Chapter 26 sensation, perception, and response

What are the five components of the sensory experience?

Stimulus, reception, perception, arousal, and response to sensations.

What is a stimulus?

Anything that triggers a sensory receptor, such as light, sound, touch, taste, or pain.

What is reception?

The process of receiving a stimulus through sensory receptors and converting it into a nerve impulse.

What happens after a sensory receptor receives a stimulus?

The nerve impulse travels along sensory pathways to the spinal cord and brain for processing.

What is perception?

The brain's ability to interpret sensory impulses and give meaning to a stimulus.

What is the difference between reception and perception?

Reception involves receiving a stimulus and generating a nerve impulse; perception involves interpreting the impulse and understanding its meaning.

What factors affect perception?

The location of receptors and pathways activated, number of receptors activated, frequency of action potentials, and changes in these factors. Past experiences, knowledge, and attitudes also influence perception.

What are specialized sensory receptors?

Receptors that typically respond to a particular type of stimulus.

What do mechanoreceptors detect?

Touch, pressure, and vibration.

What do thermoreceptors detect?

Changes in temperature.

What do photoreceptors detect?

Visible light; they are located in the retina of the eye.

What do chemoreceptors detect?

Chemical stimuli, including those involved in taste.

Where are olfactory receptors located, and what do they detect?

In the nasal cavity; they detect odors and are responsible for smell.

What is the function of proprioceptors?

They provide information about body position in space and help coordinate movement and balance.

What receptors are involved in hearing?

Hair cells in the inner ear detect sound vibrations.

Where are taste receptors located?

Taste buds in the mouth detect flavors such as sweet, sour, salty, and bitter.

What is the reticular activating system (RAS)?

A system in the brainstem that helps regulate consciousness, alertness, and awareness.

What is the role of the RAS in sensory processing?

It relays and filters sensory information and helps keep a person awake, attentive, and aware of the environment.

How does the RAS filter sensory information?

It helps the brain focus on important stimuli while filtering out insignificant background input.

What factors can decrease arousal through their effects on the RAS?

Sedatives, opioids, other central nervous system depressants, and reduced environmental stimulation.

How can the environment affect arousal?

Bright, noisy, active environments may increase alertness, while dark, quiet environments may reduce stimulation and promote sleepiness.

How does the RAS help maintain consciousness?

It sends impulses to the cerebral cortex that help maintain wakefulness, attention, and awareness.

What is adaptation to a stimulus?

A decline in the response to a continuous or repeated stimulus over time.

How does the brain respond after perceiving a stimulus?

It may disregard the information, store it in memory, or send impulses along motor pathways to produce a response.

What two conditions are needed for a person to respond to sensations?

The person must be alert and receptive to stimulation.

What factors affect a person's response to sensations?

Stimulus intensity, contrasting stimuli, adaptation to stimuli, and previous experience.

How does stimulus intensity affect a response?

More intense stimulation can produce a stronger sensory response.

What is the effect of contrasting stimuli?

A change in surrounding conditions can make a stimulus feel different or more noticeable.

What is an example of contrasting stimuli?

Entering a warm room after being outside in cold, windy weather can make the room feel especially warm.

How does adaptation affect a person's response?

A person becomes accustomed to ongoing stimulation and notices it less over time.

What is an example of sensory adaptation in nursing?

A nurse may gradually stop noticing background hospital alarms and noise because of repeated exposure.

How does previous experience affect a sensory response?

Memories of earlier experiences can influence how a person interprets and responds to the same stimulus.

How can a previous negative experience affect a patient's response to an injection?

The patient may tense up, grimace, or turn away because they anticipate pain from an earlier experience.

What factors affect sensory function?

Life-span variations, culture, illness, medications, stress, personality, and lifestyle.

How does age affect sensory function?

Sensory abilities change throughout life; newborns and infants are developing their senses, while some sensory abilities may decline in older adulthood.

What sensory abilities are present in newborns?

Newborns respond to light, sound, taste, smell, and touch, but their vision is less developed and they can be easily overstimulated.

What stimuli can overstimulate newborns?

Loud noises, bright lights, high-contrast objects, and stroking sensitive areas.

What is characteristic of newborn vision?

Newborns respond to light and can track objects, but their visual acuity is less developed than that of older children and adults.

What taste preferences can newborns demonstrate?

They can distinguish tastes and generally prefer sweet tastes over sour ones.

How do newborns respond to smell?

They respond to odors and may distinguish their mother's breast milk from another mother's.

Which body areas are especially sensitive to touch in newborns?

The tongue, lips, fingertips, and soles of the feet.

Why do infants need sensory stimulation?

Sensory stimulation supports growth, development, sensory system maturation, and bonding with caregivers.

How do visual and auditory experiences support infant development?

Exposure to light, color, contrast, voices, music, and environmental sounds supports sensory development.

How does touch support infant development?

Cuddling, feeding, and soothing provide tactile stimulation and help build bonds between infants and caregivers.

How does sensory function generally change during adulthood?

Senses are generally at their peak in early adulthood unless affected by illness or injury; sensory abilities may decline with aging.

How can culture affect sensory function?

Culture influences the amount and type of sensory stimulation a person finds comfortable, including eye contact, personal space, and physical touch.

How can illness affect sensory function?

Neurological disorders can slow nerve impulse transmission, and circulatory problems can impair sensory receptors and alter perception or responses.

How can medications affect sensory function?

