The Urinary SystemB&S

Chapter 22

The Urinary System

• Is also called the excretory system because one of its main functions is to remove waste products from the blood and then eliminate it from the body

• The urinary system is also responsible for regulation of fluid volume of the body

• It is also responsible for acid-base balance and electrolyte composition of body fluids

• Just like the accessory organs that work along with the alimentary system to rid the body of waste, our body has other systems that aid in elimination of wastes from the body….they are as follows…………….

Other systems involved in eliminating wastes

• Urinary system

• Digestive system

• Respiratory system

• Integumentary system

Urinary System

• This system excretes water and waste products containing nitrogen and salts, these are all products in urine

Digestive System

• This system eliminates water, some salts, bile and the waste products of digestion which are contained in feces

• The liver is important in eliminating the destroyed RBCs end products and the breaking down of toxins such as alcohol and certain drugs

Respiratory System

• This system eliminates carbon dioxide and water, that changes into vapor

• We can see this when we breathe on a windowpane

Integumentary System

• Excretes water, salts and small amounts of nitrogenous wastes, all of which appear in perspiration

• Evaporation of water from the skin may go on most of the time without even being conscious of it

Part of the Kidney System

• We have:

• 2 kidneys

• 2 ureters

• A single bladder

• A single urethra

2 Kidneys

• These organs:

• Extract wastes from the blood

• Balances body fluids

• Forms urine

Excretion of unwanted substances

• Such as waste products from cell metabolism, excess salts and toxins

• Urea is filtered from amino acids (proteins) through the liver and then sent to the kidneys for elimination

2 Ureters

• These are tubes that carry urine from the kidneys down to the bladder

A single urinary bladder

• This is a reservoir that receives the urine brought into it by the 2 ureters

A single urethra

• This is a tube that carries urine from the bladder to the outside and into the toilet for elimination

Where are the kidneys?

• The 2 kidneys lie against the muscles of the back in the upper kidney

• The kidneys and ureters lie behind the peritoneum in a space called the retroperitoneal space

• The kidneys are up under the dome of the diaphragm and are protected by the lower ribs and the coastal cartilage

Covering over the kidneys

• The kidneys are very important to our bodies

• They have a special covering made of fibrous connective tissue that is loosely connected to the kidney itself

• There is also an adipose layer (fat) around each kidney

• And remember…the adrenals sit on top of each kidney

Blood Supply to the Kidneys

• The kidney is supplied with blood by a short branch of the abdominal aorta called the renal artery

• The renal artery extends off into the branch that supplies the kidney

• After the renal artery enters into the kidney, the renal artery subdivides into smaller and smaller branches which eventually make contact with the functional units of the kidney known as the nephron. The blood goes into the afferent artery

• Finally, blood leaves the kidney by efferent vessels that merge to form the renal vein which ends up carrying blood into the inferior vena cava for return to the heart

Blood Vessels and Ureters

Structure of the kidney

• The kidney is somewhat flattened

• The kidney is approximately 4 inches long x 2 inches wide x 1 inch thick

• The inner or medial border of the kidney contains a notch called a hilus. This is where the renal artery , the renal vein and the ureter connect with the kidney.

• The outer or lateral border is convex or curved outward giving the entire organ a bean-shaped appearance

The Kidney is divided into 2 regions

• Renal cortex – is the outer portion of the kidney

• Renal medulla – is the innermost portion of the kidney that contains the tubes in which urine is formed and collected

A Deeper Look Into the Renal Medulla (use your picture book)

• In the tubes where urine is made, there are 8-10 cone-shaped structures called the renal pyramids

• The tips of the pyramids point toward the renal pelvis which is a funnel-shaped basin that forms the upper end of the ureter

• The renal pelvis is the upper extension of the ureter that breaks off into all parts of the renal cortex and renal medulla or into the kidney itself

Use your picture book

• Cuplike extensions called calyces (KA-lih-seze) (or one called calyx [KA-liks]) of the renal pelvis surround the tips of the pyramids and collect urine

• The urine that collects in the pelvis then passes down the ureters to the bladder

Cross Section of Kidney

Nephron

• This basic unit inside of the kidney is too small to be seen with the naked eye

