Exam 5 Study Guide Flashcards
external ear
sound waves travel from auricle and are funneled into external acoustic meatus and then to the tympanic membrane.
inner ear
bony labyrinth is filled with fluid called perilymph.
membranous network is filled with endolymph.
sound waves send fluids into motion.
vestibulae
bony labyrinth composed of perilymph.
has two membranous labyrinths, the utricle and the saccule, which have receptors for equilibrium and balance called maculae. maculae respond to linear acceleration and change in head position
semicircular canals
bony labyrinth has membraneous labyrinths called semicircular ducts. has ampulla with receptors cristae ampullaris. responds to angular acceleration and rotation of head
cochlea
membranous labyrinth in each turn of cochlea is cochlear duct. duct contains spiral organ of Corti or receptor of hearing.
each turn of cochlea there are three chambers and bony labyrinths, the cochlear duct (endolymph), Scala vestibuli and Scala tympani (perilymph).
when fluid is set in motion, it activates the spiral organ of Corti which is the receptor for hearing.
spiral organ of Corti
inside cochlear duct and contains a basilar membrane and tectorial membrane, and supporting and hairs cells sandwiched in between.
sound wave path
auricle catches waves, funnels waves into EAM, then vibrates the tympanic membrane, which vibrates ossicles, which pushes on oval window, and that sets perilymph in Scala vestibuli in cochlea in motion.
sounds with frequency below our hearing generates waves in s. vestibuli and they stay in the bony labyrinth and Scala tympani.
sounds within hearing range go into cochlear duct or membranous labynth.
cochlear duct bends, the basilar membrane of organ of Corti also bends, so an action potential will be generated in the cochlear nerve.
sound waves then go to the Scala media and then die out.
Interpretation of sound
sound wave or pressure waves is a pressure disturbance and regions of compressed air molecules and lower pressure air molecules.
sound is interpreted from pitch (frequency of wavelengths) and loudness (amplitude of each wave).
middle ear
membrane vibrates are sounds waves are transferred to ossicle bones (males, incus, stapes). stapes sits in oval window. middle ear connects to throat via eustatian tube, which is why ear infections can occur with sore throat.
determining frequency/pitch
basilar membrane has stuff and floppy fibers, so frequency can be determined by where the membrane is bent or deflected. high pitch/frequency sounds are stronger so the stiff fibers will be bent more.
sound transduction
when there is a deflection of basilar membrane, hair cells (stereocillia are mechanosensitive, so they respond to bending.) are bent and generate action potentials on cochlear nerve, which are sent to the brain for sound interpretation.
bending of stereocillia and generates tension in tip links and opens channels which causes graded depolarization of hair cells. NT is then released at synapse with cochlear nerve, and AP is generated on cochlear nerve.
pitch
basilar membrane allows pitch discrimination
auditory pathway
ascending multi neuronal path. start with neurons innervating spiral organ of Corti. bring AP to two neurons in medulla. then neurons bring info to synapse at inferior colliculi or auditory reflex center. then synapses at thalamus which relays sensory info about sound to primary auditory cortex.
conduction deafness
sound conduction path is impaired from perforated tympanic membrane or otosclerosis (stiffening of ossicles, so they won’t vibrate).
sensorineural deafness
damage to neural structures from loss of hair cells or stroke affecting brain structures that relay sound info
static equilibrium
sensing changes in head position or linear head position
anatomy of maculae
each macula has many hair cells and supporting cells.
has stereocillia (long microvilli) with ion channels
1 kinocillium- an individual cilium, longest protrusion on hair cells and helps with directionality
has otoliths or little rocks that increase mass or inertia in the gel or membrane (otolith membrane)
Utricle
macula is oriented horizontally and responds to head tilt or horizontal acceleration
saccule
macula sits on the side of the membranous labyrinth and the hair cells are horizontal, so the hair cells respond to vertical acceleration
difference between organ of Corti and maculae
In organ or Corti, bending of hair cells causes action potentials.
in maculae, bending of hair cells increases or decreases action potentials
dynamic equilibrium
crista ampullaris senses changes in dynamic equilibrium because hair cells (with stereocillia and a kinocillium) that are embedded in a gel to increase the mass called ampullary cupula.
bending and basal firing
bending in one direction increases firing and bending in opposite direction decreases basal firing because of the endolymph movement.
