Ch16: Sensation

38 terms by loubruck 

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Sensation

-conscious or subconscious awareness of changes in the internal or external environment.
- each unique one has its own modality
-there are general and special types

Perception

the process of organizing and interpreting sensory information by the cerebral cortex of the brain

Generator Potential

sensationlarge enough to reach threshold and initiate an action potential

Receptor Potential

graded potential which are affected by neurotransmitters.

Free Nerve Endings

-bare dendrites of sensory receptors.
-transmit the feeling of pain,temperature,tickling, itch and touch

Encapsulated Nerve Endings

-Dendrites enclosed in a CT capsule
-transmit sensation of pressure,vibration,and touch

Exterceptors

located on the external surface of the body

Interoceptors

located in blood vessels, visceral organs, muscles and nervous system

Proprioceptors

-located in muscles, tendons, inner ear, and joints
-allow the body to know its position even when moving

Mechanoreceptors

-sensitive to deformation, stretching, and bending of cells
-function in touch, pressure, vibration, proprioception, hearing and equilibrium

Thermoceptors

sensitive to temperature

Nociceptors

sensitive to chemicals that register pain

Photoreceptors

sensitive to light

Chemoreceptors

sensitive to chemicals in the mouth, nose, and body fluids

Osmoreceptors

sensitive to osmotic pressure in body fluids

Tactile

refers to the sense of touch, pressure, vibration, itch, tickle etc.

Touch

result from stimulation of tactile receptors in skin or subcutaneous

Pressure

sustained sensation over a larger area than touch; receptors adapt rapidly

Vibration

rapid repeating impulses from tactile receptors (Meissner/Pacinian Corpuscles)

Itch

chemical stimulation of free nerve endings

Tickle

stimulation of free nerve endings

Cold

Thermal sensation who's receptors react to 50-105 F; most abundant; adapt rapidly

Warm

Thermal sensation who's receptors react to 90-118 F; adapt rapidly

Pain

-Sensation necessary for survival
-In all tissues of the body except the brain
-React to chemicals released from damaged tissue as well as excessive stretching, muscle spasms and ischemia.

ischemia

insufficient blood flow to an area of the body

Fast Pain

very precisely located surface sensation; impulse moves rapidly

Slow Pain

wide spread and deeper sensation; movement of impulse is slow and persistent

Referred Pain

regions of the body sense pain on the surface from an internal source
ex) pain in left arm during a heart-attack

First-order Neurons

conduct impulses from the body to the CNS

Second-order Neurons

conduct impulses from the brain and spinal cord to the thalamus

Third-order Neurons

conduct impulses from the thalamus to the primary somatosensory area of the cerebral cortex

Lemniscus Pathway

Impulses of touch,pressure,vibration,conscious perception of limbs, trunk,neck and posterior head ascend to the cerebral cortex.

Anteriolateral (Spinothalamic) Pathway

Sensory input for pain,temperature,itch and tickle ascend to the cerebral cortex

Trigeminothalmic Pathway

Nerve impulses for most somatic sensations

Direct (Pyramidal) Pathway

1)Corticospinal pathway from motor cortex to skeletal muscles in limbs and trunk

2)Corticobulbar connect the motor cortex to muscles in the head

Indirect (Extra Pyramidal) Pathway

-Travel from cerebral cortex through nuclei of cell bodies
-include rubrospinal, tectospinal, vestibulospinal, lateral reticulospinal, and medial reticulospinal pathways

Basal Ganglia

-Influence muscle tone as well as sensory,limbic,cognitive and linguistic functions.
-Function in the initiation and termination of movements

Cerebellar Function

-Monitors intentions for movements
-monitors actual movements
-compares intentions with actual movements
-corrects incorrect movements

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