Some medications cause unpleasant or metallic tastes, while medications affecting the central nervous system can alter neurological or sensory function.

How can stress affect sensory function?

Stress from illness, pain, hospitalization, tests, or surgery can contribute to sensory overload.

How can personality and lifestyle affect sensory function?

Individual preferences and habits affect sensory stimulation and sensory acuity; for example, habitual smoking can reduce smell and taste sensitivity.

What is sensory deprivation?

An alteration in sensory perception caused by insufficient meaningful sensory input or difficulty receiving and processing it.

What can cause sensory deprivation?

Understimulation, an unfamiliar or deprived environment, or nervous system dysfunction.

Who may be at risk for sensory deprivation?

Hospitalized patients and older adults, particularly those who are ill or injured.

What is sensory overload?

A condition in which the amount or intensity of sensory stimulation exceeds a person's ability to process it comfortably.

What can contribute to sensory overload in a hospital?

Pain, unfamiliar sights and sounds, frequent interruptions, alarms, procedures, and other excessive stimulation.

What are sensory deficits?

Impairments in one or more senses or in the ability to perceive sensory information.

What are the major types of sensory deficits?

Visual, auditory, olfactory, gustatory, tactile, and kinesthetic deficits.

Which sensory deficits are especially common in nursing practice?

Impaired vision and impaired hearing.

What is a visual sensory deficit?

Impaired ability to see or interpret visual information.

What is an auditory sensory deficit?

Impaired ability to hear or interpret sounds.

What is an olfactory sensory deficit?

Impaired ability to detect or identify smells.

What is a gustatory sensory deficit?

Impaired ability to taste.

What is a tactile sensory deficit?

Impaired ability to perceive touch, pressure, pain, or temperature.

What is a kinesthetic sensory deficit?

Impaired awareness of body position and movement.

What is a seizure?

An abrupt disturbance of electrical activity in the brain.

What are the two main types of seizures?

Generalized seizures and focal seizures.

What is a generalized seizure?

A seizure involving widespread abnormal electrical activity across both sides of the brain.

What is a focal seizure?

A seizure that begins with abnormal electrical activity in a limited area or one side of the brain.

What are recurrent seizures associated with?

They may be associated with epilepsy, a brain disorder characterized by a tendency to have recurrent seizures.

What other conditions can cause seizures?

Brain tumors, head trauma, and other conditions affecting the brain.

What is an electroencephalogram (EEG)?

A test that records the brain's electrical activity and can help evaluate seizure activity.

What is epilepsy?

A brain disorder characterized by a tendency to experience recurrent seizures.

What is the difference between sensory deprivation and sensory overload?

Sensory deprivation occurs when meaningful sensory input is insufficient; sensory overload occurs when stimulation exceeds the person's ability to process it.

What are the main components of a sensory assessment?

Nursing interview, physical assessment, risk factors for impaired sensory perception, mental status, level of consciousness, support network, and environment.

What should a nurse assess during the nursing interview?

The patient's usual and current sensory function, history of sensory problems, and use of sensory aids.

What should a physical assessment of sensory function include?

Vision, hearing, taste, smell, touch, balance, response to stimulation, muscle tone, and coordination.

Why is it important to assess a patient's usual sensory function?

It establishes a baseline so the nurse can identify new or worsening sensory changes.

Which patients are at increased risk for impaired sensory perception?

Older adults, bedbound patients, people with central nervous system disorders, and patients with decreased mobility.

Why can acute sensory changes be difficult to recognize?

Patients may have difficulty noticing or reporting sensory deficits, especially when the change occurs suddenly.

What should a nurse assess during a mental status examination?

Behavior, appearance, responses to stimuli, speech, mood, and judgment.

What does an altered mental status indicate?

A change in a person's usual mental functioning that may affect behavior, thinking, awareness, or responses.

What does level of consciousness (LOC) indicate?

The patient's degree of arousal and awareness, which helps indicate cerebral function.

What two major features are assessed when evaluating level of consciousness?

Arousal and orientation to person, place, time, and situation.

How should a nurse assess a patient who does not respond to auditory stimuli?

Progress to tactile stimulation and then painful stimulation as clinically appropriate and according to protocol.

Why should a nurse assess the patient's support network?

Support persons can provide comfort, reduce stress, and help the patient adapt to sensory deficits.

How can a support person help a patient with sensory deficits?

By assisting with tasks the patient can no longer perform independently and providing emotional support.

What should a nurse assess about the patient's environment?

Environmental conditions, the amount and type of stimulation, and how the patient responds to the surroundings.

Why is the environment important when assessing sensory function?

Unfamiliar or excessive environmental stimulation can affect comfort, perception, and the patient's responses.

What is an auditory alteration?

A change in or diminished ability to hear.

What is a cerebral alteration?

A change in or reduction of mental processes.

What is confusion?

A state of disorientation or impaired awareness of one's surroundings.

What is a comfort alteration?

A change in sensation that causes distress or discomfort.

What is a gustatory alteration?

A change in or diminished ability to taste.

What is a kinesthetic alteration?

A change in or diminished ability to sense body position and movement in space.

What is memory impairment?

A diminished ability or inability to recall past events or information.

What is an olfactory alteration?

A change in or diminished ability to smell.

What is a sensory perceptual alteration?

A change in or diminished ability to perceive or respond to sensory stimuli.

What is a tactile alteration?

A change in or diminished ability to feel sensations through touch.