Nervous System Flashcards
Basic Layout of Nervous System
CNS: Brain and Spinal Cord
PNS: Autonomic, Somatic
Autonomic: Sympathetic, Parasympathetic, Enteric
Which nerve roots do sensory and motor neurones accompany
Sensory- Dorsal
Motor- Ventral
Connective Tissue arrangement in nerves
Endoneurium- Around each nerve fibre
Perineurium- Around each fascicle
Epineurium- Between fascicles
Paraneurium- Separates nerves from surrounding structures
2 cell types in Nervous System
Neurons
Glial Cells
Types of glial cells?
Microglial
Ependymal
Astrocytes
Schwann, Oligodendrocytes
Schwann VS Oligodendrocyte in terms of location and myelination
Schwann- PNS, Wrap around one axon
Oligodendrocyte- CNS, Wrap around multiple axons
What are astrocytes, what do they do?
- Star-like structure, Control nutrient flow in CNS
- Perineurial feet carry nutrients from vessel—>Cell body—> Neurons
- Regulate impulses by releasing inhibitor glutamate
What are Microglial Cells, what do they do?
- Long, flat nuclei, many projections from soma
- Throughout CNS, develop into Macrophages
- Remove damaged nerve cells from brain, by sensing increased K+ and moving to area
What are Ependymal cells, what do they do?
- Found in centre of Grey Commisure, centre of spinal canal
- Apical surface has cilia and microvill
- Make and secrete CSF in ventricles
- Cilia move CSF through ventricles to spinal canal
- Microvilli absorb CSF for presenting pathogens to astrocytes and Microglial cells
Compare Grey and White matter
Grey:
Peripheral in brain (in ‘nuclei’)
Central in spine
Consist of Nerve cell bodies, non-myelinated neurons
White:
Peripheral in spine
Central in brain
Consist of myelinated neurons
What connects ventral and Dorsal horns
Grey Commisure (Contains interneurons)
What are Nissl bodies
In soma
Contain ribosomes and RER
What are the 4 Neuron TYPES
Motor- Long axon from Soma to target tissue
Sensory- Environmental signals to integrative centre
Integrative: In CNS, collate Info. (Pyramidal, Purkyne, Inter-Most common)
Anaxonic: Retina. Role in memory and recall. Take in and send out info by Retrograde Progression
What are the the neuron VARIATIONS
Multipolar: 1 axon, multiple dendrites. Most common, mostly in CNS
Unipolar: Single process leading away from soma
Bipolar: 1 axon 1 dendrite,
Anaxonic: Many dendrites, no axons
What is Retrograde Vesicle Transport
Dynactin gathers on microtubule, brings empty vesicles back to soma
Anterograde Vesicle Transport
Kineisin gathers on microtubule, empty vesicles and mitochondria bind to microtubule, and are carried to synapse.
Empty vesicle has enzyme on membrane that makes neurotransmitter as it travels along axon
How is toluidine blue stain used
Toluidine blue stains fat, so myelin and Schmidt-Lanterman Cells (Schwann cell cytoplasm no myelin) can be seen
How does Myelination occur
- Axon in groove is surrounded by Schwann cell
- Mesaxon membrane surrounds embedded axon
- Mesaxon membrane wraps around axon forming multiple layers
What is MS
• Relapsing, degenerative, autoimmune degeneration of myelin
Fatigue, slurred speech, mobility issues, constipation, urinary retention, numbness and tingling (Parasthesia)
What is Referred pain
Pain is perceived at a site distant to source of pain
Somatic VS Visceral Pain?
Somatic- From joints/ muscles/ bones/ soft tissues
Visceral- From internal organs
Major source of parasympathetic preganglionic input to thoracic and abdominal viscera?
Vagus Nerve (X)
Where are the Preganglionic neurones in CNS?
Sympathetic: Lateral horn, T1-L2 segments
Parasympathetic: Brainstem, S2-S4 segments
What are 3 ways sympathetic fibres are distributed to skin ?
- Synapse at level of entry: Preganglionic neurons synapse at same level
- Ascend the chain: Preganglionic neurons go up sympathetic chain, synapse at required level. Postganglionic neurons reach target via vascular walls
- Descend the chain: Preganglionic neurons go down chain, synapse at required level. Postganglionic neurons reach target via spinal nerves
What is the Sympathetic Chain
Chain of ganglia either side of spine
How do sympathetic fibres distribute to Abdominal Viscera
Preganglionic neurons traverse the chain
Synapse in a pre-aortic Ganglion
Postganglionics reach target via blood vessels
What are the 4 specialised parasympathetic ganglia in head?
Ciliairy: Receives Preganglionics from Oculomotor Nerve. Sends Postganglionics to Eye
Otic: From Glossopharyngeal Nerve, to Parotid Gland
Submandibular: From Facial Nerve, to Submandibular/ Lingual Glands
Pterygopalatine: From Facial Nerve, to Lacrimal Gland
