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The resting membrane potential of a cell is measured to be−70 mV in a solution with ion concentrations resemblingextracellular fluid. Which of the following manipulationswould result in a hyperpolarization of the cell?A. Reduction in the membrane permeability to sodium ionB. Reduction in the membrane permeability to potassiumionC. Influx of calcium ion through the cell membraneD. Increase in the extracellular sodium ion concentrationE. Increase in the extracellular potassium ion concentration2.
The rapid depolarization during phase 0 upstroke of theaction potential in neurons is caused by opening of:A.B.C.D.E.ligand-gated Ca2+ channels.voltage-gated Ca2+ channels.voltage-gated Na+ channels.voltage-gated K+ channels.voltage-gated Cl− channels.3. In the myelinated regions of an axon,A.B.C.D.E.internal resistance is reduced.membrane resistance is reduced.the space constant is reduced.membrane capacitance is reduced.conduction velocity is reduced.4.
When depolarization of an axon reaches the synapticbouton, release of neurotransmitter stored in presynapticvesicles is most closely associated with:A.B.C.D.E.influx of Ca2+.influx of Na+.efflux of Na+.influx of K+.efflux of K+.5. Which of the following is primarily a characteristic of endplate potentials at the neuromuscular junction, but not ofneuronal action potentials?A.B.C.D.Depolarization is rapidDepolarization to a potential of +40 mVUpstroke caused by opening of voltage-gated channelsCharge is carried by a single, large channel for Na+ andK+E. Repolarization is associated with increased K+conductanceCHAPTER 4: ORGANIZATION AND GENERALFUNCTIONS OF THE NERVOUS SYSTEM6.
The outermost tissue of the spinal cord is:A.B.C.D.E.white matter.gray matter.pia mater.the arachnoid membrane.dura mater.7. Cerebrospinal fluid circulating through the lateral ventricles, third and fourth ventricles, and the subarachnoid spaceis produced by:A.B.C.D.E.the arachnoid membrane.the choroid plexus.the lymphatic system.arachnoid granulations.the pia mater.8. Association pathways linking the two cerebral hemispheresare found in the:A.B.C.D.E.corpus callosum.anterior commissure.posterior commissure.hippocampal commissure.All of the above.9. Centers involved in integration of cardiovascular andrespiratory functions are mainly found in what region of thebrainstem?A.B.C.D.E.MidbrainPonsMedulla oblongataThalamusHypothalamusCHAPTER 5: SENSORY PHYSIOLOGY10.
Which type of mechanoreceptor responds best to lowfrequency stimuli such as flutter?A.B.C.D.E.Meissner’s corpusclesPacinian corpusclesMerkel’s disksHair follicle receptorsRuffini’s corpuscles94The Nervous System and Muscle11. Light reception by photoreceptors results in reduction ofpermeability of what ion?A.B.C.D.E.K+Na+Cl−HCO3−Ca2+12. The endolymph of the scala media resembles which bodyfluid in its composition?A.B.C.D.E.Interstitial fluidPlasmaCSFLachrymal gland secretionsIntracellular fluid13. During angular acceleration of the head, neurotransmitter release by hair cells within the ampullary crest of the semicircular canal alters the firing rate of afferent nerve fiber axonsthrough cranial nerve:A.B.C.D.E.IV.V.VI.VII.VIII.16.
The inhibitory efferent output of the cerebellar cortexemanates from which type of cell?A.B.C.D.E.Granule cellsGolgi cellsPurkinje cellsBasket cellsStellate cells17. Which of the following structures has as a primary function the regulation of the level of excitation in the motorcortex, resulting in smooth movement and maintenance ofposture?A.B.C.D.E.Limbic systemBasal gangliaThe medulla oblongataHypothalamusThe ponsCHAPTER 7: THE AUTONOMICNERVOUS SYSTEM18. Preganglionic nerve cell bodies in the sympathetic nervoussystem are located in the:A.B.C.D.E.cervical spinal cord.thoracolumbar spinal cord.sacral spinal cord.sympathetic chain ganglia.brainstem.CHAPTER 6: THE SOMATIC MOTOR SYSTEM14.
The knee jerk reflex is an example of a:A.B.C.D.E.stretch reflex.Golgi tendon reflex.flexor withdrawal reflex.bisynaptic reflex.polysynaptic reflex.19. Release of acetylcholine and subsequent binding to muscarinic receptors is the major mode of neurotransmission at:A.B.C.D.E.parasympathetic ganglia.neuroeffector junctions of the SNS.sympathetic ganglia.neuroeffector junctions of the PNS.All of the above.15. The most important descending pathway(s) for controlof fine motor movements originating in the cortex is (are)the:20.
