Waves for the MCAT: If you spend more time texting and calling, then you only need a light data use plan. Phone number is required. Iodinated contrast comes in two forms: Annals of the ICRP.
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Ciliated cuboidal cell clora cell L. Alveolar sacs are disintended space Elastic fibre? Encircles tube From trachea? Fxn Provide semirigid support so that tracheal wall does not collapsed inward. These branchioles serve as areas of transition between conducting and respiratory portions.
Elastic fibres enable the alveoli to expand with inspiration and to contract with expiration Reticular fibre serve as a walls that prevents over distention and damage to capillaries and thin alveolar duct. Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow.
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Related More from user. Some toxins are ingested in food and others are byproducts of metabolism. Some toxins, like carbon dioxide, can be tolerated in small amounts and can be easily disposed of as they are, but some toxins are so dangerous that the body must change them in some way to make them less toxic, or find a way to quickly remove them.
Detoxifying and modifying dangerous substances so that they can be quickly and easily removed from the body is one of many jobs of the human liver. Ammonia is a major byproduct of human metabolism, but it's extremely toxic, so the liver converts it to a less toxic form called urea, which can be created from two ammonia molecules and one carbon dioxide molecule. Here is a depiction of the chemical reaction: Of course, then we still have to get rid of the urea, but it's far less toxic than ammonia so we can concentrate it and store it for several hours without it harming us.
So once the liver has converted the ammonia into much less toxic urea, then what? Well, first the urea is allowed to leave the liver through the bloodstream. The circulating urea will eventually reach the kidneys where it will be filtered out of the bloodstream and concentrated in the urine. Here is how it works.
In the outer layer of the kidneys are structures called glomeruli , which are ball-like structures of the kidney composed of very porous capillaries. You can think of the capillaries in the glomeruli as being like garden hoses with hundreds of holes all over them that let water spray out when the pressure is on. The blood pressure in these capillaries forces large amounts of water and small molecules including urea out through the pores, but blood cells and larger molecules that are too big to fit through the pores stay in the bloodstream.
Surrounding the glomeruli are the ends of the renal tubules , which are long, looping tubes in the kidney that collect filtrate from the blood and concentrate it into urine. The water, nutrients, salts, urea and other waste products in the filtrate are collected by the surrounding renal tubule and begin a twisted journey. The filtrate travels through the tubule that crosses back and forth between the outer and inner layers of the kidney. As it does, nutrients, water, and sodium chloride are reabsorbed from the renal tubules and returned to the blood.
As water is reabsorbed, the urea and other waste products become very concentrated in the tubules and become urine. The whole structure from the glomerulus to the end of the renal tubule is called a nephron and is the basic functional unit of the kidney.
By filtering out a large volume of water and small molecules and then selectively allowing most of the water and nutrients to be reabsorbed, the nephrons allow humans to get rid of urea and other wastes in high concentrations and conserve water when needed.
Sodium chloride and other salts can also be reabsorbed back into the bloodstream as needed, but that function of the kidney is a key component for homeostasis which is another topic for another day. Get access risk-free for 30 days, just create an account. The urine exits the kidneys through two long tubes called ureters which carry the urine to the bladder.
Repeated contraction and relaxation of muscles in the ureter walls ensure that the urine flows in one direction from the kidneys to the bladder. The bladder itself is a balloon-like muscular organ, which is capable of stretching as it fills with urine. As the bladder fills with urine and the walls stretch to create a larger holding capacity, a signal is sent by the nerves of the bladder which gives us the sensation of the need to urinate.
The more that the bladder stretches, the more intense this sensation becomes until the bladder reaches its full capacity and the sensation becomes so overwhelming that it feels like you're gonna burst! Most of the time, people don't let their bladder reach full capacity because it becomes so uncomfortable. Instead, people normally have control over when they empty their bladder by controlling a muscular valve at the exit point of the bladder.
When this valve is opened, and the bladder muscles contract, the urine enters the urethra , which the urine travels through before it exits the body. Detoxifying and modifying dangerous substances so that they can be quickly and easily removed from the body is accomplished by the human liver.
An example of this would be ammonia, which is very toxic, so the liver converts it to urea which is far less toxic and can be easily removed from the body. The kidneys are the organs that filter waste products out of the blood and help regulate blood composition and pressure. The filtrate travels through the tubules and as it does, nutrients, water and sodium chloride are reabsorbed from the renal tubules and returned to the blood. As water and nutrients are reabsorbed, the waste products are concentrated in the tubules and become urine.
After the urine is concentrated by the kidneys, it is stored in the bladder. Most people have control over when they empty their bladder by controlling a muscular valve at the exit point. To unlock this lesson you must be a Study.
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By creating an account, you agree to Study. Explore over 4, video courses. Find a degree that fits your goals. Excretory System Each year in the U. Kidneys, the workhorses of the excretory system, perform these same functions more effectively than any machine. In this lesson, we'll talk about how the excretory system removes toxic substances from the body. Try it risk-free for 30 days. An error occurred trying to load this video.
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