Remaining lectures Today respiration Friday circulation Mon Weds digestion Friday osmoregulation Animal Cardiovascular Respiratory Systems Lectures 9 10 Atmospheric pressure 760 mmHg Partial Pressure Partial pressure of N2 pN2 760 x 78 mmHg 593 mmHg Partial pressure of O2 pO2 760 x 21 mmHg 160 mmHg Partial pressure of CO2 pCO2 760 x 0 03 mmHg 0 2 mmHg The partial pressure p of a gas is defined as its fractional concentration relative to other gases present multiplied by the overall i e the atmospheric pressure exerted on the gases N2 78 O2 21 CO2 and trace gases 0 03 The partial pressure p of a gas is defined as its fractional concentration relative to other gases present multiplied by the overall i e the atmospheric pressure exerted on the gases Differences in PP Drive Diffusion Cardiovascular and Respiratory Systems oxygen O2 carbon dioxide CO2 Gas Exchange via Diffusion Skin Diffusion of gas and other substances Tissue Digestive cavity Gas exchange in MC organisms alternates between bulk flow and diffusion CO2 1 The Ventilation by bulk flow Breathing moves air containing oxygen into the lungs and air containing carbon dioxide out of the lungs Lung O2 alveolus CO2 O2 O2 CO2 Blood vessel 2 Diffusion across the respiratory surface Oxygen diffuses from the lung into the blood and carbon dioxide diffuses out of the blood into the lungs Blood vessel Cell O2 CO2 O2 CO2 Heart 4 3 Circulation by bulk flow Oxygen and carbon dioxide are transported by the circulatory system to and from cells Diffusion between blood and cells Oxygen diffuses from the blood into the cells and carbon dioxide diffuses out of the cells into the blood The Ventilation by bulk flow Breathing moves air containing oxygen into the lungs and air containing carbon dioxide out of the lungs Diffusion across the respiratory surface Oxygen diffuses from the lung into the blood and carbon dioxide diffuses out of the blood into the lungs Circulation by bulk flow Oxygen and carbon dioxide are transported by the circulatory system to and from cells Diffusion between blood and cells Oxygen diffuses from the blood into the cells and carbon dioxide diffuses out of the cells into the blood How you inflate lungs Tidal Ventilation Inhalation Exhalation Rib Lung Thoracic cavity Diaphragm Negative pressure draws air into lungs Positive pressure expels air from lungs Humans and other mammals ventilate their lungs by increasing their lung volume by expanding their thoracic cavity outlined in yellow to draw oxygen rich air into the lungs inhalation and reducing their lung volume to expire oxygen poor air from the lungs exhalation Humans and other mammals ventilate their lungs by increasing their lung volume by expanding their thoracic cavity outlined in yellow to draw oxygen rich air into the lungs inhalation and reducing their lung volume to expire oxygen poor air from the lungs exhalation Diaphragm at work rest Tidal Volume At rest we exchange 1L Increases during exercise Never fully exhale all gas leaving stale air Atmospheric O2 160 mmHg lungs 100 mmHg 25 efficient Total lung capacity L m l e m u o v g n u L Tidal volume Maximum possible inhalation Maximum possible exhalation Time sec Larynx contains the vocal cords Trachea Cartilage Primary bronchi Right lung Capillary network Alveoli O2 rich blood CO2 rich blood Bronchiole carries air to alveoli Smooth muscle Left lung Thoracic cavity Intercostal muscles Diaphragm Lung Anatomy Pleural cavity An alveolus in action Think Write Share We ve established that differences in partial pressure PP drives gas exchange across membranes and cell layers Where in the body would you expect to find the lowest PP of Oxygen The highest Red Blood Cells 20 trillion RBC s or roughly 3 4 of the cells in the body Only about 4 by mass About 25 smaller than the smallest capillary Made in B M regulated by the spleen Each contains 270 million hemoglobin proteins No nuclei mitochondria or cytoplasm wait what Structure of Hemoglobin and Myoglobin b subunit Heme group oxygen binding site a subunit Myoglobin Hemoglobin When to pick up and drop off CO2 O2 Cooperative binding once 1 heme binds O2 the other 3 want O2 even more conformational change in hemoglobin works in reverse as well When to dump Allosteric inhibition via byproducts of cellular respiration CO2 and H Places where cells and muscle tissue is active When to dump Allosteric inhibition via byproducts of cellular respiration CO2 and H Places where cells and muscle tissue is activeCooperative binding once 1 heme binds O2 the other 3 want O2 even more conformational change in hemoglobinworks in reverse as well The curve is sigmoidal due to cooperative binding of oxygen by hemoglobin In the middle of the curve small increases or decreases in pO2 result in large increases or decreases in hemoglobin saturation Hemoglobin Hemoglobin Dissociation Curve f o n o i t a r u t a s 2 l i n b o g o m e h O Partial pressure of oxygen pO2 mmHg The curve is sigmoidal due to cooperative binding of oxygen by hemoglobin In the middle of the curve small increases or decreases in pO2 result in large increases or decreases in hemoglobin saturation A decrease in pH often the result of increased cell activity causes a right shift in hemoglobin s O2 dissociation curve Hemoglobin then releases more O2 to these active cells Affect of pH on Dissociation Curve pH 7 4 pH 7 2 f o n o i t a r u t a s 2 i l n b o g o m e h O Partial pressure of oxygen pO2 mmHg A decrease in pH often the result of increased cell activity causes a right shift in hemoglobin s O2 dissociation curve Hemoglobin then releases more O2 to these active cells At any given pO2 myoglobin binds oxygen more readily than hemoglobin As a result hemoglobin delivers oxygen to myoglobin in muscle tissues when needed most Myoglobin P50 P50 f o n o i t a r u t a s 2 i l n b o g o m e h O Hemoglobin P50 is the pO2 at which hemoglobin is 50 saturated with O2 Myoglobin Dissociation Curve Partial pressure of oxygen pO2 mmHg At any given pO2 myoglobin binds oxygen more readily than hemoglobin As a result hemoglobin delivers oxygen to myoglobin in muscle tissues when needed most P50 is the pO2 atwhich hemoglobinis 50 saturatedwith O2 Fetal vs Adult Hemoglobin Fetal hemoglobin s curve is left shifted relative to that of maternal hemoglobin allowing the fetus to take up O2 from the mother s circulation Fetal hemoglobin Maternal hemoglobin f o n o i t a r u t a s 2 i l n b o g o m e h O Partial pressure of oxygen pO2 mmHg Fetal