lecture 16 - nervous system organisation Flashcards
What are the two types of cells in the nervous system?
Neurons and glia
What are the key components of a neuron (4)?
Dendrites, cell body, axon, axon terminals
In the CNS, what is the name for a group of cell bodies?
Nucleus
In the CNS, what is the name for a bundle of axons?
Tract
In the PNS, what is the name for a bundle of cell bodies?
Ganglion
In the PNS, what is the name for a bundle of axons?
Nerve
In cerebral cortex or spinal cord, what is the name for an area made up of a group of cell bodies?
Grey matter
In cerebral cortex or spinal cord, what is the name for an area made up of bundle of axons?
White matter
What is the direction of information flow along a neuron?
From dendrites (input zone) to axon terminals (output zone)
What are the four ‘zones’ of a neuron?
Input zone, summation zone, conduction zone, output zone
What are the components of the input zone of a neuron?
Dendrites, cell body
What are the components of the summation zone of a neuron?
Axon hillock
What are the components of the conduction zone of a neuron?
Axon
What are the components of the output zone of a neuron?
Axon terminals
What is the function of the input zone of a neuron?
Receive chemical signals via synapses from pre-synaptic cells
What is the function of the summation zone of a neuron?
Sums together multiple chemical signals into a single electrical impulse (action potential)
What is the function of the conduction zone of a neuron?
Carrying electrical signals (action potentials) from the cell body to the output
What is the function of the output zone in a neuron?
Connect with input zone of other neurons or effectors, and communicate with neurotransmitters during a synapse
What are the 4 morphological types of neuron?
Multipolar, bipolar, unipolar, anaxonic
What a multipolar neuron?
A neuron with multiple input processes.
What is a bipolar neuron?
A neuron with 1 input and 1 output process only
What is a unipolar neuron?
A neuron with 1 process, which splits into the input and output regions
What is an anaxonic neuron?
A neuron that has no distinct axon
What are the types of glia found in the CNS?
Astrocytes, Microglia, Ependymal cells, oligodendrocytes
What is the function of astrocytes?
Supply neurons with nutrients and ensheath blood capillaries to regulate CNS blood supply. Control chemical environment by mopping up leaked ions and recycling excess neurotransmitters. Involved in injury response
What is the function of microglia?
They are immune cells that are able to engulf microorganisms and debris
What are ependymal cells?
Glia that line fluid filled spaces and have cilia that circulate cerebrospinal fluid.
Where are the cilia located on ependymal cells?
On the apical surface
How is cerebrospinal fluid circulated in the CNS?
Ependymal cells which have cilia
What is function of oligodendrocytes?
Support nerve fibres. Ensheath CNS axons with myelin which forms insulating sheath that increase conduction velocity
What is the key glial cell of the PNS?
Schwann cell
What is the function of Schwann Cells?
Support peripheral nerve fibres. Ensheath fibres with myelin to facilitate rapid conduction
What is the name for gaps between Schwann cells on the axon of a neuron?
Nodes of Ranvier
Is communication electrical or chemical at a synapse?
Chemical
What occurs at the pre-synaptic cell before/during a synapse?
Action potential travels down axon causes synaptic vesicles to release packets of neurotransmitter via exocytosis. These enter the synaptic cleft between the post-synaptic cell.
What occurs during/after the synapse at the post-synaptic cell?
neurotransmitters bind to receptors in the dendrites, which create electrical signals that sum at the summation zone, creating an action potential.
What is type of information flow when info flows from PNS to CNS?
afferent/ascending
What is type of information flow when info flows from CNS to PNS?
Efferent/descending
What are interneurons?
Neurons found exclusively in the CNS, that connect spinal sensory and motor neurons.
