Final Exam Learning Objectives PDF

Block 1: Homeostasis- condition in which body’s internal environment remains relatively constant within physiological limits Elements of feedback loop- stimulus, receptor, control center, effector, response, controlled condition, stimulus (repeat!!) Negative- opposes initial stimulus -​ Most fee...

Block 1: Homeostasis- condition in which body’s internal environment remains relatively constant within physiological limits Elements of feedback loop- stimulus, receptor, control center, effector, response, controlled condition, stimulus (repeat!!) Negative- opposes initial stimulus -​ Most feedback systems in body -​ Body temp, blood sugar, blood levels, blood pressure, etc. -​ Example: heat, temp sensor, brain, sweat gland, sweat, body temp decrease Positive- reinforces initial stimulus -​ Childbirth -​ Example: Uterine contraction, stretch receptors, brain, oxytocin release, uterine muscle, uterine contraction, cervical stretch, cervix diameter increase Five classes of organic compounds ( principal structural elements) Lipids (CH) Carbohydrates (CHO) Proteins (CHON) Nucleotides and Nucleic acids (CHONP) Membrane transport Passive diffusion- down concentration gradient (high to low) does not need energy Active transport-against concentration gradient (low to high) requires energy ATP Facilitated diffusion- type of mediated transport, no energy needed (high to low), glucose transport Carrier mediated transport- protein binds to solute Resting membrane potential/ Na K ​ RMP- electrical potential difference across a cells plasma membrane when cell is not excited ​ High concentration of Na outside cell ​ High concentration of K in cell ​ 3 na out and 2 k in, overall resting membrane potential approx. -70 mv ​ Membrane more permeable to K than Na Block 2: Components of bone and function of each (including cell types and extracellular components) -​ Osteogenic cells= stem cells, formed in mesenchyme, give rise to osteoblasts  -​ Osteoblasts (differentiation)- builders, immature bone cells, secrete organic component of extracellular matrix, initiate calcification (remove calcium from blood and deposit it in matrix via exocytosis) -​ Osteocytes- maintenance crew, mature b one cells, regulate remodeling in response to mechanical stress -​ Osteoclasts- destroyers, from blood stem cells, secrete acid + proteolytic enzymes to dissolve matrix (bone resorption) Osseous matrix- very strong, slightly flexible (varies in response to specific bone needs) -​ Organic ⅓- osteoblasts and osteoid (GAGs, proteoglycans, glycoproteins, and collagen fibers) tough but flexible -​ Inorganic ⅔ - mostly calcium phosphate crystals and minerals, crystallizes around collagen fibers, strong but inflexible (stiff) Compact vs. spongy bone- Compact -​ Dense bone -​ Outer layer -​ Made up of osteons (concentric lamellae around central canal) -​ Thick where stress is high -​ Handles stress well in one direction Spongy -​ Trabecular bone -​ lightweight -​ Surrounds inner cavity -​ Resists stress from multiple directions -​ Provides support for bone marrow *Steps and purpose of remodeling bone -Achieve strength and maintain lightness (remove bone where not needed) -Bone remodeling allows structure and to support function by continually adjusting shape of bone to reflect mechanical stress that bone is exposed to Steps: 1.​ Activation- osteocytes sense damage, recruit osteoclasts 2.​ Resorption- 2 weeks, osteoclasts dissolve mineral matrix via acid secretion & organic matrix via enzyme secretion 3.​ Reversal- 2 weeks, resorption ends & recruitment of osteoblasts 4.​ Formation- 13 weeks, osteoblasts create new matrix 5.​ Quiescence- lasts indefinitely, cells & precursors hang around but are not active unless damage is detected again Calcium homeostasis -Regulated blood levels between 9.2 - 10.4 mg/dL -Balance between intake (food + drink), excretion (urine + feces), and storage (osseous tissue) *-Key hormones: Calcitonin- lowers blood calcium levels Parathyroid hormone- raises blood calcium levels (dominant regulator) Calcitriol- raises blood calcium levels Block 3: ***Major steps involved in crossbridge cycle Calcium responsible for exposure of myosin binding sites 1.​ ATP bound to myosin head, ATP hydrolyzed (split apart) causing myosin head to cock back into position (products of ATP hydrolysis ADP and Pi inorganic phosphate are still bound to myosin head 2.​ Myosin binds to spot on actin forming cross bridge , only if calcium is in cytoplasm of muscle cell 3.​ Power stroke- ADP and Pi leave from myosin head, resulting in change of structure of myosin that causes head ot swing toward the middle of the sarcomere, pulling actin thin filament along for the ride -​ Actin filament slides towards center of sarcomere, Pi dissociates during powerstroke and ADP dissociates after the powerstroke 4.