Anatomy Exam 3: Sensory Systems (Part 2)

Somatosensory System

involves detecting sensory receptors all around the body

• tactile

• thermoreception

• prorioception

• nociception

tactile

somatosensory system that detects…

• touch

• pressure

• texture

• vibration

thermoreception

somatosensory system that detects…

• temperature

priorioception

somatosensory system that detects…

• body position

• body movement

nociception

somatosensory system that detects…

• harmful stimuli

• injury

general properties of sensory systems

• sensitivity

• resolution

• receptive field

sensitivity

general property of sensory system:

• ability to detect stimulus

high sensitivity

can detect a weak stimulus

low sensitivity

needs a strong stimulus in order to detect it

resolution

general property of sensory system

• ability to distinguish separate stimuli

touch (ex: high resolution)

when 2 different things touching, you can feel 2

touch (ex: low resolution)

when 2 different things touching, you can’t feel 2 things, only 1

receptive field

general property of sensory system:

• area within stimulus can be detected

receptor of somatosensory system

unipolar sensory neurons

encapsulated dendrites of somatosensory system

in connective tissue which helps direct specific types of stimulus energy to the dendrites

unencapsulated dendrites of somatosensory system

also called “free nerve endings”

encapsulated types of dendrites in tactile system

• merkel disks

• meissners corpusules

• lamellar (Pacinian corpusules

merkel disks

• encapsulated dendrite in tactile system

• cells in epidermis that direct certain types of stimulus energy to the sensory receptor

• high resolution

• detects: shape, size, texture

meissners corpusules

• encapsulated dendrite in tactile system

• located at the boundary of epidermis and dermis

• detects: movement, slippage

  • important for gripping

lamellar (Pacinian) corpusules

• encapsulated dendrite in the tactile system

• located in dermis

• detects: deep presure and vibrations

  • important for tool use (ex: pencil, wrench)

proprioception receptors locations

• muscle spindle

• tendon organs

• joint kinesthetic receptors

muscle spindle

• proprioception receptor

• detects stretch of muscle

tendon organs

• proprioception receptor

• detect the force generated by muscles

joint kinesthetic receptors

• proprioception receptors

• detect movement at joint

  • various receptors

chemical senses

• olfactor system

• gustatory system

olfactor system

• chemical sense of smell

• detects airborne/waterborne chemicals

• oflactory epithelium w/ receptors in nasal cavity

• receptors are modified bipolar cells

gustatory system

• chemical sense of taste

• detect chemicals in food

taste buds

• the location of sensory receptor cells in gustatory system

  • located in papille

  • chemoreceptor cells

  • diff types of taste receptors which respond to diff stimuli

different types of taste buds

• bitter

• sweet

• salty

• sour

• umami

visual system

gathers information from light and sends to brain

layers of eye

• fibrous tunic

• vascular tunic

• nervous tunic

fibrous tunic

• layer of eye

• includes sclera and cornea

• outer layer of fibrous connective tissue

vascular tunic

• uvea

• layer of eye

• includes ciliary body, iris, and choroid

nervous tunic

• retina

• pigmented epithelium

structures of eye

• conjunctiva

• lacrimal glands

• nasolacrimal duct

• sclera

• cornea

• pupil

• iris

• lens

• ciliary body

• suspensory ligaments

conjunctiva

connective tissue holding eye in place

lacrimal glands

produce tears

nasolacrimal duct

drains tears from eye nasal cavity

sclera

• outer covering structure of eye

• tough, white, protective outer layer

cornea

• outer covering of eye

• dome-shaped; focuses light

• curved which helps with focusing light into pupil

pupil

• aperture through which light enters eye 

dilated pupil

• more light enters eye

• light scatters more

• blurry image

• low light

constricted pupil

• less light enters eye

• less scattering

• clearer image

• bright light

iris

adjusts size of pupil

iris: radial smooth muscle

• causes dilation of pupil

• pulls pupil outwards

• sympathetic

iris: circular smooth muscle

• causes constriction of pupil

• parasympathetic

lens

• inside eye

• accommodation: adjusts focus of light

rounded lens

light from nearby objects focused onto retina

flat lens

light from distant objects focused onto retina

ciliary body

• inner layer of eye

• forms ring

  • adjusts shape of lens; has epithelial tissue

suspensory ligaments

anchor lens to ciliary body

aqueous humor

• watery; produced by ciliary body

• delivers oxygen and nutrients to cornea and lens 

vitreous humor

• gelatinous; provides shape and support for eye

• behind the lens 

retina

• the back of the eye

• photoreceptors

• rods

• cones

photoreceptors

• recieve light energy

• synaptic terminal, inner segment, outer segment (produces pigment)

