The Urinary System

2 Paired kidneys A ureter for each kidney Urinary bladder Urethra Also known as the RENAL SYSTEM

Main Functions of Urinary System 3 Kidneys filter blood to keep it pure  Toxins  Metabolic wastes (i.e. H2O, CO2, etc.)  Excess water  Excess ions (Potassium, Calcium, Chloride) Dispose of nitrogenous wastes from blood  Urea (a chemical compound of urine used in nitrogen excretion)  Uric acid (a chemical created when the body breaks down substances called purines)  Creatinine (A chemical waste by-product of normal muscle contractions. Creatinine is made from creatine, a supplier of energy to the muscle) Regulate the balance of water and electrolytes, acids and bases

INSIDE YOUR KIDNEY Renal artery bring blood that need to be filtered into the kidney The renal vein takes filtered blood out of the kidney  When blood enters the kidney through the renal artery, it flows into the renal medulla and enters a nephron (or renal tubule).  More than 1 million nephrons occupy each kidney 4

F.Y.I. Urine is yellow because it contains urobilinogen, which is a compound formed from bacteria breaking down bilirubin in the colon. Bilirubin is produced when red blood cells are broken down in the liver. The ammonia like smell of urine comes from the fact that urine contains ammonia in addition to other substances derived from ammonia (like urea). 5

NEPHRON 6 Tiny working units of the kidneys. They are microscopic structures that are basically a single tubule coined and coiled into various shapes The basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes, etc.

Understand at least this much: 7 Filtration a. Fluid is squeezed out of the glomerular capillary bed (a network of capillaries that performs the first step of filtering blood) Reabsorption b. Most nutrients, water and essential ions are returned to the blood of the peritubular capillaries (tiny blood vessels that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron) Secretion c. Moves additional undesirable molecules into tubule from blood of peritubular capillaries

F.Y.I. If you’re exercising and sweating heavily, your body’s fluid level is decreased. Therefore, your body holds onto the water that it has, and less water goes into your urine. Your urine becomes more concentrated and appears darker. If your body has more water than it needs, the excess water goes into the urine, making it more dilute. But as long as the urine is effectively removing all the toxins and wastes, it’s doing its job. 8

9 KIDNEY REGIONS Kidneys are retroperitoneal organs (situated or occurring behind the peritoneum which is the serous membrane lining the cavity of the abdomen and covering the abdominal organs)  Superior lumbar region of posterior abdominal wall Adrenal glands lie superior to each kidney (the yellow blob in pic) Kidney has two regions  Cortex: outer  Medulla: inner

URETERS 10 Slender tubes about 25 cm (10 “) long leaving each renal pelvis One for each kidney carrying urine to the bladder This oblique entry helps prevent backflow of urine

Urinary Bladder 11 Collapsible muscular sac Stores and expels urine  Males: anterior to rectum  Females: just anterior to the vagina and uterus

URETHRA 12 Smooth muscle with inner mucosa  Drains urine out of the bladder and body Male: about 20 cm (8”) long Female: 3-4 cm (1.5”) long  Short length is why females have more urinary tract infections than males Urethra____ urethra

Things to know 13 What is a renal transplant? Adrenal glands are critical in creating hormones that are necessary for a healthy life. Identify what hormones are created by the adrenal glands and the purpose of each hormone. What is creatinine? What is micturation? Regions of the kidney What is pyuria and what can cause it?