• Each kidney contains about 1 million coiled nephrons

• If all of the 1 million coiled nephrons were stretched out, they would span 75 miles

Nephrons

• These are where the work of the kidney is actually done

• A nephron is a tiny coiled tube with a bulb known as the Bowman’s capsule, at the end

• This bulb, known as Bowman’s capsule, surrounds a cluster of capillaries called the glomerulus

Afferent Arteriole

• This is a small blood vessel that supplies the glomerulus with blood

• Its diameter is bigger than in the efferent arteriole

Efferent Arteriole

• This is a small vessel that carries blood from the glomerulus. Diameter of the vessel is smaller to keep the pressure going so the blood gets pushed on out to the rest of the nephron

• When blood leaves the glomerulus, it does not head immediately back towards the heart. Instead, it flows into a capillary network that surrounds the tubular portion of the nephron

Tubular Part of the Nephron

• Has several parts to it:• The coiled part leading from Bowman’s Capsule is called

proximal convoluted tubule

• The tube then uncoils to form a hairpin-shaped segment called Loop of Henle

• Continuing from the loop, the tubule coils once again into the distal convoluted tubule

• The distal end of the tube empties into a collecting duct, which then continues through the medulla of the kidney toward the renal pelvis

What is where????

• Renal Cortex Renal Medulla• Glomerulus *Loop of Henle

• Bowman’s Capsule collecting ducts

• Distal convoluted Tubes

• Proximal convoluted Tubes

Efferent arteriole

Juxtaglomerular Apparatus

• There are specialized epithelial cells in this apparatus which are sensitive to changes in BP

• The name means “near the glomerulus” which describes the location of this apparatus

Juxtaglomerulus Apparatus

• This is a structure forming a cuff surrounding the afferent arteriole that leads to the glomerulus

• This appartus is concerned with the production of renin and is involved in sodium metabolism

Blood Pressure

• When a person’s BP falls, cells in the wall of the afferent arteriole secrete the enzyme “renin” which raises BP by activating a protein called angiotensin that causes blood vessels to constrict, thus raising BP

Functions of the Kidney

• Maintenance of water balance takes place in the kidney

• Our body can have water taken in and then it knows how to release the right amount to balance it back out in urine

Regulation of acid-base balance

• Acids are constantly being produced from cell metabolism and by certain foods that cause an acid build up

• Our body balances acids as in bicarb that is released from the kidney when our body becomes too acidic

Regulation of RBC’s

• When the kidneys do not get enough O2, they produce the hormone erythropoietin

• Erythropoietin stimulates the production of RBC’s in the red bone marrow

• Erythropoietin is now made in a lab and is given to pts who suffer from anemia as in a cancer pt who needs and increase in RBC’s

The First part of urine formation

• Begins when blood leaves the left ventricle and heads towards the rest of the body out of an artery

• Blood enters through the renal artery which leads into the kidney

• Blood travels through the inner part of the kidney (medulla) through the renal pelvis to the tips of the renal pyramid where the top of the cone is, this is where the nephrons are

Formation of Urine

• The actual process of urine formation then begins with the glomerulus in Bowman’s capsule

• The membranes that form the walls of the glomerular capillaries are sieve like and permit the free flow of water and soluble materials through them

Glomerular Filtration• Blood can enter the glomerulus easier through the afferent

arteriole than it does when it leaves via the efferent arterioles because the afferent arteriole is slightly larger in diameter than the efferent arteriole.

• The blood entering the glomerulus is at a high pressure because this was left vent. Blood. When it leaves through the efferent arteriole (smaller in diameter), there is still pressure, allowing particles to constantly be pushed out of the blood into Bowman’s capsule of the nephron This type of movement of materials under pressure is known as glomerular filtration

• At this time, the blood is filtered and the bowman’s capsule is left with filtrate while the blood continues onward to eventually make its way back to the heart

Glomerular Filtrate

• The fluid that enters Bowman’s capsule is called glomerular filtrate and it makes its journey along the tubular system of the nephron

• Along with water and normal substances in the blood, drugs may be filtered and may become part of the glomerular filtrate

Glomerular Filtrate

• Contains mostly water

• Any salt like Ca+, Na+, K+, Cl-, Phosphorous

• Any medication we take

• Possible protein or sugar or blood

• alcohol

• As the filtrate travels through the tubular system of the nephron, substances leave the tubule by active transport and diffusion

• It is at this time that certain substances like K+ move into urine and with movement of H+ ions, the kidneys can use the hydrogen to regulate acid-base balance

How does our urine get concentrated?

