Urinary System

Your body must eliminate wastes to remain healthy.

These systems function together as parts of your excretory system.

The urinary system (also called the excretory system) is the organ system that produces, stores, and eliminates urine.

In humans it includes two kidneys, two ureters, the bladder, the urethra, and two sphincter muscles

Functions of the Urinary System

The Urinary SystemThe Urinary SystemThe urinary system

rids the blood of wastes produced by the cells.

The urinary system also controls blood volume by removing excess water produced by body cells during respiration.

Gets rid of excess salts

Urinary SystemThe human urinary system functions to

remove waste from the human body. This system consists of specialized

structures and capillary networks that assist in the excretory process.

The human urinary system includes the kidney and its functional unit, the nephron.

The excretory activity of the kidney is modulated by specialized hormones that regulate the amount of absorption within the nephron.

KidneysThey are bean-shaped

organs located on either side of the backbone at about the level of the stomach and liver.

Blood enters the kidneys through renal arteries and leaves through renal veins.

Tubes called ureters carry waste products from the kidneys to the urinary bladder for storage or for release.

KidneysThe kidneys receive their blood supply of 1.25 L/min

(25% of the cardiac output) from the renal arteries which are fed by the abdominal aorta.

This is important because the kidneys' main role is to filter water soluble waste products from the blood.

Humans produce about 2.9 liters of urine over 24 hours, although this amount may vary according to circumstances of filtration at the kidney is proportional to the glomerular filtration rate.

Some medications interfere directly or indirectly with urine production. Diuretics achieve this by altering the amount of absorbed or excreted electrolytes

In approximately 5 min, all of the blood in your body passes through the kidneys

Approx. 2,000 L of blood is filtered daily by the kidneys.

Filtration in the Kidney

Filtration in the KidneyBlood enters the kidneys through the renal artery.Blood enters the nephrons.Water, sugar, salt and wastes in the blood enter a

cuplike structure in nephron.Capillaries reabsorb most of the water, sugar, and

salt.The renal vein returns purified blood to be

circulated.Urine drains from each collecting tubule into

funnel shaped areas of the kidneyUrine flows from ureters to the urinary bladderUrine flows from the bladder through the urethra

and out of the body.

Organs of the Urinary System

The main organs of the urinary system are two bean-shaped kidneys.

The kidneys filter blood that contains wastes collected from cells.

It is made up of about 1 million tiny filtering units called nephrons (NEF rahnz).

NephronThe functional and

structural unit of the kidney is the nephron.

The nephron produces urine and is the primary unit of homeostasis in the body. It is essentially a long tubule with a series of associated blood vessels.

Bowman’s CapsuleThe upper end of the tubule is

an enlarged cuplike structure called the Bowman's capsule.

Within the Bowman's capsule is a coiled ball of capillaries known as a glomerulus.

Blood from the renal artery enters the glomerulus. The force of the blood pressure induces plasma to pass through the walls of the glomerulus, pass through the walls of the Bowman's capsule, and flow into the proximal tubule. Red blood cells and large proteins remain in the blood.

Still in the NephronAfter plasma enters the proximal

tubule, it passes through the coils, where usable materials and water are reclaimed.

Salts, glucose, amino acids, and other useful compounds flow back through tubular cells into the blood by active transport.

Osmosis and the activity of hormones assist the movement. The blood fluid then flows through the loop of Henle into the distal tubule.

Once more, salts, water, and other useful materials flow back into the bloodstream.

Homeostasis is achieved by this process: A selected amount of hydrogen, ammonium, sodium, chloride, and other ions maintain the delicate salt balance in the body.

Regulating Fluid LevelsThe hypothalamus constantly monitors

the amount of water in the blood.

When the brain detects too much water in the blood, the hypothalamus releases a lesser amount of a specific hormone

This signals the kidneys to return less water to the blood and increase the amount of wastewater, called urine, that is excreted.

UrineThe fluid moving from the

distal tubules into the collecting duct contains materials not needed by the body.

This fluid is referred to as urine.

Urea, uric acid, salts, and other metabolic waste products are the main components of urine.

