Theme 3 Flashcards
How do the mechanoreceptors function?
Detect physical changes in their receptors
Define encapsulated
Free nerve ending wrapping around the hair
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Hair Follicle Receptors
- A-beta
- Motion & direction
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Free Nerve endings
- A-beta & C fibres
- Pain
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Meissner corpuscle
- A-beta
- Tap & Flutter (5-40hz)
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Merkel cells
- A-beta
- Touch & Pressure
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Pacinian corpuscle
- A-beta
- Vibration 60-30hz
- What is the type of sensory receptor shown?
- What type of sensory fibres does it use?
- What does it sense?
- Ruffini corpuscle
- A-beta
- Skin stretch
How does a rapid adapting receptor differ from a slow adapting receptor?
Rapid Adapting: ADAPTs = no maintained stimulus
- responds to the application and removal of a stimulus
Slow adapting: Slow adapting receptors remains active for the duration of a maintained stimulus.
List some example of rapid adapting and slow adapting receptors.
Rapid Adapting Receptor:
- Meissner Corpuscles
- Pacinian Corpuscles
Slow Adapting Receptors:
- Merkel cells
- Ruffini Corpuscles (Some hair follicle receptors for both)
Define Receptive field
area in which a nerve cell sends its receptors and can pick up information from the skin
What is Lateral inhibition?
Ability of activated neurones to inhibit neighbours - inhibiting the outside of a receptive field
In terms of the number of sensory receptors and size of receptive fields, how does the skin on the back of a person differ from the skin on the fingertips of a person?
Receptors on back are fewer with larger receptive fields.
Receptors on fingertips are more numerous with smaller receptive fields - highly discriminatory
What effect does the convergence of some pathways have?
Increases the efficiency and sensitivity to see something, but reduces the discrimination
What is the function of an Alpha-motoneuron?
Activation of skeletal muscle fibres
Branch extensively
What are the different musculature in the lower spinal cord?
Distal musculature: controls fine movements e.g. fingers
Proximal & Axial musculature: controls position
What is the difference in function between the muscle spindle and the golgi tendon organ?
Muscle spindle stimulates muscle contraction, whereas golgi tendon organ inhibits muscle contraction.
What would happen if the lower motor neurones are harmed?
Flaccid paralysis
What happens if the Upper motor neurones are harmed?
Spastic paralysis, as lower motor neurones are still active
Which reflex might be acting when an arm adjusts to carrying an increased load?
Which type of afferent fibres are involved in the stretch reflex?
Stretch reflex
1a fibres
Which reflex will act to release strain on a tendon when it is being overstretched? How?
Inverse stretch reflex/inverse myotatic reflex/ 1b tendon reflex
stimulates activation of the antagonistic muscle. Opposite to simple stretch reflex
How do tendon & stretch reflexes work together?
Oppossite effect to each other
Tendon damps down stretch reflex = prevention of excessive muscle contraction
What is a central pattern generator?
programmed movements (e.g. chewing, swallowing) regulated by local C.P.Gs in spinalcord/brainstem
What are each of the four brodman areas of the cortex responsible for?
Area 1: Cutaneous stimulus
Area 2: touch and proprioception (size and shape)
Area 3a: Proprioception
Area 3b: Cutaneous stimulus and Primary Somatosensory cortex
Where is the primary somatosensory cortex?
Postcentral gyrus
Where is the Secondary somatosensory cortex located?
Gyrus next to post-centre gyrus
Where are the upper motor neurones found?
Cerebral cotex
What are the direct pathways from Upper motor neurones to lower motor neurones?
Corticospinal tract
Corticobulbar tract
What happens if the direct & indirect pathways are damaged?
DP: Paresis (weakness), paralysis (total loss) Local reflexes will still be present, only damaged descending stuff not locally
IDP: Act on spinal reflexes - Damage: spastic paralysis
What is the corticobulbar tract responsible for innervating?
Motor nuclei of cranial nerves V, VII, XI, and XII
What is the ‘babinski sign’, and what does it indicate when present in adults?
stroking the sole of the foot causes an abnormal fanning of the toes and the extension of the big toe. There is damage to the direct pathway - upper motor neurons (corticospinal and corticobulbar tracts)
What does damage to the basal ganglia cause?
causes movement disorders – e.g. too much movement or too little movement depending on where damage is located
Define Reticular Formation.
What is the role?
Functions?
all the neurones, in pons or medulla, that are not in specific nuclei/ axons that are not in a specific pathway
Role:
- Lots of nuclei/area/clumps of nuclei, that send fibres up into cortex where they release neuromodulators – things that are not directly conveying information but excite stuff
- Down to spinal cord: where it controls patterned activity
Functions:
- Cranial nerve activity
- Slow pain conduction and modulation
- Voluntary movements
- Autonomic nervous system activity
- Respiration
- Sleep
Which 4 cranial nerves carry parasympathetic preganglionic fibres?
III, VII, XI, X
What is the nucleus of CNIII?
Edinger-Westphal nucleus
Where do all the pain fibres in the head & neck end up?
spinal trigeminal nucleus
What is tooth pain mediated by?
Plexus of Raschkow - central plexus in the pulp of each tooth
Where are A & C fibres found in the teeth?
A: dentine tubules
C: Centre of pulp
What is the Anterior Cingulate Cortex (ACC) responsible for in the processing of pain?
Emotional association with pain
Which nerve is responsible for initiating the Corneal reflex when the cornea is touched?
V1 - Opthalmic → Spinal nucleus of V → Facial motor nucleus → Orbicularis Oculi
Which nerve is responsible for initiating the gag reflex when the back of the oropharynx is touched?
Glossopharyngeal nerve → vagus nerve