Cells of the nervous system Flashcards
What are the 4 functional regions of the brain?
Frontal
Parietal
Temporal
Occipital
What does the brainstem consist of?
Midbrain
Pons
Medulla
What are neurons?
Main functional cells of the nervous system
What is the most basic type of neural cell?
Unipolar neural cell
Only one axonal projection
What is the second type of neural cell?
Pseudo-unipolar
Single axonial projection that divides into two
What is the third type of neural cells?
Bipolar
One axon but two projections from body
What is the fourth type of neural cells?
Multipolar
Numerous projections from cells body
e.g. pyramidal cells, purkinje cells
What are the 4 different types of neural cells?
Unipolar
Pseudo-unipolar
Bipolar
Multipolar
What’s the deal with neurons?
Excitable cells of CNS
Heterogenous morphology
Non-dividing cells
Share common features
What’s the deal with neurons?
Excitable cells of CNS Responsible for electrical transmission Heterogenous morphology Non-dividing cells Share common features
What is the function of the cell body?
Contains nucleus and ribosomes
Neurofilaments for structure and transport
What’s the deal with the axon?
Long nerve fibre that originates from soma at axon hillock
Can branch off into collaterals
Usually covered in myelin
What is an astrocyte?
Most abundant cells in CNS
Avle to proliferate
What are the functions of astrocytes?
Structural cell: holds neurones in place and created the blood-brain barrier
Cell repair: Synthesise neurotrophic factors
Homes
What are the functions of astrocytes?
Structural cell: holds neurones in place and created the blood-brain barrier
Cell repair: Synthesise neurotrophic factors
Homeostasis: Neurotransmitter removal and reuptake
What is an oligodendrocyte?
Cell that produces myelin
Numerous projections
One oligodendrocyte myelinated many axons
What are Schwann cells?
Produce myelin fo peripheral nerves
One Schwann cells myelinated one axon segment
What are microglial cells?
Specialised cells similar to macrophages
Perform immune functions
What are ependyma cells?
Epithelial cells lining the ventricles
What are the 4 types of neuroglia cells?
Astroccytes
Oligodendrocytes
Microglia
Ependyma
What are the 4 main physiological ions?
Potassium
Sodium
Chloride
Calcium
What is RMP?
Resting membrane potential
How can ions move through the membrane?
Channels and proteins
Which ions have a high extracellular concentrations?
Na+
Cl-
Which ions have a high extracellular concentrations in CNS?
Na+
Cl-
Which ions have a high intracellular concentrations in CNS?
K+
What is the RMP of neuronal cells?
/
What is the RMP of neuronal cells?
-40mv to -90mv
How is an action potential generated?
Voltage-gated Na+ and K+ are closed
Membrane depolarised: VGCS open, Na+ influx causes further depolarisation
VGKS open at a slower rate and causes efflux of K+ causes membrane repolarisation
What is saltatory conduction?
AP jumps between nodes of ranvier
What are nodes of ranvier?
Small gaps of myelin intermittently along axon
What are the main events at a synapse?
Propagation of action potential AP opens voltage gated calcium channels Neurotransmitter release from vesicles Neurotransmitter acts on post-synaptic membrane Activation of postsynaptic receptors?
What are the three types of synapses?
Axodendritic
Axosomatic
Axoaxonic
What are axodendritic synapses?
Connection between presynaptic terminal and neuronal dendrite
What are axosomatic synapses?
Connection between presynaptic terminal and neuronal soma
What are axoaxonic synpases?
Connection between presynaptic terminal and neuronal axon
Define neuromuscular junction
Specialised structure incorporating axon terminal and muscle membrane allowing unidirectional chemical communication between peripheral nerve and muscle
What happens at the neuromuscular junction?
Action potential propagated along axon Ca2+ entry ACh release into synapse ACh binds ti receptors of sarcolemma Change in end-plate potential
What’s the deal with the sarcolemma?
Skeletal muscle membrane
T-tubules continuous with sarcolemma and closely connected to sarcoplasmic reticulum
AP travel through T-tubules
What’s the deal with the sarcoplasmic reticulum?
Location: Surrounds myofibrils
Function: Ca2+ storage and release following sarcolemma depolarisation
Effect: Ca2+ causes myofibril and muscle contraction
Name three disorder of the neuromuscular junction
Botulism
Myasthenia Gravis
Lamber-Eaton myasthenia syndrome
How is Botulism caused?
Botulinum toxin irreversibly disrupts stimulation induced ACh release from presynaptic nerve terminal
How is MG caused?
Autoimmune disorder
Antibodies block ACh receptor
Causes fatigable weakness
How is Lamber-Eaton myasthenia syndrome caused?
Autoimmune disorder
Antibodies directed against VGCC
Prevents calcium entry
