Practical Questions Flashcards
What are the functions of mitochondria and ribosomes?
Mitochondria: energy (ATP) production
Ribosomes: translation of mRNA into polypeptide chains (and thus proteins)
What are synaptic boutons? What are the small circular structures they are full of?
Synaptic boutons are the contact points between axons and dendrites. The small circular structures in them are synaptic vesicles containing neurotransmitter.
What does the Electromyogram (EMG) represent in the reflex practical?
The muscle AP generated at the motor end plate
The electrical activity in the muscle fibre which results in the opening of Ca2+ gated channels in the SR
The electrical event that precedes mechanical contraction: excitation-contraction coupling
Motor unit activity (increases in size as larger MUs recruited)
The number of active motor units & their rate of activation
How is Henneman’s size principle reflected in the EMG trace of the muscle during voluntary movements?
Shown by small amplitude EMG spikes which gradually increase in size as the contraction proceeds and more force is required.
The decrease in force is represented by a gradual decrease in the amplitude of muscle action potentials.
What enables the increase in voluntary activation of the muscle to increase force?
[Henneman’s size principle]
Recruitment of small → large motor units
Place the statements in the correct order for the pathway in a di-synaptic reflex arc:
Receptor, muscle, motor neurone, sensory neurone, interneurone
Receptor
Sensory neurone
Interneurone
Motor neurone
Muscle
Why are neurones much larger than glial cells?
Neurones more metabolically & transcriptionally active so have much larger somas & nuclei (to contain all of associated machinery i.e., ribosomes, ER, Golgi)
What does Nissl stain mark?
Marks neuronal soma & nuclei
What does (Golgi) silver stain mark?
Neurofilaments in axons & dendrites
What does the Weigert stain mark?
Marks myelin
What lies within post-synaptic densities?
Receptors for NTs (& associated proteins - e.g., channels & G-proteins)
Scaffolding proteins
What is the function of the Nodes of Ranvier?
Facilitate saltatory conduction
(AP ‘jumps’ between nodes - allowing for faster conduction)
What are the functions of the paranodal loops?
Seal the internodal membrane from the node (to prevent current leakage)
Provide metabolic support
What do oligodendrocytes do?
Produce the myelin sheaths of the CNS
What are (some of) the functions of astrocytes?
Synaptic modulation (‘the tripartite synapse’ - via gliotransmitters)
Removal / buffering of excess NT
Formation of the BBB (glia limitans)
Axon guidance (mainly during development)