​ Detachment- myosin head remains bound to actin until a new ATP molecule comes and binds to the myosin head, then cross bridge breaks and a new cycle can begin *Order of events that occur at neuromuscular junction leading to electrical stimulation of skeletal muscle fiber Electrical signal (nervous system) Electrical signal (muscle cell) Ca2+ release from SR Ca2+ -> troponin Crossbridge cycling Ca2+->SR (relaxation) Strategies used to increase force in muscle (motor unit recruitment, frequency of activation, and length of muscle at beginning of contraction) Spatial summation- more motor unit recruitment Temporal summation- increase frequency of stimulation Gross-anatomical Micro-anatomical Optimal muscle length at rest allows for the most overlap between actin and myosin creating the most cross bridges Describe the several substrates and/or metabolic sources of ATP used to support muscle contraction and the approximate length of time each is capable of sustaining contraction 1.​ Cell ‘pool’ of ATP 2.​ Anaerobic- 10-15 sec -​ Creatine phosphate 3.​ Anaerobic- a few minutes -​ Blood glucose, glycogen => glucose 4.​ Aerobic- 40 min to several hours (low intensity) -​ Fat, glycogen => glucose, protein Block 4: Role of neurons and neuroglia in the nervous system and their interdependence in terms of function -​ Neurons- primary signaling cells of nervous system -​ Neuroglia- nerve glue Astrocytes-glycogen (nourishment), structural support Microglia-immune defense cells Oligodendrocyte- myelin insulation CNS, growth regulating Ependymal cells- create CSF, neural stem cells Schwann- myelin insulation in PNS, growth regulating Satellite-surround cell Describe the difference between nucleus/ganglion and tract/nerve in the context of the nervous system Nucleus- cluster of neuronal cell bodies in CNS Ganglion- cluster of neuronal cell bodies in CNS Tract- CNS bundle of axons Nerve- PNS bundle of axons Trace the path taken by sensory information entering the spinal cord and motor information exiting the spinal cord, including the location of the different cell bodies in the spinal gray matter (efferent motor neurons, afferent sensory neurons and visceral motor neurons). Gray matter found in middle surrounding central canal (containing spinal cord and CSF) -​ Organized into horns (posterior, lateral, anterior) Posterior horn- cell bodies of somatic and visceral (autonomic) sensory neurons Anterior horn- cell bodies of somatic motor neurons Lateral horns- cell bodies of motor neurons White matter- outer portions of spinal cord -​ columns Posterior columns (dorsal)- sensory tracts ascending info to brain Lateral columns- mix of sensory and motor tracts Anterior columns- motor info down Dorsal root of spinal nerve- sensory (afferent) info + dorsal root ganglion (cell bodies of somatic and visceral sensory neurons reside) Ventral root of spinal cord- motor (efferent) info ****Differentiate between the parasympathetic and sympathetic nervous systems in terms of anatomy, receptors involved, neurotransmitters used, and the effects produced by each system Parasympathetic- rest and digest -​ Post have nicotinic receptors -​ Pre and post release ACh -​ Target (effector) muscarinic receptors -​ Pupils and airways constrict -​ Urinary and digestive increase -​ Heart rate and bp decrease Sympathetic-fight or flight, preganglionic neurons in thoracolumbar region of spinal cord -​ Post have nicotinic receptors -​ Effectors have alpha or beta adrenergic receptors -​ Pre short release ACh on post -​ Post long release norepinephrine on target tissue (effector) -​ Pupils and airway dilate -​ Digestive and urinary decrease -​ Heart rate & bp increase List the five components of a reflex arc and discuss the spinal reflexes that were covered in lecture 1.​ Sensory receptor 2.​ Sensory neuron 3.​ Integrating center 4.​ Motor neuron 5.​ Effector Stretch reflex-stretch sensed by muscle spindle, contraction of stretched muscle Tendon reflex-inhibits contraction of muscle , tension sensed by golgi tendon organ Tendon organ, sensory neuron, integrating center, motor neuron, effector Block 5: 37 block 5 learning objectives- 35 block 5 questions on final 5.1 Describe the normal concentration gradients for Na + and K + that exist across the membrane of all cells. Describe how the activity of the Na + /K+ ATPase maintains these gradients Ionic gradient- uneven distribution of Na+ and K+ ions between intra and extracellular spaces -​ More Na+ outside cell -​ More K+ inside the cell -​ Pump/ ATPase is primary active transport and moves them against their concentration gradients- lets 3 Na+ out and 2 K+ in, making it more negative in cell and positive outside Describe how differences in ionic gradients across the membrane contribute to electrical gradients (i.e. electrochemical gradients) Electrical gradient- voltage difference across the membrane due