Midterm 2 Flashcards
(31 cards)
What somatosensations do we perceive? Ex?
Light touch: receptor structure and mechanism. Affect fibers
Temperature: specific hot and cold spots
Species-specific perception
Sensations are determined by…
Specialized cells that translate external events into neural events for stereotyped, predetermined information processing by the brain
What is species-specific perception?
Sensitivity to frequency of sounds.
Via tuning graphs we can recognize that humans can’t hear very high frequency sounds that are well within the cats hearing range. Elephants can hear better in the low frequency range
What is the law of “specific nerve energies”?
Ex?
The concept that there are particular cells that you have which are tuned to detect a particular kind of thing no matter how they are activated
Ex: eyes have receptors on them in higher retina and your brain is stuck interpreting light from the design perspective that it always interprets eye activity as light
Cold metal feeling hot
Skin receptor structure + 4 parts
Free nerve endings are cellos near the surface that interpret pains no temperature
1 pacinian (vibration) 2 meissner (touch - for sharp detailed touch) 3 merkel (touch - also sharp) 4 ruffini (stretch)
What is sensory adaptation?
A) a weak stimulus causes many action potentials at first, then less. This means the cell is rapidly adapting. For example, if you place your hand on a counter, your brain will tell you rapidly but then not overload you with more information after.
B) strong stimulus causes many more frequent action potentials at first but again they also rapidly adapt and the number of actions potentials thins out
Function relationship in receptor axon types
Ex?
Axons can be constructed
They differ because they have different types of axons
Big axons that are myelinated carry info fast
Skinny axons have a slower information speed
Ex) pain are slow sending info to brain
Center-Surround organization of reception fields
Many receptor fields are activated at the center and inhibited At the surround
The pacinian corpuscle
From receptor to brain
In the skin are pacinian cells that have ion channels. They do nt care about ligand but care about stretch (when the receptors open). If there is enough depolarization to reach the axon an action potential gets generated and the brain can detect the stretch. Stretch signals are detected by the spinal cord and then sent to the brain
Levels of sensory processing
Spinal cord > brain stem > thalamus > primary sensory cortical areas. From there into the secondary sensory areas (non primary).
Somatosensory pathways and dermatomes
A diagram that charts the organized corresponding of body areas to portions of the spinal cord
Homunculus
Representation of the body surface in the somatosensory cortex
Temperature receptors
Cold fibers are most responsive to temperatures lower Than the normal body temperature. Same goes for hot fibers.
People who do not feel pain do not have…
C-fibers or nerve endings
Anesthetics can block pain…
Pressure block, large fibers blocked first. Touch lost first pain last
Local anesthetic, small fibers blocked first, pain lost first, touch lost last.
How pain gets to the brain
When you bang your skin, a bunch of things get released. Because you have destroyed he membrane there is a leak of potassium and things involved in inflammation. These things that create inflammation stimulate free nerve endings in the skin. They send a signal into the spinal cord and to the brain.
Auditory perception
Complex sounds, communication and language fundamentals, sound intensity, frequency and localization
The basics of sound
Amplitude and frequency of sound waves. Amplitude is the height of the. Wave frequency is the width (density) of the waves. Amplitude is the difference of where the air is compressed and expanded.
Frequency is number of changes per unit of time.
Amplitude Units- decibels (dB) … 0 dB is the softest sounds most people cant hear and +20dB is an increase in pressure by power of 10… A normal conversation is at 60dB and 120 dB is a concert
Sounds
Transduction of sounds into action potentials
Structures of the ear
External ear: ear canal collects sounds and channels it into the ear. The main job of the ear canal is to deliver sounds pressure way to the tympanic membrane or eardrum
Middle ear: three small bones translate pressures in the cochlea. Vibrations from he tympanic membrane will move those three bones or ossicles. They transmit these sounds to the hairs on the cochlea via amplification. The hairs detect an extremely small change in dB. In response to the pressure in the oval window the ‘ basilar membrane vibrates’ and those near the cochlear base prefer high frequencies and those near the end of the axon prefer low frequencies. So the basilar membrane segregates the frequencies. “Spatial code” (explains frequency sorting)
Internal Ear: includes the cochlea. Outer and inner hair cells. Now inner hair cells receive the vibration and send the auditory information through the auditory nerve to the brain. Inner hair cells dont have axons because it doesn’t have to project very far the cells that carry what the hair cells signal have three or so rows of hair called stereocilia. The long cells have a polarity so they can vibrate in one direction versus another. This is all contained within the organ of corti. (Transduction)
Semi circular canals
Help with vestibular senses and are also inside the inner ear.
Inner hair cells
Afferents project to the brain. Different neurotransitters to communicate between afforestation and efferent.
Glutamate
Tends to be a fast acting neurotransmitter. There must be iconographic glutamate receptors that will depolarize the afferent nerve fibers so that the vesicles are released.
receptor cell
a specialized cell that responds to a particular energy or substance in the internal or external environment and concerts this energy into a change in the electrical potential across its membrane
