Sensory System Flashcards
Barbara Herlihy. (2020). The Human Body in Health and Illness (7th Edition) [Texidium version]. Retrieved from http://texidium.com
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Which system allows us to experience the world?
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Sensory
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___ let people see the trees, hear the voices of friends and family, feel the heat of the sun, and taste favourite foods.
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Senses
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When the external environment becomes threatening, the sensory system acts as a ___ ___.
For example, if a hand is placed on a hot surface, the sensory system experiences the episode as pain.
The pain is a danger signal indicating that the body must make an adjustment to remove the harmful stimulus.
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warning system
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In addition to sensing outside information, the sensory system also keeps track of what is happening within the body.
For example, when the stomach fills with food, sensory information is carried to the ___ ___ ___ (___).
In response to this information, the stomach is prompted to digest the food.
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central nervous system (CNS)
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What type of neuron transmits information to the central nervous system (CNS)?
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Sensory
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A ___ is a specialized area of a sensory neuron that detects a specific stimulus.
For example, the ___ in the eye respond to light, whereas the ___ on the tongue respond to chemicals in food.
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receptor
receptors x 2
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What are the five types of sensory receptors?
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Chemoreceptors
Nociceptors (Pain Receptors)
Thermoreceptors
Mechanoreceptors
Photoreceptors
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Which receptors are stimulated by changes in chemicals, such as hydrogen ion (H+), calcium, and food?
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Chemoreceptors
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Which receptors are stimulated by tissue damage or distention?
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Nociceptors
Pain Receptors
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Which receptors are stimulated by changes in temperature?
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Thermoreceptors
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Which receptors are stimulated by changes in pressure or movements of body fluids?
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Mechanoreceptors
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Which receptors are stimulated by light?
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Photoreceptors
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Some people process incoming data in the form of several senses—for example, they may not only see colour but also hear colour.
Others may taste shape and words, and still others see musical sounds.
This neurologic intertwining of the senses is called ___.
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synesthesia
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What is the conscious or unconscious awareness of incoming sensory information?
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Sensation
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A ___ is the conscious awareness of a sensation.
Yelling, “Ouch, that knife is sharp,” for example, indicates that you have become aware of a painful stimulus and what caused it.
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perception
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Sensation has four components.
Using the sense of sight as an example:
1) ___: light is the ___ for the sense of sight.
In the absence of light, sight ceases to exist.
2) ___: light waves stimulate the ___ in the eye, producing a nerve impulse.
3) ___ ___: the nerve impulse is conducted by a ___ ___ (optic nerve) to the ___ ___ of the ___.
4) Special ___ of the ___: sensory information is interpreted as sight in the ___ ___ of the ___.
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Stimulus, stimulus
Receptor, photoreceptors
Sensory Nerve, sensory nerve, occipital lobe of the brain
Area of the Brain, **occipital lobe ** of the brain
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Sensation is experienced by the ___ and not by sensory receptors.
For example, an object is seen, a voice is heard, or pain is felt because the sensory information has stimulated a part of the ___.
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brain x 2
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Each sensation has a ___, ___, ___ ___, and specific ___ of the ___ that interprets the sensation.
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stimulus
receptor
sensory nerve
area of the brain
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What are two important characteristics of sensation?
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Projection
Adaptation
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___ describes the process whereby the brain, after receiving a sensation, refers that sensation back to its source.
Seeing with eyes, hearing with ears, and feeling pain in an injured finger because the cortex of the brain receives the sensation and ___ it back to its source.
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Projection
projects
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What answers the question, “If pain is experienced by the brain, why does a finger hurt when injured?”
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Projection
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The experience of “phantom limb pain” is an example of ___.
If a leg is amputated, the person may still feel pain in the amputated leg.
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projection
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___ is illustrated by the sense of smell.
When entering a room with a strong odor, the odor at first seems overwhelming.
After a short time, however, the odor becomes less noticeable.
The sensory receptors in the nose have ___.
When they are continuously stimulated, these receptors send fewer signals to the area of the brain that interprets sensory information as smell.
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Adaptation
adapted
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An example of ___ is the advertisement for an air freshener that states, “He’s gone nose-blind.”
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adaptation
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Pain receptors do not ___, whereas receptors for smell ___ rapidly.
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adapt x 2
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Generally, receptors that regulate homeostatic mechanisms ___ very slowly or not at all.
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adapt
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What are the two groups of senses?
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General
Speical
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Which senses have receptors that are widely distributed throughout the body?
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General (Somatic)
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Which senses are localized within a particular organ in the head?
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Special
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Which senses include taste, smell, sight, hearing, and balance?
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Speical
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Which senses include pain, touch, pressure, temperature, and proprioception?
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General
Somatic
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___ for the general senses are widely distributed and are found in the skin, muscles, joints, and viscera.
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Receptors
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Receptors for pain, called ___, consist of free nerve endings that are stimulated by tissue damage.
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nociceptors
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Which receptors do not adapt and may continue to send signals after the stimulus has been removed?
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Nociceptors
Pain Receptors
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Which receptors are widely distributed throughout the skin and other internal tissues?
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Nociceptors
Pain Receptors
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The nervous tissue of the brain lacks ___ ___.
Tissues surrounding the brain, such as the meninges and the blood vessels, however, do contain ___ ___, causing the feeling of a headache.
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pain receptors x 2
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Pain serves a ___function.
Being unpleasant, pain motivates the person to remove its cause.
Failure of the pain receptors to adapt is also ___.
For example, if a person complains of right-lower-quadrant (RLQ) abdominal pain, the pain serves as a valuable clue to what is wrong.
