Reflexes Flashcards
(29 cards)
Sensory Modality
Type of stimulus activating a particular receptor
touch, pressure, pain, temperature, light
Adequate Stimulus
Type of energy a receptor normally responds to
Causes a generator potential (mVolts)
Mechanoreceptors
Adequate Stimulus - Pressure, Stretch, Deformation
Activates Stretch-Sensitive ion channels causing ion flow across the membrane
Respond to mechanical stimuli
Proprioceptors
Mechanoreceptors in joints and muscles
Signal Body, Limb position and movement in space
Control Voluntary Movement
Nociceptors
Pain (Noxious) Stimuli - Tissue damage and heat
Free Nerve Endings
Transduction in Sensory Receptors involves?
Opening or Closing Ion Channels
Pacinian Corpsule
Senses Vibration
Ruffini Corpsule
Skin Stretch
Merkel Receptors
Sense steady pressure and texture
Meissners Corspule
Respond to flutter and stroking movement
Mechanoreceptor Adaptation
Respond only to change or novel event
Signal the onset of stimulus
Rapidly Adapting Receptors
Pacinian corpuscles
Meissner corpuscles
Slowly Adapting Receptors
Merkel’s Disks
Ruffini Endings
Non Adapting Receptors
Nociceptors - free nerve endings
Its Important not to ignore painful stimuli
Pacinian corpuscle Structure
A myelinated nerve with a naked nerve ending enclosed by a connective tissue capsule of layered membrane lamellae separated by fluid
Pacinian corpuscle Action
Mechanical Stimulus deforms capsule Nerve Ending is Stretched Ion Channels Open Local Depolirisation Generator Potential APs Fire Fluid Redistribution in capsule rapidly dissipates stimulus
Receptive field
Stimuli in a specific area activates somatic sensory neuron
Acuity
Ability to locate a stimulus on the skin and differentiate it from another closeby
Lateral Inhibition
Sharpening sensory information
In spinal cord for cutaneous information
Contrast bw relevant and irrelevant stimuli
Inhibition of Lateral neurons in 2ry neuron
High precision information components use it
Sensory Information goes?
Brain
Via thalamus to somatosensory cortex
Sensitive areas occupy greater cortical space
Muscle Spindles
Monitor Rate of change of muscle length and muscle length Control Reflexes and Voluntary movement Ends shorten but central area doesnt so it stretches In parallel to muscle fibres
Golgi tendon organs
Monitor tension.stretch on tendons
Stretch receptors
In series with muscle fibres
Joint Receptors
Monitor Joint angle, rate of angular movement and tension on the joint.
Intrafusal Fibers
Muscle Fibres with specialised sensory and motor intervention
Contained within a capsule
Central Area has no contractile material
Gamma Motor Neuron from CNS contract the ends contain contractile sarcomeres
