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©1996 Norton Presentation Maker, W. W. Norton & Company Blood movement within the four-chambered heart of vertebrates return from body …to lung …from lung …to body Note: arteries take blood away from the heart…veins return to heart The difference is NOT about whether the blood is oxygenated or not! tricuspid valve semilunar valve mitral valve

©1996 Norton Presentation Maker, W. W. Norton & Company Heart relaxes: atria filled by system pressure Atria contract: ventricles filled, valves close Ventricles contract: blood sent to lungs and body Heart relaxes: system pressure closes valves LUB DUB!!

©1996 Norton Presentation Maker, W. W. Norton & Company initial instrinsic stimulus from “pacemaker” atrial contraction “LUB” “DUB” and Purkinje fibers ventricular contraction Frog Lab Exercise: neural and intrinsic control The sounds are the slamming of valves…contraction is silent!

An electrocardiogram (EKG): the electrical changes recorded from electrodes attached to the skin reveal the electrical activity of the heart. In abnormal heart behavior, this recording may reveal where trouble spots exist within the heart’s electrical controls. ventricle filling ventricle contraction ventricle relaxation ventricular depolarization atrial depolarization ventricular release Electrical Potential (mV) Blood Pressure (mm Hg) See Fig pg 922

©1996 Norton Presentation Maker, W. W. Norton & Company Comparative structure of blood vessels Which of these has the greatest surface to volume ratio? High PressureLow Pressure Exchange See Fig pg 918

©1996 Norton Presentation Maker, W. W. Norton & Company artery vein smooth muscle no valves less smooth muscle valves significant

©1996 Norton Presentation Maker, W. W. Norton & Company Veins in valves: “check valves” prevent back flow during heart cycles: Pressure Pulse Pressure Subsides Valves prevent backflow abnormal valve during atrial contraction “varicose veins”

©1996 Norton Presentation Maker, W. W. Norton & Company Blood clotting (thrombosis) in a veinule A thrombus that breaks free and moves through the rest of the circulation system is called a thromboembolus and can lodge in other areas of the body resulting in pulmonary (lung) embolism, stroke (brain), or myocardial (heart) infarction. thrombus no flow blood flow

©1996 Norton Presentation Maker, W. W. Norton & Company Normal artiole Arteriole occluded with fatty plaque Blood flow will be restricted, oxygenation will be reduced. Even a small group of cells could completely cut off the flow (myocardial infarction). Atheroschloersis: “hardening of the arteries” plaque

Blood pressure varies with distance from heart mean pressure Distance traveled by blood from left ventricle aorta arteries arterioles capillaries veinules veins vena cava systolic pressure diastolic pressure Blood pressure (mm Hg) BP is usually measured in the radial artery When a sphygmomanometer gives a result of 120/80 mm Hg, it is interpreted as close to normal for men. See Fig pg 923

Flow rate in blood vessels in a circulation system Branching explains why you don’t get the “thumb on the hose nozzle” effect AortaArteriesArteriolesCapillariesVenulesVeinsVena cava -5,000 -4,000 -3,000 -2,000 -1,000 Cross-sectional Area (cm 2 ) Distance travelled by blood from left ventricle Velocity (cm/sec)

©1996 Norton Presentation Maker, W. W. Norton & Company Frog foot webbing capillaries come close to each body cell Human capillaries are only wide enough for one RBC to pass

©1996 Norton Presentation Maker, W. W. Norton & Company Capillary walls are a single endothelial celljoined at edges pinocytosis (vesicular transport) brings materials through capillary wall

©1996 Norton Presentation Maker, W. W. Norton & Company Red Blood Cells (erythrocytes) and White Blood Cells

Figure page 985 Figure page 989

Oxygen is bound to hemoglobin at the chelation site of iron (Fe) in heme: Iron is a macroelement for vertebrates! H3CH3C CC C C C C C C C C C C CH C C C C HC CH 2 CH 3 CH 2 H2CH2C H3CH3C COOH CH 2 COOH CH 3 N N N N Fe notice the resonating bond system to help trap the oxygen molecule in large electron cloud O=O..

tissue cell cytosol CO 2 O2O2 + H 2 OHCO H + CO 2 + H 2 OHCO H + CO 2 + HbO 2 H + + HbO 2 HHb + O 2 HbCO 2 + O 2 capillary plasma red blood cell Gas exchanges at the blood-tissue interface

O2 lungs tissues CO 2 H2OH2O HbO 2 H2OH2O O2O2 HHb HCO 3 - HHb O2O2 O2O2 HCO 3 - HbO 2 HCO 3 - H+H+ CO 2 H2OH2O HbO 2 CO 2 HbO 2 HCO 3 - H+H+ CO 2 O2O2 circulation direction

Percent saturation of Hb with O Normal blood pH Oxygen partial pressure (mm Hg) Unloading to tissues at normal pH RestLungsExercise Dissociation curves for hemoglobin explain oxygen exchange circulation

Percent saturation of Hb with O Normal blood pH Oxygen partial pressure (mm Hg) Low blood pH Unloading to tissues at normal pH Oxygen unloaded at low pH (high CO 2 ) RestLungsExercise Dissociation curves for hemoglobin explain oxygen exchange circulation

A placental mammal fetus has fetal hemoglobin with higher affinity for oxygen than the mother’s hemoglobin in the placenta Percent saturation of Hb with O Unloading to fetal tissues transfer of oxygen from maternal to fetal hemoglobin in the placenta Fetus Mother Oxygen partial pressure (mm Hg) Myoglobin in tissues has higher oxygen affinity than hemoglobin

©1996 Norton Presentation Maker, W. W. Norton & Company Note: What kind of circulation is shown in placenta? Human and Maternal/Fetal circulation artery or vein? artery or vein? capillary bed veinules arterioles shunts away from lungs artery

The mammal body tissues possess myoglobin, which has an even higher affinity for oxygen: Myoglobin in tissues has higher oxygen affinity than hemoglobin Percent saturation of Hb with O Unloading to fetal tissue myoglobin transfer of oxygen from maternal to fetal hemoglobin in the placenta Fetus Mother Oxygen partial pressure (mm Hg) See Fig pg. 915

©1996 Norton Presentation Maker, W. W. Norton & Company Circulation system in mammal (Homo sapiens) absorbing nutrients gas exchange glucose control nitrogenous waste gas exchange nutrient exchange blood cell replacement muscular pump