Phsyio: Ch 10 Sensory

what are sensory receptors?

cells that receive sensory information (aka a stimulus) from the environment

What do sensory receptors do?

Transduce different energy forms
(like pressure, temperature, chemical, light etc)
into graded potentials that initiate action potentials

what is an action potential?

rapid sequence of changes in the electrical signal across a membrane

Name the 5 classes of sensory receptors

-Mechanoreceptors
-Thermoreceptors
-Photoreceptors
-chemoreceptors
-Nociceptors

what are mechanoreceptors?

receptors that respond to mechanical stimuli

(ex. touch and pressure)

what are Thermoresptors?

respond to cold and warmth

what are Photorecptors?

respond to light

What are Chemoresptors?

receptors that respond to bonding of particular chemicals

(ex. taste)

What are Nociceptors?

receptors that respond to painful stimuli

when a sensory stimuli arrives at a sensory receptor cell, the membrane potential of the sensory receptor cell changes by a variable amount

the variable change is called....

a Graded potential

what does transduction involve?

opening of ion channels

What does AP (action potential) generate?

It generates depolarization at an initial segment of axon

this reaches a threshold which causes an ion channel to open

What is adaptation?

a decrease in receptor sensitivity (responsiveness) during maintained stimulation.

What does adaption cause?

it causes a decrease in action potential (AP) frequency in an afferent neuron despite continuous presence of a stimulus

What are the two phase of Adaption.

1.Phasic/fast-adaptaion receptors
2. Tonic/slow-adapting receptors

Describe the phasic phase.

They respond quickly before adapting to a constant stimuli
(ex. pressure when seated on a chair)

[think... phas=fast]

Describe the tonic phase

where persistent action potential
or a slow decrease of AP firings.

ex. receptors in a joint or muscle that maintains posture

Describe somatic sensation

Touch, Pressure, pain temperature and senses of posture and movement (proprioception)

What are the two types of Chemoreceptors

-Gustation (taste)
-Olfaction (smell)

What is the sensory nerve of Gustation connected to?

taste buds! (located in lingual papillae

What are some characteristic of tastebuds?

-comprised of 50-100 specialized epithelial cells called (taste cells)
-various shapes and sizes

What is the relationship between different tastes and taste cells?

Different types of tastes (salty, sour, sweet, umami, bitter) activate taste cells differently

What ion causes a salty taste

Na+ going through an ion channel

[think NaCl = salt]

what ion causes a sour taste?

H+ going through an Ion channel

[Think...H= more acid]

how do we recieve sweet and umami flavors?

They bind to membrane receptors

how do we receive bitter flavors?

Quinine bind to membrane receptors

What is olfaction?

sense of smell

What is the stimulant of olfaction?

Odorants

Describe the pathway of olfaction

Odorants bind to proteins which attach to dendrites of the olfactory receptor neurons.

the axons of the olfactory receptors then synapse onto olfactory bulb of the brain.

which then go into the afferent pathway

What interprets a specific odor?

The unique pattern of the binding of odorants and receptor proteins

where do olfactory receptor cells synapse?

in 2 olfactory bulbs

what is the vestibular system?

a structure in the inside of your ear

what is the function of the vestibular system.

to keep track of your head position/movement, spacial orientation and linera acceleration)

(ex. head movement (up/down, side to side, forward/back)

What are the two vestibular sensors?

Otolith organs (or maculae) and semicircular canal

What do the 2 otolith organs consist of?

the saccule and utricle

What does the Otolith organs do?

They sense *linear* acceleration

(ex. jumping, bending down)

Characteristic of maculae (aka otolith organ)

each sensor has a mass of otoliths (tiny stones) on top of a *gelatinous* substance

What do the semicircular canals do?

they sense angular acceleration of the head in a three dimensional space to maintain balance

ex head movement (up/down, side to side, forward/back

Characteristics of semicircular canals

-each canal has a crista (a sesnroy organ in ampulla)
-each crista has a gelatinous mass (aka cupula) on top which is moved by endolymph movement

How do otolith organs work?

otoliths (tiny stones) are inside a gelatinous substance that covers hair cells in the utricle and saccule.

[when head moves, the gel moves causing the hair cells to move, which sends signals to brain]

How does the Cupula work?

-the cupula is connected to the semicircular canals of the ear
- when the head moves side to side, the cupula moves/bends which stimulate hair cells that send signals to brain.

