Flashcards in 1 Organisation of the Nervous System Deck (21):
Q: How is the nervous system structurally divided?
A: 2 parts
-central nervous system (brain and spinal cord)
-peripheral nervous system (nerves and ganglia outside the brain and spinal cord)
Q: What are ganglions?
A: clusters of neuronal cell body
Q: Draw a diagram summarising the organisation of the nervous system. Identify efferent and afferent flow.
A: brain and spinal cord = 1. CNS
3. sensory division // 4. motor division
5. autonomic motor division // 6. somatic (motor) division (spinal nerves and cranial nerves)
5 goes into
7. sympathetic division (spinal nerves only)
8. parasympathetic division (spinal nerves and cranial nerves)
go into 3
9. somatic sensory
10. autonomic sensory
9+10-> 3->2->1 (afferent)
Q: What is the PNS functionally divided into? (2-1,3)
A: Somatic (motor) PNS
-Controls motor and sensory function of the body wall e.g. skin and skeletal muscles
Autonomic Nervous System
-Has Sympathetic and Parasympathetic arms
-Also called: Visceral NS, Vegetative NS, Involuntary NS
-controls function of viscera (internal organs)
Q: Differentiate between efferent and afferent axons. What are interneurones?
A: efferent= propagate AP from brain and spinal cord to the periphery (motor neurones)
afferent= propogate AP towards brain and spinal cord from PNS (sensory neurones)
interneurones= CNS neurons that synapse with other CNS neurons within the brain and spinal cord (can be either of the top 2)
Q: How do axons enter and leave the CNS?
A: through pairs of spinal nerves and cranial nerves
Q: Name the 3 main parts of the brain.
A: 1. cerebral cortex (cerebrum)
2. cerebellum (hind brain)
3. brain stem
Q: Describe the cerebrum. (2)
A: -made of 2 hemispheres
-each receives sensory information from and controls movement on opposite of body
Q: What does the cerebellum control?
A: coordination of movement
Q: Describe the brain stem. (2) Function? Damage?
A: -most primitive part
-densely packed fibres
-regulates vital functions (eg consciousness and breathing)
-damage here can be fatal
Q: What is the spinal cord? Includes?
A: -string of nerve tissue from below brain to first lumbar vertebrae
Q: Where does the CNS end in terms of the spinal cord? What emerges from the spinal cord? what are they part of?
A: margins of spinal cord
dorsal and ventral roots (part of the PNS)
Q: What do spinal nerves contain? (3) How? What is the whole nerve surrounded by? components?
A: -both afferent and efferent axons = bundled into fascicles surrounded by perineurium
-tough epineurium capsule
-individual axons are also wrapped with myelin and endoneurium (though some are unmyelinated eg pain neurones)
Q: What is a neurone function? How?
A: transmit and receive AP/ stimulate target tissue eg induce contraction of smooth muscle/secretion from a gland
when AP reaches a neuronal chemical synapse -> neurotransmitters released by a presynaptic terminal bind to post-synaptoc receptors of the neuron/muscle/gland it is synapsing with
Q: Apart from neurones, name 4 other cell types essential to nervous system development, microanatomy and function.
A: glial cells
Q: How does regeneration differ between PNS and CNS? (3,4)
A: -axons in peripheral nerves can regenerate after injury
-recovery is often compromised by non-specific target reinnervation and aberrant axon sprouting (eg can lead to neuropathic pain)
-axons in CNS are unable to regenerate over long enough distances to be useful. This is because:
- presence of inhibitory molecules in the CNS but not in the PNS (e.g. differences in myelin)
-Absence of guidance cues that stimulate axon growth during development
-Some loss of intrinsic axon growth capabilities by the neurons
Q: Are neuronal cell bodies in grey or white matter? therefore the other?
white comprises ascending and descening axon tracts to and from the brain
Q: Is grey or white matter peripheral?
A: white is peripheral and grey is central
Q: What do sensory inputs activate? where? What occurs?
A: sensory neurones in the spinal cord grey matter
transmit AP upwards to sensory cortex of the brain (ascending tracts)
Q: Where do neurones in the motor cortex extend? What occurs?
A: -opposite direction to sensory inputs
-extend downward to synapse with spinal motor neurones
transmit AP for voluntary movement (descending tracts)