What Are the Lungs
Content
What are the lungs? The lungs are a pair of organs in the chest, which are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and the blood. What does breathing accomplish? The cells in the body constantly need a new supply of oxygen to produce energy. With lack of oxygen, cellular function is impaired and damage or cell death may occur. As energy is utilized, waste products are created, one of which is the gas carbon dioxide. Eliminating carbon dioxide from the body is just as important as breathing in oxygen from the air. If carbon dioxide builds up in the blood it will lead to headaches, drowsiness, coma, and eventually even death. What is the structure of the respiratory system? Air enters the body via the nose (preferably) or the mouth. The air enters the mainwindpipe, called the trachea, and continues en route to each lung via either the right or left bronchi. The lungs are separated into sections called lobes, two on the left and three on the right. The air passages continue to divide into ever smaller tubes, which finally connect with tiny air sacs called alveoli. This gradually branching array of tubes is referred to as the tracheobronchial "tree" because of the remarkable similarity to the branching pattern of a tree. The other half of the respiratory system involves blood circulation. Venous blood from the body is returned to the right side of the heart and then pumped out via the pulmonaryartery. This artery splits in two for the left and right lungs and then continues to branch much like the tracheobronchial tree. These vessels branch into a fine network of very tiny tubes called capillaries. The capillaries are situated adjacent to the alveoli and are so small that only one red blood cell at a time can pass through their openings. It is during this passage that gases are exchanged between the blood and the air in the nearby alveoli. After passing the alveoli, capillaries then join together to begin forming the pulmonary veins, which carry the blood back to the left side of the heart.
Lungs Design And Purpose (cont.) How is air moved into and out of the lungs during respiration? Respiration is divided into two components, inhalation and exhalation. Inhalation is active, because it requiresmuscle contraction. The major muscle of respiration is a sheet-like dome shaped muscle called the diaphragm. The diaphragm separates the chest and abdominal cavities. As the diaphragm contracts, it flattens out, moving toward theabdominal cavity. This action causes an increase in the size of the chest cavity, thus creating a vacuum. Air is then sucked in through the mouth. When physical activity increases dramatically, or with some lung conditions, other muscles like those of the neck and those between the ribs also assist in the increase in size of the chest cavity. These muscles are referred to as accessory muscles. Exhalation is passive because it does not require muscle contraction. During this phase, the expanded lung acts like a stretched rubber band and simply contracts to its resting position. This contraction forces air out of the lungs and through the mouth. How does gas exchange occur? As energy is utilized by cells, one of the waste products is the gas carbon dioxide. Oxygen-enriched red blood cells release oxygen to the cells of the body and then pick up the waste carbon dioxide. This oxygen- deprived, dark blue blood is then delivered to the blood vessels of the lungs. Carbon dioxide is released by the red cell, easily passes through the capillary wall into the space in the air sac of the adjacent alveoli, and is then eliminated with each breath out of the mouth (exhalation). Oxygen present in the air sac easily passes into the capillaries and into the red blood cells. The capillary network carrying this oxygen-rich, bright red blood empties into the left side of the heart where it is pumped to all the tissues of the body. Thus, the cycle or circle of blood is complete; hence, the name circulation. What are other important events during the breathing cycle? Outside air needs to be heated and moistened to match the body's temperature and humidity. As air passes down the tracheobronchial tree, it is warmed and water is added. Contaminants must also be removed. Nose hairs and tiny microscopic hairs called cilia, along with sticky mucusproduced by the lining membrane help cleanse the air of impurities. Cilia beat in a synchronized fashion brushing any collected dirt and mucus up toward the mouth. The accumulated material is then coughed out or swallowed.
