excretion

• Excretion is the process of removing wastes and excess water from the body, which is necessary for maintaining homeostasis.
• Carbon dioxide, a waste product of cellular respiration, is dumped into the blood stream and eventually removed by the lungs.
• Renal Calculi can be dissolved with medicines, or it passes with urine by improving diet and water intake.
• Symptoms of Renal Calculi include severe abdominal pain and nausea.
• Renal Calculi, also known as kidney stones, are deposits of salt and minerals in our body.
• Ammonia (NH3), a waste product from the cells breakdown of old proteins, is removed through water.
• Once excreted into the blood stream by cells, ammonia is carried to the liver where it is converted from ammonia into urea which is less toxic.
• Urea is then carried from the liver to the kidneys where it is removed.
• The kidneys are able to regulate water concentration in the blood by removing excess water if the blood is too dilute or conserving water in the blood if it is not dilute enough.
• The two kidneys in the body receive between 1100 –2000 liters (1160 –2100 quarts or 500 gallons) of blood per day, about the volume of a car.
• The kidneys are composed of thousands of nephronsthat contain the glomerulus, a cluster of intertwined blood vessels that filter the blood to eliminate urea and excess water.
• Internally, the kidney has three regions: an outer cortex, a medulla in the middle, and the renal pelvis in the region called the hilum of the kidney.
• The hilum is the concave part of the bean-shape where blood vessels and nerves enter and exit the kidney; it is also the point of exit for the ureters.
• The outer layer of the kidney is a tough capsule.
• On the inside, the kidney is divided into an outer renal cortex and an inner renal medulla.
• The hilum extends inside the kidney into a funnel-like space called the renal pelvis.
• The renal pelvis has projections called calyces (sing: calyx).
• The medulla is divided into medullary pyramids, which project into the calyces.
• Between the medullary pyramids, the cortex extends as renal columns called Columns of Bertini.
• The kidney is made up of millions of smaller units called nephrons which are also the functional units.
• Blood enters the kidney as a substance called filtrate (or pre-pre-urine) via the afferent arteriole.
• Uremia is a condition where the kidneys are damaged, and there is a buildup of urea and other toxins in the blood, which is fatal and can cause kidney failure.
• Within the nephrons, the glomerulus processes the filtrate and passes it to Bowman's capsule for further processing.
• Urine begins as blood flows into the nephrons of the kidney.
• The kidneys maintain the body’s pH, reabsorb nutrients, regulate blood pressure, excrete wastes, remove excess fluid, and secrete hormones such as EPO that stimulate bone marrow to produce red blood cells.
• Ultrafiltration occurs at the kidney within the glomerulus and transports it through Bowman's capsule.
• Substances reabsorbed include water, sodium chloride, glucose, amino acids, lactate, magnesium, calcium phosphate, uric acid, and bicarbonate.
• The urine then passes through the proximal tubules, to the loop of Henle and collecting ducts, and is passed to the ureter for excretion.
• The urinary system consists of the kidneys, ureters, bladder, and urethra.
• Hormones which signal the tubules to alter the reabsorption or secretion rate, and thereby maintain homeostasis include antidiuretic hormone, aldosterone, parathyroid hormone, atrial natriuretic peptide, and brain natriuretic peptide.
• The maximum reabsorption of water takes place in the collecting duct to produce concentrated urine.
• Glomerular diseases include diabetic nephropathy and glomerulonephritis, which are characterized by symptoms such as pink urine, oedema or swelling on the face, and high blood pressure.
• Renal tubular diseases include acute tubular necrosis and polycystic kidney disease, which are characterized by symptoms such as fatigue, itching, muscle twitching, and loss of mental concentration.
• Collecting duct is a long, straight tube where H+ and K+ ions are secreted to maintain the electrolyte balance of the blood.
• Reabsorption is responsible for absorbing water, ions, and molecules in the glomerulus and carrying these back into the bloodstream.
• The urinary system works closely with the circulatory, endocrine, and nervous system to regulate the body's pH balance, fluid levels, blood composition, and blood pressure.
• Secretion is the step in urine formation responsible for transferring hydrogen ions, drugs, urea, and creatinine to the collecting duct for removal.
• DCT maintains the pH and sodium-potassium level in the blood cells.
• There are about 1,000,000 nephrons in each human kidney.
• The glomerulus arises from an afferent arteriole and empties into an efferent arteriole.