1.  Chapter 42 Circulation and Gas Exchange

2. Label the heart vessels & valves Trace the flow of blood beginning with return through the Vena cava (list)

3. If you are only a couple of cell layers thick or very flat—a simple distribution system works just fine.  Gastrovascular cavity in cnidarians  Highly branched gastrovascular cavity in flatworms

4. Circulatory Systems  Complex animals  2 types  3 basic components: 1. circulatory fluid (blood) 1. circulatory fluid (blood) 2. set of tubes (blood vessels) 2. set of tubes (blood vessels) 3. muscular pump (heart) 3. muscular pump (heart)

5. The 2 Types of Circulatory Systems:  Open circulatory arthropods, mollusks circulatory fluid directly bathes cells--exchange hemolymph (blood & interstitial fluid) pumped into sinuses (spaces surrounding organs) through vessels  Closed circulatory: blood confined to vessels; earthworm, squid, vertebrates

6. Cardiovascular system  vertebrates  vertebrates  blood-circulatory fluid- circulates within vessels (arteries, veins, capillaries)  Chemical exchange at capillaries  Within organs:  Arteries arterioles capillary beds tissues – exchange venules veins tissues – exchange venules veins return blood to heart return blood to heart

7.  Arteries: carry blood AWAY from the heart  Veins: return blood TO THE HEART

8. The Vertebrate Heart  Atria: receive blood returning to the heart  Ventricles: pump blood out of the heart

9. Generalized Circulatory schemes  Fish: 2-chambered heart (1 atrium & 1 ventricle); single circuit of blood flow. Heart-to gills picks up O2, eliminates CO2--to systemic capillaries—then back to heart.  Disadvantage: low pressure from Gills

10. Generalized Circulatory schemes  Amphibians: 3-chambered heart; 1 Ventricle, 2 Atria; 2 circuits of blood flow- (double circulation) 1.pulmocutaneous (lungs and skin); 2.systemic (some mixing of O2-rich and O2-poor blood occurs)  Mammals, birds, crocodilians: 4-chambered heart; double circulation; complete separation between oxygen-rich and oxygen poor blood (2 ventricles)

11.  The mammalian heart  located beneath  consists mostly of cardiac muscle.   Two atria:   relatively thin walls   collection chambers for blood returning to the heart.   The ventricles have thicker walls and contract much more strongly than the atria. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

12. Fig. 42.5

13. Double circulation  Advantage--Provides vigorous flow of blood- blood pumped through heart 2 TIMES  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

14. The mammalian heart  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

15. Heart Valves  Prevent backflow  Keep blood moving in correct direction  AV valves close at ventricular contraction  Semilunar Valves: at the 2 arterial exits of the heart  forced open at ventricular contraction (arteries stretch under this pressure) (arteries stretch under this pressure)

16.   For a human at rest with a pulse of about 75 beat per minute, one complete cardiac cycle takes about 0.8 sec. (1) During the relaxation phase (atria and ventricles in diastole) lasting about 0.4 sec, blood returning from the large veins flows into atria and ventricles. (2) A brief period (about 0.1 sec) of atrial systole forces all the remaining blood out of the atria and into the ventricles. (3) During the remaining 0.3 sec of the cycle, ventricular systole pumps blood into the large arteries. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

17.  Cardiac output depends on two factors:  1. the rate of contraction or heart rate (number of beats per second)  and  stroke volume, the amount of blood pumped by the left ventricle in each contraction.  The average stroke volume for a human is about 75 mL.  Cardiac output can increase about fivefold during heavy exercise.  Heart rate can be measured indirectly by measuring your pulse - the rhythmic stretching of arteries caused by the pressure of blood pumped by the ventricles. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

18.   A defect in one or more of the valves causes a heart murmur, which may be detectable as a hissing sound when a stream of blood squirts backward through a valve.   born with   damage to the valves by infection (rheumatic fever)   Most heart murmurs do not reduce the efficiency of blood flow enough to warrant surgery. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

19.   Continuity and control of the heartbeat.   Each cell has its own intrinsic contraction rhythm.   Synchronized by the sinoatrial (SA) node, or pacemaker   which sets the rate and timing at which all cardiac muscle cells contract.   Located in the wall of the right atrium. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

20.   The cardiac cycle is regulated by electrical impulses that radiate throughout the heart.   Cardiac muscle cells are electrically coupled by intercalated disks between adjacent cells. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 42.7

21. (1) The SA node generates electrical impulses that spread rapidly (2) through the wall of the atria, making them contract in unison. Delayed by about 0.1 sec at the atrioventricular (AV) node, the relay point to the ventricle, allowing the atria to empty completely before the ventricles contract. (3) Specialized muscle fibers called bundle branches and Purkinje fibers conduct the signals to the apex of the heart and (4) throughout the ventricular walls. This stimulates the ventricles to contract from the apex toward the atria, driving blood into the large arteries. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

22.   Impulses generated during the heart cycle produce electrical currents that are conducted through body fluids to the skin.   Here, the currents can be detected by electrodes and recorded as an electrocardiogram (ECG or EKG). Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

23.   While the SA node sets the tempo for the entire heart, it is influenced by a variety of physiological cues.   Two sets of nerves affect heart rate with one set speeding up the pacemaker and the other set slowing it down   Heart rate is a compromise regulated by the opposing actions of these two sets of nerves.   hormones.   For example, epinephrine from the adrenal glands increases heart rate. .  temperature and with exercise. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

24.   arteries and veins have three similar layers.   On the outside, a layer of connective tissue with elastic fibers allows the vessel to stretch and recoil.   A middle layer has smooth muscle and more elastic fibers.   Lining the lumen of all blood vessels, including capillaries, is an endothelium, a single layer of flattened cells that minimizes resistance to blood flow. 5. Structure of arteries, veins, and capillaries Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

25.  Structural &function  Capillaries lack the two outer layers and their very thin Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 42.8

26.   Arteries have thicker middle and outer layers than veins.   strength to accommodate blood pumped rapidly and at high pressure by the heart. .  Their elasticity (elastic recoil) helps maintain blood pressure even when the heart relaxes. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

27.   The thinner-walled veins convey blood back to the heart at low velocity and pressure.   Blood flows mostly as a result of skeletal muscle contractions when we move that squeeze blood in veins.   Within larger veins, flaps of tissues act as one-way valves that allow blood to flow only toward the heart. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 42.9

28. Blood  Plasma: liquid matrix of blood in which cells are suspended (90% water)  Erythrocytes (RBCs): transport O 2 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)

29. 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

30. Gas exchange  CO 2 O 2  Aquatic: gills ventilationcountercurrent exchange  Terrestrial: tracheal systems lungs

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

32. 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: CO 2 concentration in blood (medulla oblongata).  Detects blood pH changes

33. Respiratory pigments: gas transport  Respiratory Pigments  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

34.  Cooperative oxygen binding  Diffusion of O2 in air greater  Drop in pH lowers the affinity of hemoglobin for O2  Bohr Shift

35. The heartbeat  Label the pictures below.  Describe or list the steps in the Control of Heart Rhythm