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  • Senses by which individuals maintain contact w/ the external environment are:
    • Vision (visual)
    • Hearing (auditory)
    • Smell (olfactory)
    • Taste (gustatory)
    • Touch (tactile)

§         Stereognosis- sense that perceives solidity of objects & their size, shape, & texture

example putting the hand in a bag and guessing what it is

Ø       Visceral – pertains to inner organs; both visceral & Kinesthetic senses arise internally from muscles & hollow organs, respectively, and are the body’s basic orienting systems

• Perception – conscious process of selecting, organizing, & interpreting data from the senses into meaningful info.
  • Influenced by the intensity, size, change, or representation of stimuli, as well as by past experiences, knowledge, & attitudes.

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  • To receive the necessary data to experience the world four conditions must be met:
    • Stimulus – an agent, act, or other influence capable of initiating a response by the Nervous System…must be present

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    • Receptor – a sense organ must be able to receive the stimulus & convert it into a nerve impulse

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    • Nerve Impulse – must be conducted along nervous pathway from the receptor or sense organ to the brain.

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    • Brain – a particular area in the brain must be able to receive & translate the impulse into a sensation

• The Arousal Mechanism – to receive & respond appropriately, the brain must be alert or aroused
  • Reticular Activating System (RAS) –  a poorly defined network that extends from hypothalamus to medulla, mediates arousal
    • Optimal arousal state of RAS is a general drive state called Sensoristasis

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    • Nerve impulses from all sensory tracts reach the RAS, selectively allowing certain impulses to reach the cerebral cortex to be perceived, the center of this area is called the mesencephalic portion
    • Stimulation of this area produces the most pronounced & long lasting effects on cerebral cortex

RAS serves to monitor & regulate incoming sensory stimuli either maintaining, enhancing, or inhibiting cortical arousal (awareness

o        States of Awareness (2)

§         Conscious -  

Ø       Delirium- disorientation, restlessness, confusion, hallucinations, agitation, alternating w/ other conscious states

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Ø       Confusion- reduced awareness, easily distracted, easily startled by sensory stimuli, alternates between drowsiness & excitability; resembles minor form of delirium

Ø       Somnolence- extreme drowsiness; but will respond to normal stimuli

Ø       Chronic Vegetative State- conscious but unresponsive, no evidence of cortical function

§         Unconscious –

Ø       Asleep- can be aroused by normal stimuli (light touch, sound, etc)

Ø       Stupor- can be aroused by extreme or repeated stimuli

Ø       Coma- cannot be aroused & does not respond to stimuli

         Adaptation- quickly adapting to constant stimuli to which extent it eventually goes unnoticed….like city traffic or a bad odor. Impulses that are not acted on maybe used in a later date in response to similar stimuli through memory

• Disturbed Sensory Perception- stimuli that are different in quality & quantity to which a person is accustomed, resulting in severe sensory alteration

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  • Factors Contributing to Sensory Alteration:
    • Sensory Overload- condition that results when experiencing so much sensory stimuli that the brain is unable to either respond meaningfully or ignore the stimuli

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    • Sensory Deprivation- experiencing decreased sensory input or input that is monotonous or meaningless

Ø       w/ decreased sensory input the RAS is no longer able to project a normal level of activation to the brain, as a result a person may hallucinate in order to maintain optimal level of arousal (Sensoristasis)

Ø       Can lead to various effects including: perceptual, emotional, & cognitive disturbances

v      Perceptual Response- inaccurate response to sights, sounds, tastes, smells, & body position, coordination & equilibrium. Disturbances can range from daydreams to hallucinations

v      Emotional Response- manifested by apathy, anxiety, fear, anger, belligerence, panic or depression. Rapid mood changes may also occur

v      Cognitive Response- inability to control the direction of thought content. Attention span & ability to concentrate are decreased

§         Sleep Deprivation- can result from coming from a relatively quiet environment and being thrust into a healthcare setting affecting sleeping patterns and inhibiting sensory input

§         Cultural Care Deprivation- not being able to maintain cultural, religious, ethnic norms that can result in ineffective care and decreased sensory input

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          • Cultural- may dictate the amt. of stimulation considered normal. Examples include affectionate touching of a child in A Hispanic family as opposed to a German one. Or the differences placed on gender roles in certain cultures. In some customs touching is a welcome gesture and in others an act of insult. Ethnic & religious norms also play a role, as in religious symbols as comfort & healing that may be absent in hospital settings.

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    • Developmental- different types of sensory stimulation are needed for growth as sensory receptors, organs, & nervous system grows. For instance a baby’s need to be held, and soothed. Sensory functioning declines as we age and encounter chronic illnesses. The adult may exchange the loss of stimuli for an increase in another.