Neural tissues Flashcards
(37 cards)
Role of afferent neuron
- Transmit sensory info to brain/spinal cord
Role of efferent neuron
- Motor neurons transmitting info from the brain to effector organ ie muscle
What is a ganglion
- Group of cell bodies outside CNS
Where are motor ganglia located
- Many motor ganglia are located in the sympathetic trunks, two long chains of ganglia stretching along each side of the vertebral column from the base of the skull to the coccyx, these are referred to as paravertebral ganglia
Where are prevertebral motor ganglia located
- Located near internal organs innervated by their projecting fibres, while terminal ganglia are found on the surfaces or within the walls of the target organs themselves
What are eccentric nuclei
- Eccentric nuclei aren’t in the centre
- Usually in smaller neurons
What type of ganglion is the dorsal root ganglion
- A sensory ganglion
What are the broadmann areas of the neocortex numbered between
- 1-52
- boundaries determined by cellular cortex
What does broadmann area 4 correspond to
- Primary motor cortex
What does broadmann area 17 correspond to
- Primary visual cortex
What are the protruding processes of a neuron also known as
- Neurites
What does arborization refer to
- Refers to the fact that the dendrite splits into branches that make it look like a tree
What are the two main factors that increase conduction velocity
- Myelin increases it
- Increase in diameter increases it
Describe the classification of neurons
- Multipolar
- Bipolar
- Unipolar
- All neurons have just 1 axon
- Majority of neurons have several dendrites ‘multipolar’
Where are pyramidal cells located
- Pyramidal cells are located in the neocortex
- Neocortex is the part of the mammalian brain involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning and language
What are the type of cells in the cerebellum
- Purkinje cells which are GABAergic
- Single layer of them in the cerebellum
What type of neurons are present in the dorsal root ganglion
- Pseudounipolar
- One axon
- One dendrite
Give an example of where bipolar neurons are present
- Retina
- One dendrite
- One axon
- least numerous
- Sensory neurons
Where are true unipolar neurons present
- Sensory cells such as rods and cochlear hair cells
How big is the gap of a chemical synapse on average
- 30nm
- Common throughout nervous system
- Signalling is not in retrograde direction(with some exceptions)
Give an example of divergent signalling
- Skin receptors
- A single neruon sends its output signal to many neurons
Give an example of convergent signalling
- Retina
- Multiple inputs influence a single neuron
What percentage of the brain is roughly composed of interneurons
- Brain is 80% interneurons
- Cortex is only 20-30% interneurons
How do interneurons receive signals from an alpha neuron
- Receive an excitatory collateral from the alpha neuron’s axon as they emerge from the motor root, and are thus ‘kept informed’ of how vigorously that neuron is firing
