P15 Respiratory System, Part Gas Exchange Oxygen and Carbon Dioxide constant need for oxygen constant production of carbon dioxide exchange (and movement) lung alveoli pulmonary arteries pulmonary capillaries pulmonary veins present present C present right atrium left atrium C present systemic veins right ventricle left ventricle systemic capillaries systemic arteries from figure 17.1 interstitial fluid body cells
Oxygen and Carbon Dioxide movement of gases in lungs: gases diffuse between alveoli and blood throughout body: gases diffuse between blood, interstitial fluid and body cells alveoli blood interstitial fluid cells mitochondria for gas exchange to work by diffusion... there must be a an oxygen alveoli blood interstitial fluid cells oxygen mitochondria oxygen and there must be a concentration gradient alveoli blood interstitial fluid cells mitochondria carbon dioxide carbon dioxide diffusion of a gas depends on difference in amount of a gas depends on difference in of a gas partial pressure atmospheric air has a pressure about mm Hg at sea level air is a mixture of gases each gas in air contributes part of the total pressure contribution is proportional to what percent of the total air that the gas is so... each gas in a mix of gases (air) has a examples of partial pressure of gases in air N nitrogen 79 % of air 0.79 X 760 mm Hg = 600 mm Hg oxygen % of air 0.1 X 760 mm Hg = mm Hg C carbon dioxide % of air 0.0003 X 760 mm Hg = mm Hg partial pressure of a gas is related to higher partial pressure of a ga: a gas has a partial pressure whether it s in or it s dissolved in a PN P PC
diffusion of gases partial pressures help determine in which direction gases diffuse partial pressure always true whenever / wherever a gas is diffusing... partial pressure P alveoli blood interstitial fluid cells mitochondria P PC alveoli blood interstitial fluid cells mitochondria PC partial pressures for a person at rest lung alveoli PC mm Hg P mm Hg diffusion C diffusion pulmonary arteries pulmonary capillaries pulmonary veins mm Hg P mm Hg P mm Hg PC right atrium left atrium mm Hg PC systemic veins right ventricle left ventricle systemic capillaries systemic arteries from figure 17.4 diffusion mm Hg C diffusion PC P body cells mm Hg interstitial fluid
diffusion of gases gases can diffuse until partial pressures are breathing repeatedly adds oxygen air spaces in lungs P 100 mm Hg P P 100 mm Hg pulmonary arteries pulmonary capillaries pulmonary veins right side of heart systemic veins systemic capillaries systemic arteries left side of heart P unless prevented P 100 mm Hg body cells P cellular metabolism continuous use oxygen breathing repeatedly removes carbon dioxide air spaces in lungs PC PC 46 mm Hg PC pulmonary arteries pulmonary capillaries pulmonary veins right side of heart systemic veins systemic capillaries systemic arteries left side of heart PC 46 mm Hg unless prevented PC body cells PC 46 mm Hg cellular metabolism continuous production carbon dioxide
equilibration in pulmonary capillaries under resting conditions, equilibration happens as blood flows along capillaries 100 mm Hg oxygen diffusing into pulmonary capillaries 46 mm Hg carbon dioxide diffusing out of pulmonary capillaries partial pressure oxygen partial pressure carbon dioxide beginning middle blood flow end beginning middle blood flow end from figure 17.5 under resting conditions, diffusion of O and CO has finished about of the total distance along pulmonary capillaries when more oxygen is needed and more carbon dioxide is produced (exercise) more time and distance are available under very demanding conditions (losts of O and CO) full equilibration might not happen by the time blood leaves pulmonary capillaries several factors help equilibration be rapid walls of blood vessels and alveoli distances that gases diffuse blood flow in capillaries but... tain t a perfect world and problems can occur that llimit diffusion and interfere with equilibration
diffusion of gases partial pressure says something about the amount of oxygen present in blood for example, P = 100 mm Hg P = in blood in blood but, P does NOT tell us the of oxygen present in blood four reasons #1 P indictes only the oxygen # #3 amount of oxygen dissolved in blood plasma because oxygen is not very in water (blood plasma) most oxygen in blood is bound to in RBCs #4 bound oxygen does to partial pressure of oxygen in blood plasma H O H O H O O H O RBCs with Hb = hemoglobins carrying oxygen total amount of oxygen in blood depends on how much is in blood plasma and how much is bound in RBCs this leads us to one of the primary functions of circulating blood... of oxygen and carbon dioxide in blood three steps: 1) ) 3)
transport of gases in blood oxygen oxygen enters blood passing along pulmonary capillaries 00 milliliters of oxygen present in every liter of blood how is that oxygen carried?? 00 ml 3 ml ( % of total oxygen) 197 ML ( %) hemoglobin (Hb) molecules globin strands heme groups with an Fe alpha strand beta strand beta strand alpha strand each heme group with iron in Hb holds oxygen molecule each Hb holds up to oxygen molecules lots of Hb molecules in each RBC lots of RBCs in CVS blood has enormous oxygen carrying capacity in capillaries deoxyhemoglobin oxygen some oygen oxyhemoglobin
