Exercise 26

Functional Anatomy of The Urinary System

Renal capsulea tough fibrous layer surrounding the kidney and covered in a thick layer of adipose tissue. It provides some protection from trauma and damage.

Gross Anatomy of the Human Urinary System

Organs of the Urinary System

Figure 15.1a

• Kidneys• Hilium• Ureters• Urinary

bladder• Urethra• Renal Artery

Urinary System Organs

Function

Kidneys • Maintains water and electrolyte balance of the blood

• Produces urine

Ureters • Transports urine to urinary bladder

Urinary bladder • Serves as a storage area for urine

Urethra • Transports urine to the body’s exterior• Is shorter in women than in men

Renal Artery • Transports arterial blood to the kidney

Internal Anatomy of the Kidney

Renal cortex —outer region; contains most of nephron structureRenal medulla —inside the cortex; contains inner collecting ductsRenal pelvis – basin continuous with ureterRenal columns —extensions of cortex-like material inward that separate the pyramidsCalyces —cup-shaped structures, extensions of pelvis that funnel urine Renal or fibrous capsule -- a tough fibrous layer surrounding the kidney

Internal Anatomy of the Kidney

Functional Microscopic Anatomy of the Kidney

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Glomerulus= site of filtrate formationRed arrows = BloodBlue arrows = Filtrate

Glomerulus = a tiny ball-shaped structure composed of capillary blood vessels actively involved in the filtration of the blood to form urine .

Bowman’s Capsule =Fluids from blood in the glomerulus are collected in the Bowman's capsule (i.e., glomerular filtrate) and further processed along the nephron to form urine.

Proximal convoluted tubule= primary site of tubular reabsorption

Glucose, Amino Acids, Na+, and Water are being reabsorbed by the Proximal Convoluted Tubule

Collecting Ducts- collects the urine from the nephron and send it to the renal pelvis.

renal pelvis

Collecting Ducts-

nephrons

Peritubular capillaries – receives substances from the tubular cells

Bowman’s Capsule: the inner membrane forms part of the filtration mechanism

• There are two layers of cells that fluid (with its contents) has to pass through during filtration.

The first layer is the endothelium of the glomerular capillary.

The second layer is the visceral layer of the Bowman’s capsule, formed by podocytes

• The renal corpuscle is where plasma is filtered from capillaries into the renal tubules. At the center of renal corpuscle is the glomerulus, a meshwork of capillaries. The glomerulus is surrounded by Bowman's capsule

Glomerulus and Bowman’s Capsule

Visceral layer

Parietal layer

Podocytes make up the visceral layer of Bowman’s Capsule

Glomerulus is a high-pressure capillary bed

The afferent arteriole feeding the glomerulus is larger than the efferent arteriole which drains the glomerulus

The high pressure forces out fluid and blood components smaller than proteins from the glomerulus into the glomerular capsule

Proximal Convoluted Tubule The cuboidal cells of the proximal convoluted tubule have long microvilli (brush border) on their inside surface that dramatically increase the surface area for reabsorption from the filtrate.

What is the purpose of this brush border epithelium?

Filtrate

Close up of brush border (microvilli)

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Glomerular capsuleProximal convoluted tubuleLoop of HenleDistal convoluted tubuleCollecting duct

Nephron in Cortex

Renal Cortex = nephronMedullary pyramid = collecting ductsCalycesRenal pelvisUreter

(Ureter)BladderUrethra

Urinalysis: Characteristics of Urine

In 24 hours, about 1.0 to 1.8 liters of urine are produced

Nitrogenous wastes normally found in urine:Urea, uric acid, creatine

UREAURIC ACID

CREATINE

Gout

Uric acid is derived from the breakdown of DNA and RNA. This is taking place continuously in the body as large numbers of cells are produced and replaced, particularly from the blood.

Purines are one type of nitrogenous base found in nucleic acids. In DNA and RNA, which are both nucleic acids, the major purines are guanine and adenine. Purines are found in many foods, including meat, shellfish, and sweetbreads

Birds excrete most of their nitrogen in the form of uric acid, an oxidized purine.

