Introduction to the nervous system Flashcards
Label the structure of a neurone.
What is the function of a neurone?
-Receive info from sensory receptors & transmit info to other neurons or effector organs
- A single neurone can synapse with how many other neurones?
- Synapses are constantly being….
- We have approx … neurones in the human NS
- 1000s
- Created and destroyed
- 10(10)
What are the 3 types of neurones?
> Named after number of processes (axons/dendrites) leaving cell body
-A pseudounipolar neuron is a type of neuron which has one extension from its cell body.
What is the function of glial cells?
> Support the nervous system
* Provide nutrition, oxygen, insulation
What is the function of the following subtype of Glial cells?
- Astrocytes
- Ependymal cells
- Microglia
- Myelinating glia
> Oligodendrocytes -CNS
> Schwann cells -PNS
- Astrocytes: Forms the blood brain barrier, which acts as a very selective permeable membrane.
- Ependymal cells: Lines the ventricles of the brain
- Microglia: Primary immune cells
- Myelinating glia
> Oligodendrocytes - IN CNS: Insulate a lot of neurons at once
> Schwann cells - In PNS: Insulate one neuron at a time
In the CNS, what are found within the grey and white matter?
- Grey: Cell bodies & synapses
- White: Myelinated axons
connecting areas of grey matter
(Spinal cord is opposite to brain)
- How is the nervous system divided up structurally?
- How is the nervous system divided up functionally?
What are located within:
Nerves, Tracts, Ganglia, Nuclei?
Nerves: Location of axons in the PNS
Tracts: Location of axons in the CNS
Ganglia: neuronal cell bodies in the PNS
Nuclei: neuronal cell bodies in the CNS (grey matter)
What are the 3 ways the CNS is protected?
- Skull & vertebral column
- Meninges
- 3 protective layers between bone and CNS
-Holds the CNS in position and holds the CSF - Cerebrospinal fluid (CSF)
- Surrounds & floats CNS
- Shock absorber
- Within ventricles & subarachnoid space
What are the 3 layers of the Meninges, and what are their features?
- Dura mater - Most external, thick and tough layer
- Divided in Periosteal and inner Meningeaal layers - Arachnoid mater - Thinner layer
- Pia mater - Thinnest layer (almost invisible)
Label the following in meninges.
- Where can the CSF be found in the CNS?
- Where can the Subdural space be found?
- Between the Arachnoid mater and the Pia mater (the Subarachnoid space)
- Between the Dura mater and the Arachnoid mater
Describe the 3 components of the gross anatomy of the brain.
Brain:
1. Cerebrum – right & left cerebral hemispheres
2. Cerebellum – ‘little brain’
3. Brain stem – midbrain, pons, medulla oblongata
- What is the gross anatomy of the spinal cord?
- Name what the continuation of nerves is known as.
Spinal cord:
1. Extends from brain stem to L1/L2 IV disc
2. Below this, nerves continue as the cauda equina
- Where are the spinal enlargements found?
> Why do they exist?
- Cervical enlargement : C4 - T1
- Lumbar enlargement : L2 - S3
> The high number of nerves innervating the muscles and the skin of the limbs are present within these enlargements. (Cervical enlargements= Upper limb, Lumbar enlargement= lower limb)
Label the cross section of spinal cord.
Explain how the Spinal cord tracts are specifically organised. (White matter organisation)
-Axons are organised into functional groups
* Motor tracts descend
* Sensory tracts ascend
* All tracts decussate (cross the midline)
We have 31 spinal cord segments which give rise to pairs of spinal nerves.
What are the 5 types?
Why do we have 8 cranial nerves but 7 cervical vertebrae?
- Cervical nerves emerge superior to corresponding vertebrae
- Thoracic nerves emerge inferior to corresponding vertebrae
Describe the structure of peripheral nerves.
-Layers are continuous with meninges around CNS
> Endoneurium = surrounds individual myelinated axon (Continuous with pia mater).
> Perineurium = surrounds fascicles - bundles of neurons (Continuous with arachnoid).
> Epineurium = surrounds entire peripheral nerve (Continuous with Dura mater).
Label when the CNS meets the PNS.
What neurons do the mixed spinal nerves contain?
>Lesions in mixed spinal nerves lead to …
- Motor neurons (multipolar): cell bodies in CNS
- Sensory neurons (pseudo-unipolar): cell bodies in DRG
> Lesions in mixed spinal nerves lead to sensory & motor deficits
What is the spinal cord blood supply?
-Blood vessels are in subarachnoid space.
What is the spinal cord venous drainage?
> Typically 6 spinal veins: anterior, posterior, anterolateral, posterolateral
- Internal vertebral venous plexus drains into external vertebral venous plexus, which returns blood to either azygos system or lumbar veins to return to the heart.
> IMPORTANT: IVVP has no valves… metastasis of cancers
The autonomic nervous system has a pathway of 2 multipolar neurons.
Describe where you find the bodies in pre ganglionic and postganglionic.
1- Cell body of preganglionic neuron = in CNS
2- Cell body of postganglionic neuron = in PNS
- Where does the pre-ganglionic sympathetic nerves arise from?
- Where does the post-ganglionic sympathetic fibres arise from?
- Lateral horn of the spinal cord grey matter (T1-L2)
- Sympathetic chain
- Prevertebral ganglia
- Where does the pre-ganglionic parasympathetic fibres arise from?
- Where does the pre-ganglionic parasympathetic fibres exit the CNS?
- Where are post-ganglionic parasympathetic fibres found?
- Brainstem
S2-S4 sacral segments of spinal cord
2.
- Cranial nerves 3,7,9,10
- Pelvic splanchnic nerves S2-S4
- Postganglionic neurons = within walls of target organ