By the time the air reaches the alveoli, it is virtually sterile. Amazingly, all of the above is occurring naturally while you are reading this information! Lungs Design And Purpose At A Glance
y
The lungs exchange oxygen and carbon dioxide between the air we breathe and the blood. The tracheobronchial tree is the passage way from the mouth to the interior of the lung. Gas exchange occurs in the alveoli deep in the lungs. Breathing air in (inhalation) requires muscular effort. Air is warmed, humidified, and cleaned by the nose and lungs. Introduction to nitrogenous wastes: Nitrogenous waste products are result of protein breakdown in cells. Cells breakdown amino acids to obtain energy by a process called deamination resulting in removal of amino group as ammonia. This is proven to be toxic at low concentration and needs to be flushed out of body eventually requiring large amount of water. All animals including humans form less toxic substance called urea by involving ammonia and carbon dioxide. Some animals keep urea for sometime in the body and they combine with water to form urine and some like birds, insects and snails excrete it as uric acid. Filtration The first step in formation of urine is filtration. Filtration is the process by which the blood that passes through the glomerulus is filtered out, so that only certain structures pass through into the proximal convoluted tubule. The rate at which the blood is filtered is known as the glomerular filtration rate, which is normally 125 ml/minute or 180 liters/day! The glomerulus lining is such that it only allows small molecules to filter through, like glucose, plasma, ions like sodium and potassium, urea, etc. The larger molecules, like blood cells and protein cannot pass through the glomerulus. This is the reason that when there are kidney diseases, the glomerulus lining is affected, due to which the protein molecules also pass through, leading to blood and protein in urine. Selective Reabsorption As mentioned above, in filtration step of urine formation, there is only crude and elementary separation of waste products and a lot of water, glucose and other important materials also pass through. Thus, there is need for reabsorption of these important elements back into the body,
which is where the second step, that is reabsorptions, comes in. This step is known as selective reabsorption because only some elements are reabsorbed back into the body. Reabsorption occurs in two steps, which is active reabsorption (which requires energy) and passive reabsorption (which does not require energy). Due to the difference in concentration of the fluid inside and outside the tubules, 99% of the water returns into circulation and thus, is passively absorbed, which is important for urine formation and flow. Provided the glucose levels are normal, almost all of the glucose is reabsorbed back into the blood from the proximal tubules. This glucose is actively transported into the peritubular capillaries. However, when there is a very large amount of glucose in the blood, then some of it passes into the urine, which is one of the signs of diabetes. Sodium ions are the only ions that are partially absorbed from the renal tubules back into the blood. Tubular Secretion The last step in urine formation is tubular secretion. This is the step where the urine is made concentrated by increasing the concentration of waste elements. Thus, in this stage, substances move into the distal and collecting tubules from blood in the capillaries around these tubules. These substances are secreted by the mechanism of active transport. The substances secreted include hydrogen ions, potassium ions, ammonia, and certain drugs or metabolic end products. Thus, the kidney tubules play a crucial role in maintaining the body's acid-base balance and maintaining the electrolyte balance in the body. The distal convoluted tubules then drain the urine into the collecting tubules. Then, several collecting tubules join together to drain their contents into the collecting duct, which finally, after urine formation, flows into the ducts of Bellini. This then eventually reaches the renal pelvis, from where the urine flows into the ureter to reach the urinary bladder. Thus, these were the various urine formation steps that take place right from the time when blood flows into the kidneys, till urine is passed into the ureters. The various urinary system diseases occur when there are problems with the functioning of the kidneys, which reflects in the final urine color, odor and concentration.
y
y y y
Some diseases and disorders of the excretory system include:
y
Nephritis is an inflammation of the glomeruli, due to a number of possible causes, including things like strep throat. Symptoms include bloody urine, scant urine output, and edema (swelling/puffliness).
