Chapter 10 Sensory Physiology Flashcards
What type of information do receptors recieve
Sensory
What do receptors do
Transduce different energy forms into graded potentials which initiate action potentials
Where do receptors send information
To the CNS through Afferent sensory
Name the 5 different receptors and what do they respond to
- Mechanoreceptors = touch/pressure
- Thermoreceptors = temperature
- Photoreceptors = light
- Chemoreceptors = chemicals
- Nociceptors = pain
What is a Receptor potential
Graded potential in sensory receptor in response to environmental stimulus
What does the transduction process involve
opening and closing of ion channels
What is adaptation and what does it lead to
Decrease in receptor sensitivity during maintained stimulation
Leads to… decrease in AP frequency in afferent neuron
What are the two types of adaptation
Phasic (fast adapting receptor) = AP very quickly cease
e.g Pressure when seating
Tonic (slow adapting receptors) = persistent or slow decay of the firing APs
e.g. joint and muscle receptors that maintain posture
What is somatic sensation
Touch Pressure Pain Temperature Proprioception - posture and movement
What is chemosensation
Taste = Gustation Smell = Olfaction
Where are taste cells located
Taste buds on the surface of the tongue
Taste buds are located on
lingual papillae
Papilla = small bump
Name the 5 taste categories and where they are localised on the tongue
Bitter = back Sweet = tip Sour = sides Salty = tip Umami = pharynx
What taste category is related to H+
Sour
What taste category is related to Na+
Salty
What does GPCR stand for
Gene protein couple
What steps allow us to smell
Odorants bind to the proteins in the membrane of cilia attached to dendrites of olfactory receptor neurons
- GPCR
- Axons of receptor neurons synapse onto olfactory bulb of brain
- Unique pattern of activity that brain interprets to percieve an odor
How many odors are coded and how many receptor proteins
10,000
380
What does the Vestibular system do and where is it located
Senses:
Head position
Head movement = angular acceleration in 3 dimensions
Linear acceleration
Structures are in the inner ear
What are the two types of vestibular sensors
Otolith organs (maculae) Semicircular canals
What are the two otolith organs and what do they do
- Saccule
- Utricle
Sense linear acceleration with respect to gravity
Each sensor has a mass of Otoliths on top of a gelatinous substance
Where do Olfactory receptor cells synapse
In the 2 olfactory bulbs
What are Otoliths and what do they cover
Calcium carbonate crystals
Utricle and saccule
Makes them heavier
What are semicircular canals and what do they do
Fluid filled endolymph
They sense ANGULAR ACCELERATION of the head in three Dimensions (X-Y-Z)
What do each semicircular canal have
Crista (sensory organ)
What does each crista have and what happens to it
gelatinous mass, cupula on top
It is pushed by endolymph movement
Sensory hair cells are located where
And what does each hair cell have
Otolith organs
Kinocilium and Stereocilla
What does bending of the
stereocilla do
Stimulates or inhibits action potential frequency
Therefore effects membrane potential
The movement of fluid will cause what to bend which stimulates hair cells
Cupula
Sound can be the result of vibration of what (3)
Solid
Liquid
Gas
What do sound waves cause to move and what occurs because of this movement
auditory structures which transduce into action potentials
Define frequency and what does it determine
number of cycles per second
Determines Pitch
Define Intensity and what does it determine
Amplitude of wave
Determines Loudness
What is the Stapes attached to and what do vibrations cause to happen
The oval window
Auditory transduction - ripples in the cochlear fluid
Ripples in the cochlear fluid cause what to move?
What does different pitches result in this movement
Basilar membrane
Different pitches = movement in different area of basilar membrane
Where are high frequency sounds vibrate
Basal (at the bottom) cochlea
Where are low frequency sounds vibrate
Apical (at the top) cochlea
What is a pattern known as and what is it arranged by
Tonotopic
Arranged by FREQUENCY
What are the steps of the audition
- Tympanic membrane
- Ossicles
- Oval window
- Movement of fluid in cochlea
- Vibration in basilar membrane
- Shearing between basilar and tectorial membrane
- Bending of hair cells in organ of Corti to depolarise them
What is the Organ of Corti made up of
Basilar membrane + hair cells + tectorial membrane
What does depolarisation cause
NT release
APs in sensory neurons
What are the visual spectrum range in humans and what colours are at each end
400 - 750 nm
400 = blue 750 = red
What is the Sclera
White fibrous tissue
Attachment of muscles that move eye
What is the Cornea
Clear
Allows transmission of light
What is the Pupil
Opening for light
What is the Iris
Pigmented muscle around pupil
Allows for pupillary dilation and constriction
What is the Uvea
Blood vessels
What are the ciliary muscles
Muscles for lens accomodation
What is the Retina
Posterior portion of eye
Has photoreceptors such as rods and cones
What is the Fovea
Small region in retina with highest concentration of CONES
Therefore has the greatest visual acuity (resolution)
What is the blind spot and where is it
Exit point for optic nerve
Has no photoreceptors
What is accomodation
What happens for far vision and near vision
Changing of lens shape to focus light on retina
Far vision = flattened lens
Near vision = rounded lens
What happens to the tension when ciliary muscles are contracted for near vision
Suspensory ligaments have lower tension and more rounded lens
Parasympathetic
What happens to the tension when ciliary muscles are relaxed for far vision
Suspensory ligaments have HIGHER tension and more flattened lens
Sympathetic
What is Emmetropia
Normal vision
What is Hyperopia
- Farsightedness
- Rays focus behind retina
- Short eye
- Convex lens needed for correction
What is Myopia
- Nearsightedness
- Rays focus in front retina
- Long eye
- Concave lens needed for correction
What is astigmatism
- Irregular curvature of eye or lens
- Rays do not focus
- Uneven lens for correction
What does light do to photopigment molecules
Causes a chemical change
What is the Photopigment in rods
Rhodopsin
How many photopsins provide colour vision in cones
3
Red, Green, Blue
What protein allows for transduction to occur
Transducin
Rods cells allow for
Black and white vision
Most sensitive photoreceptor
Vision in dim light
Cone cells allow for
Colour Vision
High resolution vision
What happens in the dark
Na channels open
Depolarisation
What happens in the light
Na channels are closed
Hyperpolarisation
Where is the visual cortex
Occipital lobe
