BIO181-06LC – Anatomy & Physiology I

BIO181-06LC, Fall 2016Anatomy & Physiology IEXAM 2 – EXTRA CREDITContextWhen you feel thirst, your instinct of self-preservation compels you to hydrate your body by drinking copiousamounts of Coca-Cola. To do this, your brain instructs your muscles to perform a specific set of movementswhich involve extending your arm, grabbing the glass, and bringing it close to your mouth to ingest the healthy,deliciously cold soft drink. The executive order is generated in the motor control centers of your cerebralcortex, which then relay this information to the motor tracts that travel down your spinal cord to the level of thecervical vertebrae, where a synapse is established with the motor neurons that innervate your brachialis,biceps brachii and triceps brachii muscles, which in turn contract or extend in order to perform fine-tunedmovement. This movement involves the action of the arm muscles on your forearm bones across the elbowjoint (for the sake of simplicity we will ignore the hand movements).Knowing:• that the synapse between the upper (spinal) motor neuron and the lower (peripheral) motor neuronrequires the neurotransmitter acetylcholine (ACh); and• that ACh binds its ionotropic receptor AChR,Explain with all possible detail the following sequence of events:a) the transmission of the nerve impulse from the upper to the lower (peripheral) motor neuronb) the generation and propagation of the nerve impulse through the peripheral motor neuronc) the events that occur at the neuromuscular junctions (NMJs) of all motor units involved in theprocessd) the events that follow NMJ activity and lead to contraction of muscle fibers at the brachialis, bicepsbrachii and triceps brachii muscles; don’t forget to point out which of these muscles exert the mainforce, and which ones add fine-tuning or opposing forcese) what are the structures involved in the transmission of tension from the contracting muscles to thebones in the forearm? Be explicit with the anatomy of muscles, bones and joints and its supportingstructures, including muscle origin and insertions, and proximal and distal articulationsf) what happens in the muscles after you have quenched your thirst and decide to relax your muscles?Provide evidence of your knowledge about the molecular processes involved, when pertinent. Forexample: generation of action potentials, in both neurons and muscle fibers, involves membrane depolarizationdue to opening of ion channels. You must specify what type of channels, the effect on channel opening onmembrane potential, how the membrane repolarizes and how the effect is propagated along the membrane,etc; same thing for neurotransmission at the NMJ, excitation-contraction coupling and all molecular eventsinvolved in the processes outlined above. Use the Amerman textbook as a guide and provide a completeanswer. No credit will be given to partially complete answers.You must hand-write this assignment. I will not accept typed work. There will be no limit on the number ofpages given the scope of this assignment, but I ask you to be mindful of both your time and mine when itcomes to the length of your submission.Deadline: Saturday, November 19, 11 AM (immediately after class). You might accrue up to 10 extra points(equivalent to 10 correct exam questions).