Urinary System Unit 6.12 (6 th Edition) Chapter 7.12 (7 th Edition) 1
Learning Objectives Identify the major organs of the urinary system and their functions. Explain the major functions of the kidneys. Explain the major functions of nephrons. Contrast the differences between the urethra in males and females. Explain five terms describing urinary conditions. Describe three diseases of the urinary system. 2
Fun Facts About the Urinary System The average human urinates between 1 1.5 Liters of liquid waste daily. In a healthy adult, approximately 440 gallons of blood passes through the kidneys daily. Kidney beans were named after their resemblance to the kidney organ (not the other way around!). Ancient Roman spies used urine as invisible ink to write secrets between the lines of their official documents, hence the saying: read between the lines. The messages appeared only when heated. One kidney could handle the task of filtering the blood and making urine perfectly well. In fact, if one kidney is removed, the remaining kidney can increase in size by 50% within two months to take over the whole job. 3
Urinary System Overview Review of Elimination Lungs eliminate CO 2 Sweat glands eliminate excess heat, salt Digestive tract- indigestible solids, bacteria Urinary tract is the main system of elimination Also Known as Excretory System removes waste removes excess water maintains body s acid-base balance Main Components Two kidneys Two ureters one bladder one urethra 4
Kidneys Overview two bean-shaped organs behind upper part of abdominal cavity protected by ribs and heavy fat cushion connective tissue helps keep in place enclosed in mass of fatty adipose tissue covered by tough, fibrous tissue Anatomy divided into two main sections cortex: outer-section containing most of nephrons that aid in urine production medulla: inner-section that contains most of collecting tubules which carry urine from nephrons through kidney hilum: notched or indented area through which ureter, nerves, blood and lymph vessels enter and leave kidney 5
Nephrons Definition microscopic filtering units located in kidneys more than one million nephrons per kidney Anatomy & Physiology renal artery carries blood to kidneys as blood passes through glomerulus (cluster of capilaries), water, mineral salts, sugar, and metabolic products are filtered out of blood red blood cells and proteins are not filtered out filtered blood leaves glomerulus via the renal vein that carries it away from kidneys Bowman s capsule: C-shaped structure that surrounds glomerulus it picks up materials filtered from blood in glomerulus and passes them into the convoluted tubule as these materials pass through sections of the tubulue, substances needed by body are reabsorbed and returned to blood capilaries excess sugar and mineral salts, other wastes, and water remain and 6 become urine
How the Kidneys Work 7
Ureters and Bladder Ureters two muscular tubes approximately 10-12 inches in length extends from renal pelvis of each kidney to the bladder peristalsis moves urine through the ureter from the kidney to bladder Bladder hollow, muscular sac that lies behind the symphysis pubis and at midline of the pelvic cavity mucous membrane lining arranged in series of folds called rugae rugae disappear as bladders expands to fill with urine the urge to urinate occurs when bladder contains 250 ml (1 cup) of urine, the bladder can hold much more circular sphincter muscle controls the opening of bladder 8
Urethra and Urine Urethra tube that carries urine from bladder to the outside external opening is called the urinary meatus females: tube is ~3.75 cm in l length; opens in front of vagina males: ~20 cm in length and passes through prostrate gland and out through the penis it carries both urine and semen (not at the same time) Urine liquid waste product produced by urinary system ~95% water 9
Conditions Affecting Urination Polyuria excessive urination Oliguria below normal amounts of urination Anuria absence of urination Hematuria blood in the urine Pyuria pus in the urine Nocturia urination at night Dysuria painful urination Retention inability to empty the bladder Incontinence involuntary urination 10
Diseases & Abnormal Conditions Cystitis inflammation of bladder usually caused by pathogen and more common in females Glomerulonephritis or Nephritis inflammation of glomerulus of kidney can follow strep throat infection, scarlet fever, or rheumatic fever Pyelonephritis inflammation of kidney tissue and renal pelvis Renal Calculus kidney stone formed when salts in urine precipitate Renal Failure kidneys stop functioning Uremia toxic condition that occurs when kidneys fail and urinary waste products are present in blood stream Urethritis inflammation of urethra caused by germs or chemicals 11