Lecture 2 - Nervous System I Flashcards
What is the CNS surrounded by?
Bone
What is the major division of the nervous system?
CNS
PNS
Describe the difference in the neuraxis of quadrupeds and humans
Quadrupeds: neuraxis runs horizontally
Humans: neuraxis is vertical and curved at the head
What is the neuraxis?
Rostro - Caudal axis
Rostro: head
Caudal: tail
What is the dorsal ventral axis?
What is the more common term for humans?
Dorsal: stomach
Ventral: back
More common is anterior and posterior
Describe the different terms for the sections that can be taken of the brain, and of the body more generally
Coronal
Sagittal
Horizontal
Ganglia (such as dorsal root, chain etc. ) belong to which division of the nervous system?
Peripheral
What are the meninges?
Protective layers over the brain
What are the three meninges?
Dura mater
Arachnoid mater
Pia mater
What type of tissue are the meninges?
Connective
What is CSF?
Where is it located?
Cerebrospinal fluid - protects the brain
Lies in the sub arachnoid space
How does CSF return to circulation?
It drains out of the subarachnoid space through arachnoid granulations into the superior sagittal sinus, which is located within the dura mater.
This blood then goes back into venous return
Where and how is CSF made?
How much per day?
Made in the ventricles by specialised vasculature called the choroid plexus
1/2 L per day
What are the four ventricles in the body?
Two lateral ventricles
Third ventricle
Fourth ventricle
What happens if CSF isn’t properly returned to circulation?
Babies: hydrocephalus
Increase in intra-cranial pressure –> cerebro vascular accident
How is hydrocephalus treated in babies?
Catheter drains the fluid
What is a haematoma?
Pooling of blood in the brain
What is the difference between white and grey matter?
White: axons are myelinated
What are the locations where a haematoma can occur in the brain?
Intracerebral: within brain tissue
Subdural - venous blood
Epidural - dura peeled away from skull, arterial blood
Where is white matter found?
Interior of brain
Exterior of spinal cord
Differentiate between the two types of transmission that occur within neurons and between neurons
Within neurons: electrical, fast
Between neurons: chemical, slower
What is a nerve?
Bundle of thousands of axons in the PNS surrounded by connective tissue
What are e connective tissue layers in nerves?
Epineurium
Perineurium
Endoneurium
What is a fascicle?
Sub-group of axons within a nerve, surrounded by the perineurium
What does the endoneurium surround?
A single axon
What is the role of astrocytes?
- Recycle neurotransmitters
- Maintain ionic composition of ECF
- Blood brain barrier
What type of cells are astrocytes?
Glial
What is the structure of the blood brain barrier?
- Many tight junctions
* Foot processes of the astrocytes
What is the blood brain barrier?
What does it do?
It is the largely impenetrable endothelium of the vasculature in the CNS
It lets only certain molecules into the interstitial fluid of the brain
What are the various types of nerve present in the body?
How many of each?
Cranial: 12
Spinal: 31
What are nerve plexes?
These are the nerves that supply the limbs in the cervical and lumar-sacral regions of the spinal cord
What are the different nerve plexes?
Cervical
Brachial
Lumbar
Sacral
What is the role of the cranial nerves?
- Sensory
- Motor
- Autonomic
of head and neck
Which nerves are in the thoracic segments of the spinal cord?
Intercostal nerves
Differentiate between afferent and efferent
Where do they enter and exit the CNS?
Afferent: towards CNS, Dorsal horn of spinal cord
Efferent: away from CNS, ventral horn
Where do the myelin sheaths come from?
Compare in CNS and PNS
CNS: Oligodendrocytes
PNS: Schwann cells
How is neuronal action potential conduction sped up?
Saltatory conduction, myelin sheaths around the axon
What situations could lead to an increase in intracranial pressure?
Haematoma
Tumour growth
Too much CSF
What is the difference between astroglia and astrocytes?
No difference
What are plexuses and where are they found?
Complex arrangements of nerve roots
Supply the limbs
Where do the cranial nerves leave the CNS?
11: brain stem
Cranial nerve I leaves from brain