β2-adrenergic receptors mediate which of the followingeffects of the sympathetic nervous system?A.B.C.D.E.A.B.C.D.E.pontine reticulospinal tract.medullary reticulospinal tract.lateral and medial vestibulospinal tracts.tectospinal and rubrospinal tracts.corticospinal (pyramidal) tract.Constriction of vascular smooth muscleIncreased cardiac contractilityDilation of bronchial smooth muscleDilation of the pupil (mydriasis)Sweat gland secretionSection3CARDIOVASCULARPHYSIOLOGYThe main function of the cardiovascular system is transport of gases, nutrients,and wastes.
It transports oxygen from the lungs to the rest of the body; carbondioxide to the lungs from tissues throughout the body; nutrients between sitesof absorption, utilization, and storage; and metabolic waste products fromthroughout the body to sites at which they are eliminated or recycled. Thecardiovascular system also has important roles in thermoregulation, defensemechanisms, endocrine system function, and embryonic development.
All ofthese roles are served by the continuous flow of blood, pumped by the heart, tocapillary beds, where exchange between tissues and blood takes place. Nearlyall living cells in our body are located no more than a few cell thicknesses froma capillary. In the following chapters, key concepts of cardiovascular physiologyare presented, from basic electrophysiological and biophysical principles, tointegrated mechanisms for control of cardiovascular system function.Chapter 8Overview of the Heart and CirculationChapter 9Cardiac ElectrophysiologyChapter 10Flow, Pressure, and ResistanceChapter 11The Cardiac PumpChapter 12The Peripheral CirculationReview Questions95This page intentionally left blank97CHAPTER8Overview of the Heartand CirculationThe main functions of the cardiovascular system are gas transport, nutrient delivery, and waste removal.
These functionsare dependent on circulation of blood, which requires structural integrity of the heart and vessels. In this chapter, themajor structural features of the human heart and circulationare presented.GENERAL SCHEME OF THE CIRCULATIONThe cardiovascular system consists of the heart, blood vessels,and blood. The overall circulation can be characterized as aseries circuit (Fig. 8.1), in which:■■■■oxygenated blood is pumped by the left ventricle intothe systemic arterial circulation,deoxygenated blood returns to the right atrium throughthe systemic veins,the right ventricle pumps this blood into the pulmonarycirculation, andreoxygenated blood subsequently returns to the leftatrium through the pulmonary veins.Thus, all of the oxygenated blood returning to the left side ofthe heart from the lungs flows through the systemic circulation, and all of the deoxygenated blood returning to the rightside of the heart is pumped to the pulmonary circulation forreoxygenation.
Within these circulations, the regional circulations are parallel to each other. For example, skeletal musclevascular beds lie in parallel to the renal vasculature. In boththe systemic and pulmonary circulations, arteries are the distributing vessels, supplying blood to capillary beds of the bodyand lungs, respectively. The veins can be considered collectingvessels for return of capillary blood to the heart; they alsoserve a reservoir function, whereby generalized venous constriction produces an overall rise in blood pressure, forexample during compensation for dehydration or blood loss.Of the total blood volume of 5 liters (L), more than 60% isfound in the systemic veins (see Fig. 8.1).STRUCTURE OF THE HEARTThe human heart consists of four chambers: the two muscularventricles and the two atria. High-pressure ejection of bloodinto the systemic circulation is accomplished by the action ofthe muscular left ventricle (Fig.
8.2). The interventricularseptum functions as part of the left ventricle in this pumpingaction. The right ventricle ejects blood at lower pressures intothe pulmonary circulation. The contraction of the left ventricle consists of constriction of the chamber and shortening ofthe heart from base to apex; the less forceful contraction ofthe right ventricle consists of a lateral to medial bellows-likemotion, with some shortening from base to apex. In the leftheart, backflow of blood into the atria is prevented by themitral valve between the left ventricle and atrium.
The rightventricle and atrium are separated by the tricuspid valve. Thechordae tendinae are tendons connecting the papillarymuscles to the mitral and tricuspid valves. The chordae tendinae and papillary muscles function to prevent eversion ofthe mitral and tricuspid valves into the atria during ventricular ejection, thereby preventing “regurgitation” of blood backinto the atria.
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