B2W4 Med Phys Flashcards
Hair Cell Structure
All hair cells have stereovilli
Type 1 cells have stereovilli and Kinocilium on the tallest end
Type 2 Cells only have stereovilli
Type 1 Hair Cells
Stereovilli are arranged from short to tall and connected via cadherins
The tallest kinocilium is not connected via cadherins
Type 2 Hair Cells
Stereovilli are arranged from short to tall and starting from the second tallest stereovilli down are connected via cadherins
Cadherins Opening and closing
When hair cells are bent towards the long end the cadherins undergo tension
When hair cells are bent towards the short side the cadherins are relaxed
The more tense the cadherin the more potassium flows into the cell
Endolymph
Cytosol like fluid
High K+, Low Na+
Bathes the stereovilli
Perilymph
CSF like fluid
High Na+, Low K+
Located on the basolateral portion of hair cells
Auditory Neurotransmitter
Glutamate
Vestibular neurotransmitter
Glutamate and Aspartate
Positive and negative deformation of hair cells
Positive
- Toward tall side
- K+ Channels Open
- K+ Influx
Negative
- Toward short side
- K+ Channels close
- Cell hyperpolarizes
Vestibule Cochlea Anatomy
Cochlea is snail like spiraling structure
Vestibula is made of the otolith organs and semicircular canals
Otolith Organs
Organs responsible for the detection of gravity, linear movement, and horizontal movement.
Utricle
Detects horizontal movement
Hairs radiate from tall to short
Saccule
Detect vertical movement
Hairs radiate from small to tall
Semicircular Canals
Detect head rotation
Ampullae
Detect rotational acceleration
Impeding Matching Device
Tympanic Membrane in the ear along with the ossicles convert air pressure into fluid pressure
30:1 surface area of tympanic membrane to oval window
Cochlea Frequency
Base of the cochlea
- Stiff and narrow
- Detects high frequency
Apex
- wide and floppy
- detects low frequency
Helicotrema
Apex of basilar membrane where perilymph of scala vestibuli and scala tympani communicate
Process of Cochlea audio detection
Sound transferred into oval window -> Moves fluid in scala vestibuli -> Fluid in scala tympani moves in the opposite direction -> Scala Media moves and opens hair cells
Inner Cochlea anatomy
Oval Window Side to Round window
Scala Vestibuli -> Reissner’s Membrane -> Scala Media -> Tectoral membrane and Basilar membrane -> Scala Tympani
Physiology of hearing
K+ channels open allowing for K+ from scala media endolymph to enter the cell -> Causes contraction in prestin protein -> Prestin protein causes outer hair cells to contract -> Outer hair cells move basilar membrane to increase endolymph upward movement -> More endolymph causes more stereovilli to bend positively and depolarize -> Ca2+ channels open and enter the cell -> Release of glutamate into the auditory cochlear nerve
Thermoreceptors
Senses cold and hot
Heat Receptor
TRPV1-4
Capsaicin Receptor
Cold Receptor
TRPM8
Menthol Receptor
Tissue Damage Response
Causes release of inflammatory soup
Noiceceptors
Detect pain
Spinal Circuit
Sensory information enters from the dorsal root ganglion -> follow dorsal root into the spinal cord -> Axon splits into two or more synapses -> signal travels to both alpha motor neurons and interneurons
Interneurons in the spine
Can inhibit or excite muscles and detect which muscles need to be fired
Myotatic Knee Jerk Reflex
Patellar tendon stretches -> stretches quad muscle -> stimulates muscle spindles -> afferent signal travels to spinal cord via dorsal horn -> Afferent axon splits and one (Monosynaptic) axon synapses with alpha motor neurons of the quad to stimulate it
Other axon ends synapse onto inhibitory interneurons (Polysynaptic) and inhibit the hamstring muscle
Golgi Tendon Reflex
Type 1b afferent neurons from golgi tendon organ senses shortening of muscle -> synapses onto interneurons (Polysynaptic) -> interneurons inhibit motor neurons of contracting muscle -> stimulate antagonistic muscle
P
Think prevent too much squeezing
Flexion - Withdrawal Reflex
Noxious stimulus activate delta afferent nociceptor -> synapse with multiple interneurons (Polysynaptic) -> in the limb that this happened flexion is stimulated and extension is inhibited -> in opposite limb stretching is stimulated and flexion is inhibited
Layer 4 of Primary visual cortex
Projects to other layers and striate cortex
Both eyes visual information converges
Layers 2 and 3 of visual cortex
Have blobs that detect motion or color
High Frequency Sound Localization
CNS measures the change in sound intensity from one cochlea as compared to the other
Low Frequency Sound Localization
CNS measures the time it takes for sound to reach both cochlea