3 layers of the eye
outer fibrous, middle vascular, and inner layer
outer fibrous layer
dense connective tissue, avascular. composed of the sclera and cornea
cornea
allows light to enter the eye, light bending apparatus
vascular layer/pigmented layer
contains blood vessels and melanocytes for pigment and functions to absorb light that enters the eye
composed of the choroid, the cilliary body, and the iris.
choroid
dense in melanin and blood vessels
cilliary body
has smooth muscle called cilliary muscles and cilliary processes that function for producing aqueous humor, and provides a point of attachment for ligaments
the cilliary zonule or suspensory ligaments hold the lens in place and change the shape of it
iris
composed of an inner smooth muscle layer called sphincter papillae, smooth muscle cells are oriented circularly. parasympathetic input causes pupil to constrict.
outer layer is dilator papillae and cells are oriented radially. contracted pulls on the sphincter papillae. sympathetic input causes pupil to dilate.
inner layer/retina
external pigmented layer
inner neural layer is composed of modified neurons in sequence, the axons of the last neuron become a part of the optic nerve.
neurons from ext. to int. are photoreceptors, bipolar cells, and ganglion cells. axons of ganglion cells become a part of the optic nerve and send sensory info about light to the brain. light passes through bipolar and ganglion cells to activate photoreceptors.
the opening at the back of the retina called the optic disc/blind spot is where optic nerve exits the eye.
anterior limit of neural layer is sawtooth region (name)
rods
very sensitive so used to sense dim light and important for peripheral vision. located more so on the periphery. cannot interpret color and cannot produce sharp images.
cones
are used for bright light and for color and sharp/detailed vision. not distributed uniformly, most concentrated in macula lutea. foveae centralis is the central pit of the macula lutea. good for visual acuity
internal structures
behind the lens to back of eye: posterior segment: filled with virtuous humor developed in the fetus and persists for life. very important for structural support to posterior regions off the eye and keeps layers of eye held together. important for maintaining intraocular pressure.
back of the lens forward: anterior segment: filled with aqueous humor secreted by cilliary processes and provides nutrients to anterior eye structures, and drains into scleral venus sinus. flows from post to anterior chamber and then drains back into venus blood
anterior segment can be divided into chambers. iris to cornea is anterior chamber
glaucoma
scleral venus sinus doesn’t drain aqueous humor properly and increases pressure within the eye and can damage eye structures, especially neural layer
lens
separates anterior and posterior regions of the eye. extremely flexible because of protein called crystalline. needs flexibility to change shape for near vision.
in cataracts, there is clouding of the lens because crystalline proteins start to accumulate and causes the lens to be less flexible.
x
light appears to bend or refract and the speed changes when passing from one medium to another of a different density.
light bending apparatus
cornea, lens- trying to bend and refract light tays and converges in the retina
convex lens
refracts light so regardless of where light rays hit the lens, the shape of the lens causes bending of light so the light converges on the same focal point on the other side of the lens. Image is inverted and brain flips image back.
cornea
anterior bulge of the fibrous layer- bends majority light, and the amount of refraction is constant unlike the lens because it can’t change shape.
distant visiom
In distant vision, cornea does majority of refraction and lens in flattened because of sympathetic input sent to the eye that stimulates relaxation of the ciliary muscles, which causes tightening of the ciliary zonules which pulls on the lens. Tightens because of muscle orientation. causes pupil dilation.
close vision
cornea refracts light, but lens plays a bigger role refracting and bulges from parasympathetic input. Ciliary muscle contracts and relaxes ciliary zonules. also causes pupil constriction.
accomodation
viewing objects less that 20 feet away.
parasympathetic input occurs so lenses bulge.
Pupil constricts and eyes converge (cross eyed to view objects up close)
presbyopia
lens becomes less flexible because of crystalline, so objects cannot be seen as close
emmetropia
normal vision
myopia
near sighted, eyeball is too long so focal point is in front of the retina. corrected with concave lens which moves focal point back so light converges on the retina
hyperopia
farsighted, eyeball is too short, focal point is behind the retina. convex lens is used to bring focal point forward to let light converges on the retina
astigmatism
unequal curvatures of the eye, causes blurs along one direction
macular degeneration
degeneration of the macula lutea that causes progressive blind spot that appears at the center of vision.
photoreceptors
outer segment, inner segment, cell body, synaptic endings
outer segment of photoreceptor
outer segments consists of discs that contain pigments, retinal and opsin. retinal absorbs light and opsin determines what wavelength of light retinal can absorb. 4 different types of opsin that make 4 visual pigments. rods contain one type of opsin, cones have 3 opsins to absorb different wavelengths of light. wavelengths overlap to see a range of color.
phototransduction
process of taking a stimulus (light) and transforming it into a graded potential. when visual pigment absorbs light, retinal changes shape from bent or kinked to straight and then, triggers transduction and production of a graded potential
phototransduction in the dark
cyclic GMP gated channels are open and positively charged ions to flood to the photoreceptors, causing it to depolarize, which opens VG Ca channels, releasing an inhibitory NT, and the NT produces an IPSP, causing the bipolar cell to hyper polarize so there are no AP on ganglion cells that are part of optic nerve.