y
y
y
Another, more severe form, is due to an autoimmune attack on the glomeruli. Other types of nephritis affect the tubules. Nephrosis also affects the glomeruli, and is characterized by excretion of abnormally large amounts of protein (often causing ³foamy´ urine) and generalized edema (water retension/swelling) throughout the whole body, especially noted as ³puffy´ eyelids. Because these people¶s kidneys often do not handle sodium properly, a low-salt diet is usually prescribed. My younger brother developed nephrosis at age 4, and to control it, had to stay on a no-added-salt diet and take prednisone on a regular basis from then until age 16, at which point, his body finally responded positively to being weaned off the drug. Most urinary tract infections (UTIs) are caused by Gram negative bacteria such as E. coli. If there is an obstruction of the urethra, catheterization may be needed, but as a general rule, catheterization in cases of UTI is contraindicated because it can actually introduce pathogens and make the infection worse. Women tend to acquire more urethral and bladder infections than men, perhaps because the opening of the urethra is closer to the anus. The way a woman cleans the area after relieving herself can influence her chances of contracting a UTI and/or vaginal infection. When parents are toilet-training toddlers, the common mistake is to wipe young girls from back to front. The toddlers get used to this feeling, and when they start to wipe themselves, they also go from back to front. This technique wipes bacteria from the anal area towards or into the ends of the vagina and urethra. Rather, young girls should be trained to wipe from front to back, and women who were not trained this way should make a conscious effort to change their habits. There are a variety of types of kidney stones depending on what conditions caused their formation. According to the Merck Manual, in the United States, about 80% are calcium oxalate (and/or other calcium-based stones), 5% are uric acid, 2% are cystine, and the other 13% due to magnesium ammonium phosphate or other causes. Stones may be microscopic to large ³staghorn´ stones that fill the whole renal pelvis. Often, as the stone is passed down the ureter, the person experiences much pain, and the affected kidney may even temporarily become nonfunctional. Stones may be broken up by ultrasound so they can be passed more easily, but large stones may have to be surgically removed. If possible, the underlying cause of the stone(s) should be identified and alleviated. For example, calcium stones might be caused by
anything from a parathyroid gland problem to too much vitamin D to some forms of cancer to a genetic predisposition. Diseases & Disorders Diseases and disorders that affect the excretory system include gout, kidney failure, urinary tract infections, diarrhea and constipation. Kidney failure occurs through the body's loss of kidney functions. When the kidneys fail, there is no filtering of the blood, which leads to a buildup of waste in the body. Gout is a disorder in which the body builds up excess amounts of uric acid as the kidneys are unable to process it properly. Gout causes joint pain and kidney stones. Urinary tract infections are caused by bacteria in the urethra and bladder. UTIs are more common in women than men. This is believed to be due to the female urethra's proximity to the anus. Constipation is the loss of regular and easy bowel movements. Stool passed through constipation is often hard. Diarrhea is the opposite of constipation; the body experiences stomach cramps and frequent loose, watery bowel movements. Read more: Excretory System Diseases & Disorders | eHow.com http://www.ehow.com/howdoes_5531760_excretory-system-diseasesdisorders.html#ixzz0x3UL4uK1
Lungs Design And Purpose (cont.) How is air moved into and out of the lungs during respiration? Respiration is divided into two components, inhalation and exhalation. Inhalation is active, because it requiresmuscle contraction. The major muscle of respiration is a sheet-like dome shaped muscle called the diaphragm. The diaphragm separates the chest and abdominal cavities. As the diaphragm contracts, it flattens out, moving toward theabdominal cavity. This action causes an increase in the size of the chest cavity, thus creating a vacuum. Air is then sucked in through the mouth. When physical activity increases dramatically, or with some lung conditions, other muscles like those of the neck and those between the ribs also assist in the increase in size of the chest cavity. These muscles are referred to as accessory muscles. Exhalation is passive because it does not require muscle contraction. During this phase, the expanded lung acts like a stretched rubber band and simply contracts to its resting position. This contraction forces air out of the lungs and through the mouth. How does gas exchange occur? As energy is utilized by cells, one of the waste products is the gas carbon dioxide. Oxygen-enriched red blood cells release oxygen to the cells of the body and then pick up the waste carbon dioxide. This oxygen- deprived, dark blue blood is then delivered to the blood vessels of the lungs. Carbon dioxide is released by the red cell, easily passes through the capillary wall into the space in the air sac of the adjacent alveoli, and is then eliminated with each breath out of the mouth (exhalation). Oxygen present in the air sac easily passes into the capillaries and into the red blood cells. The capillary network carrying this oxygen-rich, bright red blood empties into the left side of the heart where it is pumped to all the tissues of the body. Thus, the cycle or circle of blood is complete; hence, the name circulation. What are other important events during the breathing cycle? Outside air needs to be heated and moistened to match the body's temperature and humidity. As air passes down the tracheobronchial tree, it is warmed and water is added. Contaminants must also be removed. Nose hairs and tiny microscopic hairs called cilia, along with sticky mucusproduced by the lining membrane help cleanse the air of impurities. Cilia beat in a synchronized fashion brushing any collected dirt and mucus up toward the mouth. The accumulated material is then coughed out or swallowed.
