1. BALANCE & AGING
January

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 detect
tension)

3. Static vs. Dynamic Equilibrium
Static equilibrium has to do with our position or straight-line changes in speed
e.g. upside down, tilted to the left, slowing down, etc.
Sensed by the maculae of the vestibule
Dynamic equilibrium has do to with angular acceleration
E.g. spinning, roller coasters, boat rides
Sensed by the crista ampullaris of the semicircular canals

4. Static Equilibrium
The 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 hairs
When the hairs
are bent, the hair
cell generates a
nerve 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 one
or more canals will
move, pushing against
the hair cells
When the hair cells are
bent, they generate a
nerve impulse.

6. Types of Sensory Receptors
What senses / sensory receptors have we discussed? What have we not yet covered?

7. Sense
Type of Sensor
Name
Location
Vision
Photoreceptor
Rods & cones
Retina of eye
Hearing
Mechanoreceptor
Hair cells ( on organ of Corti)
Cochlea of ear
Balance
macula
Hair cells (on crista ampullaris)
Proprioceptors
Vestibule of ear
Semicircular canals of ear
Tendons, muscles, joints
Smell
Chemoreceptor
Olfactory receptor
Top of nasal cavity
Taste
Taste buds
Papillae of tongue
Pain
nocioreceptor
nocioreceptors
Skin, muscles, bladder, digestive system, mucus membranes, cornea
Temp
thermoreceptor
Thermoreceptors
Skin
Pressure
mechanoreceptor
Pacinian corpuscle
Skin & internal organs
Touch
Meissner’s corpuscle

8. Senses and Aging Vision Develops slowly in babies
Kids are far-sighted until around
6 because the eye needs to grow
In old age
Lens loses elasticity, causing presbyopia – an inability to accommodate and focus on near items
Other factors which reduce visual acuity include discolored lens, inability to fully dilate pupil, loss of photoreceptors
Many 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 Corti
A type of sensorineural hearing loss
Associated with age and noise exposure
Conductive 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 40
Most people over 80 have poor taste sensation and almost no ability to smell
Balance, Touch, Pain
Begin to decline around age 50
Leads to increased risk of falls
Inability to recognize injury
Babies’ senses
Elderly 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?