Unit FourHuman PhysiologySection A1—c 2—g 3—h 4—b 5—i6—a 7—f 8—e 9—j 10—dSection BPassage 1I. Reading Comprehension1.What does physiology deal with?Physiology is the study of processes and functions in living organisms. It is a broad field that encompasses many disciplines and has strong roots in physics, chemistry, and mathematics. The scope of physiology ranges from the activities or functions of individual molecules and cells to the interaction of our bodies with the external world. An important part of physiology is understanding how different parts of the body are controlled, how they interact, and how they adapt to changing conditions.2.What are the common characteristics of different forms of cells?Though cells differ widely in form and function, they all have certain common characteristics. First, they are bounded by a limiting membrane, the plasma membrane. Secondly, they have the ability to break down large molecules to smaller ones to liberate energy for their activities. Thirdly, at some point in their life history, they possess a nucleus which contains genetic information in the form of deoxyribonucleic acid.3.Could you describe the functions of the right ventricle and the left ventricle?Contractions of the right ventricle propel deoxygenated blood through the lungs where it absorbs oxygen from the air, while the left ventricle pumps oxygenated blood returning from the lungs to the rest of body to supply the tissues.4.How do you understand the concept of balance in the human body?The concept of balance is very important to human body. It can be applied to any of the body constituents including water and salt. Intake must match requirements and any excess must be excreted to maintain balance. If balance can’t be maintained well, sickness even death may happen.5.What are two coordinating systems and how do they perform their functions?Two coordinating systems are the nervous system and the endocrine system. The nervous system coordinates the movements of the limbs and body, stimulates themuscles to contract, and senses muscle tension and limb position. The endocrine system helps adjust blood flow and the supply of various metabolic substrates to the working muscles. The endocrine system produces hormones which travel in the bloodstream to the cells upon which they exert a regulatory effect.6—A 7—A 8—D 9—B 10—DII. Vocabulary StudyPart A1—platelets 2—physiological 3—Extracellular 4—nitrogen 5—Indigestible 6—urinary 7—lymphatic 8—glycogen 9—deoxygenated 10—oxidationPart B1—excrete 2—Evolution 3—stabilize 4—locomotion5—notion 6—dysfunction 7—intricate 8—endowed9—liberate 10—exquisitelyIII. TranslationPart A1.The success of physiology in explaining how organisms perform their daily tasksis based on the notion that they are intricate and exquisite machines whose operation is governed by the laws of physics and chemistry.生理学成功地解释了生物体如何进行日常活动，基于的观点是生物体好比是结构复杂而灵巧的机器，其运行机制受物理和化学规律的调控。
2.Although it is helpful to study how each organ performs its functions, it isessential to recognize that the activity of the body as a whole is dependent on the intricate interactions between the various organ systems.虽然研究各器官如何行使功能很有益处，但我们必须认识到机体作为一个整体所做的活动依赖于各器官系统间错综复杂的相互作用。
3.If there is an excess of potassium in the extracellular fluid, the cardiac musclecells become too excitable and may contract at inappropriate times rather than ina coordinated manner.如果细胞外液中钾离子过多，心肌细胞的兴奋性增强，可能出现不规律收缩。
4. A negative feedback loop requires a sensor of some kind that responds to thevariable in question but not to other physiological variables.负反馈环是在机体出现紊乱时，通过感受器对出现的各种问题做出反应，而不是对其他生理变化做出反应。
5.Each functional structure contributes its share to the maintenance of homeostaticconditions in the extracellular fluid, which is called the internal environment.每个功能结构都在维持细胞外液稳态方面发挥其作用，这称之为内环境。
Part B1.血小板和血浆蛋白通过阻止伤口继续流血并修复伤口，从而维持机体的稳态。
(hemostasis)Platelets and plasma proteins control hemostasis, a process that stops blood loss after injury and promotes wound healing.2.钠钾泵将钠离子（Na+）主动转运至细胞外，钾离子（K+）转运到细胞内。
每3个钠离子被转运出细胞，就有2个钾离子被转运到细胞内。
(transport)A sodium-potassium pump actively transports sodium ions (Na+) to the outsideand potassium ions (K+) to the inside, with three Na+ moved out for every two K+ moved in.3.体内的水平衡由位于大脑下丘脑的渗透压感受器自动调控。
(regulate)Water is autonomically regulated by osmoreceptors located in the hypothalamus of the brain.4.营养物质和液体由小肠绒毛内的毛细血管吸收进入血液循环系统。
(absorb)Capillaries within the villi of the small intestine are sites where nutrients and fluids are absorbed into the circulatory system.5.所有的细胞每时每刻都需要氧气（O2），并不断排出二氧化碳（CO2）等代谢废物。