to the separation of charged particles Since 3 Na+ go out and 2 K+ go in, there is relatively more positive charge outside making the inside slightly negative having an overall resting potential of -70 mv Define equilibrium potential and how the equilibrium potential for different ions relates to the membrane potential Equilibrium potential- the electrical potential difference across cell membrane that exactly balances concentration gradient for an ion Each ion moves to bring the membrane potential closer to their equilibrium potential but how much it actually influences the membrane potential depends on the membranes permeability to that specific ion K+ most permeable and makes largest contribution Na+ and Cl- cancel each other out (ish) by pulling the membrane potential in different directions Predict what will happen to the membrane potential of a cell if the permeability of the membrane increases or decreases for Na+ , K + , or Cl - Na+ -​ Increase- more Na+ enters the cell and cell depolarizes (more positive) b/c brings membrane potential closer to +60 mV (eq potential of Na+) -​ Decrease- less Na+ enters cell and cell hyperpolarizes (more negative) K+ -​ Increase- more K+ leaves the cell (hyperpolarizes) since it brings membrane potential closer to -90 mV (eq potential of K+) -​ Decrease- less K+ leaves the cell (depolarization) Cl- -​ Doesn’t have much influence on membrane potential i think Compare and contrast the characteristics of leak-channels, voltage-gated, chemically-gated, and mechanically-gated channels. Leak- open and close spontaneously Voltage-open when membrane potential becomes less negative— cell depolarized!! Chemically-open whenever specific molecule binds to channel protein Mechanically- open by physical stimulus (touch and pressure receptors (membrane physically stretched) 5.2 Define the terms depolarization, repolarization, and hyperpolarization Depolarization- less negative (increase Na+ permeability) Repolarization- cell membrane potential returns to resting state after a period of depolarization Hyperpolarization- more negative (increase K+ permeability) Describe what graded potentials are, how they are generated, and the difference between EPSPs and IPSPs Graded potentials- local change in membrane potential, happens when a stimulus causes ion channels to open (voltage, mechanical, or chemically gated) EPSP- excitatory postsynaptic potentials (depolarization, increase permeability to Na+) IPSP- inhibitory postsynaptic potentials (hyperpolarization, increase permeability to K+ or Cl-) List (and describe) in order the principal events associated with an action potential 1.​ Local change in membrane potential (graded potential!!!) 2.​ Depolarization to ‘threshold’--> opens voltage gated Na+ channels ‘positive feedback cycle’ 3.​ Shortly after Na+ channels open, they spontaneously close ‘Inactivation’ (critical point) 4.​ Depolarization also opens (more slowly) a 2nd population of channels: voltage gated K+ channels —> ‘repolarization’ Describe spatial and temporal summation and how they contribute to neuron activation Spatial- inputs from multiple presynaptic neurons Temporal-increase in frequency of AP’s from one pre synaptic neuron They influence the postsynaptic neurons membrane potential and its likelihood of firing an action potential Define the phrase ‘all-or-none’ in the context of the neuronal action potential Once you reach threshold, you’re going to get an action potential Hinges on ability to depolarize the cell to the threshold value via graded potentials Compare and contrast the characteristics of graded vs. action potentials Graded- local, short-distance signals that can vary in size and fade over time -​ occur when stimuli activate ligand-gated or mechanically-gated ion channels Action- Large, long-distance signals that are all-or-none -​ They occur when voltage-gated Na⁺ and K⁺ channels create rapid depolarization and repolarization Describe the basis of absolute and relative refractory periods and their importance Absolute refractory period- cannot restimulate for another AP -​ resetting Na+ channels Relative refractory period- new AP can be produced, but takes larger than normal stimulation -​ resetting of K+ channels Importance of refractory periods- 1.​ Establish maximum rate of APs 2.​ Influence characteristics of AP propagation- forward propagation 5.3 List and describe the events that result in propagation of the action potential 1.​ Entry of Na+ produces a ‘local current’ 2.​ Local Na+ current spreads to adjacent areas like a domino effect Describe the factors that influence the speed of propagation of the action potential 1.​ Size (diameter of axon) —Axial resistance 2.