ch 16 general senses

what’s sensation?

The conscious or subconscious awareness of changes in the external or internal environment

what’s perception?

The conscious interpretation of sensations performed mainly by the cerebral cortex

what’s it called if sensory impulses go to ur cerebral cortex?

perceived

if sensory impulses go to the cerebral cortex, what does that mean?

u are consciously aware of stimuli ex:touch, pain

what’s sensory modality?

each unique type of sensation

what carries the information for only 1 modality?

sensory neuron

what are the 2 groups of sensory modalities?

general sense and special senses

what are examples of special senses?

gustation, olfaction, vision, hearing, and equallibrium

what are the 2 types of general senses?

somatic senses and visceral senses

what are examples of somatic senses?

tactile sensations (touch, itch)

thermal sensations

proprioception

what are visceral senses?

provide information about conditions within internal organs

what are examples of visceral senses

pressure, temp, hunger, chemical, stretch

where does the process of sensation begin?

in a sensory receptor

what can be either a specialized cell or the dendrites of a sensory neuron?

sensory receptor

what’s a stimulus?

a change in the environment

what activates only certain sensory receptors

stimulus

what’s selectivity?

a specific sensory receptor will only respond to one type of stimulus

a specific sensory receptor will respond to what?

one kind of stimulus

what’s the first step that must occur for a sensation to arise?

stimulation of the sensory receptor

what’s the 2nd step that must occur for a sensation to arise?

transduction of the stimulus

what’s transduction of a stimulus?

sensory receptors exhibit selectivity and respond to only one particular stimulus

what’s the 3rd step that must occur for a sensation to arise?

generation of nerve impulses

what occurs during generation of nerve impulses?

sensory neurons conduct nerve impulses about one sensory modality from PNS TO CNS

what’s the 4th step that must occur for a sensation to arise?

integration of sensory input to the CNS

what’s a free nerve ending?

a dendrite

what’s an encapsulated nerve ending?

connective tissue surrounding dendrite

what’s the function of free nerve endings?

used to detect pain, temp, tickle, itch, and some touch

what do encapsulated nerve endings detect?

pressure, vibration, and some touch

what are examples of encapsulated nerve endings?

pacinian corpuscle and Meissner corpuscles

what sensations do separate cells detect?

gustatory receptors photoreceptors and hair cells

where are exteroceptors located?

at or near the external surface of the body

what type of sensory receptor responds to external stimuli?

exteroceptors

where are interoceptors located?

blood vessels, organs, and muscle

what sensory receptor causes impulses which usually are not consciously perceived but may be felt as pain or pressure l?

interocepters

where are proprioceptors located?

muscles, tendons, joints, and the inner ear

what type of sensory receptor provides information about body position, movement of joints, muscle length, and tension, and balance?

proprioceptors

what are the different type of sensory receptors that are named according to type of stimulus?

mechanoreceptors, thermoreceptors, nocioceptors, photoreceptors, chemoreceptors, and osmoreceptors

what are mechanoreceptors sensitive to?

deformation, stretching, or bending of cells

what sensations do mechanoreceptors detect?

touch, pressure, vibration, proprioception, stretching, hearing, and equilibrium

what do thermoreceptors detect?

changes in temp

temp above 48°C and below 10°C stimulates what receptors?

norcioceptors (pain receptors)

what do nociceptors respond to?

painful stimuli

what sensory receptor responds to physical or chemical damage?

nociceptors

what activates photoreceptors?

light

what do chemoreceptors detect?

chemicals in the mouth, nose, and bodily fluids

what do osmoreceptors detect?

the osmotic pressure of bodily fluids

what’s the definition of adaptation of sensory receptors?

potentials decrease in amplitude during a maintained constant stimulus (constant stimulus=decrease in nerve signals)

what are rapidly adapting sensory receptors?

specialized for signaling changes in a stimulus

what type of sensory receptor adaptation detects pressure, touch, and smell?

rapidly adapting receptors

what are slowly adapting sensory receptors?

they continue to send impulses as long as stimulus persists

what type of sensory receptor adaptation detects pain, body position, and chemical composition of the blood?

slowly adapting receptors

what serves a protective function and is indispensable for survival?

pain

what are nociceptors

chemoreceptive free nerve endings activated by tissue damage from intense thermal, mechanical, or chemical stimuli

what’s found in every tissue of the body except the brain?

nociceptors

what are the 2 types of pain?

fast and slow

what’s examples of fast pain?

a cute, sharp, or prickling sensation

what’s fast pain?

well localized, perceived within 1 second

what’s slow pain?

