Nervous System Overview Flashcards
What are the functions of the nervous system?
- Communication
- Regulating internal events
- Organising behaviour (external)
- Information storage (memory)
- Sensations, perceptions, emotions
Which cells make up the nervous system?
Neurons and glial cells
Which cells are more numerous in the nervous system: glial cells or neurons?
Glial cells
What is the role of glial cells?
- Supportive nutritive role
- Responsible for myelin formation
- Schwann cells (peripheral NS)
- Oligodendrocytes (central NS)
What is the role of astrocytes?
Nutrition (nutrient supply to neurons in CNS)
What is the role of microglia?
Defence role
Phagocytic
What is the role of ependymal cells?
Involves in production of CSF (cerebrospinal fluid)
What is the role of oligodendrocytes?
Neuronal support and myelin formation in CNS
What is the role of Schwann cells?
Neuronal support and myelin formation in PNS
Name 5 types of glial cells
- Astrocytes
- Microglia
- Ependymal cells
- Schwann cells
- Oligodendrocytes
What are neurons?
- Excitable cells
- Generate and transmit signals
- Make connections through synapses
- Synaptic processing, memory
- Structure is related to function
What is the peripheral nervous system composed of?
Spinal nerves, cranial nerves
What is the central nervous system composed of?
Brain and spinal cord
Where do sensory pathways bring information from/to?
From periphery to CNS via afferent nerves
What are the 2 subtypes of afferent nerves?
Somatic afferents (conscious info), visceral afferents (non-conscious info)
Where do motor pathways bring information from/to?
From CNS to the periphery via efferent nerves
What are the 2 subtypes of efferent nerves?
Somatic efferent and visceral efferents (autonomic nervous system)
How many pairs of spinal cord nerves are there?
31
What are the 31 pairs of spinal cord nerves (broadly)?
8 Cervical Nerves 12 Thoracic Nerves 5 Lumbar Nerves 5 Sacral Nerves 1 Coccygeal Nerves
What type of axons does each spinal cord nerve contain?
Sensory and motor axons
Axons of each sensory nerve supply structures in a well-defined part of the body surface. What are these regions termed?
Dermatomes
What is a myotome?
A group of muscles that a single spinal nerve innervates
Motor axons supply blocks of muscle called ________
Myotomes
What is a nerve plexus?
A plexus of intersecting nerves
Composed of afferent and efferent fibres
How many pairs of cranial nerves are there?
12
What do cranial nerves do?
Provide sensory and motor nerve supply to head and neck structures
Where is the vagus nerve (CN X) distributed?
To the trunk
Which cranial nerves contain autonomic nerve fibres?
CN 3, 7, 9 10
Which 3 layers of a nerve cell does anaesthetic need to penetrate?
Epineurium, perineurium, endoneurium
Lidocaine is amphiphilic. What does this mean?
Has both hydrophilic and hydrophobic parts
What are afferent signals in somatic nerves associated with?
Sensations/perceptions
What do ‘somatic’ efferents control?
Voluntary muscle
What do ‘visceral’ efferents constitute?
The automatic nervous system (smooth muscle, cardiac muscle, some glands)
Describe A-alpha neurons
Myelinated
Some sensory neurons
Motor neurons
Describe A-beta neurons
Myelinated
Sensory neurons
Describe A-gamma neurons
Myelinated
A special form of motor neuron
Describe A-delta neurons
Sensory neurons
Describe C neurons
Sensory neurons
Some autonomic nerves
Why is local anaesthetic often used in conjunction with a vasoconstrictor?
Local anaesthetic works for a longer time if you reduce the amount of blood vessels in that area