​ Myelination —-- Oligodendrocytes (CNS) -​ Schwann cells (PNS) -​ Membrane resistance Describe the importance of myelination and the function of oligodendrocytes and Schwann cells Myelination-acts like insulation around a cable -​ Limits amount of ions that leak across membrane and when leak is limited the signal can travel a longer distance down the axon Oligodendrocytes- myelinate axons in CNS Schwann cells- myelinate axons in PNS Compare and contrast ‘continuous’ and ‘saltatory’ conduction Saltatory- “jumping” conduction -​ Quick, about 100 times faster than continuous conduction and uses 5000 times less energy (since APs only need to be regenerated at nodes of ranvier) -​ Along myelinated axon Continuous conduction- slower -​ Unmyelinated axon Draw a picture showing the structure of a synapse. Label the principal structures on the pre-synaptic neuron and post-synaptic neuron. Include the astrocyte in your picture and describe its function related to synaptic transmission. List (in order) the physiological events associated with synaptic transmission 1.​ Action potential reaches axon terminal. 2.​ Voltage-gated Ca²⁺ channels open. 3.​ Ca²⁺ enters the presynaptic terminal. 4.​ Vesicles fuse with the presynaptic membrane. 5.​ Neurotransmitter is released into the synaptic cleft. 6.​ Neurotransmitter binds to postsynaptic receptors. 7.​ Postsynaptic potential is generated. 8.​ Postsynaptic cell integrates the signals. 9.​ Neurotransmitter action is terminated. Astrocytes modulate neuronal signaling and remove/recycle neurotransmitters that have been released by neurons **Describe the differences between ionotropic and metabotropic receptors Ionotropic-ion channel receptor, fast voltage changes Metabotropic-g protein coupled receptor GPCR, slower, longer lasting effects 5.4 List and describe the general senses and special senses General senses- receptors distributed throughout body Types: 1.​ Pain (nociceptors) 2.​ Temp (thermoreceptors) 3.​ Touch, pressure, proprioception (mechanoreceptors) 4.​ Chemical stimuli (chemoreceptors- O2, CO2) -​ Somatic (body surface) and visceral (internal organs) senses Special senses- receptors collected in specialized sense organs 1.​ Smell (olfaction) 2.​ Taste (gustation) 3.​ Sight (vision) 4.​ Balance/equilibrium 5.​ Sound (hearing) Define the terms receptive field and receptor potential Receptive field- specific area or region of the sensory surface that a sensory receptor is sensitive to -​ discrimination between similar stimuli Receptor potential-graded electrical signal that occurs when a sensory receptor is stimulated Describe how receptive field size is related to sensory resolution/discrimination -​ Smaller receptive fields allow for more precise localization of stimuli (e.g., fingertips), while larger fields are less precise (e.g., back). -​ Smaller receptive fields = bigger receptor density Explain the concept of ‘appropriate stimulus’ with respect to interpretation within the CNS of incoming sensory information ​ specific type of input that a sensory receptor is designed to detect Ex. Photoreceptors in the eyes detect light. Mechanoreceptors in the skin detect pressure or touch. Chemoreceptors in the nose detect smells Describe in general how intensity or duration of a stimulus is coded and relayed to the nervous system Through changing the frequency or pattern of action potentials Frequency: -​ For light pressure the sensory neuron may send only one AP per second -​ As you increase the pressure, the frequency increases to 5 APs per second Pattern: -​ Rhythm that is more spread out can convey different info than sending triplets of APs Define sensory transduction and list the events commonly associated with it Sensory transduction- conversion of external stimulus to and electrical signal interpreted by nervous system 1.​ Stimulus —> receptor —-> changes membrane potential -​ ‘Graded potential’ (depolarizing or hyperpolarizing) —> receptor potential 2.​ Receptor potential influences rate of AP production in sensory neuron 3.​ APs travel to CNS along afferent pathway 4.​ CNS interprets/processes these incoming signals Describe the structure of the olfactory epithelium, olfactory receptors, and the neurons within the olfactory bulb Olfactory epithelium-specialized area in the upper part of the nasal cavity that contains sensory cells responsible for detecting odors Olfactory receptors- located in olfactory epithelium, have cilia that extend out onto the epithelial surface in contact with the air **Describe the specific sensory events associated with olfaction (i.e. what cellular events happen when an odorant molecule is detected by an olfactory receptor cell) Odorant molecules bind to olfactory receptors on the cilia This activates a G-protein, which increases cAMP levels cAMP opens ion channels, causing depolarization and the generation of a receptor potential The signal is transmitted as an action potential to the olfactory bulb and brain for processing 5.5 Describe the principal parts of the eye and their function