L3 Introduction to the Nervous System Flashcards
What are nuclei in the central nervous system?
Nuclei in the CNS are functional clusters of nerve cell bodies. They give rise to functionally distinct regions in the CNS.
What is a tract, when referring to the nervous system?
Tracts are groups of axons that allow for communication between specific nuclei.
Fill in the gaps: \_\_1\_\_ cells (\_\_2\_\_) are excitable cells that communicate via electrical and \_\_3\_\_ signals. \_\_4\_\_ cells account for 90% of the cells in the nervous system and \_\_5\_\_ neurons.
1) Nerve
2) neurons
3) chemical
4) Glial
5) support
If a cell has a single process from the cell body, what is its structural classification?
Unipolar.
Very rare in humans - found in olfactory system and retina
Describe the structure of a cell that is classified as multipolar.
The cell has multiple (more than 2) processing coming from the soma (cell body).
One is the axon, the others are dendrites.
If a cell has 2 projections from the cell body, what is its structural classification?
Bipolar.
One of the projections is the axon and the other is a dendrite.
Describe the structure of a cell is classified as pseudo-unipolar.
A pseudo-unipolar cell has a single process from the cell body, but this projection splits into a distinct dendrite and axon.
Common structure for sensory neurons
What is an afferent neuron?
The neuron that takes the signal from a receptor to the CNS.
Most afferent neurons are pseudo-unipolar and have cell bodies that are in clusters called ganglia. These ganglia lie outside the CNS.
What is an efferent neuron?
The neuron that relays a signal from the CNS to the effector organ(s)
Fill in the gaps:
__1__ make up 99% of all neurons in the body. Located entirely in the __2__, they go between the __3__ and __4__ neurons and carry out functions within the brain.
1) Interneurons
2) CNS
3) afferent
4) efferent
What are the 5 types of glial cell, plus their function.
1) Astrocytes - support, nutrients, develop/maintain BBB
2) Microglia - small, mobile, macrophages for CNS
3) Ependymal cells - line cavities and fluid-filled spaces
4) Oligodendrocytes - form myelin sheath in CNS
5) Schwaan cells - form myelin sheath in PNS (only 1 schwaan per axon, though)
True or false:
Oligodendrocytes form myelin sheaths in the PNS
False. Oligodenrocytes form myelin sheaths around axons in the CNS.
Schwaan cells form myelin around axons in the PNS.
Fill in the gaps:
__1__ form myelin around axons in the CNS. Each __2__ forms myelin around the axon of just one neuron.
1) Oligodendrocytes
2) Schwaan Cell
Schwaan cells are loyal.
Fill in the gaps:
The nervous system is made up of two major constituents: the __1__ and the __2__.
1) central nervous system
2) peripheral nervous system
The central nervous system comprises of the __1__ and the __2__.
1) brain
2) spinal cord
The peripheral nervous system is subdivided into the __1__ (which gives rise to __2__ and __3__ function) and the __4__ (which is made up of the __5__ and __6__ nervous systems).
1) somatic
2) sensory
3) motor
4) autonomic
5) parasympathetic
6) sympathetic
The somatic nervous system (SoNS) has dual functionality. What are the two functions of the SoNS?
Sensory and motor.
Sensory (afferent nerves): communicates information about the environment (internal or external to the body)
Motor (efferent nerves): voluntary movement
What are four things protect the brain?
1) Skull
2) Cranial meninges
3) Cerebrospinal fluid
4) Blood brain barrier
What 3 things protect the spine?
1) Vertebral column
2) Spinal meninges
3) Cerebrospinal fluid
What are the three layers of the meninges (from most deep to most superficial)?
1) Pia mater (deepest)
2) Arachnoid mater
3) Dura mater (most superficial)
In addition to the meninges, what other layers or spaces protect the brain and spine?
Epidural space: between dura mater and vertebral canal (contains fat). Only present in the spine, as the dura mater around the brain is attached to the skull
Subdural space: between dura mater and arachnoid (contains interstitial fluid)
Subarachnoid space: between arachnoid and pia mater (contains CSF)
Roughly how much CSF do humans have?
100-150ml
True or false: CSF is normally clear. Cloudiness or discolouration indicates underlying pathology
True
Where is cerebrospinal fluid (CSF) produced?
Choroid plexus
Fill in the gaps:
Cerebrospinal fluid contains __1__ amounts of protein, glucose and potassium. It also contains relatively __2__ amounts of sodium chloride.
1) small
2) large
True or false: CSF maintains it’s own pressure in healthy individuals
True
How is CSF sampled?
Lumbar puncture (spinal tap)
Fill in the gaps:
The brain contains __1__ cavities called __2__, which are continuous with the __3__ - a long, thin cylindrical cavity that runs the length of the spinal cord.
1) four
2) ventricles
3) central canal
What are the four ventricles?
There are two lateral ventricles, which are the largest, and further down are the ‘Third Ventricle’ and ‘Fourth Ventricle’
True or false: In patients with neurodegenerative diseases, such as Alzheimer’s, the ventricles appear larger
True. As the brain degenerates, the ventricles increase in size.