2_8_08_The_Circulatory_System

2_8_08_The_Circulatory_System - Clicker Question Should...

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Unformatted text preview: Clicker Question Should animals be used and even killed for medical and biological studies? Where are we? Last time... time... I talked about the intestines and the passage of gas. This time... time... I will talk about the circulatory system and the exchange of gas-- gas-- which, incidentally, allows for more classy music. A) Never, it is unethical to use or kill animals B) C) D) E) without their consent for the good of humans. Leaning toward A. Yes, but only within guide lines that respect the reverence of all life: human and animal. Leaning toward E. Yes, it is more ethical to kill animals than to let humans live with pain and illness. Photosynthesis: Eating and Digestion: Absorption: Circulation: Making organic matter from carbon dioxide and water as well as nitrogen, phosphorous and sulfur using the Sun's Sun' energy. Breaking down the ingested food mechanically, chemically and enzymatically into small molecules and atoms. Transport of the small molecules and atoms across the mucosa "into" the body. into" Function of a Circulatory System Picture the original single-celled singleorganism, with a surrounded by flowing water that can bring oxygen and food to the cell and carry away waste. large surface to volume ratio, Cellular Respiration and Biosynthesis (Monday) Transport of small molecules and atoms from the intestines to the cells in the rest of the body. Transport of oxygen from the lungs to the cells in the rest of the body. Transport of carbon dioxide from the cells to the lungs where it is expired. Function of a Circulatory System The cells in our multicellular body are remote from the sources of oxygen and food and removed from the sites of waste elimination. functions to keep each cell in our body connected to a source of food and oxygen as well as a sewerage system to remove wastes. Convection: Long Distance Mass Movement of Substances Driven by a Force When diffusion is too slow to move molecules The circulatory system from one place to another because the distances are too far, convection is necessary. Convection in the form of cytoplasmic streaming is used to circulate molecules throughout large cells. Convection in the form of xylem and phloem transport are used to circulate molecules throughout the plant. Convection in the form of the circulatory system is used to circulate molecules throughout the animal. 1 Components of the Blood and their Functions Sugar, Oxygen, Carbon Dioxide and Nutrients Diffuse through the Interstitial Fluid Between the Capillaries and All Cells of the Body Red Blood Cells Travel Single File in Thin-Walled Porous Capillaries Thin- Sugars and Amino Acids Enter the Blood Stream at the Small Intestine Sugars and amino acids move into the leaky capillaries that penetrate each villus. villus. The Path of a Sugar Molecule or an Amino Acid to the Heart The capillaries converge into venules which converge into the hepatic portal vein which supplies the liver. In the liver, the hepatic portal vein divides up into venules and then capillaries, which are a single epithelial layer thick. From the liver the capillaries converge into venules and into a large vein, called the vein, vena cava that empties into the heart. The Path of a Sugar Molecule or an Amino Acid from the Heart The blood flows from the right atrium to the right ventricle and out the pulmonary artery to the lungs where it becomes oxygenated. From the lungs, oxygenated blood flows through the pulmonary vein to the left atrium, to the atrium, left ventricle and then to a large artery called the aorta. aorta. The aorta, which is one inch in diameter, ramifies into other arteries, arterioles and capillaries, where the sugar molecules come into contact with every cell in the body, including the cells in the mucosa of the small intestine. 2 Arteries and Veins The arteries always carry blood away from the heart. Except for the blood in the pulmonary artery, the blood is usually oxygenated and reddish. The veins always carry blood toward the heart. Except for the blood in the pulmonary vein, the blood is usually not oxygenated and is bluish. In the body, most capillaries connect the arterioles, which carry blood away from the heart, to the venules, which carry blood toward the heart. Tissue Layers in Blood Vessels Capillaries: Single epithelial layer only Veins and Arteries: Epithelial layer, smooth muscle layer, and an elastic connective tissue layer The smooth muscle and connective tissue layers are thicker in the arterial system, which is under high pressures, than in the venous system. Portal Veins While most veins drain directly into the heart, the portal veins do not drain into the heart, but drain through example, the hepatic portal vein drains into the liver. How Did Harvey Discover that the Blood Moves from the Heart to the Arteries and Back by way of the Veins? In the arm, the (reddish) arteries are capillaries into other organs. For deeper than the (bluish) veins. Consequently, a loose ligature blocks the venous flow and a tight ligature blocks the venous and arterial flow. When the ligature is loose, the veins are blocked and they swell. The hand becomes flushed and there is a pulse. A tight ligature stops the pulse but does not cause swelling. The hand becomes cold and is normally colored. 