7More Blood Pressures: Pulse and Mean Arterial Pressures Figure 15-5: Pressure throughout the systemic circulation
8Pressure Respiratory Respiration involves 3 processes Ventilation/ breathing- bulk movement of air into and out of lungsGas exchange between air in lungs and bloodGas exchange between blood and tissues
11Lungs Alveoli- small air sacs So numerous that the walls are little more than a succession of alveoliAlveolar ducts end into alveolar sacs- chambers connected to about 3 alveoli300 million alveoli in each lungNO NEED TO SHAKE!!!
13Pleural Cavities Lungs are in thoracic cavity Lungs are surrounded by pleural cavityCavity lined with serous membrane called pleura- 2 partsParietal pleura- thorax, diaphragm, mediast.Visceral pleura- covers surface of lungPleural cavity- between pleurae, filled with pleural fluid, lubricate and stick pleurae together
14Ventillation 2 phases of ventilation Inspiration- inhalation Expiration- exhalationDue to changes in thoracic volume- changes in air pressure in lung
15Changing Thoracic Volume Muscles of inspiration- diaphragm, external intercostals, othersDiaphragm- dome shaped muscle separating thoracic cavity from abdominalMuscles of expiration- internal intercostals, abdominals
20Lung Recoil SADuring quiet expiration- recoil of lungs and thoracic wallLung recoil- due to elastic fibers and surface tension of fluid in alveoliTwo things prevent lung collapseSurfactantPressure in pleural cavity
21Surfactant Mixture of lipoproteins produced by epithelium Forms a thin layer inside lungsReduces surface tensionReduces tendency of lungs to collapse
22Pressure There are three important pressure in respect to breathing: atmospheric pressure- the pressure of the air around us. At sea level the atmospheric pressure is 760 mmHg, at higher altitudes the pressure is lower. intrapleural pressure- the pressure within the potential pleural space between the parietal and visceral pleura. Intrapleural pressure is always slightly below atmospheric pressure. This is called negative pressure because the elastic lungs are always tending to collapse and pull the visceral pleura away from the parietal pleura. The serous fluid, however, prevents separation of the pleural membranes.intrapulmonic pressure- the pressure within the bronchial tree and alveoli. This pressure fluctuates below and above atmospheric pressure during each cycle of breathing.
23Gas Exchange – partial pressure Diffusion of gases between alveoli and pulmonary capillariesDoes not occur in bronchioles, bronchi and trachea = dead spaceDiffusion is dependant upon the partial pressure of that gasPartial pressure is very similar in concept to concentration
25Carbon dioxide Plays a vital role in pH balance CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-
26Chemical controlIncrease in pH = decrease in CO2 = decrease in ventilation = increase in CO2 = decrease in pHDecrease in pH = increase in CO2 = increase in ventilation = decrease in CO2 = increase in pH
27Aquatic system Gas solubility CO2 higher solubility O2 low solubility TemperatureHigh temp – low solubilityLow temperature – high solubility
28Metabolic functionsHow can we measure indirectly the rate of photosynthesis?How can we indirectly measure the rate of respiration?
29Aquatic System Photosynthesis and Respiration Plants – higher rate of photosynthesis high concentration of DO and low dissolved CO2Plants – higher rate of photosynthesis lower concentration of DO and low dissolved CO2Global warming and partial pressures of gas