By the time the air reaches the alveoli, it is virtually sterile. Amazingly, all of the above is occurring naturally while you are reading this information! Lungs Design And Purpose At A Glance
y
The lungs exchange oxygen and carbon dioxide between the air we breathe and the blood. The tracheobronchial tree is the passage way from the mouth to the interior of the lung. Gas exchange occurs in the alveoli deep in the lungs. Breathing air in (inhalation) requires muscular effort. Air is warmed, humidified, and cleaned by the nose and lungs. Introduction to nitrogenous wastes: Nitrogenous waste products are result of protein breakdown in cells. Cells breakdown amino acids to obtain energy by a process called deamination resulting in removal of amino group as ammonia. This is proven to be toxic at low concentration and needs to be flushed out of body eventually requiring large amount of water. All animals including humans form less toxic substance called urea by involving ammonia and carbon dioxide. Some animals keep urea for sometime in the body and they combine with water to form urine and some like birds, insects and snails excrete it as uric acid. Filtration The first step in formation of urine is filtration. Filtration is the process by which the blood that passes through the glomerulus is filtered out, so that only certain structures pass through into the proximal convoluted tubule. The rate at which the blood is filtered is known as the glomerular filtration rate, which is normally 125 ml/minute or 180 liters/day! The glomerulus lining is such that it only allows small molecules to filter through, like glucose, plasma, ions like sodium and potassium, urea, etc. The larger molecules, like blood cells and protein cannot pass through the glomerulus. This is the reason that when there are kidney diseases, the glomerulus lining is affected, due to which the protein molecules also pass through, leading to blood and protein in urine. Selective Reabsorption As mentioned above, in filtration step of urine formation, there is only crude and elementary separation of waste products and a lot of water, glucose and other important materials also pass through. Thus, there is need for reabsorption of these important elements back into the body,
which is where the second step, that is reabsorptions, comes in. This step is known as selective reabsorption because only some elements are reabsorbed back into the body. Reabsorption occurs in two steps, which is active reabsorption (which requires energy) and passive reabsorption (which does not require energy). Due to the difference in concentration of the fluid inside and outside the tubules, 99% of the water returns into circulation and thus, is passively absorbed, which is important for urine formation and flow. Provided the glucose levels are normal, almost all of the glucose is reabsorbed back into the blood from the proximal tubules. This glucose is actively transported into the peritubular capillaries. However, when there is a very large amount of glucose in the blood, then some of it passes into the urine, which is one of the signs of diabetes. Sodium ions are the only ions that are partially absorbed from the renal tubules back into the blood. Tubular Secretion The last step in urine formation is tubular secretion. This is the step where the urine is made concentrated by increasing the concentration of waste elements. Thus, in this stage, substances move into the distal and collecting tubules from blood in the capillaries around these tubules. These substances are secreted by the mechanism of active transport. The substances secreted include hydrogen ions, potassium ions, ammonia, and certain drugs or metabolic end products. Thus, the kidney tubules play a crucial role in maintaining the body's acid-base balance and maintaining the electrolyte balance in the body. The distal convoluted tubules then drain the urine into the collecting tubules. Then, several collecting tubules join together to drain their contents into the collecting duct, which finally, after urine formation, flows into the ducts of Bellini. This then eventually reaches the renal pelvis, from where the urine flows into the ureter to reach the urinary bladder. Thus, these were the various urine formation steps that take place right from the time when blood flows into the kidneys, till urine is passed into the ureters. The various urinary system diseases occur when there are problems with the functioning of the kidneys, which reflects in the final urine color, odor and concentration.