In this example, the pain is indicative of acute appendicitis, requiring an appendectomy (surgical removal of the appendix).
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protective x 2
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Some patients are at risk because of a ___ or alteration in the sensation of pain.
Persons with diabetes mellitus, for example, often develop nerve damage in the legs and feet; the nerve damage is called diabetic neuropathy.
Because of the distortion in the sensation of pain, diabetic persons may ignore the discomfort of ill-fitting shoes and may develop blisters on their feet.
The blistered site continues to expand and eventually becomes infected and gangrenous, requiring amputation.
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diminution
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Specific signals that stimulate pain are not well understood.
The following three pain triggers have been identified:
- First, ___ ___ promotes the release of chemicals that stimulate pain receptors.
- Second, a deficiency of ___ stimulates pain receptors.
For example, if the blood supply to an internal organ is diminished—a condition called ischemia—the tissue is deprived of ___ and the person experiences pain.
- Third, pain may be experienced when tissues are ___ or deformed.
The stimulus is mechanical distortion rather than chemical.
For example, if the intestine becomes distended, the person will often experience severe cramping pain.
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tissue injury
oxygen x 2
stretched
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Pain from a heart attack is caused in part by ___ deprivation experienced by the cardiac muscle.
Restoration of blood flow and improved ___ of the heart muscle is pain-relieving.
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oxygen
oxygenation
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Pain originating in the ___ (___ pain) is often experienced in the shoulder and left arm.
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heart (visceral pain)
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What refers to feeling pain as if it were coming from an area other than the site where it originates?
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Referred Pain
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Patients with ___ disease often complain of pain or an aching sensation that starts in the shoulder region and moves down the left arm into the fourth and fifth fingers.
In other words, stimulation of pain receptors in the ___ causes pain that is experienced as being away from the ___.
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heart
heart x 2
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What occurs as the result of shared sensory nerve pathways?
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Referred Pain
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___ ___ that carry information from the heart are the same pathways that carry information from the shoulder and left arm.
As a result, the brain interprets heart pain as shoulder and arm pain.
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Nerve pathways
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Pain impulses for most of the body travel up the spinal cord in a sensory nerve tract called the ___ ___.
The information is then transmitted to the ___, where the person first becomes aware of the pain, and then to the ___ ___.
The ___ ___ identifies the source of the pain and judges its intensity and other characteristics.
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spinothalamic tract
thalamus
parietal lobe
parietal lobe
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Sites of ___ ___
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Referred Pain
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Receptors for touch and pressure are ___; they respond to forces that press, move, or deform tissue.
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mechanoreceptors
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Touch receptors are also called ___ receptors and are found mostly in the skin; they allow feeling, for example, a cat’s soft fur.
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tactile
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Which receptors are particularly numerous in the lips and tips of the fingers as well as in the toes, tongue, penis, and clitoris?
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Tactile
Touch Receptors
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Fingers have the highest concentration of ___ ___.
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touch receptors
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Receptors for heavy ___ are located in the skin, subcutaneous tissue, and the deep tissue.
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pressure
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Which receptors are stimulated by a heavy ball in a boy’s arms?
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Pressure
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What is the first sensory system to develop in the fetus and is essential to growth and development?
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Touch
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Receptors for temperature are called ___.
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thermoreceptors
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The two types of thermoreceptors are ___ and ___ receptors.
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heat
cold
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What are found on free nerve endings and are scattered widely throughout the body?
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Thermoreceptors
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Which receptors are stimulated at between 50°F and 76°F (10°C and 25°C)?
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Cold
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Which receptors are stimulated between 76°F and 112°F (25°C and 45°C)?
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Heat
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At both ends (extremes) of the temperature scale, ___ receptors are stimulated, producing a freezing or burning sensation.
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pain
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Both heat and cold thermoreceptors display ___, so that the sensation of heat or cold fades rapidly.
When immersing hands in warm water, the feeling of warmth quickly disappears even though the temperature of the water has not decreased.
In this case, heat receptors have ___.
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adaptation
adapted
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___ receptors do not adapt.
Placing a hand in boiling water leads to intense continuous pain and promps quick removal.
Sensory information regarding temperature is sent to the ___ ___.
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Pain
parietal lobe
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What is the sense of orientation, or position?
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Proprioception
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Which sense allows you to locate a body part without looking at it?
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Proprioception
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Which sense includes not having to see an arm to know that it is raised over the head?
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Proprioception
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What plays an important role in maintaining posture and coordinating body movements?
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Proprioception
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Receptors for proprioception, called ___, are located in muscles, tendons, and joints.
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proprioceptors
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What are found in the inner ear, where they function in balance or equilibrium?
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Proprioceptors
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The ___, which plays a major role in coordinating skeletal muscle activity, receives sensory information from proprioceptors.
Sensory information regarding movement and position is also sent to the ___ ___ of the cerebrum.
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cerebellum
parietal lobe
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What are the five special senses?
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Smell
Taste
Sight
Hearing
Balance
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Receptors for the special senses are located in the ___.
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head
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The sense of smell, or ___, is associated with sensory structures located in the upper nose.
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olfaction
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Which receptors are very sensitive and classified as chemoreceptors, meaning they are stimulated by chemicals that dissolve in the moisture of the nasal tissue?
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Olfactory
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Once olfactory receptors have been stimulated, sensory impulses travel along the ___ ___ (___ ___).
The sensory information is eventually interpreted as smell within the olfactory area of the ___ and ___ ___.
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olfactory nerve (CN I)
temporal, frontal lobes
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The sense of taste is often called the social sense, as in “let’s do lunch”; it is also called the ___ sense or ___.
