1a Cells of the Nervous System Flashcards
What are the four lobes of the brain called?
Frontal, temporal, parietal and occipital
What does the frontal lobe do?
Executive functions like personality
What does the parietal lobe do?
Contains the somatosensory cortex for processing tactile information
What does the temporal lobe do?
Contains the hippocampus (short term memory), amygdala (behaviour) and Wernicke’s area (auditory and speech)
What does the occipital lobe do?
Processing of visual information
What is the function of the cerebellum?
Fine movement, balance and fine coordination
What is a soma?
A cell body (aka perikaryon)
What is a unipolar neurone?
Single cell body with 1 axonal projection
What is a bipolar neurone?
Single cell body with 2 projections (axon + dendrite)
What is a pseudo-unipolar neurone?
Single axonal projection splits into two
Cell body is not embedded into the axon
What are the three shapes of the multipolar cells?
Pyramidal, Purkinje and Golgi cells
What multipolar cell type is this?
Pyramidal
What multipolar cell type is this?
Purkinje
What multipolar cell type is this?
Golgi
What are dendrites?
Projections off the axon which receive signals from other neurones and are not covered in myelin
What is an astrocyte? And what is its function?
A highly abundant cell which is important in maintaining blood brain barrier and keeping the neurones in place
They function as structural cells and are known to play an important role in cell repair, synapse formation, neuronal maturation and plasticity.
What is the function of the oligodendrocytes?
They produce myelin in the CNS
How many cells do oligodendrocytes produce myelin for?
Myelinates many axons
What is the function of a Schwann Cell?
Functions to produce myelin for the peripheral nervous system
How many axons does one schwaan cell myelinate?
One
What are microglial cells?
They are the immune cells of the CNS
(similar to macrophages)
What are ependymal cells?
Epithelial cells lining the ventricles that regulate the production of cerebospinal fluid
How is resting membrane potential generated?
3Na+ pumped out for every 2K+ that are pumped in
Results in a high concentration of Na+ outside the neurone
Sets up a high concentration gradient so that Na+ can flow in to generate an action potential
Is the inside of the neurone more positive or negative than the outside?
More negative
What helps to move the NA+ and K+ ions to generate resting membrane potential?
The Na+/K+ ion pump (active transport so ATP dependent)
Which ions are in high concentration outside the neurone?
Na+ and Cl-
Which ions are in high concentration inside the neurone?
K+
What is the resting membrane potential?
-70mV
When the inside of the neurone becomes more negative, what is this known as?
Hyperpolarisation
When the inside of the neurone becomes more positive, what is this known as?
Depolarisation
What is the neuromuscular junction?
The junction between the motor neurone and muscle
Describe what happens at the neuromuscular junction?
- Action potential arrives at the pre-synaptic bouton
- Ca2+ ion channels open
- Ca2+ binds to NT vesicles containing ACh
- They diffuse and ACh released into synaptic cleft through exocytosis
- ACh binds to nicotinic ACh receptors on sarcolemma of skeletal muscle
- Action potential then travels down the T-tubules which runs close to the sarcoplasmic reticulum
- The depolarisation of the sarcolemma causes the sarcoplasmic reticulum to release Ca2+ which leads to muscle contraction
What is botulism?
When botulinum toxin disrupts the ACh release from the pre-synaptic terminal, leading to muscle weakness
What is the name of the condition where you produce autoantibodies against the nAChr’s on the skeletal muscle?
Myasthenia gravis
What is Lambert-Eaton Myastenic Syndrome?
An autoimmune disorder where you produce antibodies directed against voltage gated calcium channels
What is the difference between Myasthenia Gravis and Lambert-Eaton Myastenic Syndrome?
MG = antibodies against nAChrs
Lambert-Eaton = antibodies against voltage gated calcium channels
What are golgi cells?
GABA neurones found in the cerebellum
What are purkinje cells?
GABA neurones found in the cerebellum
What are pyramidal cells?
Cells with pyramid shaped cell bodies
What are the three common features of neurones?
Soma, axon and dendrites
What is the difference between dendrites and axons?
Dendrites are highly branched and are not covered in myelin
What can axons branch off into?
Collaterals
What are microglia?
Neuronal macrophages
At resting membrane potential, what happens to the voltage-gated Na+ channels (VGSCs) and voltage-gated K+ channels (VGKCs) ?
They are closed
What happens to the voltage gated sodium channels when the membrane undergoes depolarisation?
Sodium influx
What causes membrane repolarisation?
VGKCs opens at a slower rate and cause efflux of K+ from cell
What pump restores the ion gradients across the membrane of a neurone?
Na+/K+ ATPase pump
How does the myelin prevent the AP from spreading?
It high resistance and low capacitance
What are the nodes of ranvier?
Small gaps of myelin intermittently along axon
What is saltatory conduction?
The jumping of the AP between the nodes of ranvier
What is an axodendritic cell?
Connection between presynaptic terminal and a neuronal dendrite
What is a axosomatic synapse?
Connection between presynaptic terminal and neuronal soma
What is an axoaxonic synapse?
Connection between presynaptic terminal and neuronal axon
What type of communication occurs between nerve and effector cells?
Paracrine communication due to neurotransmitter release
What is the pathophysiolgy of Botulism?
Botulinum toxin (BTx) irreversibly disrupts stimulation-induced ACh release from presynaptic nerve terminal
What symptoms does myasthenia gravis cause?
Fatigable, painless muscle weakness that improves with rest
Severe facial weakness
What symptoms does Lambert-Eaton myastenic syndrome cause?
Generalised fatigue and weakness
What symptoms does botulism cause?
Difficulty swallowing
Muscle weakness
Double vision
Drooping eyelids
Blurry vision
Slurred speech
Difficulty breathing
