2. Hemolymph in sinuses surrounding organs Heart Anterior vessel Ostia Tubular heart An open circulatory system. Lateral vessel A closed circulatory system. Auxiliary hearts Ventral vessels Dorsal vessel (main heart) Small branch vessels in each organ Interstitial fluid Heart

3. FISHES Gill capillaries AMPHIBIANS Lung and skin capillaries REPTILES (EXCEPT BIRDS) Lung capillaries MAMMALS AND BIRDS Lung capillaries Gill circulation Heart: Ventricle (V) Atrium (A) Artery Vein Systemic circulation Systemic capillaries Systemic capillaries Systemic circuit Pulmocutaneous circuit Right Left A A V A V A V Systemic capillaries Right Left Pulmonary circuit Right systemic aorta V A V Systemic capillaries Right Left Pulmonary circuit A Systemic circuit Left systemic aorta Systemic circuits include all body tissues except lungs. Note that circulatory systems are depicted as if the animal is facing you: with the right side of the heart shown at the left and vice-versa.

4. Anterior vena cava Pulmonary artery Capillaries of right lung Aorta Pulmonary vein Right atrium Right ventricle Posterior vena cava Capillaries of abdominal organs and hind limbs Pulmonary vein Left ventricle Left atrium Aorta Pulmonary artery Capillaries of head and forelimbs Capillaries of left lung

5. Semilunar valves closed AV valves open 0.1 sec 0.3 sec 0.4 sec Atrial and ventricular diastole AV valves closed Ventricular systole; atrial diastole Semilunar valves open Atrial systole; ventricular diastole

6. Pacemaker generates wave of signals to contract. Signals are delayed at AV node. Signals pass to heart apex. Signals spread throughout ventricles. SA node (pacemaker) ECG AV node Bundle branches Heart apex Purkinje fibers

7. Artery Artery closed Pressure in cuff above 120 120 Rubber cuff inflated with air Pressure in cuff below 120 120 Sounds audible in stethoscope Pressure in cuff below 70 70 Blood pressure reading: 120/70 Sounds stop

9. Systolic pressure Venae cavae Veins Venules Capillaries Arterioles Arteries Aorta Diastolic pressure Pressure (mm Hg) 120 100 80 60 40 20 0 Area (cm 2 ) 5,000 4,000 3,000 2,000 1,000 0 Velocity (cm/sec) 50 40 30 20 10 0

10. Precapillary sphincters Thoroughfare channel Capillaries Venule Arteriole Sphincters relaxed Venule Arteriole Sphincters contracted

11. Capillaries and larger vessels (SEM) 20 µm

12. Valve (open) Skeletal muscle Valve (closed) Direction of blood flow in vein (toward heart)

13. Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering, and regulation of membrane permeability Plasma 55% Constituent Major functions Water Solvent for carrying other substances Ions (blood electrolytes) Albumin Osmotic balance, pH buffering Plasma proteins Fibrinogen Immunoglobulins (antibodies) Clotting Defense Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O 2 and CO 2 ) Hormones Substances transported by blood Cellular elements 45% Cell type Number Functions per µL (mm 3 ) of blood 5–6 million Transport oxygen and help transport carbon dioxide Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Monocyte Basophil Eosinophil Lymphocyte Neutrophil Platelets Blood clotting 250,000– 400,000 Erythrocytes (red blood cells) Separated blood elements

14. Capillary Red blood cell 15 µm Tissue cell Capillary Net fluid movement out INTERSTITIAL FLUID Net fluid movement in Blood pressure Osmotic pressure Inward flow Direction of blood flow Pressure Outward flow Venous end Arterial end of capillary

15. Respiratory medium (air or water) Organismal level Cellular level Energy-rich fuel molecules from food Respiratory surface Circulatory system Cellular respiration CO 2 O 2 ATP

16. Branch from pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch from pulmonary artery (oxygen-poor blood) Alveoli 50 µm Colorized SEM SEM Nasal cavity 50 µm Left lung Heart Larynx Pharynx Esophagus Trachea Right lung Bronchus Bronchiole Diaphragm

17. Breathing control centers Cerebrospinal fluid Medulla oblongata Pons Carotid arteries Aorta Diaphragm Rib muscles

19. Inhaled air Blood entering alveolar capillaries Alveolar epithelial cells Alveolar spaces Alveolar capillaries of lung Exhaled air Blood leaving alveolar capillaries Pulmonary veins Pulmonary arteries Tissue capillaries Heart Systemic veins Systemic arteries Blood leaving tissue capillaries Blood entering tissue capillaries Tissue cells CO 2 O 2 CO 2 O 2 O 2 CO 2 CO 2 O 2 < 40 > 45 40 45 CO 2 O 2 100 40 CO 2 O 2 CO 2 O 2 40 45 CO 2 O 2 104 40 O 2 CO 2 CO 2 O 2 CO 2 O 2 CO 2 O 2 104 40 120 27 160 0.2

20. Polypeptide chain O 2 unloaded in tissues O 2 loaded in lungs Iron atom Heme group

21. O 2 unloaded from hemoglobin during normal metabolism O 2 reserve that can be unloaded from hemoglobin to tissues with high metabolism P and hemoglobin dissociation at 37°C and pH 7.4 O 2 P (mm Hg) O 2 Tissues during exercise Tissues at rest Lungs 100 80 60 40 20 0 0 20 40 60 80 100 O 2 saturation of hemoglobin (%)

22. Bohr shift: additional O 2 released from hemoglobin at lower pH (higher CO 2 concentration) pH and hemoglobin dissociation P (mm Hg) O 2 100 80 60 40 20 0 0 20 40 60 80 100 O 2 saturation of hemoglobin (%) pH 7.2 pH 7.4

23. CO 2 transport from tissues CO 2 produced Tissue cell CO 2 CO 2 CO 2 Interstitial fluid Blood plasma within capillary Capillary wall Hemoglobin picks up CO 2 and H + To lungs H 2 CO 3 Carbonic acid H 2 O Hb HCO 3 – Bicarbonate Red blood cell H + + HCO 3 –

24. CO 2 transport to lungs HCO 3 – Hemoglobin releases CO 2 and H + H + + HCO 3 – CO 2 H 2 CO 3 H 2 O CO 2 CO 2 CO 2 Hb Alveolar space in lung