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gustatory
gustation
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What are the special organs of taste?
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Taste Buds
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Taste receptors are located primarily on the tongue and are classified as ___, meaning that they are activated by the chemicals in food.
A small number of ___ ___ are also located on the palate, tonsils, and throat.
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chemoreceptors
taste buds
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What are the four basic taste sensations?
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Salty
Sweet
Sour
Bitter
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Each sensation is concentrated on a particular area of the tongue.
The tip of the tongue is most sensitive to ___ and ___ substances.
___ sensations are found primarily on the sides of the tongue, and ___ substances are most strongly tasted on the back part of the tongue.
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sweet, salty
Sour, bitter
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When taste receptors are stimulated, taste impulses travel along three cranial nerves [___ (___), ___ (___), and ___ (___) nerves) to various parts of the brain, eventually arriving in the ___ and ___ ___ of the cerebral cortex.
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facial (VII)
glossopharyngeal (IX)
vagus (X)
temporal
frontal lobes
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Sense of Taste: Four Taste Sensations
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___ are the organs of vision; they contain the visual receptors.
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Eyes
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Assisting the eyes in function and protection from injury are the ___ ___ ___.
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visual accessory organs
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What is the study of the eye and its function?
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Ophthalmology
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What includes the eyebrows, eyelids, conjunctiva, eyelashes, lacrimal apparatus, and extrinsic eye muscles?
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Visual Accessory Organs
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What are the patches of hair located above the eyes that perform a protective role?
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Eyebrows
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What keeps perspiration out of the eyes and shades the eyes from glaring sunlight?
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Eyebrows
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The eyelids, called ___, protect the eyes.
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palpebrae
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What prevents the entrance of foreign objects and washes tears over the surface of the eye?
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Palpebrae
Eyelids
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The upper and lower eyelids meet at the corners of the eyes.
The corners are called the ___ (inner) ___ and ___ (outer) ___.
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medial canthus, lateral canthus
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Eyelids are composed of four layers: ___, skeletal muscle (___ ___), ___ ___, and an inner ining called the ___.
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skin
(orbicularis oculi)
connective tissue
conjunctiva
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The margin of the eyelids contains ___ or ___ glands, special types of sebaceous glands that secrete an oil that coats the surface of the eye and reduces evaporation of tears.
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tarsal
meibomian
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Skeletal muscles open and close the eyelids.
The ___ ___ ___ muscle (___ means “to raise,” like an elevator) is attached to the eyelid and the upper bony orbit; contraction of this muscle opens the eye.
Contraction of the ___ ___ muscle closes it.
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levator palpebrae superioris (levator)
orbicularis oculi
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What lines the edges of the eyelid and helps to trap dust?
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Eyelashes
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What is a thin mucous membrane that lines the inner surface of the eyelids?
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Conjunctiva
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The ___ folds back to cover a portion of the sclera on the anterior surface of the eyeball; this part of the sclera is called the white of the eye.
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conjunctiva
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The ___ does not cover the cornea.
It secretes a thin mucous film that moistens the surface of the eye.
The (anterior/posterior) surface of the eye must be kept moist; otherwise it will ulcerate and scar.
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conjunctiva
anterior
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The ___ is very vascular, meaning that it has many blood vessels.
Evidence of its rich vascularity is its bloodshot appearance when the blood vessels are dilated.
Eyedrops that claim to “get the red out” cause the blood vessels of the ___ to constrict, thereby decreasing the amount of blood.
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conjunctiva x 2
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What is concerned with the secretion, distribution, and drainage of tears?
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Lacrimal Apparatus
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What is composed of the lacrimal gland and a series of ducts called tear ducts?
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Lacrimal Apparatus
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The ___ ___, in the upper lateral part of the orbit, secretes tears, which flow across the surface of the eye toward the nose.
The tears drain through small openings called ___ ___ and then into the ___ ___ and ___ ___.
The ___ ___ eventually empties into the nasal cavity.
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lacrimal gland
lacrimal puncta, lacrimal canals, nasolacrimal duct
nasolacrimal duct
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What moistens, lubricates, and cleanses the surface of the eye?
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Tears
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Tears also contain an enzyme called ___, which helps destroy pathogens and prevents infection.
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lysozyme
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Blinking stimulates ___ and helps spread tears over the surface of the eye.
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lacrimation
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Extrinsic eye muscles function as ___ ___ ___.
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visual accessory organs
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What has a spherical shape and is approximately ¾ to 1 inch (2 to 3 cm) in diameter?
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Eyeball
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Most of the ___ sits within the bony orbital cavity of the skull, partially surrounded by a layer of orbital fat.
Thus the ___ is recessed and well protected.
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eyeball x 2
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What are the three layers of the eyeball?
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Sclera
Choroid
Retina
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What is the outermost layer of the eyeball?
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Sclera
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What is the tough fibrous connective tissue that covers most of the eyeball?
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Sclera
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The ___ helps contain the contents of the eye; it also shapes the eye and is the site of attachment for the extrinsic eye muscles.
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sclera
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What extends toward the front of the eye?
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Sclera
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The anterior sclera is covered by ___ and is called the white of the eye.
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conjunctiva
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A transparent extension of the sclera is called the ___.
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cornea
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What covers the area over the iris (the colored portion of the eye)?
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Cornea
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What is avascular (contains no blood vessels) and transparent, allowing light rays to pass through?
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Cornea
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What is called the window of the eye because it is the first structure that light enters through?
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Cornea
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What has a rich supply of sensory nerve fibers and therefore is sensitive to touch?
