Senses
Distinguish between general and special senses
General senses: distributed through the body and have receptor cells within structures of other organs. They are associated with touch, pain, temperature, vibration, and proprioception.
Special senses: Vision, sound, equilibrium, smell, and taste. They have specialized organs which detect and process stimuli.
Match each sensory receptor to the type of stimulus to which it is likely to respond
Chemoreceptor A. approaching headlights
Pain receptor B. a change in blood pressure
Thermoreceptor C. the smell of roses
Mechanoreceptor D. an infected tooth
Photoreceptor E. a cool breeze
List the five general types of sensory receptors
Mechanoreceptors
Thermoreceptors
Nociceptors
Photoreceptors
Chemoreceptors
What do all types of receptors have in common?
They convert stimuli into nerve impulses
You fill up the tub to take a hot bath, but the water is too hot. You test it a second and third time within a few seconds, and it feels okay. Which of the following is the most likely explanation?
The water has cooled down unusually quick
Your ability to sense head has adapted
Your nervous system is suddenly not functioning properly
The initial heat deformed your thermoreceptors
None of the above
What is sensory adaptation?
the natural reduction in sensitivity to a stimulus after constant, unchanging exposure
Describe three types of touch and pressure receptors
Merkel Cells - responsible for light touch and sustained pressure
Meissner’s Corpuscels - responsible for light touch, flutters, and vibrations
Pacinian corpuscles - responsible for deep pressure and fast vibration
Describe thermoreceptors
thermoreceptors are receptors that detect stimulus regarding temperature and temperature change
Describe a muscle spindle
A muscle spindle proprioceptors located within skeletal muscles that detect changes in muscle length and the velocity of stretch
Explain how muscle spindles help maintain posture
Muscle spindles help maintain posture by triggering a stretch reflex which cause muscles to contract
Where are Golgi tendon organs located?
Musculotendinous junction
What is the function of Golgi tendon organs?
monitor muscle tension or force, protecting muscles from excessive strain
Where are the olfactory receptors located?
Olfactory receptors are located in the upper part of the nasal cavity
Trace the pathway of an olfactory impulse from a receptor to the cerebrum
begins when odorant molecules bind to receptors on bipolar olfactory neurons in the nasal mucosa. These neurons send signals through the cribriform plate via the olfactory nerve (CN I) to synapse in the olfactory bulb then travel along the olfactory tract directly to the primary olfactory cortex in the cerebrum
Explain how the senses of smell and taste function together to create the perception of the flavors in food?
combining chemical signals from the mouth and nose to create sensation
Which two of the following are part of the olfactory organs?
Olfactory receptors
Columnar epithelial cells in the nasal mucosa
The brain
The mouth
The nose
Why is saliva necessary to taste?
it dissolves the food molecules which allow for it to be sent to the taste receptors in the tounge
Name the five primary taste receptors
sweet
sour
salty
bitter
umami (savory)
What characteristic of taste receptors helps maintain a sense of taste with age?
continuous regeneration of taste buds
Trace a sensory impulse from a taste receptor to the cerebral cortex
receptors convert chemical signals to electrical signals which release neurotransmitters
electrical signals are carried to the brain via cranial nerves
Travel to the brainstem
travels to thalamus
Reaches cerebral cortex
Describe the outer, middle, and inner ears
Outer: part of the ear that we can see, collects sound waves and directs them to the eardrum
Middle: chamber in the temporal bone, between the part we can see and eardrum, transmits from the eardrum to inner ear
Inner ear: Part of the ear inside the skull responsible for hearing and balance
Match the ear area with the associated structure
Outer ear A. eardrum
Middle ear B. auditory ossicles
Inner ear C. cochlea
Explain how sound waves are transmitted through parts of the ear
by transforming acoustic energy into mechanical vibrations and finally into electrical signals for the brain
Describe the tympanic reflex
an involuntary muscle contraction in the middle ear—specifically the stapedius muscle—that occurs in response to high-intensity sounds (>70–100 dB).
Distinguish between the osseous and membranous labyrinths
osseous labyrinth is the outer, rigid, petrous temporal bone cavity, containing perilymph and housing the inner, delicate membranous labyrinth
Explain the function of the spiral organ
converting sound into nerve impulsess
The function of the auditory tube is to____.
Equalize air pressure on both sides of the eardrum
Transmit sound vibrations to the eardrum
Contain the hearing receptors
Contain the auditory ossicles
Secrete cerumen
Which of the following best describes the hearing receptor “hair cells”?
