Cells of the nervous system and neuromuscular junction Flashcards
What are the roles of the frontal,temporal,parietal and occipital lobe?
Frontal-higher processing,feelings,emotions
Temporal-sound hearing
Occipital- visual processing
Parietal -motor and sensory processing
What does the brainstem consist of?
Midbrain, pons, medulla (descending order)
What is the role of the cerebellum?
Motor coordination, balance and posture
What are the 4 components of the CNS?
Cerebral hemispheres, brainstem, cerebellum and Spinal cord
what are the 4 types of neuron morphology
unipolar, pseudo-unipolar, dipolar, multipolar
what are the three types of multipolar neurons
pyramidal, purkinje and golgi (both of which are GABA neurons found in the cerebellum)
what are the 3 components of a neuron
soma, axon, dendrites
what is one key difference between an axon and a dendrite
axons are usually covered in myelin and dendrites are not
how many axons do neurons have
ONE
What is the most abundant cell type in the CNS
Astrocytes
What are the three functions of an astrocyte
cell repair (synthesis neurotrophic factors), homeostasis (neurotransmitter removal and uptake) , structural cells (blood brain barrier)
What is the function of an oligodendrocyte
produces myelin
what are the two differences between a oligodendrocyte and a schwaan cell
oligodendrocyte-CNS , schwaan-PNS.
oligodendrocyte myelinates parts of many axons. Schwaan cells only myelinate a segment of one axon.
what is the function of a microglial cell
immune function- similar to a macrophage
what is the function of the ependymal cell
epithelial cells- line fluid filled ventricles to control the movement and regulate the production of CFS
what are the 5 types of neuroglia cells
astrocytes, oligodendrocyte, schwaan cell, microglial, ependymal
what are the 4 major ions that affect resting membrane potential?
K+, Na+, Cl-, Ca2+
how do ions travel across the neuron’s cell membrane?
by channels and pumps
which ions are of high concentration OUTSIDE of the neuronal cell?
Na+, Cl-
which ion is there a high concentration of INSIDE of the neuronal cell?
K+
Which ion has a high concentration gradient?
Ca2+
What is the RMP usually ?
-70mv (between -40 to -90)
Is the outside or the inside of the neuronal cell more negative?
inside. charges are concentrated around the membrane
if the RMP is more negative ( eg -90mV), is the neuronal cell more or less excitable?
Less
At RMP are VGSC and VGKC open or closed?
closed
what happens during membrane depolarisation?
opening of VGSC, Na+ influx
what happens during membrane repolarisation?
opening of VGKC, k+ efflux. VGKC are slower at opening
how is the ion gradient restored?
using Na+-K+-ATPase (pump)
what happens during resting configuration?
Na+ enters vestibule (leaves cell) and upon phosphorylation- ions are transported through protein
what happens during active configuration?
Na+ removed from cell- K+ enters the vestibule (cell)
why does myelin prevent AP from spreading?
it has high resistance and low capacitance ( ability to store charge)
whats the term for when AP ‘jumps’ from one node of ranvier to another?
saltatory conduction
what are the 4 steps of neurotransmission that occur at the synapse?
1) propagation of an action potential
2) neurotransmitter release from vesicles
3) activation of post-synaptic receptors
4) neurotransmitter reuptake
what happens to the neurotransmitter once it dissociates from the receptors?
- metabolised by enzymes in synaptic cleft
- recycled by transporter proteins
what are the two types of communication between nerve cells?
autocrine(same cell) and paracrine(nearby cell)
what are the 3 types of synpatic organisation?
- axodendritic synapse
- axosomatic synapse
- axoaxonic synapse
at the neuromuscular junction is chemical communication unidirectional or bidirectional?
unidirectional
what is the neurotransmitter at the neuromuscular junction and what are the post synaptic receptors on the skeletal muscle?
acetylcholine (ACh)
nicotinic ACh receptors (nAChR)
what must happen to the end plate potential (EPP) for an AP to be generated ?
increase. need lots of miniature EPP to generate an AP.
what is the sarcolemma?
cell membrane of muscle cell
Describe the excitation-contraction coupling?
nAChR activation-> depolarisation->AP.
It then moves down T-tubules.
Sarcoplasmic reticulum releases Ca2+ following depolarisation.
Muscle contraction (myofibril)
what is the sarcoplasmic reticulum’s location, function and effect?
location: surrounds myofibrils-contractile units of muscle
function: Ca2+ storage and release following sarcolemma depolarisation
effect: myofibril contractions and muscle contraction
what occurs during the disorder botulism?
botulinum toxin: irreversible disrupts stimulation-induced ACh release form presynaptic nerve terminal ( acts on proteins which then prevent fusion of vesicles)
what occurs during the disorder Myasthenia Gravis and what are the effects?
autoimmune disorder where antibodies directly bind to MUSCLE TYPE nicotinic acetylcholine receptors.
causes fatigable weakness
what occurs during the disorder Lamber-Eaton myastenic syndrome (LEMS)?
autoimmune disorder where antibodies directly bind to VGCC on the presynaptic terminal. prevent calcium entry. causes fatigable weakness.
