呼吸系统的应激状态 英文课件课件

1、呼吸系统的应激状态- 英文课件 2 OBJECTIVES Use the knowledge to predict the response of the respiratory system to three physiologic stresses Exercise Ascent to altitude Diving 3 ?Identifies the physiologic stresses involved in exercise ?Predicts the responses of the respiratory system to acute exercise ?Describes

2、 the effects of long-term exercise programs (training) on the respiratory system 4 ?Identifies the physiologic stresses involved in the ascent to altitude ?Predicts the initial responses of the respiratory system to the ascent to altitude ?Describes the acclimatization of the cardiovascular and resp

3、iratory systems to residence at high altitude 5 ?Identifies the physiologic stresses involved in diving ? Predicts the responses of the respiratory system to various type of diving 6 EXERCISE AND THE RESPIRATORY SYSTEM Exercise increase Metabolism (the working muscles) the demand for oxygen the prod

4、uction of carbon dioxide lactic acid production the respiratory system the cardiovascular system 7 EXERCISE AND THE RESPIRATORY SYSTEM Acute Effects the effects of exercise in an untrained person are mainly a function of an increase in the cardiac output coupled with an increase in alveolar ventilat

5、ion 8 EXERCISE AND THE RESPIRATORY SYSTEM ?Mechanics of breathing ?Alveolar ventilation ?Pulmonary blood flow ?Ventilation-perfusion relationships ?Diffusion through the alveolar-capillary barrier ?Oxygen and carbon dioxide transport by the blood ?Acid-base balance 9 EXERCISE AND THE RESPIRATORY SYS

6、TEM ?Mechanics of breathing Elastic work of breathing Resistance work of breathing Moderate exercise Severe exercise 10 EXERCISE AND THE RESPIRATORY SYSTEM ?Alveolar ventilation Tidal volume Frequency Anatomic dead space Alveolar dead space (if present) VD/VT Moderate exercise Severe exercise 11 EXE

7、RCISE AND THE RESPIRATORY SYSTEM ?Pulmonary blood flow Perfusion of upper lung Pulmonary vascular resistance Linear velocity of blood flow Moderate exercise Severe exercise 12 EXERCISE AND THE RESPIRATORY SYSTEM ?Ventilation-perfusion relationships Ventilation-perfusion matching Ventilation-perfusio

8、n ratio Moderate exercise Severe exercise 13 EXERCISE AND THE RESPIRATORY SYSTEM ?Ventilation-perfusion relationships Distance up the lung top bottom rest exercise 1 2 3 V A / Q 14 EXERCISE AND THE RESPIRATORY SYSTEM ?Diffusion through the alveolar-capillary barrier ?Surface area ?Perfusion limitati

9、on ?Partial pressure gradients Moderate exercise Severe exercise 15 EXERCISE AND THE RESPIRATORY SYSTEM ?At the tissues Oxygen unloading Carbon dioxide loading Moderate exercise Severe exercise 16 EXERCISE AND THE RESPIRATORY SYSTEM PAo2 Pao2 Paco2 pHa Arteriovenous O2 difference Moderate exercise S

10、evere exercise or 、 17 Training Effects ?The ability to perform physical exercise increases with training ?Alterations in the cardiovascular system and in muscle metabolism rather than changes in the respiratory system ?The increase of maximal oxygen uptake is mainly a result of an increased maximal

11、 cardiac output 18 Training Effects ?Physical training lowers the resting heart rate and increases the resting stroke volume -inducing mitochondrial proliferation -increasing the concentration of oxidative enzymes - increasing the synthesis of glycogen and triglyceride 19 ALTITUDE AND ACCLIMATIZATIO

12、N PAo2 =PIo2-PAco2 /R+F PIo2 =0.21(PB-47torr) altitude (ft ) PB (torr) PIo2 PA co2 PAo2 15000 429 80.2 32 45 18000 380 20000 349 50000 87 63000 47 (the fluid in blood “boils”) 20 ALTITUDE AND ACCLIMATIZATION ? Acute Effects The symptoms are mainly due to hypoxia and may include: sleepiness decreased

13、 visual acuity laziness clumsiness a false sense of well-being tremors impaired judgment loss of consciousness blunted pain perception death increasing errors on simple tasks 21 ALTITUDE AND ACCLIMATIZATION ?Acute Effects Acute mountain sickness a group of symptoms include headache dizziness breathl

14、essness at rest weakness malaise nausea anorexia sweating palpitations dimness of vision partial deafness sleeplessness fluid retention dyspnea on exertion These symptoms are a result of hypoxia and hypocapnia, and alkalosis or cerebral edema, or both. 22 ALTITUDE AND ACCLIMATIZATION ?Control of bre

15、athing ?The decreased PAo2 and Pao2 result in stimulation of the arterial chemoreceptors rather than the central chemoreceptors ?Pao2 =45torr, minute ventilation is doubled ?Paco2 fall , causing respiratory alkalosis ?The pH of the cerebrospinal fluid increasing ?the central chemoreceptors is depres

16、sed by hypocapnia alkalosis 23 ALTITUDE AND ACCLIMATIZATION ?Mechanics of breathing ?Rate and depth of breathing ?Interstitial fluid volume of the lung (vc in the first 24h) ?More turbulent airflow, resistance work of breathing ?Maximal airflow rates , due to decreased gas density 24 ALTITUDE AND AC

