Nervous System Organization and Spinal Cord Flashcards
What is a dendrite?
Highly branched processes that typically function as the “receiving end” for information coming to the neuronal cell body
What is an axon hillock?
point of axon origin from the cell body
What is an axon terminal?
where the neuron communicates with other cells
What is an axon?
A single process arising from the
neuronal cell body that carries information away from the cell body toward other cells
What is a neuronal cell body? (soma)
Neuronal cytoplasm contains organelle
that provide energy and synthesize chemical signaling molecules (neurotransmitters) that are critical in cell-to-cell communication.
Define synapse
the specialized site of the axon where the neuron communicates with another cell
What do synaptic vesicles do?
filled with chemical neurotransmitters that are released upon stimulation
What is a synaptic cleft?
narrow gap between pre- and post- synaptic cells into which neurotransmitters are released
What are bipolar neurons?
have two distinct processes – one dendrite and one axon. They are found in special sense organs where they relay information about sight, smell or hearing.
What are unipolar neurons?
have a dendrite and axon that are basically continuous. This is the typical shape of sensory neurons of the peripheral nervous system.
What are multipolar neurons?
have two or more dendrites and an axon. They are the most common type of neuron. This is the typical shape of a motor neuron controlling skeletal muscles.
What are the 5 functions of astrocytes?
• help to create and maintain the blood-brain barrier that isolates the CNS from substances circulating in blood • Provide structural support • Regulate ion, nutrient and dissolved gas concentrations in fluid surrounding neurons • Take up and recycle neurotransmitters • Form scar tissue after neural injury
What are the 6 functions of microglia?
• Migratory cells that continuously move through neural tissue
• Scavenge and remove cellular debris, wastes and pathogens by phagocytosis
• Help to remodel synapses
• Fight microbes and cancer
• Repair trauma
• Respond to autoimmune
diseases
What are the 2 functions of oligodendrocytes?
- Provide a structural framework in the CNS by stabilizing the positions of axons
- Produce myelin, a membranous wrapping around CNS axons that functions like insulation on a wire, increasing the speed of nerve impulse transmission
What is the function of a Schwann cell?
Produce myelin, a membranous wrapping around PNS axons that functions like insulation on a wire, increasing the speed of nerve impulse transmission
Participate in repair of damaged nerves in the peripheral nervous system
Where does the spinal cord end?
Between the L1 and L2 vertebrae
What is the cauda equina?
the spinal nerve roots that extend inferiorly beyond the tapered end of the spinal cord resemble a horse’s tail and are called the cauda equina.
How many vertebrae are there?
33
How many pairs of spinal nerves are there?
31
The C1 spinal nerve exits ________ the C1 vertebra pedicle and is somatic motor only.
ABOVE
The C8 spinal nerve exits _________ the C7 vertebra pedicle
BELOW
At all levels below, spinal nerves exit _______ the corresponding vertebral pedicle.
Below
What does the cervical enlargement innervate?
shoulder and upper extremity
What does the lumbar enlargement innervate?
pelvis and lower extremity
What is the conus medullaris
tapered end of spinal cord
What is cauda equina
Nerve roots extending beyond the tapered end of the spinal cord; bundle of nerve roots looks like a “horse’s tail”
What is filum terminale
Slender fibrous strand that extends to the coccyx providing longitudinal support to the spinal cord
What are the spinal meninges?
3 layers of membranes that surround the spinal cord and provide physical stability and shock absorption. They are continuous with the cranial meninges that surround the brain.
What are the functions of cerebrospinal fluid?
this fluid functions as a shock absorber and a diffusion medium for dissolved gases, nutrients, chemical messengers and wastes
In a lumbar puncture where is the needle inserted?
Between the 3rd and 4th lumbar vertebrae
What is gray matter
Contains the cell bodies of neurons and neuroglial cells
What is white matter
contains myelinated axons that are running in bundles carrying either information that is ascending toward the brain or descending from the brain.
What do dorsal roots do
carry sensory information into the CNS.
What do ventral roots do
carry motor information out of the CNS.
What do spinal nerves do
carry both sensory and motor information.
What is the directions of sensory information
IN over dorsal root; coming from sensory receptors
What is the directions of motor information
OUT over ventral root; going to skeletal muscles
Where are sensory neuron cell bodies located?
Dorsal root ganglion
