Ch. 10: Sensory Physiology
List the somatosensory receptors:
-Merkel receptors -Meissner's corpuscle -Free nerve ending -Pacinian corpuscle -Ruccini corpuscle -Sensory nerves
What are complex neural receptors?
-Nerve endings are enclosed in connective tissue capsules -Adaption for detection of vibration and pressure -Ex: pacinian corpuscle (touch) *registers sensation differently... such as a pinprick to hand versus hand with a glove on
Describe simple receptors.
-Neurons with free nerve endings -Some are myelinated (cold, fast pain) -Some are unmyelinated (slower transmission, such as dull pain) *Opioids are postsynaptic inhibition of secondary sensory neurons
Which primary-to secondary neuron ratio would allow for the greatest receptive field sensitivity?
1:1
What is is called when a stimulus reaches a threshold?
Action potential to the CNS
Where are photoreceptors found?
Back of the retina
What are special sense receptors?
Cells that release neurotransmitter onto sensory neurons, initiating an action potential
What is a result and an example of being able to distinguish different pitches (frequencies) of sound?
Changing sensitivity to pitch along the length of the basilar membrane
What do photoreceptors do?
Convert light energy into electrical signal
What are opioids?
Ex: endorphins. They are postynaptic inhibition of secondary sensory neurons.
Describe where the light goes if it is shined in your eye.
Light passes through layers of cells to reach the back of the retina, where photoreceptors are found. 1. photoreceptors (receptor cells) to the, 2. bipolar cells (neurons) to the, 3. ganglion cells (neurons; axons form optic nerve) *It converges in the retina.
Baroreceptors in the aortic arch and carotid bodies are mechanoreceptors that respond to the stretch that occurs in these arterial walls with changes in blood pressure. If pressure changes rapidly, the baroreceptors initiate a feedback mechanism that reduces blood pressure; however, if pressure changes slowly, as in developing hypertension, the receptors do not respond. Given this information, the baroreceptors are most likely which type of receptor?
Phasic receptors
What are two photoreceptors?
Rods and cones
What is opsin?
Separated from rhodopsin in rods during phototransduction. It decreases cGMP, closes CNG channels, and hyperpolarizes the cell. It is recombined with the retinal during the recovery phase. (it helps the eyes work again to see appropriately)
What does the lens do?
The lens focuses light (accommodation) onto the retina (which contains photoreceptors); controlled by ciliary muscle
How does a photoreceptor respond to light?
The receptor hyperpolarizes, decreasing the amount of neurotransmitter it releases
What is rhodopsin?
The visual pigment in rods that is part of phototransduction. In the darkness, rhodopsin is INACTIVE, cGMP is high, CNG and K+ channels are open. Rhodopsin "bleaches" and separates into opsin and retinal.
Vision is especially acute in the fovea and surrounding macula. This is due to a high density of cone cells and which other reason?
There are no blood vessels or neurons covering the cones
What is an example of a mechanism that causes hair cell depolarization as stereocilia bend in response to sounds waves?
Tip links open ion channels, which causes membrane depolarization
How contributes to color-blindness?
Usually there is a mutation from one of the three pigments in the cones
A receptor potential is:
a graded potential
The modality of a stimulus can be determined within the central nervous system by:
adequate stimulus for the sensory receptor cell
What are some sensory pathways that synapse in the thalamus?
auditory, vision, gustation
Rods see:
black and white vision, low light and night vision
What is an example of a visceral stimuli that is subconscious?
blood pressure, distension of gastrointestinal tract, blood glucose concentration
Somatosensory receptor: sensory nerves
carry signals to spinal cord
Which of the following would be an adequate stimulus for a mechanoreceptor?: oxygen, pH, cold, temperature, cell stretch, photon of light
cell stretch
Equilibrium pathways are in the:
cerebellum
What is the integration in CNS?
cerebral cortex
What is an intracellular signal?
change in membrane potential
Visual pigments convert light energy into:
changes in membrane potential; depending on wavelength, that is the color we see
Which of the following structures contains sensory receptors for hearing?
cochlea
The perception threshold describes the:
concept that neurons higher in the sensory pathway can dampen the intensity of a stimulus
Opening a Na+ channel in a non-neural sensory receptor cell would cause that cell to:
decrease neurotransmitter release
The CNS must distinguish four properties of a stimulus. These properties include location, intensity, modality, and which other property?
duration
Damage to the fovea of the eye would interfere with the ability to:
focus on an image and detect the detailed image of objects in the middle of one's field of vision
In the eye, light is converged onto the:
fovea, region of our sharpest vision
Somatosensory receptor: free nerve ending
free nerve ending of the hair room senses hair movement; free nerve ending of nociceptor responds to noxious stimuli
A decrease in one's perception of a stimulus who's intensity has not changed due to higher neural inhibition is:
habituation
Cones see:
high-acuity, color, daytime vision
Convergence describes:
how multiple primary sensory neurons synapse on a single secondary neuron
What structure focuses light for clear vision?
lens
Which of the type of receptors is involved in hearing?
mechanoreceptor
Which receptors are the hair cells of the ear?
mechanoreceptors
The larger the receptive field, the more:
more primary sensory neurons synapse on a secondary sensory neuron
What is an example of a somatic stimuli that is subconscious?
muscle length and tension, proprioception
The extension of the forebrain that receives odor input from the nose is in the:
olfactory bulb
Olfactory receptors include:
olfactory bulb and olfactory cortex
Which of the following would be an adequate stimulus for a chemoreceptor?: photon of light, vibration, cold, temperature, cell stretch, oxygen
oxygen
Optic disk (blind spot) has no:
photoreceptors
The intensity of a stimulus can be determined within the central nervous system by:
population coding and/or frequency coding
The two-point discrimination test:
provides a measure of receptive field size for touch receptors
A graded change in membrane potential within a sensory receptor cell is always called:
receptor potential
What does a cornea do?
refracts light
Somatosensory receptor: Meissner's corpuscle
responds to flutter and stroking movements
Somatosensory receptor: Ruccini corpuscle
responds to skin stretch
In regards to photoreceptors, rods contain:
rhodospin
What structure contains a receptor that detects rotation of the head?
semicircular canals
Somatosensory receptor: Merkel receptors
sense steady pressure and texture (closer to top of skin)
Somatosensory receptor: Pacinian corpuscle
senses vibration
What do tonic receptors do?
slowly decrease the frequency of action potentials generated to a constant stimulus
What is a sensory receptor?
stimulus as a physical energy
With the exception of olfaction, all sensory pathways first travel to the _______, which acts as a relay and processing station.
thalamus
Most sensory pathways goes through:
thalamus; it relays information and sends to the cortex
Pupil size is controlled by:
the iris; it changes amount of light entering the eye
Our perception of the pull of gravity and linear acceleration is the result of:
the pressure exerted by otoliths on hair cells of the saccule and utricle
Accommodation describes the focusing of light on the retina by changing:
the shape of the lens
What are the somatic senses?
touch, temperature, pain, itch, proprioception
Which special sense would be most affected by a vitamin A deficiency?
vision
What are the special senses?
vision, hearing, taste, smell, equilibrium