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Cornea
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What is the middle layer of the eye?
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Choroid
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What is highly vascular and attached to the innermost layer, the retina?
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Choroid
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The choroid performs two functions: (1) it provides the ___ with a rich supply of blood and (2) ___ ___ located in the choroid absorb any excess light to prevent glare.
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retina
dark pigments
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What extends toward the front of the eyeball to form the ciliary body and iris?
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Choroid
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Collectively, the middle layer (choroid, ciliary muscle, and iris) is called the ___.
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uvea
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What secretes a fluid called aqueous humour and gives rise to a set of intrinsic eye muscles called the ciliary muscles?
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Ciliary Body
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The most anterior portion of the choroid is the ___, the coloured portion of the eye.
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iris
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The opening, or hole, in the middle of the iris is called the ___.
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pupil
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The size of the pupil is determined by two sets of intrinsic eye muscles located in the ___.
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iris
(Herlihy, 2020, p. 245)
What regulates the amount of light entering the eye?
(Herlihy, 2020, p. 245)
Iris
(Herlihy, 2020, p. 245)
What is the innermost layer of the eyeball?
(Herlihy, 2020, p. 245)
Retina
(Herlihy, 2020, p. 245)
Which layer lines the posterior two-thirds of the eyeball?
(Herlihy, 2020, p. 245)
Retina
(Herlihy, 2020, p. 245)
What is the nervous layer containing the visual receptors, which are sensitive to light and are therefore called photoreceptors?
(Herlihy, 2020, p. 245)
Retina
(Herlihy, 2020, p. 245)
What are the two types of photoreceptors?
(Herlihy, 2020, p. 245)
Rods
Cones
(Herlihy, 2020, p. 245)
What are scattered throughout the retina but are more abundant along its periphery?
(Herlihy, 2020, p. 245)
Rods
(Herlihy, 2020, p. 245)
What are sensitive to dim light and provide us with black-and-white vision?
(Herlihy, 2020, p. 245)
Rods
(Herlihy, 2020, p. 245)
What are most abundant in the central portion of the retina and provide colour vision?
(Herlihy, 2020, p. 245)
Cones
(Herlihy, 2020, p. 245)
The area of the retina that contains the highest concentration of cones is called the ___ ___, an area in the center of a yellow spot called the macula lutea.
(Herlihy, 2020, p. 245)
fovea centralis
(Herlihy, 2020, p. 245)
What is considered the area of most acute vision because it contains so many cones?
(Herlihy, 2020, p. 245)
Fovea Centralis
(Herlihy, 2020, p. 245)
A second small circular area of the retina is in the back of the eye.
The neurons of the retina converge there to form the ___ ___; it contains no rods or cones.
This area is called the ___ ___.
(Herlihy, 2020, p. 245)
optic nerve
optic disc
(Herlihy, 2020, p. 245)
Because there are no photoreceptors on the ___ ___ images that focus on this area are not seen.
The ___ ___ is therefore called the blind spot.
(Herlihy, 2020, p. 245)
optic disc x 2
(Herlihy, 2020, p. 245)
What are the two cavities in the eyeball?
(Herlihy, 2020, p. 245)
Posterior
Anterior
(Herlihy, 2020, p. 245)
Which cavity is larger and is located between the lens and the retina?
(Herlihy, 2020, p. 245)
Posterior
(Herlihy, 2020, p. 245)
The posteior cavity is filled with a gel-like substance called ___ ___, which gently pushes the retina against the choroid layer, thereby ensuring that the retina receives a good supply of oxygenated blood?
(Herlihy, 2020, p. 245)
vitreous humour
(Herlihy, 2020, p. 245)
Which cavity is located between the lens and the cornea?
(Herlihy, 2020, p. 245)
Anterior
(Herlihy, 2020, p. 245)
The anterior cavity is filled with a watery fluid called ___ ___, which is produced by the ciliary body and circulates through the pupil into the space behind the cornea.
(Herlihy, 2020, p. 245)
aqueous humour
(Herlihy, 2020, p. 245)
Aqueous humour performs two functions: (1) it maintains the shape of the (anterior/posterior) portion of the eye and (2) provides nourishment for the ___.
(Herlihy, 2020, p. 245)
anterior
cornea
(Herlihy, 2020, p. 245)
Aqueous humour leaves the anterior cavity by way of tiny canals located at the junction of the sclera and cornea.
These outlet canals are called venous sinuses or the ___ of ___.
(Herlihy, 2020, p. 245)
canals of Schlemm
(Herlihy, 2020, p. 245)
Drainage of aqueous humour through the canals of Schlemm may become impaired.
Consequently, aqueous humour accumulates in the eye and elevates pressure.
An elevated intraocular pressure is called ___.
(Herlihy, 2020, p. 245)
glaucoma
(Herlihy, 2020, p. 245)
What condition is serious because elevated pressure compresses the choroid, chokes off the blood supply to the retina, and damages the optic nerve?
(Herlihy, 2020, pp. 245, 246)
Glaucoma
(Herlihy, 2020, pp. 245, 246)
A) Structure of the Eyeball
B) Cavities and Fluids
C) Flow of Aqueous Humor from the Ciliary Body to the canal of Schlemm
(Herlihy, 2020, p. 244)
(Herlihy, 2020, p. 244)
What are the two groups of muscles associated with the eye?
(Herlihy, 2020, p. 246)
Extrinsic
Intrinsic
(Herlihy, 2020, p. 246)
Which eye muscles move the eyeball in its bony orbit?
(Herlihy, 2020, p. 246)
Extrinsic
(Herlihy, 2020, p. 246)
Which eye muscles move structures within the eyeball?