photoreceptor are on, bipolar turns off, ganglion cells turn off
in the light
retinal absorbs light rays and detaches from opsin, and cyclic AMP channels are going to close, so photoreceptor is not going to depolarization, so NT will not be released so the bipolar cells will not be inhibited. bipolar cells spontaneously depolarize and release an excitatory NT at the synapse with ganglion cell. Produces EPSP on the ganglion cells which will result in action potentials on ganglion cells that are part of optic nerve
photoreceptors off, so bipolar turns on, ganglion cell turns on
G protein signaling cascade
activates G protein transducer which activates PDE…
crossing at the optic chiasma
ganglion cell axons make up optic nerve
optic nerve crosses incompletely at optic chiasma, so some axons will cross and some will not. Some need to go left and some stay on one side depending on where they need to go in the brain.
axons of thalamic cells travel in optic radiations to visual cortex
branches to superior colliculi, pineal body, cerebellum
endocrine gland vs endocrine tissue
if an entire organ functions for endocrine, it can be called an endocrine gland. Some organs have endocrine tissue but other things as well.
endocrine glands
invagination of epithelial sheet, have no ducts (lose during development), secrete protein or steroid hormones into ECF and are picked up by blood stream and distributed systemically.
hormones
produced by endocrine cell in endocrine gland or tissue to be secreted and distributed
have specificity, act at target tissues that contain receptors for hormone, functions for control
can interact with one another
permissiveness
one hormone needs anther hormone to exert its full effect ex. is reproductive and thyroid hormones needs each other for timely development
synergism
hormones have effect at target cells
ex. glucagon and epinephrine- both act at the liver to increase blood glucose levels
antagonism
hormones oppose actions of one another
insulin and glucagon
chemical structure
chemical structure of hormone is very important for how it is transported in the blood stream, or at target tissues
amino acid/protein based hormone
amino acid/protein based, which are polar and water soluble. can be transported directly in blood and do not need a transport protein carrier
they are lipid insoluble so they cannot cross the lipid barrier, so they use an indirect or secondary messenger system to actually act at their target tissue
steroid based hormone
lipids, lipid soluble, water insoluble
they require a carrier protein in the blood stream because they are water insoluble. They can cross the membrane at their target cells because they are lipid soluble, so they act directly at the cells using direct gene activation
ex. testosterone, estrogen, glucocorticoids
eicosanoids
derived from polyunsaturated fatty acids, they are paracrine agents and local, are not distributed systemically
ex. prostaglandins
humoral stimulation
change in concentration in some molecule triggers the release of a hormone
ex. change in calcium concentration triggers release of PTH from PTH glands
neural stimulation
AP on neurons are sent to endocrine gland and stimulate release of a hormone
ex. in CNS, single preganglionic neuron stimulates medulla of adrenal gland to secrete catecholamines
hormonal stimulation
a hormone targets an endocrine gland and stimulates release of other hormones.
ex. pituitary gland
negative feedback mechanisms
inhibit hormonal release
secondary messenger system
used by all amino acid water based hormones except thyroid hormone because it is small enough to sneak throughhormones travel to target tissues, using either indirect actin or direct gene activation
Cyclic AMP
use G protein signaling cascade
hormone binds to receptor on membrane and activates G protein and separates from receptor and activates an enzyme called adenylate cycles and catalyzes and produced cyclic AMP.
cAMP activates protein kinases and that triggers a response within target cell
direct gene activation
all steroid based hormones
receptor is inside the cell and hormone crosses in because it is lipid soluble and binds to its receptor. receptor hormone complex goes into the nucleus, binds to DNA and makes a change. genes get transcribed, mRNA gets translated and new protein is synthesized. turns on a gene
pituitary gland/ hypophesis
anterior/adenohypophesis: stores and releases 6 hormones
posterior/neurohypophesis:2 hormones
all hormones are amino acid based
use secondary messenger system
posterior pituitary/neural hypophesis
not a true endocrine gland
complex of neural tissue and does not synthesize hormones
neurosecretory cells in hypothalamus that reach down into PPT gland
hormones are stored in axon terminals in PPT and then are released
supraoptic nucleus SOAP
antidiuretic hormone
paraventricular nucleus SOAP
oxytocin
hypothalamic hypophyseal tract
carries hormones from hypothalamus to posterior pituitary
neural stimulation
antidiuretic hormone
targets kidneys and reduces water loss by decreasing urine volume
stimulated by osmoreceptors in hypothalamus that monitor solute and water concentration in body fluids
stimulated by low BP or low blood volume
oxytocin
triggered from axon terminals in PPT by stretching of uterus and cervix and causes strong uterine contractions
triggered by nursing or breast-feeding and produces milk
anterior pituitary/adenohypophesis
true endocrine gland because it synthesizes hormones it released
hypophyseal portal system
neurosecretory cells in hypothalamus that synthesis and release releasing and inhibiting hormones. released into hypophyseal portal system. target cells are in APT
tropic hormones
hormonal stimulation
4 hormones in APT
TSH
ACTH
FSH
LH
GH and prolactin
not tropic