• ADH regulates how much water is removed from the urine

• ADH is a hormone released from the hypothalamus (which received a message from the posterior pituitary)

• When filtrate passes through the Loop of Henle, salts like sodium are actively pumped out by the cells of the nephron this causes the interstitial fluid of the renal medulla to become more concentrated with the salt that was just pumped out

• Now the fluid of the nephron becomes dilute because the nephron’s walls don’t absorb water well in this part and all the salt was just pumped out.

• As the fluid passes through the distal convoluted tubules and through to the collecting duct, water is drawn out by the concentrated fluids around the nephron and returned to the blood because Na is now on the outside and water follows Na back into the blood

ADH

• The role of ADH is to make the walls of the distal convoluting tubules and the collecting tubule more permeable to water

• This means more water will be reabsorbed back into the body and less will be excreted with the urine

• Remember, our body uses the negative feedback system to help regulate things, when our body detects low fluids, ADH (a salt) is released to help keep more water in the body

Diabetes Insipidus

• This disease HAS NOTHING TO DO WITH SUGAR….

• There is an inadequate secretion of ADH from the which results in elimination of large amounts of dilute urine to leave the body and now the pt is excessively thirsty

Normal PH of urine

• Ph: 6.0

• Specific gravity in general: 1.005 – 1.030

• Urine spec. gravity: 1.010-1.020

• The lower the specific gravity <1.010 dilute

• Specific gravity >1.020=concentrated

The Ureters

• Measure approximately 10-13 inches long• When the bladder is completely full, the pressure

of the bladder on the ureters makes backflow of urine impossible

• The muscles of the wall of the ureters are capable of peristalsis as in digestion

• Urine is moved to the bladder by peristalsis and gravity

The Bladder

• The bladder temporarily holds urine that will be eliminated from the body

• The bladder has 3 layers of involuntary muscles that allow the bladder to stretch when full

• When the bladder is empty, the muscular wall becomes thick, when full, the muscle thins out

The bladder

• When moderately full, can hold approx. 470ml urine

• The floor of the bladder is known as the trigone (TRI-gone) because of the triangular formed by the openings of the 2 ureters and urethra

Urine

• Should be yellowish in color because it is 95% water and 5% dissolved solids and gases

• The ph is 6.0

• When kidneys are diseased, they loose the ability to concentrate urine

• Urine can contain blood = hematuria

Concentrated Urine

• At times if a pt has liver disease, urine may be amber (red) colored - (tea) brown colored. This can be d/t bilirubin breaking down from the destroyed RBC’s but not being able to be carried away

The Urethra

• This is the tube that extends from the bladder to the outside and is the means by which the bladder is emptied

• In males, the urethra is part of both the urinary AND reproductive systems and is much longer than is the female urethra

Male Urethra

• In the male, the urethra is 8 inches long and passes through the prostate gland where it is joined by 2 ducts carrying the male sex cells, and it leads to the penis and to the outside

• The male urethra serves the dual purpose of conveying the sex cells and draining the bladder

Female Urethra

• In the female, the urethra is only about 1.5 inches long

• It is located behind the pubic joint and is embedded in the muscle of the front wall of the vagina

• The external opening called the urinary meatus is located just in front of the vaginal opening between the labia minora

• The female urethra only drains urine and is separate from the reproductive system

Urination

• Another name for urinating is:• Micturition (mik-tu-RISH-un)

• The process is controlled by voluntary and involuntary muscles of the sphincters that surround the urethra

• These sphincters are called internal and external uretheral sphincters

• In order to void voluntarily, relaxing the muscles of the pelvic floor and increasing the pressure in the abdomen results in increased pressure of the bladder and the spinal reflex is triggered

Spinal Reflex

• As the bladder fills, stretch receptors in the walls of the bladder send impulses to a center in the lower part of the spinal cord

• Motor impulses from this center stimulate contraction of the bladder wall forcing urine outward as both the internal and external sphincters are made to relax

Kidney Disorders

• These can be acute or chronic

• Acute usually occurs with infections or inflammation of the nephrons, these diseases commonly run their course for a few weeks then complete recovery is likely

• Chronic conditions arise slowly and often progress and worsen and gradual loss of kidney function occurs

Reflux of the kidney

• This is referred to specifically in children under the age of 2 y.o.

