when sound waves enter the ear, the first obstacle they encounter is the
tympanum
the tympanum is also know as the
eardrum
the middle ear is filled with
air
the Organ of Corti is also known as the
spiral organ
the Organ of Corti
sterocilia on the apical surface of the hair cells project into the tectorial membrane
hairs cells sit upon the basilar membrane
during accommodation to view a close object:
the ciliary muscle contracts, which releases tension on the suspensory ligaments therefore the lens becomes more curved
in theory, the human ear could detect sound frequencies as high as
20,000 Hz
detection of a certain sound frequency:
the basilar membrane vibrates at certain locations, dependent on the sound frequency detected
hair cells sitting on the membrane at this location vibrate
the hair cells' sterocilia, which are embedded in the tectorial membrane, bend and this causes the opening of an ion channel
potassium ions from the surrounding endolymph enter the hair cell, the cell is depolarised
calcium ions enter the cell, a neurotransmitter is released and this results in sensory neuron activation
within the cochlea:
the tectorial membrane lies within the scala media (cochlear duct)
the scala media (cochlear duct) contains a fluid called endolymph
the scala tympani contains perilymph
within the semi-circular ducts, hair cells are embedded in
a cupula
there are 3 ossicles
in the dark, retinal isomerase, converts trans-retinal back to cis-retinal
the 2 components of rhodopsin are the protein opsin and retinal
the basilar membrane enables detection of high frequency sound waves near the oval window and low frequency sound detection towards the apex of the cochlea
within the utricle and saccule, there are many hair cells which each have both sensory and motor connections to the brain
skin occurs as thick skin in the palms, fingertips sand soles of the feet, and thin covering the rest of the body, which epithelial layer is less apparent in thin skin?
stratum lucidum
there are many keratinocytes in the stratum corneum of the integument
the papillary layer of the dermis:
consists of areolar tissue
contains the ridges responsible for fingertips
the nail cuticle is also known as
eponychium
eccrine sudoriferous glands secrete approximately 600ml of sweat per day, in adults
lamellated (Pacinian) corpuscles are sensitive to deep pressure in the integument