transport of gases in blood - loading oxygen difference in P helps determine in which oxygen diffuses P P alveoli Blood in Pulmonary Capillaries first part of capillaries O O O P 100 mm Hg P Hb sites occupied by alveoli Blood in Pulmonary Capillaries O O P 100 mm Hg P 60 mm Hg Hb sites occupied by alveoli Blood in Pulmonary Capillaries O O P 100 mm Hg P 80 mm Hg Hb sites occupied by alveoli Blood in Pulmonary Capillaries last part of capillaries O O P 100 mm Hg P 100 mm Hg Hb sites occupied by hemoglobin allows lots of oxygen to move into blood because... 1) there are many Hbs in RBCs to bind oxygen ) binding to Hb keeps P in blood low enough so that oxygen keeps diffusing into from - partial pressure differences still determines the direction of oxygen diffusion diffusion ends when partial pressures in and are the same
transport of gases in blood - unloading oxygen deoxyhemoglobin oxygen in capillaries oxyhemoglobin first part of capillaries interstitial Fluid Blood in SYSTEMIC Capillaries O O P P 100 mm Hg HB sites occupied by interstitial Fluid Blood in SYSTEMIC Capillaries O O O P P 70 mm Hg HB sites occupied by last part of capillaries interstitial Fluid Blood in SYSTEMIC Capillaries O O O P P HB sites occupied by hemoglobin allows lots of oxygen to move out of blood because... 1) there are many Hbs in RBCs to unload some oxygen ) unloading from Hb keeps P in blood high enough so that oxygen keeps diffusing from to - partial pressure differences still determines the direction of oxygen diffusion diffusion ends when partial pressures in and are the same
hemoglobin-oxygen dissociation curve from figures 17.9 and 17.10 100% 100% 80% 80% hemoglobin sites filled with oxygen 60% 60% 40% 40% 0% under resting conditions 0% 0 40 60 80 100 0 40 60 80 100 P (mm Hg) shift of curve to the left causes of shift ph temperature PC affinity of Hb for oxygen shift of curve to the right causes of shift ph temperature PC affinity of Hb for oxygen oxygen pickup oxygen unloading oxygen pickup oxygen unloading typical location typical location in capillaries 100% 80% in capillaries hemoglobin sites filled with oxygen 60% 40% 0% 0 40 60 80 100 P (mm Hg)
transport of gases in blood oxygen carbon monoxide (CO) poisoning carbon dioxide C enters blood in systemic capillaries 540 ml per liter of blood in systemic veins C C C 30 ml ( %) 39 ML ( %) C 470 ML ( %) in systemic capillaries as C enters blood C H O H HCO 3 enzyme more C : H ph in pulmonary capillaries as C leaves blood C H O H HCO 3 enzyme less C : H ph
Regulation of Ventilation brain s involvement respiratory control centers forebrain spinal motor neurons respiratory control centers brainstem breathing muscles diaphragm phrenic nerve spinal cord external intercostals internal intercostals intercostal nerves forebrain cerebral cortex sensory input brainstem respiratory control centers spinal motor neurons from figure 17.17 breathing muscles
Regulation of Ventilation sensory input - influence on breathing chemoreceptors - two kinds first kind: chemoreceptors chemically sensitive cells in carotid arteries from figure 17.19 brain stem sensory axons respiratory control centers blood flowing along carotid artery monitor arterial blood as it passes by sensitive cells in carotid arteries i) ii) iii) from figure 17.18 second kind: chemoreceptors nerve cells in brain stem H O C brain stem respiratory control centers C brain capillary and red blood cells H from figure 17.0 H HCO 3 monitor extracellular fluid in brain i)
Regulation of Ventilation what changes in oxygen and carbon dioxide levels stimulate breathing? arterial blood brain P PC PC ph [H ] ph [H ] peripheral chemoreceptors central chemoreceptors respiratory control centers from figure 17.1 more ventilation minute ventilation (liters/min) 30 0 10 as P PO what is declines, minute ventilation in arterial blood at rest? to what does P in arterial blood fall before breathing rate rises significantly? 0 40 60 80 100 from figure 17.19 P (mm Hg) as PC rises, minute ventilation PCO 30 what is in arterial blood at rest? minute ventilation (liters/min) 0 10 to what does PC in arterial blood rise before breathing rate rises significantly? as PC continues to rise, minute ventilation 0 40 60 80 100 PC (mm Hg)... eventually is the system that controls breathing more sensitive to the level of: oxygen? carbon dioxide? oxygen and carbon dioxide equally? why?
Regulation of Ventilation - Hyperventilation and Hypoventilation suppose someone begins to work out hypernea = in ventilation that takes care of... production of C (and use of ) as a result suppose someone at rest begins to breathe more often and more deeply hyperventilation = in ventilation that production of C (and use of ) as a result arterial arterial PC arterial P PC arterial P 100 mm Hg suppose someone at rest begins to breathe less often and more shallowly hypoventilation = in ventilation that production of CO (and use of ) as a result arterial arterial PC P 100 mm Hg ph (concentration of free hydrogen ions) in body fluids is regulated normal ph range: acidois - alkalosis - respiratory acidosis is caused by: hypernea? hyperventilation? hypoventilation? respiratory alkolosis is caused by: hypernea? hyperventilation? hypoventilation? changes in breathing can help to compensate for metabolic changes that lead to acidosis or alkalosis if someone is in metabolic acidosis due to diabetes mellitus, how would breathing help to return ph toward normal? is the respiratory response fast (within minutes) or slow (within days)?