the vestibule

Function: Sensation of rotational motion

Cochlea

Location: Inner ear

Description: Coiled snail-like section of the inner ear

Function: Sensation of sound

Oval Window

Location: Inner ear

Description: Oval shaped opening from the middle ear into the bony labyrinth of the cochlea; covered by stapes bone

Function: Permits vibration of the stapes to create pressure waves in the fluid of the cochlea

Round Window

Location: Inner ear

Description: Round-shaped opening from the bony labyrinth of the cochlea to the middle ear

Function: Allows pressure in the cochlear fluid to escape to the air of the middle ear

bony labyrinth

The inner ear is composed of two concentrically arranged tubular structures. The outer one is called the…, has a wall made of bone, and is filled with a fluid called perilymph.

perilymph.

fluid that fills the bony labyrinth

membranous labyrinth

The inner ear is composed of two concentrically arranged tubular structures. The inner one is called the…, has a flexible wall, and is filled with a fluid called endolymph.

endolymph

fluid that fills membranous labyrinth

hair cells

The sensory receptors found in the inner ear are called… because of the presence of a kinocilium and multiple stereocilia extending from the apical surface of the cell. These processes are embedded in some sort of gelatinous membrane, which shifts in response to gravity, movement, or vibration, causing these processes to bend.

These sensory receptors are found in patches within the wall of the membranous labyrinth.

describe the conduction of sound and pressure through the ear

• Auricle, Captures pressure waves in the air

• tympanic membrane, Causes vibration of the (membrane)

• auditory ossicles, Causes vibration of the (bones)

• oval window, Stapes vibrates 

• cochlear duct, Pressure is transferred

• vestibular duct, Creates pressure waves

• the spiral organ, Stimulates hair cells

• tympanic duct, Pressure is transferred

• round window, Pressure is then released

A basic sensory pathway involves four elements.

-Stimulus, Detectable aspect of the environment

-Sensory receptor, Structure that detects this aspect

-Afferent (sensory) neurons, Cells that carry impulses

-CNS Integrating Centers, Gray matter