Intro to Neuro Flashcards
Parts of nervous system
1.CNS (brain and spinal cord)
2. PNS (nerves and ganglia)
Function of nervous system
-allow the animal to detect stimuli and to respond to changes in the environment
(External: temperature, pressure/pain,etc. ; internal: blood pressure)
Steps of nervous system
- Detect sensation (PNS)
- Integrate and interpret (CNS)
- Behavioural response (PNS)- Important because in vet med, this is the only thing that we can actually see and interpret
Neuron
-a cell body and its processes (axon and dendrites)
Nerve vs. Tract
- Nerve: A bundle of axons within the PNS (myelinated vs. unmyelinated)
- Tract: a bundle of axons within the CNS
Ganglion vs. nucleus
-Ganglion (“Knot”): collection of nerve cell bodies forming a gross enlargement outside of the CNS
-Nucleus: collection of cell bodies within the CNS
Peripheral nerves
-Sensory
-Motor
Sensory peripheral nerves
-afferent
-carrying to CNS
Motor peripheral nerves
-efferent
-carrying from CNS
Peripheral nerve
-a bundle of axons (mixture of motor and sensory)
**When we say “sensory” or “motor” nerve, it is indicating what type there is more of but there is actually both types
Synapse
-a structure/connection between 2 neurons that allows the transfer of information
Spinal cord
-the neural connection from the brain to the peripheral body
How do spinal nerves exit the CNS?
-spinal nerves exit the CNS via the intervertebral foramen
Sections of spinal nerves
-cervical
-thoracic
-lumbar
-sacral
-coccygeal
Cervical spinal nerves of dogs/cats
-8
-one more than vertebrae
Thoracic spinal nerves of dogs/cats
13
Lumbar spinal nerves of dogs/cats
7
Sacral spinal nerves of dogs/cats
3
Coccygeal spinal nerves of dogs/cats
-approx 5 (depends on short vs. long tails)
Where do spinal nerves arise?
Will arise from the corresponding spinal segments
-cranial spinal nerves emerge cranial to the bone (*Reason for 7 vertebrae and 8 spinal nerves)
-thoracic spinal nerves emerge caudal to the bone
Where do sacral segments occur?
within the vertebra of L5
Where does the functional spinal cord terminate?
-at the L6-7 vertebral junction
-can be one segment more caudally in smaller cats/dogs (less than 7kg)
-terminates closer to the L1 in humans
Spinal Nerves and Nerves of the PNS
-spinal nerves combine in certain regions to form the named nerves in the PNS
-ex. C7,C8, T1= radial nerve
-ex. L4,L5,L6=femoral nerve
Plexus or intumescence
Regions of the emerging spinal nerves that are closely associated and form a dense, intersecting network of nerves
-ex. brachial plexus/cervical intumescence
-ex. lumbosacral plexus/lumbar intumescence
Grey vs. white matter
-Grey: neuronal cell bodies
-White: myelinated axons
Greatest amount of white matter
-cervical region
Proportionally more grey matter
-lumbosacral region
Spinal cord enlargements
Spinal cord enlargements in the cervical (C6-T2) and lumbar regions (L4-S1)
-Intumescense corresponds to an increase in the number of cell bodies required to innervate and control the limbs
Cranial Nerves
-12 paired nerves emerging from the brain and brainstem
-not arranged segmentally
- function as sensory and motor to the head and neck
Nervous system breakdown
-CNS vs. PNS
- CNS (brain and spinal cord)
-PNS (cranial/peripheral nerves Sensory (afferents) vs. Motor (efferents)
-Motor (efferents) broken down into Somatic vs. Autonomic (visceral)
- Autonomic (visceral) broken down into Sympathetic vs. Parasympathetic
Motor Neuron components
-Dendrites
-cell body in CNS
-nucleus
-axon
-terminal axon branches
-axonal end feet/end plates (synapse on individual muscle fibers)
-motor output out of CNS
Sensory neuron components
-Cell body in PNS
-Axon into CNS and another axon out of CNS
-Sensory input into CNS
Similarities between motor and sensory neurons
- have portions located in the PNS with synapse into CNS
- myelinated axons
- long distance transmission of information
Differences between motor and sensory neurons
- motor neuron cell body is within CNS, sensory neuron cell bodies are within the PNS
- different embryological origins
◦ Sensory= neural crest
◦ motor=neural tube - opposite direction of signal transmission
Somatic and visceral nervous system
-Types of pathways within the peripheral nervous system
-Both have sensory and motor components
>sensory pathways are the same for both the visceral and somatic nervous system but Motor neurons are different
Somatic
-conscious sensation/skeletal muscle/voluntary
-eg. Feeling fingers, walking, etc
Visceral
-unconscious sensation/smooth or cardiac muscle/involuntary
-ex. pupil dilation, heart beating, GI digestion, etc.
-Motor=autonomic (sympathetic and parasympathetic)
Somatic Motor Neurons
-1 neuron
- Cell body in CNS, axon in PNS (synapse with muscle)
Visceral motor neurons
-2 neurons
-Pre-ganglionic cell body in CNS, Post-ganglionic ganglia in PNS
Autonomic Nervous System
-Contains both sympathetic (fight or flight) and parasympathetic (rest and digest)
Sympathetic component of ANS
-active
-located in thoraco-lumbar region
-adrenergic
-located everywhere
-synapse close to CNS, preganglionic fibres short
Parasympathetic component of ANS
-restorative
-located in cranio-sacral region
- cholinergic
- mainly visceral (organs)
- synapses close to action site, preganglionic fibres long
