Flashcards in The Autonomic Nervous System Deck (18):
Describe the roles and components of the CNS and PNS.
The PNS conveys sensory information via sensory neurones...
... which is processed via interneurones of the CNS (spinal cord and brain)...
... motor neurones of the PNS produce motor responses.
What are the 2 branches of the PNS?
- Somatic: conscious perception and voluntary movement.
- Autonomic: involuntary movement and functions.
What are the 2 branches of the autonomic NS?
- Sympathetic: flight or flight
- Parasympathetic: rest & digest
What are the 3 major components of the brain?
1. Cerebral cortex
2. Cerebellum - fine motor control
3. Brain stem - more primitive (essential) control
What are nuclei in the CNS?
Collection of neuronal cell bodies
How many nerves lead of the spinal cord?
What are tracts in the spinal cord?
Bundles of nerve fibres
What tissue is the spinal cord made up of, and what is their associated function?
- Outer white matter (axons of nerve fibres) - info dissemination up and down cord.
- Inner grey matter (neurones) - info processing
What does the dorsal root of the spinal cord contain that the ventral root doesn't?
- Dorsal root ganglia
- Contain cell bodies of sensory neurones
Which type of neurones do the dorsal and ventral roots of the spinal cord conduct?
- Dorsal = sensory neurones
- Ventral = motor neurones
Compare the 3 types of neurones of the nervous system.
1. Sensory neurones (pseudo-unipolar)
- central cell body with just 1 short process: impulse can bypass body and travel faster.
2. Motor neurones (multipolar)
- terminal cell body with dendrites: receive and integrate info
- cell body has high metabolic demands - susceptible to motor neurone disease
Where are interneurones found? What is their function?
- Solely within CNS.
- Connect motor and sensory neurones - responsible for complex processing.
How are spinal nerve fibres compartmentalised?
- Some nerve fibres are unmyelinated, some are myelinated - surrounded by endoneurium.
- Fibre axons bunched together into fascicles - surrounded by perineurium.
- Fascicles held together by epineurium.
Which cells are responsible for myelinating neurones?
- Oligodendrocytes myelinate (multiple) axons in the CNS.
- Schwann cells myelinate (single) axons in the PNS. Can also be non-myelinating: support axons but don't electrically isolate them.
How do Schwann cells myelinate axons?
Envelops axon... spins around it - pushes cytoplasm away and becomes squashed... forms very dense myelin sheath that acts as a conductor.
Which 3 types of glial cells are found in the CNS?
What is the function of microglia?
- Have very fine processes that are constantly moving to detect pathogens/toxins in spaces between brain cells.
- When activated, retract processes and act as macrophages.