• If the child gets recurrent UTI’s, the pt is put through testing to see if urine is refluxing or getting stuck in the kidney itself and is simply rolling around

• A catheter is inserted into the bladder and dye is inserted and watched on screen to detect if there is a backup of dye = backup of urine

Acute Glomerulonephritis

• Is also known as acute poststreptococcal glomerulonephritis

• The is the most common disease of the kidneys

• Occurs in children 1-4 weeks after a strep throat infection occurs

• Basically antibodies formed in response to the strep, attach to the glomerular membrane and injure it

Acute Glomerulonephritis

• This injury to the glomerulus causes large protein molecules and RBC’s to filter into Bowman’s capsule and then out in urine

• Usually the pt recovers without having kidney damage

• In adults, this condition can take long to repair and leaves damaged nephrons that leads to chronic renal failure

Pyelonephritis

• Is an inflammation in the renal pelvis of the tissue of the kidney, usually from a bacterial infection

• This condition can be acute or chronic

• The bacteria can ascend along the lining membrane from an infection in the lower part of the urinary tract

Acute Pyelonephritis

• Is often seen in people with partial obstruction of urine flow d/t stasis of urine

• Occurs in pregnant women, men with enlarged prostate, in pts with kidney stones that block the ureters

• TREATMENT: antibiotics, fluids, rest, antipyretics

Chronic Pyelonephritis

• May be caused by persistent or repeated bacterial infections d/t backflow of urine or stasis

• Progressive damage of the kidney tissue is seen when the pt has HTN, a continued loss of protein in the urine and urine that is dilute (d/t the damage of tissue, wastes are not getting out)

Neurogenic Bladder

• A bladder dysfunction resulting from neurogenic lesions of the CNS, or the nerves supplying the bladder

• Neurogenic refers to the nervous tissue• Pts cannot void correctly, they usually

cannot make a direct stream and they most often need to be catheterized to remove all of the urine

Hydronephrosis

• Is the distention of the renal pelvis and calyces with accumulated fluid caused by obstruction of urine flow

• The obstruction may occur at any level of the urinary tract

• The obstruction can be anything from a kidney stone, to a tumor to an enlarged prostate or scar tissue.

• Prompt removal of the obstruction must occur or there will be permanent kidney damage

Polycystic Kidney

• Fluid containing sacs develop in the active tissue of the kidney and gradually, by pressure, destroy the functioning parts of the kidney

• This is a familial (runs in families) and treatment has not provided satisfactory results except for the use of dialysis machines and kidney transplants

Tumors of the Kidney

• Usually grow rather slowly but rapidly invading types can occur

• Blood in the kidney and dull pain in the flank kidney region are warnings that should be taken care of at once

• Surgical removal of the kidney offers the best chance of cure d/t most renal cancers DO NOT respond to chemo

Mets to the kidney

Tuberculosis to the kidney

Renal Failure

• 2 types can occur:

• Acute renal failure

• Chronic renal failure

Acute renal failure

• May result from medical or surgical emergency or from toxins that damage tubules

• Symptoms:• Sudden, serious decrease in kidney function

accompanied by electrolyte and acid-base imbalances

• Acute renal failure occurs as a serious complication of other severe illnesses and may be fatal

Chronic renal failure

• Results from the gradual loss of nephrons• As more and more nephrons are destroyed, the

kidneys gradually loose their ability to perform their normal functions

• As the disease continues, the accumulation of nitrogenous wastes get too high in the blood causing uremia

