Week 4 and 5 Flashcards
Peripheral sensory info is needed to?
- Construct a map of our body
- Make adjustments to changes in the environment
- Helping control posture and sequences of movements
4 main receptor sites for sensing movement
Muscle
Tendons
Joints
Skin
Define muscle sense
- Sensory info arising in the muscles and tendons
Define Proprioceptio
Refers to all sensory inputs from the musculoskeletal system
Define kinesthesia
- The sense of the position and movements of limbs
- The ‘sixth sense’
Define rapidly adapting
- Receptors decrease firing rate while stimulus is applied at the same strength
Define slowly adapting
- Receptors continue to fire throughout the stimulus duration at the same or slower rates
Pacinian Corpuscle - rapidly or slowing adapting?
Rapidly
Define Ruffini Endings - rapid or slow
- Slowly adapting
- Responds to steady indentation of skin with sustained discharge
Meissner corpuscle - rapid or slow
- Rapidly adapting
- Higher activation threshold than Pacinian
Merkel’s Disc - rapid or slow
- Slowly adapting
- Signals changes in intensity and steady-state values
Free Nerve endings - rapid or slow
- Slowly adapting
- Simple receptor, unmyelinated
- Responds to noxious stimuli
Define receptive field
- Area of skin served by a sensory unit
define intensity discrimination
ability to judge stimulus strength
Depth of skin indentation = ?
tactile sensitivity
spatial discrimination
- where is it highest and lowest
- Differentiate between locations of point stimuli
- Two point discrimination test
- Highest in finger tips
- Lowest on back
spatial discrimination depends on what two things
Size and overlap of receptive fields
Define extrafusal fibres
Muscle fibres that do the work
- innervated by alpha motor neuron
Define intrafusal fibres
Modified muscle fibres gathered in small bundles and surrounded by a capsule
Muscle spindle densities
- where is the highest and lowest
highest
- hand, food, neck
- some leg muscles
Lowest
- shoulder
- thigh
Define golgi tendon organ
The Golgi tendon organ is a tree-like sensory ending enclosed in a spindle-like connective tissue capsule, that lies near the junction of a tendon with a muscle
4 type of joint receptors
Type 1 - 4
Explain each type joint receptors
Type 1: - Slowly adapting Type 2: - Large - Rapidly adapting Type 3: - Found in ligaments near capsule - High threshold and rapidly adapting - Resemble GTO Type 4: - Free nerve endings - Unmyelinated fibres
two afferent pathways?
Dorsal column pathway
Spinothalamic pathway
- lateral and anterior
3 function zones of the spinal cord
- Dorsal (posterior): sensory
- Ventral (anterior): motor
Middle - association
- Ventral (anterior): motor
Define interneurons
- provide excitatory & inhibitory connections between primary sensory neurons & motor neurons in the ventral horns of the same or opposite side
Explain reflex arc
- Sensory receptors (detect the stimulus)
- afferent nerve (conveys sensory signal centrally)
- Integrative synaptic centre (analyses sensory input)
- Efferent nerve (conducts motor output to periphery)
- Motor effector (carries out response)
3 reflex loop types
M1 - short loop
M2 - long loop
M3 - voluntary
3 inhibitory reflexes
GTO
Joint
Cutaneous
Define withdrawal reflex
Thewithdrawal reflexis a spinalreflexintended to protect the body from damaging stimuli.
Define knee jerk reflex
A sudden involuntary forward movement of the lower leg that can be produced by a firm tap to the tendon located just below the kneecap
Define cross extensor reflex
Thecrossed extensor reflexis a contralateralreflexthat allows the body to compensate on one side for a stimulus on the other. For example, when one foot steps on a nail, thecrossed extensor reflexshifts the body’s weight onto the other foot, protecting and withdrawing the foot on the nail.
