Physiology

Front 1

SENSATION

Sensory Modalities

Back 1

General Senses:

Somatic senses - tactile, thermal, pain, proprioceptive

Visceral - smell, taste, vision, hearing, equilibrium

Front 2

SENSATION

Process of Sensation

Back 2

Stimulation of sensory receptor

Transduction of stimulus

Generation of nerve impulse

Integration of sensory input

Front 3

SENSORY RECEPTORS

Back 3

Microscopic:

- Free nerve endings - first order - bare dendrites - generator potential
= pain, temp, tickle, itch, touch

- Encapsulated nerve endings - first order - enclosed in connective tissue
= pressure, vibration, touch

- Separate cells - synapse with first order - specialized - receptor potentials
= hair cells for hearing & equilibrium, gustatory taste buds, photoreceptors

Front 4

LOCATION OF SENSORY RECEPTORS

Back 4

Exteroceptors:

- at or near external surface of body.
- external stimuli sensitive

hearing, vision, smell, touch, taste, pressure, vibration, temp and pain

Front 5

LOCATION OF SENSORY RECEPTORS

Back 5

Interoceptors/Visceroceptors:

- in blood vessels, viscera, muscles, nervous system
- conditions of internal environment
- not consciously perceived

Front 6

LOCATION OF SENSORY RECEPTORS

Back 6

Proprioceptors:

- muscles, tendons, joints, inner ear
- information on body position, muscle length & tension, joint movement & position

Front 7

SENSORY RECEPTORS - STIMULUS DETECTED

Back 7

Mechanoreceptors:
touch, pressure, vibration, proprioception, hearing, equilibrium

Thermoreceptors:
temperature

Nociceptors:
pain from chemical & physical damage

Photoreceptors:
light

Chemoreceptors:
chemicals in mouth (taste), nose (smell), BFs

Osmoreceptors:
osmotic pressure of BFs

Front 8

SENSORY RECEPTORS -
TACTILE

Back 8

Touch:
Meissner corpuscles (hairless), hair root plexuses, Merkel discs (tactile), Ruffini corpuscles (hands/soles)

Pressure:
Pacinian/lamellated corpuscle (multilayered connective tissue capsule enclosing a dendtrite - WIDELY DISTRIBUTED

Vibration:
Meissner & Pacinian

Itch:
Stimulation of free nerve endings by chemicals

Tickle:
Stimulation of free nerve endings by sensation

Front 9

SENSORY RECEPTORS -
THERMAL

Back 9

Cold receptors:
Free nerve endings
10-40º
below 10 = pain receptors

Warm receptors:
Free nerve endings
10-40º
above 40 = pain receptors

Front 10

SENSORY RECEPTORS -
PAIN

Back 10

Fast Pain:
Myelinated A fibers, Acute, sharp, pricking, Superficial

Slow Pain:
Unmyelinated C Fibers, gradual intensity, chronic, burning, aching, throbbing, Superficial and deep

Superficial Somatic:
skin receptors

Deep Somatic:
Skeletal muscles, joints, tendons, fascia

Visceral:
eg: kidney stone

Front 11

SOMATIC SENSORY PATHWAYS

Back 11

First Order Neurons:
somatic receptors into brain stem or spinal cord

Second Order Neurons:
impulses from brain stem and spinal column to the thalamus

Third Order Neurons:
impulses from thalamus to primary somatosensory area of cortex

Front 12

SOMATIC SENSORY PATHWAYS

Back 12

Posterior Column-Medial Lemniscus Pathway:

ascends 1st order nerve impulses to cerebral cortex for touch, pressure, vibration, conscious proprioception for limbs, trunk, neck, post-head, into spinal cord

Front 13

SOMATIC SENSORY PATHWAYS

Back 13

Anterolateral/Spinothalamic Pathway to Cortex:

ascends 1st order nerve impluses to cerebral cortex for pain, temp, itch, tickle from limbs, trunk, neck, post-head into spinal cord

Front 14

SOMATIC SENSORY PATHWAYS

Back 14

Trigeminothalamic Pathway to Cortex:

ascends 1st order nerve impluses to cerebral cortex for somatic sensations: tactile, thermal, pain, from face, nasal cavity, oral cavity, teeth