They are neurons
They lack ion channels
They are epithelial, but function like neurons
They are made of keratin
They are attached to the tympanic membrane
Distinguish between the senses of static and dynamic equilibrium
Static equilibrium describes a system at rest where all forces are balanced, resulting in zero velocity and acceleration. Dynamic equilibrium represents a constant state where, despite ongoing, opposing, and equal processes, there is no net change
Which structures provide the sense of static equilibrium? of dynamic equilibrium?
Static equilibrium: maculae, utricule, saccule
Dynamic equilibrium: crista ampullaris in the ampullae of the semicircular canals
How does sensory information from other receptors help maintain equilibrium?
Through the integration of other information such as visual information
Explain how the eyelid is moved
It is controlled by two main muscles, one that controls the upper eyelid and the other that controls the lower eyelid
Describe the conjunctiva
The conjunctiva is a membrane that covers the eye and lines the inside of the eyelid
Name the layers of the eye wall and describe the functions of each layer
Outer
Sclera - protective structure
Cornea - Allows light to enter and focuses the light into the eye
Conjuctiva - covers the eye and lines the inside of the eyelid
Middle
Iris - controls the size of the pupil, which controls the amount of light that enters the eye
Ciliary Body - controls eye shape
Choroid - provides nutrients prevents the scattering light within the eye
Inner Layer
Retina - Where photoreceptors are
Optic Disk - the blind spot because it lacks photoreceptor cells, meaning there is no image detection at this location.
The following are compartments in the eye. In which one is the vitreous humor found
Anterior chamber
Posterior chamber
Anterior cavity
Posterior cavity
Lens
What is the function of the lacrimal apparatus?
produce, distribute, and drain tears, maintaining ocular health
Describe the function of each extrinsic eye muscle
to manage the fine movements of the eye
Describe the outer and middle tunics of the eye
Fibrous tunic: sclera, cornea, conjuctiva, maintains eye shape
choroid, ciliary body, iris: blood vessels and melanin
What factors contribute to the transparency of the cornea?
Stroma, endothelium, epithelium, tear film, metabolism, proteoglycans
How does the shape of the lens change during accommodation?
ciliary muscle contracts, the elastic lens becomes more spherical
Why would reading for a long time lead to “eye fatigue”, whereas looking at something distant is restful?
It allows for the muscles to fully relax which allows the lens to focus without effort
Explain the origin of aqueous humor and trace its path through the eye
produced by the ciliary body, moves to anterior chamber and flows through it, drains and exits
How is the size of the pupil regulated
it is regulated by the contraction and extension of two muscles which allow it to dilate and contract
Describe the structure of the retina
The retina is a thin layer of tissue at the back of the eye, containing photoreceptors (rods and cones) that convert light into neural signals, linking to the brain via the optic nerve.
What is refraction?
bending of light to focus it on the retina
What parts of the eye provide refracting surfaces?
the main part is the cornea as well as the crystalline lens, pupil, iris, and virtuous humor
Why is it necessary to accommodate for viewing close objects?
The closer it is the eye, the more it allows for the eye to refract the light into the retina
Distinguish between rods and cones of the retina
Rods: perceive black and white
Cones: distinguish color
Explain why rod vision may be more important under dim light conditions
Because they are more sensitive to light
Explain the roles of visual pigments
initiate vision by converting light energy into electrical signals
What factors make stereoscopic vision possible?
Having two forward facing eyes, called binocular display, where differences in the images projected onto the retinas of each eye are processed by the brain to determine depth.
Trace the pathway of visual impulses from the retina to the occipital cortex
retina to the occipital cortex via the optic nerve, optic chiasm, and lateral geniculate nucleus (LGN)
Explain the basics of fading senses of smell and taste with aging
As people age, smell and taste often weaken due to fewer sensory receptors, slower nerve signals, and sometimes medications or health conditions, making food seem less flavorful.
List three causes of hearing loss associated with aging
Presbycusis – gradual loss of high-pitched sounds from inner ear aging, Earwax buildup – hardened wax can block sound, Noise damage – long-term exposure harms inner ear hair cells.
Explain five problems that can interfere with vision as a person
Presbyopia – difficulty focusing on close objects.
Cataracts – cloudy lens causing blurry vision.
Glaucoma – eye pressure damages the optic nerve.
Macular degeneration – loss of central vision.
Dry eyes – reduced tears cause irritation and blurry vision.