Stimulating sympathetic ns which increase heart rate

stimulating sympathetic NS which increase heart
rate & vasoconstriction
44.3 Hearing, Vibration, Detection of Body Position
Fishes’ lateral line system provides “distant touch,” enabling them to
sense objects that reflect pressure waves & vibrations
Hair cells have hairlike cilia that project into a gelatinous cupula; the
smaller hairs are stereocilia (made of actin) & the single big hair is the
kinocilium
o When stereocilia move in the same direction of the
kinocilium, it depolarizes the neuron; opposite direction has
inhibitory effect
Fish hearing
o Otoliths: rocks of calcium carbonate found in the
membranous labyrinth , a system of fluid-filled chambers;
when otoliths vibrate against hair cells, action potentials are
produced
Vertebrate hearing
o Vibrations channeled through the ear canal to the eardrum
(tympanic membrane), part of outer ear
o Vibrations of the tympanic membrane move small bones in
the middle ear (stapes aka stirrup, malleus aka hammer, and
incus aka anvil)
o Movement of these bones against the oval window (inner
membrane) create pressure waves in the fluid in the canals
of the cochlea (snail) which cause cilia to bend, producing
signals
o KNOW HOW TO LABEL THE EAR (FIGURE 44.6)
o The middle ear is connected to the throat through the
Eustachian tube (auditory tube) that equalizes the pressure
between the middle ear and the external environment
Transduction occurs in the cochlea: pressure waves go through the
cochlea to the round window which causes the cochlear duct to
vibrate
o Basilar membrane: bottom of the cochlear duct, contains
sensory hair cells with stereocilia that project into the
overhanging tectorial membrane ; this whole system of hair
cells & membranes is called the organ of Corti which resides
in the cochlea
o Frequency localization in the cochlea
o Basilar membrane consists of elastic fibers varying
in length and flexibility embedded in the
gelatinous material
o At the base (near oval window), the fibers are
short & stiff, respond to high pitch
o At the end (apex) of the cochlea, the fibers are 5x
longer & 100x more flexible, respond to low pitch
1. Sound enters cochlea through oval
window
2. Sound wave imparts the most energy to
the part of the basilar membrane that
matches the frequency (pitch) of the
sound

TA: Victor Vinh ([email protected])
3. Hair cell depolarization at the area w/
most energy is greatest & afferent
neurons stimulated the most there
4. Brain interprets as pitch
Range of hearing
o Children: 20-20,000 Hz which decays w/ age
o Dogs: up to 40,000 Hz
o Efferent axons in hair cells can increase ability to concentrate
on specific signals, ex. A voice in the crowd
Echolocation: emit sounds & determine the time it takes for the
sounds to return; sonar & radar do the same
Detection of body position
o Statocyst: ciliated hair cells in gelatinous membrane
containing carbonate crystals; used for orientation in
invertebrates
o Vertebrates: utricle & saccule
o Contain stereocilia and kincilium
o Hair cells embedded in gelatin (otolith membrane)
containing calcium carbonate crystals (otoliths)
o