3 In Harvey's Words.... Harvey' Words... "The blood doth enter into every member through the arteries, and does return by the veins, and that the arteries are the vessels carrying the blood from the heart, and the veins are the vessels and wayes by which the blood returns to the heart itself; and that the blood in the members and extremities does passe from the arteries into the veins." veins." Angelina Jolie Too much exercise, not enough food Harvey Demonstrated the Direction of Blood Flow in Veins The Circulation of the Blood by Carolyn William Harvey Eberhard Stephen William Harvey Snyder Harvey Demonstrated the Direction of Blood Flow in Veins Harvey ligated the arm and noticed that there were localized regions, which he called venous valves, where the swelling was greatest. When he pressed on the vein with his finger, the portion of the vein closest to the heart disappeared. When he pushed the blood toward the hand, the vein refilled, indicating that the venous valve is a one-way valve that ensures that the venous blood takes a one-way trip to the heart. Harvey Guessed that the Blood Must Circulate Guess: What is the volume of the heart? Say 75 ml. Guess: What is the pulse rate? Say 70 beats/min. Mathematical model using dimensional analysis: (Volume of heart) (1 emptying volume/beat)(pulse rate) volume/beat)(pulse (75 ml/vol)(1 liter/1000ml)(1vol/beat)(70 beats/min) liter/1000ml)(1vol/beat)(70 beats/min) =_5.25_ liters/min The heart pumps in one minute, a volume equal to all the blood in the human body. Conclude: The blood must circulate. That is, the blood does not travel unidirectionally from the liver to the rest of the body. The Motion of the Heart The beating of the heart was too fast for Harvey to see. Yet, he guessed that there was an orderly motion to the heart beat just as there was an orderly motion of mechanical devices. "... in the lock of a piece, by the drawing of the spring, the flint falls, strikes the steel, fires the powder, enters the touch hole, discharges, the balls flie out, pierces the mark and all these motions by reason of the swiftness of them, appear in the twinkling of an eye." eye." 4 Harvey Wanted to Study Motion at the Frontier of Time In order to observe the orderly motion of the heart, Harvey studied cold-blooded animals coldas well as warm-blooded animals that were warmslowly dying. Valves in the Pump Prevent the Blood from Flowing Backwards The atria pump blood into the ventricles, the ventricles pump blood to the rest of the body. The right ventricle pumps blood to the lungs. The left ventricle pumps blood through the aorta to the rest of the body. "This is more evident in the hearts of toads, serpents, frogs, house-snails, shrimps, crevises houseand all manner of little fishes. For it shews itself more manifestly in the hearts of hotter bodies, as of dogs, swine, if you observe attentively till the heart begins to die, and move faintly, and life is as it were departing from it." it." The atrioventricular valves (tricuspid (right) and bicuspid (left)) prevent blood from flowing backwards from the ventricles to the atria. The semilunar valves (pulmonary (right) and aortic (left)) prevent blood from flowing backwards from the arteries to the ventricles. Contraction of Heart Increases Blood Pressure Diastole: The heart is relaxed (0.4 s). The atrioventricular valves open and blood flows from the veins into all four chambers of the heart. The pressure in the arteries is low. Systole: The atria contract (0.1 s) before the ventricles contract (0.3 s) giving the typically lub-dup sound of a beating heart. The force of lubthe ventricular contraction closes the atrioventricular valves and opens the semilunar valves. Contraction of the heart forces blood into the arteries. The blood pressure in the arteries increases since blood is pumped into the arteries faster than it can flow into the arterioles. Blood Pressure: Systole/Diastole Typically: 120 mm Hg/70 mm Hg The pulse: 60-75/minute due to the rhythmic 60stretching of the arteries caused by the alternation of the systolic and diastolic phases. 