Blood proteinsRed blood cellsHemoglobinWhite blood cells (pus)

Substances absent from filtrate and urine

Albumin Hemoglobin

White blood cells (pus)

RBCs

Substances present in filtrate but not in urine product

Urine is what remains after the filtrate has lost most of its water, nutrients, and necessary ionsGlucose &

Amino AcidsAmino acid “Alanine”

Glucose

Purpose:Routine urinalyses are performed for several reasons:

A routine urinalysis usually includes the following tests: color, transparency, specific gravity, pH, protein, glucose, ketones, blood, bilirubin, nitrite, urobilinogen, and leukocyte esterase. Some laboratories include a microscopic examination of urinary sediment with all routine urinalysis tests

■general health screening to detect renal and metabolic diseases■diagnosis of diseases or disorders of the kidneys or urinary tract■monitoring of patients with diabetes

A urinalysis demonstrates kidney functionwhich maintains: Electrolyte balance Acid-base balance Fluid balance of the blood

Yellow UrineUrobilin (urochrome was the original name given to the pigment thought to give urine its color. It is now known that several related pigments are responsible, so the original name has been dropped.) resulting from the breakdown of heme.

Urine specific gravity

Urine specific gravity is a laboratory test that measures the concentration of all chemical particles in the urine.

Normal specific gravity range in urineThe normal range of specific gravity in human urine is from 1.003 to 1.030. Values outside this range may be the result of specimen dilution, adulteration or may be indicative of a number of health related problems.

The apparent specific gravity is simply the ratio of the weights of equal volumes of sample and water in air. Urine would have a higher specific gravity than water because it weighs more than water

Abnormal Specific Gravity Results

A very high specific gravity means very concentrated urine, which may be caused by not drinking enough fluid, loss of too much fluid (excessive vomiting, sweating, or diarrhea), or substances (such as sugar or protein) in the urine.

Very low specific gravity means dilute urine, which may be caused by drinking too much fluid, severe kidney disease, or the use of diuretics.

Color/Specific Gravity/Volume

The greater the solute concentration, the the higher the specific gravity, deeper the yellow, the smaller the volume

Ideal urine

'Normal' urine ranges from clear to deep amber. Urine gets it's color from the pigment urochrome. The more fluids you consume, the more diluted your urine becomes causing it to appear light in color.

Why Pee is Cool

Dark UrineDarker yellow urine usually signifies dehydration. The urochrome is much more concentrated because of the lack of fluids. Generally, increasing your fluid intake can improve this.

Neon yellow urine

Neon yellow urine can certainly catch you off guard but this is typically caused by nothing more than your daily multivitamin. Vitamin B in particular has the ability to cause the fluorescent shading.

Orange urine

Believe or not, consuming large amounts of carrots or squash can actually turn your urine orange. It's the carotene that is responsible for the strange hue. Orange urine can also be caused by certain medications including some blood thinners and laxatives.

Blue/green urineAsparagus and certain medications can actually cause a slight green coloring in the urine. Also, a rare disorder called familial hypercalcemia can cause bluish urine.

Red urine

There are several causes of red urine. Some aren't serious at all like the consumption of beets, rhubarb and certain medications. While others can be life threatening like lead or mercury poisoning. One of the most common reasons for red urine is the presence of blood. Blood in the urine can be caused by strenuous exercise, a urinary tract infection or something more serious like bladder cancer which is why it is essential to see your doctor if you detect it.

Dark brown urineDark brown or tea-colored urine is sometimes mistaken for bloody urine. Dark brown urine can be a symptom of very serious liver disorders including cirrhosis and hepatitis. It is imperative you get to an emergency room if your urine is tea-colored for proper testing. Other causes include eating excessive amount of fava beans and certain medications.

Urinary Tract InfectionsUrinary tract infection occurs as a result of the infestation of a certain bacteria called E. coli. E. coli or Escherichia coli is a resident flora of the intestines, but once it gets in contact with the urinary tract, it can pose the threat of developing UTI.

Urinary tract infection can give rise to different signs and symptoms but the most discomforting of all these is the pain and burning sensation that one may feel during urination. Bladder fullness and increased urinary frequency may also occur as a result. Unlike the normal appearance of the urine, a person with UTI may notice a cloudy and foul smelling urine output. Once your doctor diagnoses UTI, he or she will prescribe you with antibiotics as well as urinary analgesics to lessen the pain.