(Herlihy, 2020, p. 246)
Intrinsic
(Herlihy, 2020, p. 246)
Which eye muscles are skeletal muscles located outside the eye?
(Herlihy, 2020, p. 246)
Extrinsic
(Herlihy, 2020, p. 246)
Six extrinsic eye muscles attach to the bone of the eye orbit and the ___, the tough outer connective tissue layer of the eyeball.
(Herlihy, 2020, p. 246)
sclera
(Herlihy, 2020, p. 246)
What are the four rectus muscles and two oblique muscles?
(Herlihy, 2020, p. 246)
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus (LR)
Superior Oblique (SO)
Inferior Oblique
(Herlihy, 2020, p. 246)
Which eye muscles move the eyeball in various directions?
(Herlihy, 2020, p. 246)
Extrinsic
(Herlihy, 2020, p. 246)
Eyes move up, down, and sideways because of the ___ muscles.
(Herlihy, 2020, p. 246)
rectus
(Herlihy, 2020, p. 246)
Eyes roll because of the ___ muscles.
(Herlihy, 2020, p. 246)
oblique
(Herlihy, 2020, p. 246)
The extrinsic eye muscles are innervated by three cranial nerves, the most important being the ___ ___ (___ ___).
Then there is ___, which sounds like a nasty chemical formula.
However, it helps one recall that the lateral rectus (LR) muscle is innervated by the ___ ___(___ ___), whereas the superior oblique (SO) muscle is innervated by the ___ ___ (___ ___).
(Herlihy, 2020, p. 246)
oculomotor nerve (CN III)
LR6SO4, abducens nerve (CN VI), trochlear nerve (CN IV)
(Herlihy, 2020, p. 246)
What are the three nerves that observe movement of the eyeballs up, down, medial, lateral, and around?
(Herlihy, 2020, p. 246)
Oculomotor Nerve (CN III)
Abducens Nerve (CN VI)
Trochlear Nerve (CN IV)
(Herlihy, 2020, p. 246)
Which muscles are smooth muscles located in the eyeball, specifically in the iris and ciliary body?
(Herlihy, 2020, p. 247)
Intrinsic
(Herlihy, 2020, p. 247)
There are three intrinsic eye muscles:
The iris is composed of two eye muscles: the ___ muscle and the ___ muscle.
The third intrinsic eye muscle is the ___ muscle.
(Herlihy, 2020, p. 247)
radial, circular
ciliary
(Herlihy, 2020, p. 247)
What are the two muscles that control the size of the pupil and therefore regulate the amount of light that enters the eye?
(Herlihy, 2020, p. 247)
Radial
Circular
(Herlihy, 2020, p. 247)
Muscle fibers of the ___ muscle are arranged like the spokes of a wheel branching from the area of the pupil.
(Herlihy, 2020, p. 247)
radial
(Herlihy, 2020, p. 247)
Contraction of the ___ muscle causes the pupil to dilate, thereby increasing the amount of light entering the eye.
(Herlihy, 2020, p. 247)
radial
(Herlihy, 2020, p. 247)
Sympathetic nerve fibers supply the radial muscles.
Thus sympathetic nerve stimulation causes pupillary dilation, or ___.
Drugs that dilate the pupil are called ___ agents.
(Herlihy, 2020, p. 247)
mydriasis
mydriatic
(Herlihy, 2020, p. 247)
The second muscle located in the iris is the ___ muscle.
Contraction of the ___ muscles causes the pupil to constrict, thereby decreasing the amount of light entering the eye.
(Herlihy, 2020, p. 247)
circular
circular
(Herlihy, 2020, p. 247)
The circular muscle is supplied by parasympathetic nerve fibers in the ___ ___ (___ ___).
(Herlihy, 2020, p. 247)
oculomotor nerve (CN III)
(Herlihy, 2020, p. 247)
Parasympathetic nerve stimulation causes pupillary constriction, or ___.
(Herlihy, 2020, p. 247)
miosis
(Herlihy, 2020, p. 247)
Drugs that constrict the pupils are called ___ agents.
(Herlihy, 2020, p. 247)
miotic
(Herlihy, 2020, p. 247)
The ciliary muscles arise from the ___ ___.
(Herlihy, 2020, p. 247)
ciliary body
(Herlihy, 2020, p. 247)
Which muscles attach to the suspensory ligaments, which, in turn, tug on the lens, causing the lens to change its shape?
(Herlihy, 2020, p. 247)
Ciliary
(Herlihy, 2020, p. 247)
A) Extrinsic muscles: Four Rectus Muscles and Two Oblique Muscles (only five are shown)
(B) Intrinsic Eye Muscles: Iris
(Herlihy, 2020, p. 246)
(Herlihy, 2020, p. 246)
For sight, light waves must enter the eye (cornea) and focus on the ___.
Each structure of this pathway must retain its ability to allow for the passage of light.
For instance, light must pass through the lens; a clouded lens, or cataract, prevents light from reaching the ___ and stimulating the ___.
Therefore cataracts impair vision.
The same holds true for a scarred cornea.
(Herlihy, 2020, p. 247)
retina
retina, photoreceptors
(Herlihy, 2020, p. 247)
In addition to following an unimpeded path, light waves must bend to focus on the retina.
The bending of light waves is called ___.
(Herlihy, 2020, p. 248)
refraction
(Herlihy, 2020, p. 248)
Although the cornea and aqueous humor are both capable of refracting light, the ___ can change its shape and its refracting power, thereby enabling the eye to continuously adjust to near and far vision.
