Organisation Flashcards
What is gray matter within spinal cord? What does it stain?
Consists of cell bodies in sensory motor nuclei
Stains up white
What is white matter within spinal cord? What does it stain?
Consists of axons carrying information to and from brain
Stains up dark
What is staining due to?
Amount of myelin
White –> mostly myelinated axons (stains up dark)
Gray –> mostly cell bodies (stains up white)
What is stain called?
Weigert’s stain
What is a group of nerve cells (neuronal cell bodies) in the CNS called? In the PNS?
A nucleus in the CNS
A ganglion in the PNS
What is a bundle of axons called in the CNS? In the PNS?
A tract in the CNS
A nerve in the PNS
What are ganglia?
Nodular masses of neuronal cell bodies (ganglion cells) and supporting neuroglia (satellite cells)
What are sensory ganglia?
Cell bodies of sensory (afferent) neurones
What are autonomic ganglia?
Cell bodies of motor (efferent) neurones
What are spinal nerves a mix of?
Motor (efferent) and sensory (afferent) fibres
What are the 3 connective tissue layers of peripheral nerves?
- Epineurium
- Perineurium
- Endoneurium
What does the epineurium cover?
Covers the whole peripheral nerve
What does the perineurium cover?
Covers a fascicle of peripheral nerve
What does the endoneurium cover?
Covers individual nerve axons
How are nerve fibres classified?
By fibre diameter and conduction velocity (greater axon diameter and extent of myelination = faster conduction)
Myelinated fibres are thick and have much higher conduction velocity than thin non-myelinated fibres
What does classification A (fastest), B, C refer to?
Motor fibres and some (non-muscle) sensory fibres
What does classification I (fastest), II, III, IV refer to?
Sensory fibres from muscle
What causes a range of normal Nerve Conduction Velocities?
Mixed fibre types
What is ‘latency’?
Time between 1st and 2nd electrode stimulation (during NCV test)
What is a specialised sensory receptors?
Terminals of sensory neurones
Site of stimulus action
How are sensory receptors classified?
- By location within body
2. By stimulus type detected
What are types of sensory receptors classified by location within body?
- Exteroreceptors –> external surface
- Interoreceptors –> internal organs
- Proprioreceptors –> internal, but concerned with position of muscle, tendons, joints
What types of sensory receptors are classified by stimulus type detected?
- Mechanoreceptors –> touch, pressure, vibration, stretch
- Thermoreceptors –> hot, cold, temperature change
- Photoreceptors –> light
- Chemoreceptors –> chemicals
- Nociceptors –> pain (usually chemicals)
Describe spinal cord reflex pathway
- Sensory receptor (stimulus action)
- Sensory neurone (transmits afferent along peripheral nerve to CNS)
- Integration centre (one or more synapses along interneurone within CNS)
- Motor neurone (conducts efferent impulses to effector organ)
- Effector (muscle fibre/gland responds to impulse)
How do receptor terminals of sensory fibre transmit signals to spinal cord?
Transmits signals along sensory (afferent) fibre in spinal nerve (via cell body in dorsal root ganglion and dorsal root), to the dorsal horn of the spinal cord segment
How do interneurones project impulses to motor neurones in spinal cord?
Interneurones in dorsal horn project axons down to motor neurone cell bodies in ventral horn. Motor (efferent) axons leave via ventral root and enter spinal nerve, to supply motor endings to limb skeletal muscles.
What is a fascicle?
Bundle of axons in PNS
What is located in dorsal ganglia?
Cell bodies of sensory neurones
What is located in ventral ganglia?
Cell bodies of motor neurones
What is a dorsal root ganglion?
Cluster of neurones (ganglion) located in dorsal root of spinal nerve (sensory)
What is a ventral root ganglion?
Cluster of neurones (ganglion) located in ventral root of spinal nerve (motor)