y
y y y
Some diseases and disorders of the excretory system include:
y
Nephritis is an inflammation of the glomeruli, due to a number of possible causes, including things like strep throat. Symptoms include bloody urine, scant urine output, and edema (swelling/puffliness).
y
y
y
Another, more severe form, is due to an autoimmune attack on the glomeruli. Other types of nephritis affect the tubules. Nephrosis also affects the glomeruli, and is characterized by excretion of abnormally large amounts of protein (often causing ³foamy´ urine) and generalized edema (water retension/swelling) throughout the whole body, especially noted as ³puffy´ eyelids. Because these people¶s kidneys often do not handle sodium properly, a low-salt diet is usually prescribed. My younger brother developed nephrosis at age 4, and to control it, had to stay on a no-added-salt diet and take prednisone on a regular basis from then until age 16, at which point, his body finally responded positively to being weaned off the drug. Most urinary tract infections (UTIs) are caused by Gram negative bacteria such as E. coli. If there is an obstruction of the urethra, catheterization may be needed, but as a general rule, catheterization in cases of UTI is contraindicated because it can actually introduce pathogens and make the infection worse. Women tend to acquire more urethral and bladder infections than men, perhaps because the opening of the urethra is closer to the anus. The way a woman cleans the area after relieving herself can influence her chances of contracting a UTI and/or vaginal infection. When parents are toilet-training toddlers, the common mistake is to wipe young girls from back to front. The toddlers get used to this feeling, and when they start to wipe themselves, they also go from back to front. This technique wipes bacteria from the anal area towards or into the ends of the vagina and urethra. Rather, young girls should be trained to wipe from front to back, and women who were not trained this way should make a conscious effort to change their habits. There are a variety of types of kidney stones depending on what conditions caused their formation. According to the Merck Manual, in the United States, about 80% are calcium oxalate (and/or other calcium-based stones), 5% are uric acid, 2% are cystine, and the other 13% due to magnesium ammonium phosphate or other causes. Stones may be microscopic to large ³staghorn´ stones that fill the whole renal pelvis. Often, as the stone is passed down the ureter, the person experiences much pain, and the affected kidney may even temporarily become nonfunctional. Stones may be broken up by ultrasound so they can be passed more easily, but large stones may have to be surgically removed. If possible, the underlying cause of the stone(s) should be identified and alleviated. For example, calcium stones might be caused by
anything from a parathyroid gland problem to too much vitamin D to some forms of cancer to a genetic predisposition. Diseases & Disorders Diseases and disorders that affect the excretory system include gout, kidney failure, urinary tract infections, diarrhea and constipation. Kidney failure occurs through the body's loss of kidney functions. When the kidneys fail, there is no filtering of the blood, which leads to a buildup of waste in the body. Gout is a disorder in which the body builds up excess amounts of uric acid as the kidneys are unable to process it properly. Gout causes joint pain and kidney stones. Urinary tract infections are caused by bacteria in the urethra and bladder. UTIs are more common in women than men. This is believed to be due to the female urethra's proximity to the anus. Constipation is the loss of regular and easy bowel movements. Stool passed through constipation is often hard. Diarrhea is the opposite of constipation; the body experiences stomach cramps and frequent loose, watery bowel movements. Read more: Excretory System Diseases & Disorders | eHow.com http://www.ehow.com/howdoes_5531760_excretory-system-diseasesdisorders.html#ixzz0x3UL4uK1