A high urine pH may be due to:(Alkaline)•Gastric suction•Kidney failure•Kidney tubular acidosis•Urinary tract infection•Vomiting A Vegetarian Diet can result in increased alkalinity of urine

Starvation and Urine pHA low urine pH may be due to:(ACID)•Diabetic ketoacidosis•Diarrhea•Starvation

• Ketones are chemicals in the liver as a consequence of the breakdown of fat.

• When the body can't use it's glucose for energy the body burns fat for energy instead. Ketones then accumulate in the blood.

• If the body produces too many ketones the

blood becomes acidic, this is called 'KETOACIDOSIS' and can be life threatening!

Normal Range is 4.5-8.0. Average is 6.0

High Protein diet can cause urine to become acidic

AlbuminuriaAlbumin is a protein. Albuminuria (Al-byoo-mih-noo-ree-uh) is having too much protein in the urine.

Albuminuria can be a first sign of diabetic kidney disease. Other causes of albuminuria are high blood pressure, congestive heart failure, the metabolic syndrome, or kidney damage from nephrotic syndrome.

Albuminuria occurs in about 10% of pregnant women.

Apart from the measurement of blood pressure, dipstick analysis of urine for protein is the most commonly performed antenatal screening test. The presence of proteinuria is seen as a possible indication of many complications in pregnancy, from urinary tract infection to chronic renal disease and it remains central to the diagnosis of pre-eclampsia in a hypertensive pregnancy.

GlycosuriaGlycosuria (gly-koh-SOOR-ee-ah) is the presence of glucose in the urine.

Ordinarily, urine contains no glucose because the kidneys are able to reclaim all of the filtered glucose back into the bloodstream.

Glycosuria is nearly always caused by elevated blood glucose levels, most commonly due to untreated diabetes mellitus. But could also be due to eating massive quantities of candy.

Rarely, glycosuria is due to an intrinsic problem with glucose reabsorption within the kidneys themselves.

Glycosuria leads to excessive water loss into the urine with resultant dehydration.

Hematuria

It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract (kidneys, ureters, urinary bladder, prostate-(In males only), and urethra), ranging from trivial to lethal.

If white blood cells are found in addition to red blood cells, then it is a signal of urinary tract infection.

Hematuria is the presence of red blood cells in the urine.

If there are enough red cells, the urine can become bright red, pink or cola colored. Often, however, the urine appears completely normal because there is not enough blood to cause a color change. In this case, the condition is called "microscopic" hematuria.

Hemoglobinuria

Normally, there is no hemoglobin in the urine. Hemoglobinuria is a sign of a number of abnormal conditions, such as bleeding and paroxysmal nocturnal hemoglobinuria.

Hemoglobinuria: The presence of free hemoglobin in the urine, which may make the urine look dark.

Ketonuria

It is seen in conditions in which the body produces excess ketones as an alternative source of energy. It is seen during starvation or more commonly in type I diabetes mellitus. Production of ketone bodies is a normal response to a shortage of glucose, meant to provide an alternate source of fuel from fatty acids.

Ketonuria is a medical condition in which ketone bodies are present in the urine.

To test a cow for ketosis with a ketone strip you can make her urinate by rubbing her gently right beneath the vulva.

Pyuria

Pyuria is the presence of pus (leukocytes or white blood cells) in the urine. It is a laboratory finding in many diseases, most commonly infection in the urinary system.

E. Coli in urine

Kidney Stones, AKA Renal Calculi

If urine becomes excessively concentrated and solutes begin to precipitate.

The biggest risk factor for kidney stones is not drinking enough fluids. Kidney stones are more likely to occur if you make less than 1 liter of urine a day. That's slightly more than a quart.

Struvite stones are mostly found in women who have a urinary tract infection. These stones can grow very large and can block the kidney, ureter, or bladder.

Uric acid stones are more common in men than in women. They can occur with gout or chemotherapy

Kidney Stones, AKA Renal Calculi

Cloudy Urine ?

Due to bacteria growing in urine that break down urea to form ammonia

Hypercalciuria, or excessive urinary calcium excretion, occurs in about 5-10% of the population and is the most common identifiable cause of calcium kidney stone disease.

Crystals in Urine Specimen