including which eye tissues refract incoming light Light enters eye through cornea located on the anterior surface of the eye Passes through the aqueous humor on its way to the lens After passing through the lens, light goes through the vitreous humor to reach the retina Cornea and lens refract light, bending it to focus on the retina for clearer vision Outer coat- protection FIBROUS TUNIC Sclera- white part -​ Smooth -​ Site of attachment for muscles Cornea- anterior outermost portion of eye -​ Transparent -​ The cornea is the clear, dome-shaped outer layer of the eye. It refracts (bends) incoming light to help focus it onto the retina. It provides about 70% of the eye’s focusing power. Middle coat- vascularity and nutrients VASCULAR TUNIC Choroid- covers inside of sclera Ciliary body- has ligaments (ciliary ligaments) that are attached to the lens Iris-diaphragm -​ Controls the size of the pupil to regulate the amount of light entering the eye Pupil- black circular opening in the center of the iris that controls how much light enters the eye -​ size of the pupil adjusts based on light levels (dilates in low light, constricts in bright light). Inner coat- NEURAL TUNIC Retina -​ outer= pigment -​ inner= neural layer —photosensitive cells (rods and cones) -​ detect light and send visual signals to the brain through the optic nerve Vitreous humor- posterior chamber, jelly like substance, jelly like substance back Aqueous humor- anterior chamber, produced by cells in ciliary body Lens Function: The lens is a transparent structure behind the iris that fine-tunes the focusing of light onto the retina. It changes shape (accommodation) to focus on objects at different distances. Fovea- only cones, high resolution, low sensitivity because each cone must be stimulated with a signal strong enough to generate action potentials in ganglion cell Describe the pathway of information flow from the retina to the primary visual cortex Retina photoreceptor cells → bipolar cells → ganglion cells CN optic II Optic chiasm - where two optic nerves converge Lateral geniculate nucleus in thalamus Third order neurons (axons project to primary visual cortex) Primary visual cortex -​ Bipolar cells- first order neurons -​ Ganglion cells- second order neurons (axons of ganglion cells form optic nerve) Describe the mechanism of accommodation Lens changing shape Ex. for an object closer to the eye, the lens must become rounder -​ The light that enters the eye is then refracted more and the focused image now falls onto the retina Describe presbyopia and the underlying issue that impairs vision The lens loses elasticity w/age and decreases its ability to accommodate Describe Müller cells Muller cells- glial cells of retina -​ Similar to astrocytes- control potassium concentration and reuptake neurotransmitters to influence the communication between neurons) -​ Light guides!! -​ Reuptake transporters for NT Describe the principal differences between rods and cones and the basic structure of a rod photoreceptor including the function of rhodopsin Rods- night vision, low resolution, no colors Cones- day vision, high resolution, color vision Ability of photoreceptor cells to detect light is due to their light receptor molecules: Light receptors- visual pigments: Rhodopsin (rods) and Iodopsin (cones) -​ These molecules consist of 2 components - opsin (different for rods and each type of cones) and retinal (identical for all visual pigments) -​ Different opsins absorb different wavelengths, allowing detection of different colors Describe the physiology of vision - how light influences sodium channel activity, neurotransmitter release, and action potential generation DARK: -​ Dark current in photoreceptor cells due to the presence of cGMP which permits a constant influx of sodium (Na+ channels open!) -​ Cells are depolarized (dark current) -​ Release neurotransmitter glutamate at the synapse with bipolar cells -​ Neurotransmitter influences AP frequency of bipolar cells -Retinal exists in 2 conformations: cis and trans in the dark, cis form bound to opsin keeping it inactive LIGHT: -​ As retinal absorbs light it changes from cis to trans form and dissociates from opsin (leaves) which now becomes an active enzyme (RHODOPSIN) -​ Enzyme degrades cGMP, sodium channel closes, dark current stops, and glutamate secretion stops -​ Drop in glutamate tells bipolar cells that light has been absorbed -​ Info then transmitted to ganglion cells, only cells within retina that generate action potentials and send them to the brain 5.6 Describe the structures within the ear involved in the detection of sound External ear- Auricle- collect sound and direct them into external auditory canal External auditory canal Tympanic membrane- sound waves cause it to vibrate, which then transmits vibrations to auditory ossicles Middle ear- Auditory ossicles- malleus