• Renal insufficiency occurs and urine function is impaired

Results of Chronic Renal Failure

• Dehydration

• Edema

• Electrolyte imbalance

• HTN

• Anemia

• Uremia

Dehydration

• Excessive loss of body fluid may occur early in renal failure when the kidneys cannot concentrate the urine and large amounts of water are eliminated

Edema

• Accumulation of fluid in the tissue spaces may occur late in chronic renal disease when the kidneys cannot eliminate water in adequate amounts

Electrolyte Imbalance

• Na+ and K+ are off balance d/t poor or impaired urinary function

HTN

• May occur as a result of fluid overload and the increased production of renin

Anemia

• Occurs when the kidneys cannot produce the hormone erythropoietin to activate RBC production in bone marrow

Uremia

• Occurs when levels of nitrogenous waste products in the blood are very high

• Urea can be changed into ammonia in the stomach and cause ulcerations and bleeding

Kidney Stones

• Also called calculi

• Are made of substances such as Ca+ salts or uric acid that precipitate out of the urine instead of remaining in solution

• Calculi usually form in the renal pelvis and in the bladder at times

Causes of kidney stone formation

• Sometimes stones are caused by dehydration

• Stagnation of urine

• Infection of the urinary tract

• Blockage of the ureter r/t kidney stone that is lodged inside of the ureter

• Stones vary in size

Kidney stones

• Can be tiny sand-like to large masses that look like the stones in a driveway

• There is no way to dissolve the stones because substances that could do so would also destroy the kidney

Lithotriptor

• Literally means “stone cracker’

• This actually gives external shock waves to shatter the stones

• This procedure is called lithotripsy

• Many times this works well, other times, surgery is required to remove the stones

Lithotripsy

(ESWL) extracorporeal shock wave lithotripsy

• This is a procedure that is performed while the pt’s lower body is submerged in a tank of water or surrounded by a fluid-filled bag.

• Ultrasound, not radiation or a laser beam, is the mechanism used to pulverize the stones

• Pts are sedated and premedicated with analgesics to reduce the discomfort that is commonly described as a “blow to the body”

• It is common for bruises to appear as a consequence of the ultrasonic energy

The Passing of Kidney Stones

• IS EXTREMLY PAINFUL

• Pts usually present to the E.R. in horrific pain

• Lots of narcotics are given once it has been determined that the pt has stones, ultra sound is the test used most often

Renal Dialysis

• Is used in pts who have no renal function to rid the body of the natural wastes it makes

• There is an accumulation of nitrogenous wastes

• 2 types of dialysis can be performed:

• Peritoneal dialysis

• hemodialysis

Peritoneal Dialysis

• The use of the peritoneal membrane as a filter is the process

• A fluid called dialysate is delivered into the peritoneum and it sits there collecting waste, this is called “dwell-time”, the machine then pumps the waste filled dialysate fluid out into the toilet and the nitrogenous waste is removed

Hemodialysis

• A shunt is placed in the pts forearm (usually) and there is a cellophane type membrane inside of the shunt that filters the waste products

• A needle is inserted into this shunt

• NEVER TAKE BP IN THE SHUNT ARM, you can ruin the shunt

Assessment of the pt’s shunt

• The nurse assesses the shunt along with VS

• The nurse should hear a bruit (bru-wee, brew-ee) which is the adventitious sound of the blood moving through the shunt heard upon auscultation, having venous or arterial origin

• The nurse places her fingers gently over the shunt and she should also feel a “thrill”, movement of the blood

• WHAT DO YOU DO IF YOU DON’T FEEL A THRILL OR BRUIT?

• CALL DR. STAT, CIRCULATION CAN BE IMPAIRED OR CLOT CAN BE THERE-SERIOUS MATTER

Dialysis

• Usually done in a free-standing clinic

• Usually pts go to dialysis for 2-3+ hours, 3xs a week

Diet of the patient with impaired kidneys

• Low sodium <2 gms/day

• Low protein diet

• Sometimes, low K+ diets d/t K+ being held in

Kidney Transplant

• Is performed when kidney failure arises

• Many hoops to jump through before transplant can be done

• Many meds to be on post transplant

• What is major concern with any transplant?

• What is the med used for transplant pts?

