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Discover the intricate workings of the excretory system, focusing on the kidneys' vital role in filtering blood plasma, maintaining water balance, and regulating waste removal. Explore kidney anatomy, nephron function, and common diseases affecting this crucial system.
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Excretory System Jimmy, Ben & Brian
The Excretory system is comprised of three parts • The Kidneys • The Skin • The Lungs
The Kidneys • The kidneys are two bean shaped organs located between posterior to the abdomen and anterior to the lumbar vertebrae. • The kidneys’ main function are to filter and detoxify the blood.
Kidney Function The kidneys filter 150 quarts of blood plasma daily to remove: • Toxins • Metabolism wastes • Excess ingested water • Excess mineral salts
The Nephron • The nephron, the basic functional unit of the kidney, regulates blood PH, as well as the levels of water, salt, glucose, urea and minerals in the blood. • There are about a million in the cortex of each kidney.
The Nephron • Blood begins in the bowman’s capsule in the upper left. It travels down the yellow tube (the proximal convoluted tubule). Here, the blood vessels reabsorb excess water, glucose and amino acids.
The Nephron • At the bottom of the yellow tube the filtrate reaches the Loop of Helne in the medulla of the kidney. The filtrate then travels back up the (pink) tube and exits through the collecting duct.
Bowman’s Capsule • The Bowman’s Capsule contains the primary filter of the kidneys, the glomerulus. Blood passes from the Afferent atriole through the filter and out the efferent atriole, with waste exiting out of the proximal convoluted tubule.
The Glomerulus • The twisted mass in the center of the Bowman’s Capsule is the Glomerulus. It is a semipermiable membrane that allows water to pass through it. Other substances can enter, but can’t exit, and are sent out as waste.
Water Reabsorption • Our kidneys fufill the role of maintaining liquid homeostasis in the body. • The body loses water from breathing, perspiration, and solid excretion • To maintain proper water levels in the blood, the kidney carefully monitors how much water is sent to the bladder • To compensate for exessive water loss, sensitive cells in the hypothalamus called osomoreceptors become irritable.
Water Reabsorption Average Intake • Nerve impusles are sent up the spine to the posterior pituitary gland and antidiuretic hormone (ADH) is released. This causes water to be reabsorbed from the kidney’s collecting ducts until balance is reobtained • On average, 2500 milliliters are absorbed and released in one day Average Output
The Bladder • The waste from the kidneys exits through the ureters to the bladder. • The ureters pierce the bladder forming a triangular shape at the base of the bladder called the trigone • The ureteral orifices keep the urine from traveling the wrong way.
The Bladder • The bladder itself is a hollow muscular structure to hold the urine until it is excreted. • As the bladder fills with urine, it expands, holding an average maximum of 14-20 ounces. • During urination, the bladder muscles contract and the organ changes angles allowing urine to flow into the urethra.
The Prostate • Only men have a prostate • It is a doughnut-shaped gland surrounding the urethra and is just below the bladder • In young men it is about the size of a walnut, but if a man develops benign prostatic hyperplasia his prostate may grow to the size of an orange • The bladder helps prevent bladder infections, as well as helping to control urine flow into the urethra
Males v. Females • Only men have a prostate • The urethra is 1.5 inches long in females and 8 inches long in males
The Skin • The skin releases wastes such as water, salts, and urea through sweating. • The blood vessels expand under the epidermis, releasing the wastes into the sweat glands which secrete the wastes.
The Lungs • The lungs help to excrete the unwanted gases from the body like CO2. • Blood carries the unwanted waste gases that are removed through respiration.
Diseases • Kidney diseases are broken into two categories: acute (attacks quickly and dangerously) and chronic (breaks the kidneys down over years) • Some common kidney diseases include kidney cancer, polycystic kidney disease, kidney stones, cysts, and genetic disorders • The two most common kidney diseases are hypertension and diabetes. They work hand in hand to destroy the glomerulus.
Diseases • Symptoms of kidney disease include painful urination and swelling of the face/wrist/ankles • Doctors test for kidney disease by taking a urine sample and checking things like WBC/RBC count and blood acidity. Blood in urine is a sign of gross hematuria, where the kidneys leak blood into the ureturs • There are no cures for kidney disease, but kidney failure can be slowed or prevented through dialysis (a blood filtering machine) or a kidney transplant
WORKS CITED Kindersley, Dorling. "The Kidneys: What, Where, and How." Version 1.01994 May 7, 2007 <http://coe.fgcu.edu/faculty/greenep/kidney/>. Marieb, Elaine N.. Essentials of Human Anatomy & Physiology. Seventh Edition. San Fransisco: Pearson Education, Inc., 2003. V, Emily. "The Skin." The Excretory System. 7 May 2007 <www.marymount.k12.ny.us>. Poison Protection." Resources for Science Learning. 7 May 2007 <www.fi.edu>. Watson, Stephanie. The Urinary System. London: Greenwood Press, 2004.