incus stapes -​ Span across middle ear linking tympanic membrane to cochlea Auditory tube- opens up inferiorly to the nasopharynx Inner ear- Semicircular ducts- equilibrium and balance Vestibule- gravity and acceleration Cochlea- hearing Describe the basic mechanism of hair cells and explain how it relates to the general process of sensory transduction Hair cells- common receptor for balance and equilibrium -​ They have stereocilia and contain synaptic vesicles filled with neurotransmitters -​ When hair cells are activated, they can release those synaptic vesicles to release neurotransmitters onto the dendrite of an associated sensory afferent neuron List the steps associated with transduction of sound stimuli and how loudness and pitch of sound are distinguished from one another 1.​ Auricle funnels sound waves into auditory canal which then funnels those sound waves to tympanic membrane (ear drum, division point between outer and middle ear) -​ When sound waves contact tympanic membrane, it vibrates at a rate proportional to the properties of those sound waves 2.​ Sound waves then travel through and are amplified by ossicles in middle ear (malleus, incus, and stapes) until they hit oval window 3.​ Oval window is the passage into the inner ear, where it reaches the cochlea (spiraling fluid filled tubes, snail shell appearance) -​ Transduction of sound waves into neural signals takes place here -​ Conversion of mechanical stimuli into electrochemical signals, which then signal further to the brain via the auditory nerve Cochlea -​ Basilar membrane, lines bottom of cochlear duct -​ Hair cells (sensory receptor cells) in basilar membrane -​ Specialized, able to respond to outside stimuli and synapse with sensory neurons -​ Cilia attached to tectorial membrane When sound waves reach the inner ear, they initiate vibrations of the oval window which then produces waves that travel through the fluid filled cochlear duct Wave pool- wave generating engine is the oval window -​ As the wave passes through cochlear canal it initiates movement in basilar membrane (flexible) which can move in response to wave propagation -​ The tectorial membrane is stiff and can’t move in response to wave propagation -​ In the presence of sound waves, the basilar membrane moves up and down under the stationary tectorial membrane (basilar and tectorial membranes connected by hair cells) -​ As the basilar membrane moves up and down it causes bending of the hair cell cilia -​ When the cilia bend, the mechanically gated ion channels open inducing electrochemical signals in the hair cells, allowing for neurotransmitter release onto auditory sensory cells which then signal via the auditory nerve Stapes can move back and forth to move cochlear fluid and the movement of fluid causes the basilar membrane to distort in a certain region based on the frequency of the sound Compare and contrast the mechanism of transduction of rotational movements of the head to those associated with sensation of acceleration and gravity Equilibrium/balance and motion are detected by structures associated with the vestibule (utricle, saccule, and semicircular canals) Semicircular ducts are filled with fluid that moves with the rotation of the head -​ Equilibrium/balance & motion -​ Oriented along 3 different axes to detect rotating head as if shaking head, nodding head, and bending head side to side (3 ducts: anterior, posterior, lateral) -​ Widened portion at base of each semicircular duct where the hair cells are located called the Ampulla -​ There's a gelatinous mass called the crista that sits on top of the hair cells in this region when fluid flows over the crista, it bends which causes the hair cells to bend with it -​ The bending of the hair cells (like with hearing) causes mechanically gated channels to open up and change the membrane potential of the hair cells -​ This triggers the release of neurotransmitters from the hair cells onto the neurons associated with the hair cells -​ Results in action potential generation in the neurons to relay the sense of rotational movement of the head Gravity & acceleration- involve patterns of hair cell activation in the utricle and saccule -​ Hair cells that detect gravity and acceleration are located within the vestibule in regions called the utricle and saccule -​ There's a gelatinous mass (otolith membrane) that has otoliths (ear rocks- made of calcium carbonate) embedded on top When head tilts down- otoliths begin to slide forward by the force of gravity -​ Bends stereocilia, opening mechanically gated channels and producing receptor potential (the electrical change in the hair cell) -​ Acceleration is a physical phenomenon that involved changes in inertia which act on the otoliths -​ As you accelerate or decelerate, otoliths pull the otolith membrane causing the stereocilia on the hair cells to bend