Integration of the nervous system Flashcards
Sensation v. Perception
Sensation - process initiated by stimuli
Perception - conscious awareness of those sensations
General senses - 2 groups
receptors distributed over a large part of the body
Somatic - sensory info about body and environment
Visceral - provide information about various internal organs; consistent of pain and pressure
Special senses
localized to specific organs that have specialized receptors (smell taste sight hearing balance)
3 criteria that classify sensory receptors
1) type of stimulus detected
2) location in the body
3) receptor structure
Mechanorecetors
respond to mechanical force (compression, behding, stretchign of cells)
Sesnes that use mecanoreceptors include touch, pressure, proprioception, hearing, balance
Chemoreceptors
Respond to chemicals
Smell and taste
Thermo receptors
respond to changes in temperature
Photoreceptors
respond to light, necessry for vision
Nociceptors
Pain receptors, respond to extreme mechanical, chemical, and thermal stimuli
Location classification of sensory receptors (3)
Cutaneous - skin > external env
visceroreceptors - viscera/ organs > internal env.
Proprioceptors - joints, tendons, and other connective tissue > body position, movement, and stretch/ force of muscle contractions
Free nerve endings
simplest and most common sensory receptors
unspecialized neuronal branches
widely distributed in body; epithelial and connective tissues
What does the cold receptor do?
increases rate of action potential production
FUN FACT // menthol also activates the cold recptor
10-15x more numerous than warm receptors
What does the warm receptor do?
increase rate of action potnetial production as skin temperature increases
3rd type of temperature receptor // responsible for extreme cold or heat, a type of pain receptor
Pain receptor
25 - 35 c is comfortable!
Merkel disk
flattened expansions at end of axons
Ligh touch and superficial pressure
Hair follicle receptor
wrapped around hair follicles
light touch, responds to very slight bending of the hair
Pacinian corpuscle
Multi-layered onion-shaped capsule w/ single central nerve process
deep cutaneous pressure, vibration, prioprioception
Meissner corpuscle
Several branches of single axon w/ specialized Schwann cells
Two-point discrimination (paperclip exercise)
More numerous in some areas of the body (tongue, hands) than others
Ruffini end organ
branching axon
continuous touch or pressure
Muscle spindle
3-10 striated muscle fibers enclosed by loose counties; Muscle tone
Golgi tendon organ
proprioception associated with stretch fo tendon; muscle contraction
Receptor potential
The potential produced after a receptor was stimulated
If large enough, it turns into an action potential and is propagated toward the CNS
Primary receptors v secondary receptors
Primary - sensory receptor cells that conduct action potentials in response to the receptor potential (most sensory neurons)
Secondary - no axons, produce receptor potentials (hearing and taste)
Adaptation
decreased sensitivity to a continued stimulus
Tonic receptors
Generate action potentials as long as a stimulus is applied // slow adaption
Phasic receptors
adapt rapidly; sensitive to changes in stimuli
Ascending spinal pathways
How sensory information is transmeitted via action potential to the brain
Names - first half gives origin and second half termination
Anterolateral System
Conveys cutaneous sensory info to the brain
3 tracts of anterolateral system
spinothalamic tract = perception of pain, temp, touch, pressure, tickle, itch
spinoreticular tract - pain and touch to other parts of the brain, where info not consciously perceived
Spinomesencephalic tract
How does the spinothalamic tract transmit sensory signals from peripheral receptors to the cerebral cortex?
Primary neurons - sensory receptor to the spinal cord
Secondary neurons - spinal cord to the brain, crossing contralaterally
Tertiary neurons thalamus to the somatic sensory cortex
3 major ascending spinal pathways?
Anterolateral
Dorsal-Column/ Medial lemniscal
Spinocerebellar
Dorsal-Column/Medial Lemniscal System
Responsible for perceiving - 2 point discrimination - proprioception pressure vibration
2 tracts of the dorsal-column/medial lemniscal system
1) Fasciculus gracilis > sensations above midthorax
Fasciculus cuneatus > sensations below mid throax
Trigeminothalamic Tract
Facial equivalent of the ascending nerve tracts
Spinocerebellar Tracts
Proprioceptive information to cerebellum > monitor movements and compare them with intended movements
Posterior spinocerebellar tract
The upper part of the body in thoracic and upper lumbar regions
Anterior spinocerebellar tract
Carries info from lower trunk and lower limbs
