File Name: anatomy and physiology of excretory system .zip
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- Filtration, Reabsorption, Secretion: The Three Steps of Urine Formation
- Anatomy and Function of the Urinary System
- Excretory system
Click Image to Enlarge. The body takes nutrients from food and changes them to energy. After the body has taken the food components that it needs, waste products are left behind in the bowel and in the blood. The kidney and urinary systems help the body to get rid of liquid waste called urea. Urea is produced when foods containing protein such as meat, poultry, and certain vegetables are broken down in the body.
Urea is carried in the blood to the kidneys. This is where it is removed, along with water and other wastes in the form of urine. The kidneys have other important functions.
They control blood pressure and produce the hormone erythropoietin. This hormone controls red blood cell production in the bone marrow. The kidneys also control the acid-base balance and conserve fluids.
Two kidneys. Their function is to:. The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries glomerulus and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.
Two ureters. Muscles in the ureter walls keep tightening and relaxing. This forces urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters. This triangle-shaped, hollow organ is located in the lower belly.
It is held in place by ligaments that are attached to other organs and the pelvic bones. The bladder's walls relax and expand to store urine. They contract and flatten to empty urine through the urethra. The typical healthy adult bladder can store up to 2 cups of urine for 2 to 5 hours.
Two sphincter muscles. Nerves in the bladder. The nerves alert a person when it is time to urinate, or empty the bladder. This tube allows urine to pass outside the body. The brain signals the bladder muscles to tighten. This squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra.
When all the signals happen in the correct order, normal urination happens.
Filtration, Reabsorption, Secretion: The Three Steps of Urine Formation
When many people look at the cardiovascular system they often tend to accentuate the positive contents in the blood—food, water, and oxygen—and rarely focus on the negative. True, I did talk about CO 2 and the lungs, but what about other wastes, particularly nitrogenous wastes from the breakdown of proteins. This section rectifies that error and concentrates on eliminating the negative. Have you ever looked at the alcohol content of wine? It is always around 12 percent because at that concentration the alcohol a toxic waste kills the yeast that makes it.
Nephron , functional unit of the kidney , the structure that actually produces urine in the process of removing waste and excess substances from the blood. There are about 1,, nephrons in each human kidney. The most primitive nephrons are found in the kidneys pronephros of primitive fish, amphibian larvae, and embryos of more advanced vertebrates. The nephrons found in the kidneys mesonephros of amphibians and most fish, and in the late embryonic development of more advanced vertebrates, are only slightly more advanced in structure. The most advanced nephrons occur in the adult kidneys, or metanephros , of land vertebrates, such as reptiles, birds, and mammals. Each nephron in the mammalian kidney is a long tubule, or extremely fine tube, about 30—55 mm 1. At one end this tube is closed, expanded, and folded into a double-walled cuplike structure.
Urinary System. Anatomy of the Kidneys. Overview of. Renal Physiology. Renal Physiology I: Glomerular Filtration.
Anatomy and Function of the Urinary System
The kidneys filter unwanted substances from the blood and produce urine to excrete them. There are three main steps of urine formation: glomerular filtration, reabsorption, and secretion. These processes ensure that only waste and excess water are removed from the body. Each kidney contains over 1 million tiny structures called nephrons.
Quality minimal. The Urinary System is a group of organs in the body concerned with filtering out excess fluid and other substances from the bloodstream. The substances are filtered out from the body in the form of urine. Urine is a liquid produced by the kidneys, collected in the bladder and excreted through the urethra.
Click Image to Enlarge.
The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism , so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excretory systems is the elimination of the waste products of metabolism and to drain the body of used up and broken down components in a liquid and gaseous state. In humans and other amniotes mammals , birds and reptiles most of these substances leave the body as urine and to some degree exhalation, mammals also expel them through sweating.
Figure The urinary system plays a vital part in maintaining homeostasis of water and electrolyte concentrations within the body. The kidneys produce urine that contains metabolic waste products, including the nitrogenous compounds urea and uric acid, excess ions and some drugs. The first sections of this chapter explore the structures and functions of the organs described above.
Once inside the system, you can zoom and rotate your virtual skeleton. Eleven systems in total are able to view and examine. This site not only includes images of and information on the above listed systems, but it also includes interactive drills and practice questions for students. This site not only includes images, but also self-quizzing options for the excretory system as well. T hese lectures vary in length, and will open in a new window when you click on the provided link.
Туда и обратно, - мысленно повторял. - Туда и обратно. Он был настолько погружен в свои мысли, что не заметил человека в очках в тонкой металлической оправе, который следил за ним с другой стороны улицы.
Мистер Густафсон? - не удержался от смешка Ролдан.