Physiology Nervous System Advanced PDF

Physiology Nervous System Advanced 1. What is the relationship between action potentials and graded potentials? a) Two terms describing the same event b) Every graded potential causes an action potential c) Action potentials are initiated when the membrane is depolarised to threshold by a graded...

Physiology Nervous System Advanced 1. What is the relationship between action potentials and graded potentials? a) Two terms describing the same event b) Every graded potential causes an action potential c) Action potentials are initiated when the membrane is depolarised to threshold by a graded potential d) An action potential is the sum of several graded potentials 2. Why do voltage regulated K+ channels not need to inactivate? a) Because the equilibrium potential for K+ is lower than the threshold of the K+ channels (ca -60 mV) b) Because they are blocked by Na+ ions c) Because they are always open d) Because the equilibrium potential for K+ is higher than the threshold of the K+ channels (ca -60 mV) 3. Which feature of voltage-regulated ion channels is responsible for a neurons refractory period? a) K+ channel inactivation b) Na+ channel inactivation c) Na+ channel threshold d) K+ channel activation 4. What is the correct sequence of events during an action potential? I - Inactivation of voltage-gated Na+ channels II - Activation of voltage-gated K+ channels III - Activation of voltage-gated Na+ channels IV - Graded depolarisation to threshold V - Return to normal permeability a) I - II - III - IV - V b) IV - II - III - I - V c) IV - III - II - I - V d) II - IV - I - III - V 5. Why can an action potential not be initiated during the refractory period? a) Because voltage-gated K+ channels are inactivated b) Because the extracellular Na+ concentration is too low c) Because the mebrane is fatigued d) Because voltage-gated Na+ channels are inactivated 6. Why does continuous propagation of the action potential not occur in myelinated axons? a) Because the myelin sheath blocks the flow of ions across the membrane b) Because the myelin sheath conducts the electrical impulses c) Because myelinated axons do not contain voltage-gated ion channels d) Because myelinated axons are too large in diameter 7. Why do action potentials travel long distances while graded potentials do not? a) Becuase action potentials are larger b) Because a refractory period occurs c) Because action potentials are actively propagated d) Because of the myelin sheath 8. What determines the duration of an action potential? a) Stimulus strength b) Stimulus duration c) Cell type d) Neurotransmitter type 9. Which of the following CANNOT initiate a graded potential? a) Acetylcholine receptors b) Sensory receptors c) Spontaneous depolarisation d) Action potentials 10. Pick the correct statement. At a chemical synapse: a) Presynaptic and postsynaptic membranes are locked together by gap junctions b) Action potentials will always be propagated to the next cell c) Generally communication only occurs in one direction d) Only excitatory stimuli can be transmitted 11. What terminates transmission at the cholinergic synapse? a) Breakdown of acetylcholine (ACh) by acetylcholinesterase (AChE) b) Influx of Ca2+ into the synaptic terminal c) ACh receptors on the postsynaptic cell d) Blocking of exocytosis of ACh by noradrenaline 12. Pick the correct statement. Slow postsynaptic receptors: a) Are always inhibitory b) Are ideal for neuromuscular transmission c) May trigger more than one response in the postsynaptic cell d) Occur only in the central nervous system (CNS) 13. What function of neurons is performed by summation? a) Execution of motor commands b) Excitation c) Inhibition d) Integration of several different synaptic inputs 14. Why do alkalosis and acidosis affect neural impulse conduction? a) Because both states cause inflammation of cell membranes b) Because the concentration of H+ affects the potential difference across the cell membrane c) Because H+ ions block voltage-gated Na+ channels d) Because H+ ions bind to Na+ ions 15. Atropine binds to muscarinic acetylcholine receptors and prevents their activation by acetylcholine. This means it acts as an: a) Neuromodulator b) Neurotransmitter c) Agonist d) Antagonist 16. Selective serotonin reuptake inhibitors (SSRIs, Prozac) prolong the action of serotonin (5HT) at a synapse by preventing its removal from the synaptic cleft. This means they act as: a) Neuromodulators b) Neurotransmitters c) Agonists d) Antagonists 17. Parkinson's disease is caused by deficient dopamine pathways in the brain. It is therefore best treated with: a) Dopamine agonists b) Dopamine atagonists c) GABA d) Surgery 18. The tendon-stretch reflex can be classified as a: a) Autonomic reflex b) Monosynaptic reflex c) Visceral reflex d) Polysynaptic 19. Damage to which area of the brain would be expected to impair control of food intake? a) Hypothalamus b) Pons c) Cerebellum d) Medulla oblongata 20. Which of the following is part of the 'rest-and-repose' response? a) Decrease in heart rate b) Glucose synthesis and release c) Dilation of pupil d) Secretion of adrenaline