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Chapter 42

Chapter 42. Circulation and Gas Exchange. Circulation system evolution, I. Gastrovascular cavity (cnidarians, flatworms) Open circulatory •hemolymph (blood & interstitial fluid) •sinuses (spaces surrounding organs) Closed circulatory : blood confined to vessels

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Chapter 42

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  1. Chapter 42 • Circulation and Gas Exchange

  2. Circulation system evolution, I • Gastrovascular cavity (cnidarians, flatworms) • Open circulatory •hemolymph (blood & interstitial fluid) •sinuses (spaces surrounding organs) • Closed circulatory: blood confined to vessels • Cardiovascular system •heart (atria/ventricles) •blood vessels (arteries, arterioles, capillary beds, venules, veins) •blood (circulatory fluid)

  3. Circulation system evolution, II http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html Earthworm http://yucky.discovery.com/noflash/worm/multi/heart.mov • Fish: 2-chambered heart; single circuit of blood flow • Amphibians: 3-chambered heart; 2 circuits of blood flow- pulmocutaneous (lungs and skin); systemic (some mixing) • Mammals: 4-chambered heart; double circulation; complete separation between oxygen-rich and oxygen poor blood

  4. Double circulation Pulmonary/systemic http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12704 • From right ventricle to lungs via pulmonary arteries through semilunar valve (pulmonary circulation) • Capillary beds in lungs to left atrium via pulmonary veins • Left atrium to left ventricle (through atrioventricular valve) to aorta • Aorta to coronary arteries; then systemic circulation • Back to heart via two venae cavae (superior and inferior); right atrium

  5. The mammalian heart Heart anatomy http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12504 Cardiac cycle http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0028-swf_the_cardiac_cy.swf • Cardiac cycle: sequence of filling and pumping • Systole- contraction • Diastole- relaxation • Cardiac output: volume of blood per minute • Heart rate- number of beats per minute • Stroke volume- amount of blood pumped with each contraction • Pulse: rhythmic stretching of arteries by heart contraction Blood flow http://www.sumanasinc.com/webcontent/animations/content/human_heart.html

  6. The heartbeat • Sinoatrial (SA) node (“pacemaker”): sets rate and timing of cardiac contraction by generating electrical signals • Atrioventricular (AV) node: relay point (0.1 second delay) spreading impulse to walls of ventricles • Electrocardiogram (ECG or EKG) Open heart surgery http://www.abc.net.au/science/lcs/swf/heart.swf

  7. Blood vessel structural differences Capillary fluid exchange http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0029-swf_fluid_exchange.swf • Capillaries•endothelium; basement membrane • Arteries•thick connective tissue; thick smooth muscle; endothelium; basement membrane • Veins•thin connective tissue; thin smooth muscle; endothelium; basement membrane

  8. The lymphatic system • Lymphatic system: system of vessels and lymph nodes, separate from the circulatory system, that returns fluid and protein to blood • Lymph: colorless fluid, derived from interstitial fluid • Lymph nodes: filter lymph and help attack viruses and bacteria • Body defense / immunity

  9. Blood • Plasma: liquid matrix of blood in which cells are suspended (90% water) • Erythrocytes (RBCs): transport O2 via hemoglobin • Leukocytes (WBCs): defense and immunity • Platelets: clotting • Stem cells: pluripotent cells in the red marrow of bones • Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; thrombus (clot)

  10. Cardiovascular disease • Cardiovascular disease (>50% of all deaths) • Heart attack- death of cardiac tissue due to coronary blockage • Stroke- death of nervous tissue in brain due to arterial blockage • Atherosclerosis: arterial plaques deposits • Arteriosclerosis: plaque hardening by calcium deposits • Hypertension: high blood pressure • Hypercholesterolemia: LDL, HDL

  11. Gas exchange • CO2 <---> O2 • Aquatic: gills , ventilation , countercurrent exchange • Terrestrial: •tracheal systems •lungs

  12. Larynx (upper part of respiratory tract) Vocal cords (sound production) Trachea (windpipe) Bronchi (tube to lungs) Bronchioles Alveoli (air sacs) Diaphragm (breathing muscle) Mammalian respiratory systems

  13. Breathing • Positive pressure breathing: pushes air into lungs (frog) • Negative pressure breathing: pulls air into lungs (mammals) • Inhalation: diaphragm contraction; Exhalation: diaphragm relaxation • Tidal volume: amount of air inhaled and exhaled with each breath (500ml) • Vital capacity: maximum tidal volume during forced breathing (4L) • Regulation: CO2 concentration in blood (medulla oblongata)

  14. Respiratory pigments: gas transport • Oxygen transport- • Hemocyanin: found in hemolymph of arthropods and mollusks (Cu) • Hemoglobin: vertebrates (Fe) • Carbon dioxide transport- • Blood plasma (7%) • Hemoglobin (23%) • Bicarbonate ions (70%) • Deep-diving air-breathers- • Myoglobin: oxygen storing protein

  15. Respiratory System

  16. Why do we need to breathe? Gas exchange system Requirements of respiratory membranes: must be moist. Must be thin must be permeable to gases. All organisms must have a mechanism with which to transport gases. (circulatory system) Movement of gases happens by simple diffusion. Respiratory System

  17. Cutaneous Respiration Examples Why are our lungs located within the chest cavity and rib cage? Moisture protection Importance of surface area. We have a respiratory surface area of about 60 to 70 square meters. Surface Area and other Respiratory Characteristics

  18. Nostrils nasal septum nasal cavity Role of mucous membranes and hairs? Pharynx glottis epiglottis larynx Adam’s apple Why is it so easy for humans to choke? Vocal cords trachea cartilage rings incomplete rings trachea bronchi bronchioles alveoli capillaries Human Respiratory Tract

  19. Thoracic cavity pleura pleurisy diaphragm intercostal muscles Role of pressure inspiration What happens with pressure and the volume of the chest cavity? Expiration What happens with pressure and the volume of the chest cavity? How do we breathe?

  20. Where does it occur? What gases are exchanged? Simple diffusion is responsible. Erythrocytes RBCs Role of hemoglobin Structure of hemoglobin Oxyhemoglobin 4 oxygens at a time. Effects of CO Carbon dioxide is largely transported as a dissolved gas in the plasma although some is transported by hemoglobin Gas Exchange

  21. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html

  22. Respiratory Center Medulla Oblongata Brainstem Peripheral Chemoreceptors aorta and carotid arteries increase in Carbon dioxide increases H+ ion concentration. Central chemoreceptors in the brain are sensitive to this. Increase CO2, Increase breathing rate. Hyperventilation Control of breathing

  23. Gills Structure Why do fish suffocate on land? Countercurrent flow Insects spiracles tracheae tracheoles Why can’t this work in us? Snail and Frogs Have lungs, but very little respiratory surface area. Cutaneous Breathing. Other mechanisms of breathing

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