begins after a stimulus is applied and gradually increases in intensity over a period of several seconds or minutes

what type of pain may be excruciating and often has a burning, aching, or throbbing quality?

slow pain

what’s does superficial somatic pain arise from?

skin receptors on top layer of skin

what does deep somatic pain arise from?

stimulation of receptors in skeletal muscles, joints, tendons, and fascia

what does visceral pain result from?

stimulation of nociceptors in visceral organs

what type of pain is felt in or just deep to the skin that is superficial to the organ or in a different body region

visceral pain

what’s referred pain?

pain is felt in or just deep to the skin that is superficial to the organ or in a different body region

what’s proprioceptors?

sends impulses about body position to CNS

what’s the function of muscle spindles?

monitor skeletal muscle length and triggers stretch reflex

what are both encapsulated nerve endings?

muscle spindles and tendon organs

what monitors external tension developed during muscle contraction to prevent overstretching?

tendon organs

what are joint kinesthetic receptors?

detect position, pressure, acceleration, deceleration during movement to prevent strain

what are found in and around the synovial joint capsules?

joint kinesthetic receptors

type 2 cutaneous mechanoreceptors, free nerve endings, and lamellated corpuscles are what type of receptors?

joint kinesthetic receptors

what relays info from somatic sensory receptors to cerebral cortex and cerebellum?

somatic sensory pathways

what are the 3 steps of somatic sensory pathways?

1. 1st order neurons

2. 2nd order neurons

3. 3rd order neurons

what occurs during 1st order neurons?

sensory receptors travel to brainstem or spinal cord

what occurs during 2nd order neurons?

1st order neurons come in tact and head to the thalamus

what’s considered the relay station?

thalamus

what occurs during 3rd order neurons?

neurons travel from the thalamus to primary somatosensory area of the cortex (part of the parietal lobe)

what are the 3 general pathways that somatic sensory impulses ascend to the cerebral cortex?

posterior column-medial lemniscus pathway

anterolateral pathway

trigeminothalamic pathway

what somatic sensory receptors does the posterior-column medial lemniscus pathway carry?

proprioception, vibration, touch, pressure, and nerve impulses

what somatic sensory pathway signals travel up the spinal cord in the posterior column?

posterior column-medial lemniscus pathway

what somatic sensory pathway deals with the limbs, trunk, neck, and posterior head?

posterior column-medial lemniscus pathway

what do the 1st order neurons do in the posterior column-medial lemniscus pathway?

signals travel up spinal cord in posterior column

what do the 2nd order neurons do in the posterior column-medial lemniscus pathway?

fibers cross over in medulla to become the medial lemniscus pathway ending in thalamus

what do the 3rd order neurons do in the posterior column-medial lemniscus pathway?

thalamic fibers reach primary somatosensory cortex

what somatic sensory pathway carries pain, temp, tickle, itch, and nerve impulses?

Anterolateral pathway

what somatic sensory pathway deals with limbs, trunk, neck, and posterior head?

Anterolateral pathway

what somatic sensory pathway do impulses travel through anterior and lateral tracts in white matter of spinal cord?

Anterolateral pathway

what do 1st order neurons do in the anterolateral pathway?

first cell body in DRG with synapses in posterior gray horn

what do 2nd order neurons do in the anterolateral pathway?

fibers cross over spinal cord and travel through anterior and lateral tracts into thalamus

what do 3rd order neurons do in the anterolateral pathway?

thalamic fibers reach primary somatosensory cortex

what somatic sensory pathway carries touch pressure, vibration, pain, temp, itch, and tickle?

trigeminothalamic pathway

what somatic sensory pathway deals with the face, nasal cavity, oral cavity, and teeth?

trigeminothalamic pathway

what somatic sensory pathway has nerve impulses reach the pond and medulla oblongata through the trigeminal nerve?

trigeminothalamic pathway

what do 1st order neurons do in the trigeminothalamic pathway?

trigeminal nerve to the pons and medulla oblongata

what do 2nd order neurons do in the trigeminothalamic pathway?

cross over in the pond and medulla to thalamus

what do 3rd order neurons do in the trigeminothalamic pathway?

thalamic fibers carry info to the primary somatosensory cortex

what’s the posterior and anterior spinocerebellar tract?

carries proprioceptive impulses to the cerebellum

what helps to coordinate smooth and refine skilled movements and maintain posture and balance?

spinocerebellar tract (cerebellum)

where is the primary somatosensory area?

parietal lobe

what’s premotor area?

the idea or desire to move a body part is generated in this region