• two basic types

  • rods, cones

• axons of ganglion cells converge to form optic nerve

• ____ —» bipolar cells —» ganglion cells

rods

• type of photoreceptor

• rhodospin—photopigment

• monochromic vision (grayscale)

• high sensitivity (vision low light)

• low resolution (low acuity vision)

• good for nightvision, don’t see color, mostly see outlines

cones

• type of photoreceptor

• multiple opsins; different cone cells with different opsins

• color vision

• low sensitivity (daytime vision)

• high resolution (high acuity vision)

peripheral retina

• primarily rods

  • high sensitivity, low resolution

central retina

• primarily cones

  • high resolution; low sensitivity

macula lutea

• located in central retina

• high cone density

• no large blood vessels

fovea centralis

• within macula

• especially high cone density

saccades

• direct fovea to different parts of object

• rapid eye movements

optic disk

• structure of eye

• point at which it connects to eye

  • no photoreceptors

pigmented epithelium

• absorbs light

• support functions for photoreceptors

choroid

layer of blood vessels behind pigmented epithelium

side of head (placement of eye)

• wide field of vision

• limited stereoscopic (3D) vision

front of head (placement of eye)

• narrower filed of vision

• increased stereoscopic (3D) vision

inner ear: sensory functions

• auditory: hearing

• vestibular: proprioception (movement and position of head) 

middle ear & outer ear

• transmition of auditory stimulus

• directs stimulus to inner ear

vestibular system structures

• semicircular canals

• utricle

• saccule

semicircular canals

• structure of vestibular system

• detects rotational movement: acceleration and deceleration

• 3 canals along x, y, and x axes

hair cells in semicircular canals

• hair cells and cupula in ampulla

• stereocilia embedded in cupula

• canals filled with endolymph

• change in movement causes stereocilia to bend

utricle & saccule

• detects position of head when NOT body moving

• linear acceleration/deceleration of head

  • forward/backward

  • side to side

hair cells sensory receptors in vestibular and auditory system

• mechanoreceptors

  • responds to physical disturbance

• rows of stereocilia

• kinocilium

• synapes with sensory neurons

stereocilia

• sensory receptor in VS and AS 

• higher + taller from row to row

• bend; embedded in gelatinous membrane

kinocilium

• sensory receptor in VS and AS

• hair like process

• taller than stereocilia

structures of utricle and saccule

• macula

• otolith membrane

• otoliths/otoconia

macula

• structure of utricle and saccule

• support cells

• hair cells

otolith membrane

• structures of utricle and saccule

• gelatinous layer covering stereocilia

otolith/otoconia

• structure of utricle and saccule

• sand-like, pull on membrane causing stereocilia to bend

static position

tilt that causes stereocilia to bend

movement

acceleration/deceleration that causes stereocilia to bend

utricle movemnt

horizontal acceleration/deceleration of head

saccule movement

vertical acceleration/deceleration of head

auditory system stimulus

pressure waves caused by disturbance

auditory system outer layer

• pinna/auricle

• auditory canal

pinna/auricle

• structure of outer layer in auditory system

• helps detect location of sound stimulus

auditory canal

• outer layer structure of auditory system

• directs stimulus to middle ear

auditory system: middle ear structures

• tympanic membrane

• tympanic cavity

• eustachian tube

• auditory ossicles

tympanic membrane

• middle ear structure of auditory system

• vibrates in response to pressure waves; flexible

tympanic cavity

• middle ear structure of auditory system

• filled with air

  • vulnerable to changes in enviornmental pressure

eustachian tube

• middle ear structure in auditory system

• allows air to move into or out of tympanic cavity

  • connects to pharynx

  • adjust pressure in tympanic cavity

auditory ossicles

• middle ear structure of auditory system

• transmit vibrations from tympanic membrane to inner ear

  • 3 types: malleus, incus, stapes

  • amplify vibrations

  • increases sensitivity to high frequency stimuli

malleus

• type of auditory ossicle

• next to tympanic membrane

incus

• type of auditory ossicle

• inbetween malleus and stapes

stapes

• apart of auditory ossicle

• against inner ear

inner ear structures of auditory system

• cochlea

• oval window

• round window

• spiral ligament

• stria vascularis

• organ of corti

cochlea

• coiled up

• houses organ of corti w/ hari cells

• 3 ducts

  • vestibular duct

  • cochlear duct

  • tympanic duct

vestibular duct

• entry duct of cochlea

• fluid = perilymph

cochlear duct

• middle duct of cochlea 

• fluid = endolymph

• contains organ of corti w/ hair cells