5 The heart beat is initiated by a specialized region The pacemaker generates electrical signals that move along the heart and cause it to contract in a rhythmic manner. The signal spreads in such a way that the atria contract before the ventricles. of the heart called the pacemaker. Electrocardiogram The electrical signals can be monitored with an electrocardiogram (EKG). A Defibrillator If the pacemaker fails, one can get the heart started with a defibrillator. If it continues to fail, one can get an artificial pacemaker. The kind of terrifying experiments that served as a basis for Mary Shelley's Shelley' Frankenstein, also led to these wonderful technical devices. Artificial Pacemaker Artificial Heart In 2001, Drs. Gray (l) and Dowling (r) implanted the first AbioCor artificial heart into Robert Tools (c), a 58-year-old telephone 58- yearcompany employee and teacher. He natural heart was removed. Robert Tools lived for 151 days with his artificial heart. http://www.abiomed.com/products/heart_replacement.cfm Artificial Hearts In 2006, Melissa Mills, a teenager, was given an artificial "Berlin heart" since heart" her natural heart had deteriorated too much while she was waiting for a heart transplant. 146 days later, Melissa's Melissa' natural heart got enough rest so that it started pumping again and the artificial heart was removed. Berlin Heart 6 The Heart Rate is Regulated The heart is connected to the nervous system, which can speed up or slow down the heart rate (pulse) as needed. responds to the Heart Attacks are Caused by a Blockage in a Coronary Artery, which Supplies the Heart Muscle with Sugar and Oxygen Atherosclerosis The heart rate (pulse) also adrenaline released into the blood stream by the adrenal gland in times of "fight or flight" by speeding up. (hardening of the arteries) is a disease where plaques develop on the inside of the arteries. The higher the blood pressure, the greater the likelihood that a plaque or clot will break off and form a flowing body called an embolus. Heart Attacks are Caused by a Blockage in a Coronary Artery, which Supplies the Heart Muscle with Sugar and Oxygen Stroke and Pulmonary Embolism If the blockage forms in an artery in the brain, the brain is deprived of sugar and oxygen and a stroke results. the pulmonary artery, the lung is deprived of sugar and axygen and a pulmonary embolism results. A blockage is likely to form where there is another plaque. If the blockage forms in a coronary artery, a heart attack will result. If the blockage forms in Nutrition for the Heart High levels of low-density lowlipoproteins (LDL--bad LDL-- cholesterol) and low levels of high-density lipoproteins high(HDL--good cholesterol) in HDL-- the blood is correlated with greater risk for heart attacks. Saturated fats raise LDL. Trans fats raise LDL and lower HDL. Omega-3 fatty acids raise OmegaHDL. The plaques are formed by cholesterol deposits. 7 Blocked Coronary Arteries Can Be Opened by Performing an Angioplasty Now let's get back to let' the sugar molecule that left the small intestine and passed through the heart. The sugar molecule is in the blood that leaves the right ventricle via the pulmonary artery and goes to the lung, where the blood is oxygenated. The Path of Oxygen: Breathing Oxygen enters our body through our nostrils, From the nostrils, the air passes through the unless we are swallowing food. where we warm it and humidify it. pharynx and past the epiglottis, which is open trachea (windpipe), the two bronchi, the many bronchioles and into the millions of alveoli. The air then passes the larynx (voice box), the The alveoli are composed of epithelial tissue that borders the capillary system that contains the hemoglobin-containing red blood cells that take hemoglobinup the oxygen through the interstitial fluid. 8 The alveoli create a large surface to volume ratio necessary for gas exchange into and out of the body In order to exchange sufficient oxygen and carbon dioxide to keep us alive, the epithelium of the lung has a surface area of approximately 100 m2, about the size of a racquet ball court. Cilia in our Respiratory System Keep Our Lungs Clean The epithelial cells that line our trachea, bronchi and bronchioles contain cilia that push out to the pharynx dust and pollen caught by the mucus produced by the epithelial cells lining the respiratory system. In the pharynx, the mucus-coated particles leave the mucustrachea and enter the esophagus to be eliminated. Nicotine inhibits the movement of the cilia which prevents them from removing the dirty mucus. Why Does Someone Smoke? To fit in and give you an identity. Because it feels pleasant. Because it relieves stress. Because it is a reward. Because it is their choice. Because it becomes a habit. Because it becomes an addiction. 