CNS and PNS Flashcards
Definition of central nervous system
Brain and spinal chord
Definition of peripheral nervous system
Sensory and motor neurones, axons, ganglia, supporting cells
Definition of ganglion
Nerve cell bodies of neurons lying outside CNS, collected into groups
Definition of nervous system
Orderly arrangement of neurons and associated cells
Control, adjust activities of systems
Sensory, motor neurones link CNS to peripheral structrues
Definition of multipolar neurone
Has a cell body, many highly branched dendrocytes
Definition of neuroglia cells
Non nervous support cells within CNS, each gas specific function
Definition of somatic nerves
Supply body wall, skeletal muscle, skin, contains motor, sensory fibres
Definition of autonomic nerves
Supply internal organs with motor (smooth), sensory fibres
Definition of spinal nerves
Mixed nerve, carried motor, sensory, ANS signals between spinal chord and body
31 pairs of spinal nerves
Definition of dermatome
Area of skin supplied by fibres from single nerve root
Associated with a specific nerve root
Definition of peripheral nerve
Made up of fibres from different nerve roots
Definition of myotome
Group of muscles that a single spinal nerve innervated
Definition of nerve plexus
Branching network of fibres
The nervous system function
Orderly arrangement of neurons and associated cells
Controls, adjusts activities of systems
Sensory, motor neurones link CNS to periphery
Primary divisions of nervous system
CNS, brain, spinal chord
PNS, axons, ganglia, supporting cells
Components of neural tissue
Neurons, transmit impulses along cell membranes
Support cells, regulate tissue fluid, bring nutrients
Properties of neurons
No capacity for cell division Limited repair capacity Vary in length, mm-m Many RER for protein synthesis Multipolar neuron, has cell body and many dendrocytes
Types of dendritic processes, synapses
Many different types of synapses, can be inhibitory/excitatory
Support cells
Neuroglia cells, non nervous support cells in CNS Astrocytes Oligodendrocytes Microglia Ependymal cells
Function of astrocytes
Maintain blood brain barrier
Contain microfilaments, gives structural strength to CNS
Stabilise structure after injury, produce scar tissue
Direct neural growth during development
Control interstitial environment, recycle neurotrasmitters
Description of astrocytes
Processes in contact with neurons and capillary walls
Function of microglia
Similar to macrophages and monocytes, just in brain
Many cytoplasmic processes
Function of ependymal cells
Line chambers, CNS pathways
Filled w CSF, monitor it
Description of ependymal cells
Branching processes, contact other glial cells
Function of oligodendrocytes
Processes in contact with axons, either
Wrap them together
Form myelin to improve conducting velocity of axons
Neuroglia cells of PNS
Cell bodies in ganglia, supported by satellite cells
Axons supported by Schwann cells, either
Myelinated sections
Several axons enclosed in cell
Ganglia
Nerve bodies of neurons which lie outside CNS collated into ganglion, supported by satellite cells
Properties of sensory ganglia
No synapses
Pseudounipolar
Postganglionic axons are myelinated
Properties of motor ganglia
ANS controlled, multipolar
Unmyelinated
Preganglionic axon mostly myelinated
Post ganglionic axon unmyelinated
What supports and protects the brain and spinal chord
Bony cranium
Cerebral column
Meninges
How is the brain and spinal chord protected
Rigid barrier between internal, external environment
Structure of the meninges
Dura mater
Arachnoid mater
Pia mater
Properties and function of dura mater
2 layered structure, outer periosteal layer lines cranial cavity
Folds in inner meningeal layer supports brain
Venous sinuses run in gaps between layers
Properties and function of arachnoid mater
Covers brain surfaces, contains meshwork of collagen, elastic fibres linking it to pia mater
Filled with CSF
Properties and function of pia mater
Tightly attached to brain by astrocytes, follows contours of brain
Description of the peripheral nervous system
Cells bodies present in PNS organized into ganglion
Axons here, collected into bundles called nerves
Axons to CNS, supply motor fibres to muscles and collect sensory info
Subdivisions of the PNS
Somatic nerves
Nerves of special sensation
Autonomic nerves
Function of somatic nerve
Supplies body wall, skeletal muscle, skin, contains both motor and sensory fibres
Function of autonomic nerves
Supply internal organs with motor (smooth) and sensory fibres
Synapses in PNS
All cell bodies outside CNS in ganglia, no synapses
Somatic nerves, special senses, referred to spinal nerves
All motor ganglia in ANS, always have synapses
The spinal nerve and spinal cord length difference
Spinal cord ends shorter than spinal nerves, continue down
Spinal nerve distribution in dermatomes
Area of skin supplied by fibres from single nerve roots
No of dermatomes
30
No of cervical spinal nerves
C2-C8
No of thoracic spinal nerves
T1-T12
No of lumbar spinal nerves
L1-L5
No of sacral spinal nerves
S1-S5
Plexuses
Network of nerves that seem tangled, mainly serve limbs
Fibres come from several spinal nerves
Limbs receive innervation from more than 1 spinal nerve, backup in injuries