(Herlihy, 2020, p. 248)
lens
(Herlihy, 2020, p. 248)
Light waves are shown traveling in a straight line toward the retina.
Light wave 2 focuses on point X, with no need for refraction.
However, unless light waves 1 and 3 are ___, they will not focus on point X.
The bottom part of light wave 1 hits the lens first and is slowed before penetrating it.
The top of the light wave continues to travel until it hits the lens.
For a split second, the top of the light wave travels faster than the bottom.
The light wave therefore ___.
The same is true for light wave 3.
The top of light wave 3 hits the lens first and is slowed, while the bottom continues to travel faster until it, too, hits the lens.
For a split second, the bottom of light wave 3 travels faster than the top.
The light wave therefore ___.
(Herlihy, 2020, pp. 248, 249)
bent
bends
bends
(Herlihy, 2020, pp. 248, 249)
For sharp vision, light waves must be refracted to focus on one particular area of the ___.
(Herlihy, 2020, p. 248)
retina
(Herlihy, 2020, p. 248)
What can change its shape, becoming fatter or thinner?
(Herlihy, 2020, p. 249)
Lens
(Herlihy, 2020, p. 249)
What is an elastic structure held in place by the suspensory ligaments attached to ciliary muscles?
(Herlihy, 2020, p. 249)
Lens
(Herlihy, 2020, p. 249)
When the ciliary muscles contract and relax, the changes in tension cause a change in the shape of the lens.
The lens either thins out or becomes fatter.
The change in shape affects how much the light is bent.
For example, if the lens becomes (thinner/fatter), the light wave is bent at a sharper angle.
If the lens becomes (thinner/fatter), the degree of refraction lessens, and the light wave is not bent as much.
(Herlihy, 2020, p. 249)
fatter
thinner
(Herlihy, 2020, p. 249)
The ability of the lens to change its shape allows the eye to focus objects close up or at a distance.
For example, if a pencil is held 6 inches from the eyes, it is seen clearly.
The focusing of the close-up object (pencil) on the retina is caused primarily by the lens.
The lens becomes (thinner/fatter) and bends the light waves more acutely so as to focus them on the retina.
This ability of the lens to change its shape to focus on a close object is called ___.
(Herlihy, 2020, p. 249)
fatter
accommodation
(Herlihy, 2020, p. 249)
What is accompanied by pupillary constriction and by convergence, the movement of the eyes medially toward the nose?
(Herlihy, 2020, p. 249)
Accommodation
(Herlihy, 2020, p. 249)
___, pupillary constriction, and convergence all work together to focus both eyes on one object.
(Herlihy, 2020, p. 249)
Accommodation
(Herlihy, 2020, p. 249)
What refers to the ability of the eye to refract light without the assistance of a corrective lens?
(Herlihy, 2020, p. 249)
Emmetropia
(Herlihy, 2020, p. 249)
With advancing age, the lens loses some of its ability to change shape, thereby diminishing the ability to accommodate for close objects.
This condition, which is often evident after age 40, is called ___ (___ means “an old man”).
(Herlihy, 2020, p. 249)
presbyopia
presbyter
(Herlihy, 2020, p. 249)
Persons with ___ have difficulty adjusting to close objects.
(Herlihy, 2020, p. 249)
presbyopia
(Herlihy, 2020, p. 249)
What accounts for the tendency of older persons to hold a newspaper at arm’s length?
(Herlihy, 2020, p. 249)
Presbyopia
(Herlihy, 2020, p. 249)
Once light penetrates the various eye structures, it must stimulate the ___ (___ and ___) of the retina.
(Herlihy, 2020, p. 250)
photoreceptors (rods and cones)
(Herlihy, 2020, p. 250)
What are widely scattered throughout the retina but are more abundant in the periphery?
(Herlihy, 2020, p. 250)
Rods
(Herlihy, 2020, p. 250)
In low-light conditions pupils dilate, thereby allowing more light to enter the eye.
The dilated pupil also allows light rays to scatter along the periphery of the retina, thereby stimulating the ___.
The image produced by stimulation of ___ is black and white and somewhat fuzzy.
(Herlihy, 2020, p. 250)
rods
rods
(Herlihy, 2020, p. 250)
Because rods respond to dim light, stimulation of rods is often called ___ ___.
(Herlihy, 2020, p. 250)
night vision
(Herlihy, 2020, p. 250)
What are the photoreceptors for colour vision?
(Herlihy, 2020, p. 250)
Cones
(Herlihy, 2020, p. 250)
What are most abundant in the central portion of the retina, especially in the macula lutea?
(Herlihy, 2020, p. 250)
Cones
(Herlihy, 2020, p. 250)
In a well-lit environment, the pupil is constricted and directs the light toward the central ___-rich part of the retina.
The image produced by the stimulation of ___ is coloured and sharp.
(Herlihy, 2020, p. 250)
cone
cones
(Herlihy, 2020, p. 250)
There are three types of cones, each with a different visual ___ (a light-sensitive chemical).
One type of cone produces a green colour, another produces blue, and a third produces red.
Stimulation of combinations of these cones produces the many different colours and shades of colours that we enjoy.
(Herlihy, 2020, p. 250)
pigment
(Herlihy, 2020, p. 250)
(Herlihy, 2020, p. 250)
(Herlihy, 2020, p. 250)
Nerve impulses that arise from the photoreceptors leave the eye (retina) by way of the ___ ___ (___ ___).
The nerve impulses travel along the fibers of the ___ ___ (___ ___) and optic tracts to the ___ ___ of the brain.
This pathway from the retina to the brain is called the ___ ___.
