DIVISIONS OF THE NERVOUS SYSTEM Flashcards
What are the 3 main types of neuron
Multipolar neuron
Bipolar neuron
Pseudounipolar neuron
Describe multipolar neurons
One axon Multiple dendrites Common Groups are called nuclei Inside the CNS
Describe bipolar neurons
Single axon
Single dendrite
Uncommon, except in special sensory pathways
Inside CNS
Describe pseudounipolar neurons
Single process leaves the cell body and divides in two
Mainly general sensory neurons
Cell bodies grouped in ganglia
Exist outside of the CNS within the PNS
What are afferent neurons
Sensory
Carry impulse towards the CNS
What are efferent neurons
Motor
Carry impulses away from the CNS
What are interneurons
Relay
Connects two points of the CNS
Give 5 examples of sensory neurons
Chemoreceptors Pain receptors Thermoreceptors Mechanoreceptors Photoreceptors
How do you go from a stimulus to nerve impulse
Stimulus detected
Causes influx of Na+ into neuron, if this causes a change equal to or greater then threshold potential, voltage-gated Na channels open
This allows more Na to diffuse into cell depolarising the membrane
Causing an action potential to begin
What are the main structural divisions of the nervous system
- Central nervous system (CNS)
- Peripheral nervous system (PNS)
- Enteric nervous system (ENS)
What makes up the CNS
Brain and spinal cord
What structures makes up the PNS
Cranial and spinal nerves and autonomies
Nerves outside the CNS
What is the ENS
Enteric control and GIT
What are the different types of neuronal junctions
- synapses
- neuromuscular junctions
- neuroglandular junctions
What are synapses
Neurone-to-neurone
Can be excitatory or inhibitory in type
Only in grey matter
What are neuromuscular junctions
Neurone-to-muscle fibres
Always excitatory in case of skeletal muscle
What are neuroglandular junctions
Neurons-to-glandular cells
Most secretory glands
What type of neurones are multipolar
Efferent (motor) neurones
Interneurones
What are nuclei in terms of neurons
Groups of such nerve cell bodies in the CNS
What type of neurons are bipolar
Afferent (sensory ) neurons Restricted mainly to the special sensory pathways: -vision -taste -hearing -balance
What type of neurones are (pseudo)unipolar neurons
General sensory neurones
What are ganglion
Collection of nerve cell bodies in peripheral nervous system
What are intumescences
Physical enlargement of cord due to having lots of motor neurons.
Give an example of intumescences in the body
- cervical enlargement- forelimb
- lumbar enlargement - hindlimb
How do spinal nerves exit the spinal cord
Through the intervertebral foramina
How do we name spinal nerves
Cervical- named by the vertebrae behind them except the C8 nerve which roots caudal to C7
All others-named by the vertebrae above them
Why are there is a C8 root and only 7 Cervical vertebrae
During evolution C0. And C1 fused so C1 root exits through the atlas (C1 vertebrae )
What are the sections of the spinal cord and what do they contain
- Dorsal median septum/ventral median fissure
- White matter- dorsal columns ascending (sensory) tract and ventral columns descending (motor) tract
- Grey matter- neurons, synapses, dorsal horn-sensory neurons, lateral horn- atomic neurons, ventral horn- motor neurons
- central canal (continuous with ventricles in the brain)
What are the two main components of spinal nerves
Roots
Rami
What fills the vertebral canal once the spinal cord terminates
The cauda equina
Where do we administer epidurals
Into the space around the nerves of the cauda equina
What are the 3 sections of the brain
- cerebrum
- cerebellum
- brain stem
Where does the dog spinal cord terminate
L6/7
Where does the cat spinal cord terminate
S3
Where does the horse spinal cord terminate
S1
Where does the cow spinal cord terminate
L7
