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Effects of Gravity on Blood Circulation: Evolution and Mechanisms Explored

Explore how different animals adapt to gravity's impact on circulation, from fish to mammals, through various cardiovascular systems and mechanisms.

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Effects of Gravity on Blood Circulation: Evolution and Mechanisms Explored

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  1. 0 Chapter 23 Circulation

  2. 0 How Does Gravity Affect Blood Circulation? Few animals seem less alike than the giraffe and the corn snake Despite their differences They have many features in common

  3. Most animals have a circulatory system That transports O2 and nutrients to cells and takes away CO2 and other wastes The circulatory system of land animals Must deal with the problem of gravity

  4. Functions of the circulatory system:   • transporting oxygen   • transporting carbon dioxide   • transporting nutrients   • transporting metabolic wastes  

  5. 23.1 The circulatory system connects with all body tissues In many animals, microscopic blood vessels called capillaries Form an intricate network among the tissue Red blood cell Nuclei of smooth muscle cells Capillary LM 700 Figure 23.1A

  6. Capillary Capillaries Are the sites of exchange between blood and interstitial fluid Interstitial fluid Diffusion of molecules Tissue cell Figure 23.1B

  7. MECHANISMS OF INTERNAL TRANSPORT 23.2 Several types of internal transport have evolved in animals In cnidarians and flatworms the gastrovascular cavity functions in both digestion and internal transport In hydra, they do not need a circulatory system because they have very thin body walls & exchange oxygen directly with their environment.   Mouth Figure 23.2A Circular canal

  8. Tubular heart Pores In the open circulatory systems of arthropods and many molluscs, a heart pumps blood through open-ended vessels to bathe tissue cells directly With an open circulatory system, like in grasshoppers, there is no distinction between blood and interstitial fluid.   Figure 23.2B

  9. Capillary beds Arteriole Artery (O2-rich blood) In closed circulatory systems A heart pumps blood through arteries to capillaries Veins return blood to the heart Venule Vein Atrium Heart Artery (O2-poor blood) Gill capillaries Ventricle Figure 23.2C

  10. Gill capillaries 23.3 Vertebrate cardiovascular systems reflect evolution The two-chambered heart of a fish pumps blood in a single circuit From gill capillaries to systemic capillaries and back to the heart Heart: Ventricle (V) Atrium (A) Figure 23.3A Systemic capillaries

  11. Lung and skin capillaries Pulmocutaneous circuit Amphibians and reptiles Have three-chambered hearts Frog Heart A A V Right Left Systemic circuit Systemic capillaries Figure 23.3B

  12. Lung capillaries Pulmonary circuit Birds and mammals Have four-chambered hearts A A V V Left Right Systemic circuit Figure 23.3C Systemic capillaries

  13. THE MAMMALIAN CARDIOVACULAR SYSTEM 23.4 The human heart and cardiovascular system are typical of mammals The mammalian heart Has two thin-walled atria that pump blood into the ventricles Has thick-walled ventricles that pump blood to all other body organs The largest blood vessel in the human body is the aorta Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle Figure 23.4A

  14. Right atrium Left atrium Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle

  15. Capillaries of head, chest, and arms Superior vena cava 8 Pulmonary artery Pulmonary artery Aorta 9 Capillaries of right lung Capillaries of left lung 2 7 2 3 3 5 4 Blood flow through the human cardiovascular system 10 4 Pulmonary vein Pulmonary vein 6 1 9 Right atrium Left atrium Left ventricle Right ventricle Aorta Inferior vena cava Capillaries of abdominal region and legs 8 Figure 23.4B

  16. 23.5 The structure of blood vessels fits their functions A single layer of epithelial cells Forms the walls capillaries Arteries and veins Have smooth muscle and connective tissue Capillary Basement membrane Epithelium Valve Epithelium Epithelium Smooth muscle Smooth muscle Connective tissue Connective tissue Artery Vein Arteriole Figure 23.5 Venule

  17. 23.6 The heart contracts and relaxes rhythmically Duringdiastole Blood flows from the veins into the heart chambers & the heart fills with blood. During systole Contractions of the atria push blood into the ventricles Stronger contractions of the ventricles propel blood into the large arteries; blood leaves the heart.

  18. Atria contract. 2 Heart is relaxed. AV valves are open. 1 0.1sec Systole A cardiac cycle Ventricles contract. Semilunar valves are open. 3 0.3 sec 0.4 sec Diastole Figure 23.6

  19. Cardiac output the volume of blood pumped by the left ventricle each minute Heart valves Prevent the backflow of blood The sounds of the contractions that you hear are due to the sounds of the valves in the heart closing.  

  20. 23.7 The pacemaker sets the tempo of the heartbeat The pacemaker (SA node) generates electrical signals, that trigger contraction of the atria The AV node-Relays these signals to the ventricles Heart Beat Specialized muscle fibers Pacemaker (SA node) AV node Right atrium Right ventricle Apex 1 2 3 4 ECG Figure 23.7

  21. An electrocardiogram (ECG) Records the electrical changes in the heart Heart rate Adjusts to body needs Is influenced by: emotional cues. hormones. exercise. a pacemaker in the right atrium.

