2 How do we maintain balance? Cerebellum monitors and controls balance.It receives input from four main sources:Maculae (vestibule of inner ear)Crista ampullaris (semicircular canals of inner ear)Photoreceptors (eyes)Proprioceptors (receptors in muscles,tendons, and joints that detecttension)
3 Static vs. Dynamic Equilibrium Static equilibrium has to do with our position or straight-line changes in speede.g. upside down, tilted to the left, slowing down, etc.Sensed by the maculae of the vestibuleDynamic equilibrium has do to with angular accelerationE.g. spinning, roller coasters, boat ridesSensed by the crista ampullaris of the semicircular canals
4 Static EquilibriumThe macula contains hair cells surrounded by an otolithic membrane (a jelly-like material) that contains otoliths (tiny calcium stones)The otolithic membrane slides due to gravity or linear acceleration, bending the hairsWhen the hairsare bent, the haircell generates anerve impulse
5 Dynamic Equilibrium 3 canals, oriented in the three planes of space At the base of each is a receptor region called the crista ampullaris, which consists of hair cells covered with a gelatinous cap called the cupula.During angular /rotational movements,the endolymph in oneor more canals willmove, pushing againstthe hair cellsWhen the hair cells arebent, they generate anerve impulse.
6 Types of Sensory Receptors What senses / sensory receptors have we discussed? What have we not yet covered?
7 SenseType of SensorNameLocationVisionPhotoreceptorRods & conesRetina of eyeHearingMechanoreceptorHair cells ( on organ of Corti)Cochlea of earBalancemaculaHair cells (on crista ampullaris)ProprioceptorsVestibule of earSemicircular canals of earTendons, muscles, jointsSmellChemoreceptorOlfactory receptorTop of nasal cavityTasteTaste budsPapillae of tonguePainnocioreceptornocioreceptorsSkin, muscles, bladder, digestive system, mucus membranes, corneaTempthermoreceptorThermoreceptorsSkinPressuremechanoreceptorPacinian corpuscleSkin & internal organsTouchMeissner’s corpuscle
8 Senses and Aging Vision Develops slowly in babies Kids are far-sighted until around6 because the eye needs to growIn old ageLens loses elasticity, causing presbyopia – an inability to accommodate and focus on near itemsOther factors which reduce visual acuity include discolored lens, inability to fully dilate pupil, loss of photoreceptorsMany diseases more common with age: cataracts, glaucoma, macular degeneration, etc.
9 Senses and Aging Hearing Presbycusis – Conductive hearing loss - a loss of hearing, especially speech sounds and high pitches – due to damage to the organ of CortiA type of sensorineural hearing lossAssociated with age and noise exposureConductive hearing loss -Anything that prevents sound from getting to the inner ear, including fusion of ossicles
10 Senses and Aging Smell & Taste Very sharp at birth Declines starting around age 40Most people over 80 have poor taste sensation and almost no ability to smellBalance, Touch, PainBegin to decline around age 50Leads to increased risk of fallsInability to recognize injuryBabies’ sensesElderly senses
11 Closure What were our objectives, and what did you learn about them. What was our learner profile trait and how did we exemplify it?How does what we did today address our unit question?