The urine flows through the ureters toward the urinary bladder. When the bladder is full, the urine flows through the urethra to the exterior.

Control of Kidney FunctionThe activity of the nephron in the kidney is

controlled by a person's choices and environment as well as hormones. For example, if a person consumes large amounts

of protein, much urea will be in the blood from the digestion of the protein. Also, on a hot day, a body will retain water for sweating and cooling, so the amount of urine is reduced.

Humans produce a hormone called antidiuretic hormone (ADH), also known as vasopressin, which is secreted by the posterior lobe of the pituitary gland. It regulates the amount of urine by controlling the rate of water absorption in the nephron tubules.

Control of Kidney FunctionSome individuals suffer from a condition in which they

secrete very low levels of ADH. The result is excessive urination and a disease called diabetes insipidus.

Another unrelated form of diabetes, diabetes mellitus, is more widespread. Persons with this disease produce insufficient levels of insulin. Insulin normally transports glucose molecules into the cells. But when insulin is not available, the glucose remains in the bloodstream. The glucose is removed from the bloodstream in the nephron; to dilute the glucose, the nephron removes large amounts of water from the blood. Thus, the urine tends to be plentiful.

Urine Kidneys of the urinary system maintain

the amount of fluid balance in the body. Consumption of excess water results in

diluted, pale colored urine and consumption of inadequate amounts of water results in conservation of water by the kidneys, thereby conducing to dark yellow colored urine.

Urine Color Urine Color Meaning Possible Underlying Disease or Condition

Clear urine Excess liquid consumptionAny liver disease, like hepatitis or liver cirrhosis, diabetes insipidus or diabetes mellitus. This of also often the urine

color during pregnancy

Bright yellow or neon yellow Vitamin supplements Excessive consumption of vitamin capsules, leading to a

potential risk of hypervitaminosis

Dark yellow or golden color Very concentrated urine

Severe dehydration, may also be indicative of over consumption of laxatives or food supplements which

contain B complex vitamins. Read more on dark yellow urine causes

Pink or red color Hematuria, indicative of blood in urine

Kidney infections, bladder infections, excessive consumption of certain foods like beets and berries and

food dyes, also due to some laxatives

Orange

Due to certain drugs like rifampin, doxorubicin, phenazopyridine and

warfarin

If there is ornage urine color, dehydration, excess intake of certain food dyes, laxatives are often implicated

Blue or greenSide effect of certain

medications like amitriptylene, indomethacin

Over consumption of certain foods like asparagus and food dyes

Cloudy or murkyInability of the kidneys to

produce normal urine, presence of protein in urine

Urinary tract infection, like inflammation of the urethra (urethritis), bladder infection, kidney stones etc. Read

more on cloudy urine causes

Urea in everydayAgriculture

More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use. Therefore, it has the lowest transportation costs per unit of nitrogen nutrient.

A stabilizer in nitrocellulose explosives.A non-corroding alternative to rock salt for road

de-icing, and the resurfacing of snowboarding halfpipes and terrain parks.

A flavor-enhancing additive for cigarettes.

A main ingredient in hair removers such as Nair or Veet.A browning agent in factory-produced pretzels.An ingredient in some skin cream, Moisturizer, hair conditionersA reactant in some ready-to-use cold compresses for first-aid use,

due to the endothermic reaction it creates when mixed with water.A cloud seeding agent, along with other salts.A flame-proofing agent, commonly used in dry chemical fire

extinguisher charges such as the urea-potassium bicarbonate mixture.

An ingredient in many tooth whitening products.An ingredient in dish soap.Along with ammonium phosphate, as a yeast nutrient, for

fermentation of sugars into ethanol.A nutrient used by plankton in ocean nourishment experiments for

geoengineering purposes.As an additive to extend the working temperature and open time

of hide glue.As a solubility-enhancing and moisture-retaining additive to dye

baths for textile dyeing or printing

Urea in the MediaThe al-Qaeda Millennium Bomber, used

urea as one of the components in the explosives that he prepared to bomb Los Angeles International Airport on New Year's Eve 1999/2000

The explosives could have produced a blast 40 times greater than that of a devastating car bomb.