17、CLIMATIZATION ?Alveolar ventilation ?The anatomic dead space , the reflex bronchoconstriction , the opposing effect of increased VT ?VD/VT (in any event) ?Previously collapsed or poorly ventilated alveoli will be better ventilated ?Regional distribution of alveolar ventilation more uniform 25 ALTITU

18、DE AND ACCLIMATIZATION ?Pulmonary blood flow Lung inflation Arterial chemoreceptor Sympathetic stimulation of the cardiovascular system Cardiac output Heart rate Systemic blood pressure Hypoxic pulmonary vasoconstriction Cardiac output Sympathetic stimulation of larger pulmonary vessels Pulmonary ar

19、tery pressure Right ventricular work load 26 ALTITUDE AND ACCLIMATIZATION ?Ventilation-perfusion relationships regional VA/Q more uniform 27 ALTITUDE AND ACCLIMATIZATION ?Diffusion through the alveolar-capillary barrier PAo2 PVo2 Partial pressure gradients The thickness of the barrier Pulmonary vasc

20、ular distention Higher lung volumes 28 ALTITUDE AND ACCLIMATIZATION ?Oxygen and carbon dioxide transport by the blood ?PAo2 to be below the flat part of the oxyhemoglobin dissociation curve , causing a low arterial oxygen content ?Hypocapnia aid in oxygen loading in the lung and interfere with oxyge

21、n unloading at the tissues ? the hemoglobin concentration (the first 2d) 29 ALTITUDE AND ACCLIMATIZATION ?Cerebral circulation ?Hypocapnia is a strong cerebral vasoconstrictor ?Hypoxia cause cerebral vasodilation and can cause hyperperfusion ?The hyperperfusion and cerebral edema elevate intracrania

22、l pressure ?Lead to increase in sympathetic activity in the body ?increasing the possibility of pulmonary edema and promoting renal salt and water retention 30 ALTITUDE AND ACCLIMATIZATION ?Acid-base balance hypocapnia respiratory alkalosis 31 ALTITUDE AND ACCLIMATIZATION ?Acclimatization see the fo

23、llowing four lists 32 Immediate Early adaptive (72H) Late adaptive (2 to 6 weeks) Spontaneous ventilation Minute ventilation Respiratory rate variable variable variable Tidal volume Arterial Po2 Arterial Pco2 Arterial pH Arterial HCO - 3 table1 33 Immediate Early adaptive (72H) Late adaptive (2 to 6

24、 weeks) Evaluation of lung function Vital capacity Maximum airflow rates Functional residual capacity Ventilatory response to inhaled CO2 Ventilatory response to hypoxia Pulmonary vascular resistance table2 34 Immediate Early adaptive (72H) Late adaptive (2 to 6 weeks) Oxygen transport Hemoglobin Er

25、ythropoietin P50 2,3-BPG Cardiac output table3 35 Immediate Early adaptive (72H) Late adaptive (2 to 6 weeks) Central nervous system Headaches, nausea, insomnia Perception, judgment Spinal fluid pH Spinal fluid HCO - 3 Cerebral edema table4 36 DIVING AND THE RESPIRATORY SYSTEM ?The major physiologic

26、 stresses involved in diving include ?Elevated ambient pressure ?Decreased effects of gravity ?Altered respiration ?Hypothermia ?Sensory impairment 37 DIVING AND THE RESPIRATORY SYSTEM ?The severity of the stress involved depends on ?The depth attained ?The length of the dive ?Whether the breath is

27、held or a breathing apparatus is used 38 DIVING AND THE RESPIRATORY SYSTEM ?Physical principles ?At a depth of 33 ft of seawater (or 34 ft of fresh water) , total ambient pressure is equal to 1520 torr ?Follow Boyles law, at 33 ft of depth (2atm) lung volume is cut in half ?According to Daltons law,

28、 the partial pressures of the constituent gases also increase ?According to Henrys law, the amounts dissolved in tissues of the body increase 39 DIVING AND THE RESPIRATORY SYSTEM ?Effects of immersion up to the neck (Mechanics of breathing) ?Averaging about 20 cm H2O ?Decrease FRC by about 50 percen

29、t ?ERV decreased by as much as 70 percent ?IRV is increased ?RV is slightly decreased ?VC and TLC are only slightly decreased ?The work of breathing increases by about 60 percent 40 DIVING AND THE RESPIRATORY SYSTEM ?Effects of immersion up to the neck (Pulmonary blood flow) ?Augmenting venous retur

30、n, by approximately 500ml ?Right atrial pressure increases from about -2 to +16 mmHg ?The cardiac output and stroke volume increase by about 30 percent ?Pulmonary blood flow and PAP increase ?Immersion diuresis (a few minutes,45folds) 41 DIVING AND THE RESPIRATORY SYSTEM ?Breath-hold diving (Mechani

31、cs of breathing) ?The total pressure of gases within the lungs is equal to ambient pressure ?The volume within the thorax must decrease proportionately ?Partial pressures of gases increase 42 DIVING AND THE RESPIRATORY SYSTEM ?Breath-hold diving The diving reflex ?Demonstrate a profound bradycardia

32、and increased systemic vascular resistance with face immersion (especially into cold water) 43 DIVING AND THE RESPIRATORY SYSTEM ?Breath-hold diving Gas exchange in the lungs ?Before a dive, PAo2 =120torr PAco2 =30torr ?During a breath-hold dive to a depth of 33 ft ?The transfer of oxygen from alveolus to blood is undisturbed ?vice versa, re