Disorders of the ureters

• Strictures

• Can be caused by abnormal pressure from tumors or other masses outside the tube

• May be d/t stones lodged in ureters

• May be caused by kinking of the tube

• Ureteral stents can be placed inside the ureter to keep the ureter open

IVP

• Intravenous pyelogram is a dye study to see how the kidneys are functioning

The patient is injected with radiopaque dye and X-rays are taken as the dye travels through the urinary tract. This procedure is performed to confirm the presence of kidney stones, although some

somes may be too small to see. Lots of fluid must be given post-IVP

Disorders involving the bladder

• If a pt has a full bladder, it is not very protected once it is stretched

• If a blow to the abdominal area occurs, the bladder may rupture and surgery would be needed to repair the bladder

Cystitis

• Inflammation of the bladder

• Can be caused by bacteria from the colon, especially in women d/t their short length of the urethra

• Symptoms include:

• Pain

• Urgency to urinate

• Frequency to urinate

• TREATMENT: antibiotics

Tumors of the bladder

• Are seen mostly in men over 50 y.o.• 90% of bladder tumors arise from the epithelial

lining• Exams with a cystoscope can determine problems• Causes: smoking, continued stones, • Removal of the tumor before it affects the wall of

the bladder have the best outcomes• Many tumors in the actual kidney are cancerous

and NOT treatable=death

Congenital Disorders of the Urethra

• The opening of the urethra to the outside may be too small causing a back pressure of urine and then stasis = frequent infections

• Kids often have a reimplant of their ureters d/t many chronic problems, this is referred to as a ureteral reimplant

• Pt goes home with foley cath for weeks while are inside is healing

• Urine on these pts is cherry colored, pts also have a suprapubic catheter inserted to empty urine

Hypospadius

• The uretheral opening is on the underside of the penis instead of at the end

• Surgical repair of this is done early in the child

Urethritis

• Characterized by inflammation of the mucous membrane and the glands of the urethra

• More common in males than in females• Often d/t gonorrhea or Chlamydia although

other bacteria may be the cause also• Straddle injuries also cause this problem in

men

Rupture of the urethra

• Again, occurs in straddling accidents and in fractures of the pelvis bone

• Fracturing the pelvis bone can cause rupture of the urethra because the fractured pieces of the pelvic bone and tear through the urethra

Effects of aging

• Aging in itself causes the kidneys to lose some of their ability to concentrate urine

• With aging, more water is needed to excrete the same amount of waste

• Older people find it necessary to drink more water than younger people and then they urinate more (polyuria), especially during the night (nocturia)

Aging

• Starting at age 40, there is a decrease in the number and size of nephrons

• More than ½ of a person’s nephrons are lost by age 80

• There may be an increase of blood urea nitrogen (BUN) without serious symptoms

• Women who have had babies, loose muscular control of the pelvic floor causing uncontrolled urinary incontinence at times

Aging

• Prostate – a gland in males that secretes a slightly alkaline fluid that forms part of the seminal fluid

• Enlarged prostate in older men occurs frequently causing obstruction and problems. If left untreated, can cause too many backups of urine

• Meds such as Flomax are used to decrease edema in prostate

Abnormal constituents in urine

• Glucose - sugar

• Albumin - protein

• Blood – many problems called hematuria

• Ketones – burning of fat for many reasons

• WBC’s – infection, pus in urine is pyuria

• Casts – these are molds formed in the microscopic kidney tubules that usually indicate disease of nephrons

Important Lab values r/t urine

• BUN – (blood, urea, nitrogen): tells us how much urea or waste is in the blood and how much didn’t go out of the kidneys, tells us if the kidneys aren’t working

• Creatinine – it’s a normal alkaline constituent of urine and blood that comes from muscles, Dr. must tell you he wants either a blood creat. Or urine creatinine

• RFI – renal function index

• Specific gravity – used to detect dehydration

• Urine ph, ketones, sugar, protein

• Bilirubin/uroglobin – detects liver disease

• GFR - Glomerular function or filtration rate, tells us of the glomerulus are working

Why we care about lab values r/t urine

• These values can determine if one is:

• dehydrated

• Has protein in the urine

• Has blood in the urine

• Has diseased kidneys

• Has kidney failure

The End