Urinary Diseases and DisordersWaste products that are not removed build

up and act as poisons in body cells.Water that normally is removed from body

tissues accumulates and causes swelling of the ankles and feet.

Without excretion, an imbalance of salts occurs. If the balance isn’t restored, the kidneys and other organs can be damaged.

Urinary Tract InfectionA urinary tract infection most often develops when

bacteria enter the urinary tract through the urethra and travel to the bladder where they multiply.

Symptoms of a urinary tract infection include a strong urge to urinate, burning during urination, cloudy urine, blood in the urine, strong odor of the urine and pelvic pain.

A urinary tract infection can usually be successfully treated with a series of oral antibiotics.

Severe cases, in which the infection travels to the kidneys, may require hospitalization and intravenous antibiotics.

Benign prostatic hyperplasia (BPH)BPH is a condition in men that affects the prostate

gland, which is part of the male reproductive system.

The prostate is located at the bottom of the bladder and surrounds the urethra. BPH is an enlargement of the prostate gland that can interfere with urinary function in older men. It causes blockage by squeezing the urethra, which can make it difficult to urinate.

Men with BPH frequently have other bladder symptoms including an increase in frequency of bladder emptying both during the day and at night.

Most men over age 60 have some BPH, but not all have problems with blockage. There are many different treatment options for BPH.

ProteinuriaProteinuria is the presence of abnormal

amounts of protein in the urine. Healthy kidneys take wastes out of the

blood but leave in protein. Protein in the urine does not cause a

problem by itself. But it may be a sign that your kidneys are not working properly.

Kidney StonesKidney stones are small hard deposits

that develop in the kidneys as a result of the presence of excess uric acid, calcium, oxalate, phosphate or carbonate in the urine.

Dehydration is the number one risk factor for development of kidney stones, according to Medline Plus. Kidney stones usually do not cause symptoms until they move out of the kidney and into the ureter.

When symptoms do appear, they include severe pain in the stomach or back, abnormal urine color, blood in the urine, fever, chills, nausea and vomiting.

Kidney StonesKidney stones usually

pass on their own and do not require any treatment. It is usually advised to drink six to eight glasses of water per day to help pass kidney stones more easily.

Surgery to remove the stone may be required if the stone is too large to pass on its own, or if it is blocking urine flow and causing an infection.

Tips to help:

More fiber intake

More dairy intake

Less red meat

PLENTY of water

Polycystic Kidney Disease (PKD)

Polycystic kidney disease is a kidney disorder passed down through families in which multiple cysts form on the kidneys, causing them to become enlarged.

Polycystic kidney disease (PKD) is passed down through families (inherited), usually as an autosomal dominant trait. If one parent carries the gene, the children have a 50% chance of developing the disorder.

PKD is associated with the following conditions:Brain aneurysmsCysts in the liver, pancreas, and testesDiverticula of the colon

Kidney FailureAcute (sudden) kidney failure is the sudden loss of the ability of

the kidneys to remove waste and concentrate urine without losing electrolytes.

Causes: Diabetes. Diabetes mellitus occurs when the body cannot produce

and/or use insulin, the hormone necessary for the body to process glucose. Long-term diabetes may cause the glomeruli, the filtering units located in the nephrons of the kidneys, to gradually lose function.

Hypertension. High blood pressure is both a cause and a result of kidney failure. The kidneys can become stressed and ultimately sustain permanent damage from blood pushing through them at excessive pressures over long periods of time.

Gomerulonephritis. an inflammation of the glomeruli, or filtering units of the kidney. Certain types of glomerulonephritis are treatable, and may only cause a temporary disruption of kidney functioning.

Polycystic kidney disease. Polycystic kidney disease is an inherited disorder that causes cysts to form in the kidneys. These cysts impair the regular functioning of the kidney.

Points to remember…Your urinary system filters waste and extra

fluid from your blood.Problems in the urinary system include

kidney failure, urinary tract infections, kidney stones, prostate enlargement, and bladder control problems.

Health professionals who treat urinary problems include general practitioners (your primary doctor), pediatricians, urologists, gynecologists, urogynecologists, and nephrologists.