(Herlihy, 2020, p. 250)
optic nerve (CN II)
optic nerve (CN II)
occipital lobe
visual pathway
(Herlihy, 2020, p. 250)
Half of the fibers from the left eye cross over and travel to the right side of the brain and half of the fibers from the right eye cross over and travel to the left side of the brain.
The crossing over of the fibers allows the occipital lobe, to integrate the information from both eyes and produce only one image.
The point at which the fibers from the left and right eyes crisscross is called the ___ ___, which is located directly in front of the pituitary gland.
After passing through the ___ ___, the nerve impulses follow the optic tracts, eventually reaching the primary visual cortex of the occipital lobe.
(Herlihy, 2020, pp. 250, 251)
optic chiasm
optic chiasm
(Herlihy, 2020, pp. 250, 251)
(Herlihy, 2020, p. 251)
(Herlihy, 2020, p. 251)
What are the organs of the sense of hearing?
(Herlihy, 2020, p. 252)
Ears
(Herlihy, 2020, p. 252)
What are the three parts of the ear?
(Herlihy, 2020, p. 252)
External
Middle
Inner
(Herlihy, 2020, p. 252)
Which part of the ear is seen?
(Herlihy, 2020, p. 252)
External
(Herlihy, 2020, p. 252)
Which part of the ear is composed of the auricle and the external auditory canal?
(Herlihy, 2020, p. 252)
External
(Herlihy, 2020, p. 252)
The auricle, or ___ (Latin for “wing”), is composed of cartilage covered by a layer of loose-fitting skin.
(Herlihy, 2020, pp. 252, 253)
pinna
(Herlihy, 2020, pp. 252, 253)
What functions similarly to a satellite dish gathering sound waves?
(Herlihy, 2020, p. 253)
Auricle
Pinna
(Herlihy, 2020, p. 253)
What opens into the external auditory canal, a passageway allowing sound waves to enter the ear?
(Herlihy, 2020, p. 253)
Auricle
Pinna
(Herlihy, 2020, p. 253)
The ___ ___ ___ is hollowed out of the temporal bone.
(Herlihy, 2020, p. 253)
external auditory canal
(Herlihy, 2020, p. 253)
What is about 1 inch long (2.5 cm) and ½ inch (1.25 cm) wide, extending to the tympanic membrane, or eardrum?
(Herlihy, 2020, p. 253)
External Auditory Canal
(Herlihy, 2020, p. 253)
What separates the external ear from the middle ear?
(Herlihy, 2020, p. 253)
Tympanic Membrane
(Herlihy, 2020, p. 253)
What is lined with tiny hairs and glands that secrete cerumen, a yellowish waxy substance also known as earwax?
(Herlihy, 2020, p. 253)
External Auditory Canal
(Herlihy, 2020, p. 253)
The hairs and ___ help to prevent dust and other foreign objects from entering the external ear.
(Herlihy, 2020, p. 253)
cerumen
(Herlihy, 2020, p. 253)
Which part of the ear is a small, air-filled chamber located between the tympanic membrane at one end and a bony wall at the other end?
(Herlihy, 2020, p. 253)
Middle
(Herlihy, 2020, p. 253)
Which part of the ear contains the tympanic membrane, three tiny bones, several small muscles, and the eustachian tube (also called the pharyngotympanic tube or auditory tube)?
(Herlihy, 2020, p. 253)
Middle
(Herlihy, 2020, p. 253)
Which structure of the middle ear is composed primarily of connective tissue and has a rich supply of nerves and blood vessels?
(Herlihy, 2020, p. 253)
Tympanic Membrane
(Herlihy, 2020, p. 253)
What vibrates in response to sound waves entering the ear through the external auditory canal?
(Herlihy, 2020, p. 253)
Tympanic Membrane
(Herlihy, 2020, p. 253)
The vibration of the ___ ___ is passed on to the tiny bones in the middle ear.
(Herlihy, 2020, p. 253)
tympanic membrane
(Herlihy, 2020, p. 253)
The middle ear contains three tiny bones, or ___, which are the tiniest bones in the body—the ___ (___), ___ (anvil), and ___ (___).
(Herlihy, 2020, p. 253)
ossicles
malleus (hammer)
incus
stapes (stirrup)
(Herlihy, 2020, p. 253)
The ossicals transmit vibration from the tympanic membrane to the ___ ___, a membranous structure that separates the middle ear from the inner ear.
(Herlihy, 2020, p. 253)
oval window
(Herlihy, 2020, p. 253)
The middle ear has a passageway connecting it to the pharynx, or throat.
This passageway is called the ___ ___.
(Herlihy, 2020, p. 253)
eustachian tube
(Herlihy, 2020, p. 253)
What equalizes pressure on both sides of the tympanic membrane by permitting air to pass from the pharynx into the middle ear?
(Herlihy, 2020, pp. 253, 254)
Eustachian Tube
(Herlihy, 2020, pp. 253, 254)
The ___ ear consists of an intricate system of tubes, or passageways, hollowed out of the temporal bone.
This coiled network of tubes is called the ___ ___.
(Herlihy, 2020, p. 254)
inner
bony labyrinth
(Herlihy, 2020, p. 254)
Inside the bony labyrinth is a similarly shaped ___ ___.
The bony labyrinth is filled with a fluid called ___.
(Herlihy, 2020, p. 254)
membranous labyrinth
perilymph
(Herlihy, 2020, p. 254)
The membranous labyrinth is surrounded by perilymph and is itself filled with a thick fluid called ___.
(Herlihy, 2020, p. 254)
endolymph
(Herlihy, 2020, p. 254)
What are the three parts of the inner ear?