What causes sound?

vibration from gas, liquid or solid molecules

[molecules move, auditory systems move]

____ are zones of atmospheric rarefaction.

sound waves

define frequency

the number of cycles per second of the sound wave

what does frequency determine?

frequency determines pitch

[higher freq = higher pitch n vice versa]

define intensity

it is the amplitude of sound waves

what does intensity determine?

intensity determines loudness

what structures help focus sound waves to the ear drum?

the pinna and external auditory meatus

[aka the external ear, the part you can see]

what is the scientific word for 'eardrum'

tympanic membrane

Describe the auditory pathway after the tympanic membrane

Tympanic membrane --> ossicles --> oval window --> movement of fluid in cochlea --> vibrations in basilar membrane --> bending of hair cells in Corti

What makes up the organ of Corti?

basilar (bottom) membrane + hair cells + tectorial membrane

what happens in the organ of corti?

auditory transduction occurs in the cochela

What does low frequency cause?

Causes large vibrations in *apical* (at the top) cochlea
[this is a low pitched sound]

What does high frequency cause?

- Causes large vibrations in *basal* (at the bottom) cochlea
[this is a high pitched sound]

what does tonotopic mean?

Arranged by frequency

what is the stimulus in visual system?

light

light has what type of properties?

wave-like properties

[aka travels in waves]

define wavelength

wavelength is the distance between *two peaks*

(measured in nanometers (nm))

what does wavelength correspond to?

color
(ex. red = long, blue = short)
^ this is why you notice red colors before you notice blue

what is the 'visible spectrum'

what the human eye is able to see and what the brain is able to perceive

what is the range of visible spectrum (in nm) in humans?

appx. 400-700 nm

t/f the wave length is longer, the object will be less bright

FALSE

- if the wavelength is short, the object is less bright

what are the three layers of the eye from outermost to innermost?

Fibrous Tunic, Choroid, Retina

What are the two parts of the fibrous tunic?

Sclera and cornea

What is part of the eye is the sclera?

it is within the fibrous tunic and is the whites out our eyes

[this is where the muscles that move our eyes are attached]

What part of the eye is the cornea?

it is the clear cover of the eye,

this transmits light

Where is the Choroid (second layer of the eye) found?

beneath the sclera

What are the 4 structures of the Choroid?

-pupil
-iris
-uvea
-ciliary muscles

define pupil

anterior opening for light entry into the eye

[the black part of the eye]

define iris

pigmented muscle around pupil,

it dilates (expands) and constricts (small)

t/f the eye constricts when there is more light

true

t/f the eye dilates when there is less light

true

define uvea

blood vessels in the eye

[what makes ur eye turn pink]

what is the function of the ciliary muscle?

lens accommodation (lenses changes shape to focused on an image)

what are found in the retina?

Photoreceptors

what are human photoreceptors?

rods and cones

Accommodation for near vision means the lens ____

rounds

Accommodation for far vision means the lens ____

flattens

What is the problem with light rays in Hyperopia.

the light focuses behind the retina

[think hyper= adhd = behind in school work]

how do you correct hyperopia?

with convex lens to correct farsightedness

What is the problem with light rays in myopia.

light rays focus in front of retina

[ put your hand on your chest to signal 'my', hand is in front]

define accommodation

changing of lens to focus light on the retina

which photoreceptor is most responsive when a person is in a dark environments?

rods

[think... LIGHTning *rods*]

Which photoreceptor is mainly used for color?

(rod or cones?)

cones

[think *C*ones = *C*olor ]

when you look at a near view object, that means your lens is?

round in order to let less light in

[ciliary muscles are contracted]

When you look at something far away, are your ciliary muscles contracted or relaxed?

relaxed

[lens is flat, to let more light come in]

t/f contracted ciliary muscles have lower tension

True

[think opposite for eye muscles, more contracted = less tension]

t/f relaxed ciliary muscles have lower tension

False

[think opposite for eye muscles, less contracted = more tension]

Name 3 characteristics of rods

- most sensitive photoreceptors
-black and white vision
-used in dim light

Name 2 characteristics of cones

- used for color vision
-used in high resolution vision (fine detail)

M cone corresponds to what color?

green

[think greeN = M]

S cone corresponds to what color?

Blue

[think... S= Sad (blue) ]

L cone responds to what color?

Red

[think L = love]