Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
Tactile receptors - 5 types |
Free nerve endings - sensitive touch, pressure Root hair plexus -monitors distortions and movement Merkel discs -fine touch, pressure receptors Meissners capuscles- sensations of touch, pressure and low vibration Pacinian corpuscles -deep pressure, fingers and genitalia Ruffini corpuscles -pressure and distortion of skin- deep |
|
|
Lateral inhibition |
This is where a Neuron which is excited will reduce activity in other neighbouring neurons Occurs in retina and skin also |
|
|
Mechanoreceptors |
A mechanical distortion (skin) causes opening of membrane and influx of ion channels- inflow of positive charged ions The actio potential transmits a signal to the cns |
|
|
Ocular muscles |
Intra ocular muscles- control pupil diameter Extra - move eyeball in socket and innervated with specific cranial nerves Paired extra ocular muscle action- both eyes together |
|
|
5 functional types of eye movements |
Gaze stabilising mechanisms; 1- optokinetic reflex 2- vestibular ocular reflex
Gaze shifting mechanisms; 3- saccadic movements 4- smooth pursuit 5- vergence movement |
|
|
Nystagmus |
Alternation between slow drift and rapid saccades Can be abnormal in those with leisons |
|
|
Vestibular ocular reflex |
Maintaining gaze position despite head movement Occurs from activation of the vestibular system Stabilise image on retina during head movements by producing eye movements in the opposite direction to preserve the image on the centre of the visual field Impaired = hard to read print Damage can lead to vestibular nystagmus Rotation of head= inhibitory signal to the extra ocular muscles, and excitatory on other side- compensatory movement Driven by vestibular apparatus in the inner ear |
|
|
Prepositus hypoglossi |
Involved with the vestibular ocular reflex - once the head stops moving, the vestibular system also stops - this keeps the neurons firing over and over to keep the eyes in the same place |
|
|
Nystagmus |
Involuntary rhythmic shaking of the eyes Could be both unilateral or bilateral Or horizontal, vertical or combined Acquire or born
|
|
|
Superior colliculus |
A map of visual space Involved in the directing of eye movements to things in surround It is involved in saccades, fixation, smooth pursuit, vergence, It has inputs from cerebral cortex, inferior follicular, retina, basal ganglia and spinal cord Connected to many sensorimotor areas and it maps actions among these- orientations head and eye movements
It turns off the onmipause neurons - releasing oculomotor system from inhibition so eye can move- saccades occur after a hill of activity is reached
The superficial levels are only bothered with visual stimuli Deeper levels other modalities but also have motor neurons to control eye movements |
|
|
Proprioceptors |
Sense body position Based on mechanoreceptors in skin, tendons, muscles and joints Encoding for motion and posture Defence mechanisms to avoid pain IW his weren't working correctly and couldn't move well despite the connections still being there to move |
|
|
Muscle spindles |
Inside muscle Sensitive to change in length and rate of change When lengthening they can set off 2 reflexes - the muscle can get longer (mono synaptic reflex) which goes to spinal cord and onto lower motor neurons in the same muscle as the spindle (stretch reflex) This can lead also to automatic shortening of the muscle (a protective reflex)- knee jerk |
|
|
Golgi tendon organ |
This is inside the tendon Not for length- but is for tension Autogenic inhibition- after so much tension it will inhibit the muscle tendon to decrease tension Too much tension can lead to damage Inhibitory interneuron turns off the alpha motor neurons so the muscle relaxes and the tension is reduced |
|
|
Mono synaptic reflex arc |
Simple reflex system One sensory neuron and one motor neuron
Inform from sensory to motor across a single synapse in the spinal cord |
|
|
Negative feedback in control of muscle length |
Spinal reflex uses feedback to regulate muscle length, reliving the brain from posture monitoring The brain sets a desired length Alpha motor neuron is the feedback controller Controlling the muscles and joints Leading to an interaction in the envionwnt A negative feedback loops round to the muscle spindles as sensors These send information to the brain for desired length |
|
|
Gamma motor neuron |
Sets a reference value for feedback control and changes the sensitivity of the spindle Can tune spindle sensitivity (bag fibres which are sensitive to static or absolute muscle length) This can bias a spine towards being status or dynamic - regulating sensitivity during the contraction and important in regulating muscle tone |