  22. CONNECTION Aorta Superior Vena cava Left coronary artery 23.8 What is a heart attack? A heart attack results from the death of cardiac muscle cells Usually resulting from a blocked coronary artery Pulmonary artery Right coronary artery Blockage Dead muscle tissue Figure 23.8A

  23. Smooth muscle Connective tissue Plaque Epithelium In atherosclerosis Plaques develop in the inner walls of arteries and can block blood flow LM 60  LM 160  Figure 23.8B

  24. Cardiovascular disease is the leading cause of death in the United States

  25. 23.9 Blood exerts pressure on vessel walls Blood pressure Is the force blood exerts on vessel walls Depends on cardiac output and the resistance of vessels

  26. Pressure is highest in the arteries • And lowest in the veins 120 Systolic pressure 100 80 Pressure (mm Hg) 60 40 Diastolic pressure 20 0 Relative sizes and numbers of blood vessels Pressure is highest in the arteries And lowest in the veins 50 40 30 Velocity (cm/sec) 20 10 0 Aorta Vains Arteries Venules Arterioles Capillaries Venae cavae Figure 23.9A

  27. Direction of blood flow in vein Valve (open) Skeletal muscle Muscle contractions and one-way valves Keep blood moving through the veins to the heart Valve (closed) Figure 23.9B

  28. CONNECTION Bloodpressure110 systolic70 diastolic(to be measured) 23.10 Measuring blood pressure can reveal cardiovascular problems Blood pressure Is measured as systolic and diastolic pressures Pressurein cuffabove 110 Pressurein cuffat 110 Pressurein cuffat 70 Rubber cuffinflatedwith air 110 110 70 Soundsaudible instethoscope Soundsstop Arteryclosed Artery 2 1 3 4 Figure 23.10

  29. Hypertension (high blood pressure) Is a serious cardiovascular problem Can be caused by smoking

  30. Thoroughfare channel Precapillary sphincters Capillaries Venule 23.11 Smooth muscle controls the distribution of blood Constriction of arterioles and precapillary sphincters Controls blood flow through capillary beds Arteriole Sphincters relaxed 1 Thoroughfare channel Arteriole Venule Sphincters contracted 2 Figure 23.11

  31. Interstitial fluid Iumen Capillary wall Nucleus of epithelial cell 23.12 Capillaries allow the transfer of substances through their walls Cleft between two epithelial cells of the capillary wall Muscle cell TEM 5,000 Figure 23.12A

  32. Tissue cells Osmotic pressure The transfer of materials between the blood and interstitial fluid occurs By diffusion By pressure flow through clefts between epithelial cells Osmotic pressure Venous end of capillary Arterial end of capillary Blood pressure Blood pressure Interstitial fluid Net fluid Movement out Net fluid Movement in Figure 23.12B

  33. Blood pressure forces fluid out of the capillary at the arterial end And osmotic pressure draws fluid at the venous end

  34. STRUCTURE AND FUNCTION OF BLOOD Plasma (55%) Constituent Major functions Water Solvent for carrying other substances 23.13 Blood consists of red and white blood cells suspended in plasma Plasma (liquid portion of blood) is about 90% water And contains various inorganic ions, proteins, nutrients, wastes, gases, and hormones Salts (ions) Osmotic balance, pH buffering, and nerve and muscle function Sodium Potassium Calcium Magnesium Chloride Bicarbonate Centrifuged blood sample Plasma proteins Osmotic balance and pH buffering Fibrinogen Immunoglobulins (antibodies) Clotting Immunity Substances transported by blood Nutrients (e.g., glucose, fatty acids,vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Figure 23.13 (left part)

  35. Blood proteins: • fighting infection.   • maintaining osmotic balance.   • acting as buffers.    • blood clotting.  

  36. Cellular elements (45%) Functions Number per L (mm3) of blood Cell type Red blood cells (erythrocytes)-Transport O2 bound to hemoglobin (formed in the bone marrow) White blood cells (leukocytes)-Function both inside and outside the circulatory system to fight infections and cancer Phagocytes are monocytes and neutrophils   Erythrocytes (red blood cells) Transport of oxygen (and carbon dioxide) 5–6 million Centrifuged blood sample Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Lymphocyte Basophil Eosinophil Neutrophil Monocyte Platelets 250,000– 400,000 Blood clotting Figure 23.13 (right part)

  37. CONNECTION 23.14 Too few or too many red blood cells can be unhealthy Anemia is an abnormally low amount of hemoglobin or red blood cells; usually caused by an iron deficiency. Colorized SEM 3,400 Figure 23.14

  38. The hormone erythropoietin regulates red blood cell production Human red blood cells circulate in the blood 3 to 4 months before they wear out Some athletes artificially increase their red blood cell production, a dangerous practice Blood doping can increase red blood cell concentration

  39. 23.15 Blood clots plug leaks when blood vessels are injured When a blood vessel is damaged, platelets help trigger the conversion of fibrinogen to fibrin, forming a clot that plugs the leak Blood clots are formed by platelets and the plasma protein, fibrinogen. Colorized SEM 3,400 Figure 23.15B

  40. Platelets adhere to exposed connective tissue Platelet plug forms Fibrin clot traps blood cells 1 2 3 Epithelium The blood-clotting process Connective tissue Platelet Platelet plug Figure 23.15A

  41. CONNECTION 23.16 Stem cells offer a potential cure for blood cell diseases Stem cells divide in bone marrow To produce all blood cells And may be used to treat some blood disorders Cancer of white blood cells is called leukemia Stem cells Stem cells Basophils Erythrocytes Platelets Eosinophils Figure 23.15B Monocytes Neutrophils Lymphocytes

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