(Herlihy, 2020, p. 254)
Vestibule
Semicircular Canals
Cochlea
(Herlihy, 2020, p. 254)
The ___ is concerned with hearing.
The ___ and ___ ___ are concerned with balance.
(Herlihy, 2020, p. 254)
cochlea
vestibule, semicircular canals
(Herlihy, 2020, p. 254)
What is the snail-shaped part of the bony labyrinth?
(Herlihy, 2020, p. 254)
Cochlea
(Herlihy, 2020, p. 254)
Sitting on a membrane within the cochlea and immersed in ___ are the receptors for hearing.
These receptors are cells within the ___ of ___ that contain tiny hairs.
When these hairs are bent, a nerve impulse is sent by the cochlear branch of the ___ ___ (___ ___) to the primary auditory cortex of the ___ ___ of the brain, where the sensation is interpreted as hearing.
(Herlihy, 2020, p. 254)
endolymph
organ of Corti
vestibulocochlear nerve (CN VIII)
temporal lobe
(Herlihy, 2020, p. 254)
Because the receptors are stimulated by the bending of the hairs, the receptors are classified as ___.
(Herlihy, 2020, p. 254)
mechanoreceptors
(Herlihy, 2020, p. 254)
Sound waves are gathered by the auricle, travel through the external auditory canal, and hit the ___ ___, causing it to vibrate.
This vibration, in turn, causes the middle ear bones (malleus, incus, and stapes) to vibrate.
The stapes, sitting within the ___ ___, then causes the fluid in the inner ear to move.
Because the hairs of the organ of Corti are sitting within the ___, movement of the fluid causes the hairs to bend.
The bending of the hairs triggers a nerve impulse carried by the ___ ___ of the vestibulocochlear nerve (CN VIII) to the ___ ___ ___ of the temporal lobe, where it is interpreted as sound.
(Herlihy, 2020, p. 254)
tympanic membrane
oval window
endolymph
cochlear branch
primary auditory cortex
(Herlihy, 2020, p. 254)
The Three Divisions of the Ear and Structures within the Ear
(Herlihy, 2020, p. 253)
(Herlihy, 2020, p. 253)
(Herlihy, 2020, p. 256)
(Herlihy, 2020, p. 256)
The vestibule and semicircular canals, collectively called the ___ ___, are concerned with equilibrium or balance.
(Herlihy, 2020, p. 255)
vestibular apparatus
(Herlihy, 2020, p. 255)
The receptors for balance are mechanoreceptors and are located within the ___ ___ and ___.
(Herlihy, 2020, p. 255)
semicircular canals
vestibule
(Herlihy, 2020, p. 255)
What are the two types of equilibrium or balance?
(Herlihy, 2020, p. 255)
Static
Dynamic Equilibrium
(Herlihy, 2020, p. 255)
Which equilibrium senses the position of the head and maintains posture when the body makes no sudden movement?
(Herlihy, 2020, pp. 255, 257)
Static
(Herlihy, 2020, pp. 255, 257)
Which equilibrium detects sudden movements of the head and maintains posture while the body is moving or rotating?
(Herlihy, 2020, p. 257)
Dynamic
(Herlihy, 2020, p. 257)
The vestibule contains the organs of static equilibrium, called ___.
The ___ contain hair cells.
The upward-projecting hairs are embedded in a jelly-like substance that contains ___—stony particles made of calcium carbonate that add weight to the gel.
When the head is tilted in any direction, the ___-containing gel moves and bends the tiny hairs.
The bent hairs (mechanoreceptors) initiate a nerve impulse, which travels along the ___ ___ (___ ___) to the brain.
The brain analyzes the information and sends motor information to the skeletal muscles to maintain balance and posture.
(Herlihy, 2020, p. 257)
maculae
maculae
otoliths, otolith
vestibulocochlear nerve (CN VIII)
(Herlihy, 2020, p. 257)
The three ___ ___ are the organs of dynamic equilibrium and respond to sudden movement.
(Herlihy, 2020, p. 257)
semicircular canals
(Herlihy, 2020, p. 257)
What are located at right angles to each other so that any rapid change of head position or accelerating/decelerating motion can be detected?
(Herlihy, 2020, p. 257)
Semicircular Canals
(Herlihy, 2020, p. 257)
At the base of each of the semicircular canals is an ampulla; at the base of each ampulla is small elevation called a ___.
The ___ contains hair cells.
The upward-projecting tiny hairs are embedded within a jelly-like substance and sit within endolymph-containing ducts.
When a head suddenly moves, the ___ also move, but the endolymph does not move.
In response to this disparity in movement, the hairs (mechanoreceptors) bend, thereby initiating a nerve impulse.
The nerve impulse travels along the ___ branch of ___ ___ (___ ___) to different parts of the brain, particularly the ___.
The ___ analyzes the input from ___ ___ (___ ___) and sends information to the skeletal muscles to maintain balance and posture.
(Herlihy, 2020, p. 257)
crista
crista
vestibular, vestibulocochlear nerve (CN VIII)
cerebellum
cerebellum, vestibulocochlear nerve (CN VIII)
(Herlihy, 2020, p. 257)
In addition to the inner ear receptors, there are other mechanoreceptors scattered throughout the body (___ in skeletal muscle) that send information to the brain to maintain equilibrium.
(Herlihy, 2020, p. 257)
proprioceptors
(Herlihy, 2020, p. 257)
(Herlihy, 2020, p. 255)
(Herlihy, 2020, p. 240)
(Herlihy, 2020, p. 240)
(Herlihy, 2020, p. 240)