9 But No One Smokes Because It Is Healthy For You...Because it Isn't You... Isn' Breathing We inhale air in when our diaphragm muscle contracts and moves down. This creates a suction that pulls oxygen-rich oxygenair into our lungs. We exhale air when our diaphragm relaxes and moves up. This pushes carbon dioxide-rich air out of our lungs. Breathing Provides the Wind for Singing Breathing is Controlled by the Brain There is a sensor in the aorta that determines if the CO2/O2 ratio is too high in the blood and sends an nerve impulse to the brain. This sensor can indirectly tell if the CO2 ratio is too high by measuring the acidity of the blood. If there is too much acid (H+) in the blood, the brain sends an impulse to the diaphragm, increasing the rate and depth of our breathing. Remember the relationship between CO2 and H +? CO2 + H2O H2CO3 H+ + HCO3- 10 The Circulatory System Unoxygenated blood, containing nutrients, leaves the small intestine, passes through the liver and the vena cava to the right atrium. It passes through the right ventricle and the pulmonary artery to the lungs, where it exchanges carbon dioxide for oxygen. It leaves the lung through the pulmonary vein and travels through the left atrium and left ventricle, through the aorta to all the other cells of the body that need nutrients and oxygen for cellular respiration--a metabolic process that will respiration-- provide chemical energy in the form of ATP and carbon skeletons for the synthesis of proteins, lipids, nucleic acids and coenzymes necessary to build or rebuild the body. Capillary: Epithelial Cells are Leaky and are in Communication with the Interstitial Fluid Surrounding All Cells of the Body Smooth Muscle Controls the Distribution of Blood At any given time, 5-10% of your The capillaries communicating with the The capillaries communicating with all the other regions of the body, including skeletal muscles and the smooth Smooth Muscle Controls the Distribution of Blood Hormones and nerves regulate the When you are in "fight or flight" mode, distribution of blood in the body. blood goes to all the capillaries in your running muscles, but little goes to the smooth muscles in your digestive system. During "rest and digest " mode, the blood goes to all the capillaries supplying blood to the smooth muscles in your digestive system, and less goes to the running muscles. capillaries have blood flowing through them. brain, heart, kidneys and liver are always full. muscles of the digestive system must share the blood depending on need. 11 The flow of blood is regulated by smooth muscles, known as precapillary sphincters, around Regulation of Blood Flow by Vasodilators While investigating what caused brandy to become spoiled, Antoine Balard, Balard, determined which chemicals were produced. The vapor from amyl nitrite, one of the chemicals he found, momentarily caused his face to become flushed and his heart to beat faster. Contraction of the thoroughfare channel. the arterioles near the smooth muscles constrict the arterioles near the thoroughfare channel so that blood bypasses the capillary bed and passes directly from an arteriole to a venule. venule. Amyl Nitrate Affects Blood Flow and Relieves the Pain of Heart Attacks Dr. Benjamin Ward Richardson noticed that amyl nitrate caused the capillaries visible in a frog's frog' foot to dilate. Dr. Arthur Gamgee observed that amyl nitrate decreased blood pressure in animals and man. Sir Thomas Brunton (1867), a physician searching for a cure for heart attacks, found that the vasodilating action of amyl nitrite relieved the pain of heart attacks. Accidental Discoveries Alfred Nobel's factory produced Nobel' nitroglycerine to make dynamite, After realizing this, the local which is a controllable mixture of nitroglycerine and silica. Some workers, who suffered from heart troubles at home, noticed that they were relieved of their chest pains when they were in the factory. doctors began prescribing nitroglycerine for heart disease. Nitroglycerin and Alfred Nobel Now does nitroglycerin work? Certainly it doesn't doesn' cause little explosions in the blood vessels. But without knowing, Alfred Nobel was not interesting in trying it. While sick with heart disease in 1896, Nobel wrote to a friend, "My Discovery of Vasodilators Ferid Murad found that nitroglycerine, amyl nitrate and other nitrogennitrogencontaining substances that caused vasodilation, vasodilation, released nitric oxide (NO) and it was the NO that caused the muscles surrounding the blood vessels to relax. Nobel refused to follow his doctor's advice and doctor' take the explosive liquid and died of heart disease several months after he wrote this letter. heart trouble will keep me here in Paris for another few days....Isn't it the irony of fate that days... .Isn' I have been prescribed nitroglycerin to be taken internally! They call it Trinitrin, so as not to Trinitrin, scare the chemist and the public." public." 12 NO is Naturally Synthesized from Arginine, an Amino Acid Arginine, Nitroglycerin prevents heart damage by acting as a NO donor NO dilates the arteries going to the heart, which increases the oxygen supply to the heart and prevents heart damage. Fact and Fiction about NO, Science, Technology and Business NO is also Important for Sexual Arousal in Men and Women During sexual arousal, blood goes to the NO causes the smooth muscles sexual organs to cause them to swell. surrounding the arteries leading to the penis in men and the clitoris in women to relax and these arteries dilate. This results in an increased blood flow into these organs and consequently they become tumescent. And to illustrate this... this... 13 ...
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