OSMOREGULATION AND ROUTINE URINALYSIS

Peachy Mae A. Pineda

Urinary System The urinary system (also called

excretory system) is the organ system that produces, stores, and eliminates urine.

It consist of the kidneys, ureters, urinary bladder, and urethra.

Urinary System

Kidneys

Ureters

Urinary bladder

Urethra

re

Renal artery

Renal vein

Aorta

Inferior vena cava

Kidney is a compact, bean-shaped organ attached to

the dorsal body wall outside the peritoneum.

its main roles are to regulate volume and composition of the body fluids.

the structure of the kidney consists of the cortex, medulla (inner and outer zones of outer medulla and papilla or inner medulla), pyramids, renal calyxes and pelvis, and ureters. 

KidneysMEDULLA CORTEX

RENAL PYRAMID

MINOR CALYXESRENAL

PELVIS

URETER

MAJOR CALYXES

General Functions of the Kidney

Blood Filtering Excretion of Waste Homeostasis

Acid-base balanceBlood pressurePlasma volume

Hormone Secretion

General Functions of the Kidney*Blood Filtering

Takes place in the nephron.

Blood pathway in the kidney (entering) renal artery in the renal sinus

branches into segmental arteries

further divide into interlobar arteries

then supply blood to the arcuate arteries

supply a variety of additional interlobar arteries

afferent arterioles to be filtered through.

General Functions of the Kidney*Blood Filtering

Blood pathway in the kidney (exiting)blood moves through a small network of

venules that converge into interlobar veins

the interlobar provide blood to the arcuate veins

back to the interlobar veins

form the renal vein exiting the kidney for transfusion for blood

General Functions of the Kidney*Excretion of Waste Products

The excreted product came from the waste produced by metabolism.

Mostly nitrogenous waste: UREA and URIC ACID, and Water.

It is excreted through urine.

General Functions of the Kidney*Homeostasis

The kidney is one of the major organs involved in whole-body homeostasis.

Among its homeostatic functions are acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure.

General Functions of the Kidney*Homeostasis

Acid-base balanceThe kidneys regulate the pH of blood by

adjusting H+ ion levels, referred as augmentation of mineral ion concentration, as well as water composition of the blood.

Blood pressureSodium ions are controlled in a homeostatic

process involving aldosterone which increases sodium ion reabsorption in the distal convoluted tubules.

General Functions of the Kidney*Homeostasis

Plasma volumeControlled by hypothalamus.

(together with posterior pituitary gland) hypothalamus secretes antidiuretic hormone.

resulting in water reabsorption by the kidney and an increase in urine concentration.

The two factors work together to return the plasma osmolarity to its normal levels

General Functions of the Kidney*Hormone Secretions

The kidneys secrete a variety of hormones.Erythropoietin is released in response to low

levels of O2 in the renal circulation. It stimulates erythrocyte production in red bone marrow.

Renin is involved in the regulation of aldosterone secretion.

Calcitriol, the activated form of vitamin D, promotes the absorption of Ca2+ from the blood and the excretion of PO3

2-. They both help to increase Ca2+ levels.

Kidneys*Nephrons

Nephrons are microscopic tube-like structures in the kidneys which mainly facilitates the functions of the kidney.

They are the most basic structural and functional unit of the kidney, and are an integral part of the urinary system.

Each kidney contains approximately one million of them.

Kidney*Nephrons

Glomerulus Proximal convoluted

tubule Loop of Henle Distal

Convoluted tubule

Collecting ducts

Kidney *Glomerulus

A capillary network enclosed by the a cup-shaped tructure called the Bowman's capsule.

Together with the Bowman’s capsule, glomerulus is called the Renal corpuscle.

The renal corpuscle (or Malpighian corpuscle) is the beginning of the nephron.

Kidney *Glomerulus

It is the nephron's initial filtering component.

It regulates the concentration of essential substances, and removes substances not produced by the body.

Blood enters the glomerulus, it is filtered out to the space made by the Bowman’s capsule.

The blood then enters the convoluted tubules through the interstitial space, combines with efferent venules of other glomerulus then rejoins the main blood stream.

Kidney*Renal Tubule

Renal tubule or the convoluted tubules is composed of proximal convoluted tubule, (2) loop of Henle, and (3) distal convoluted tubule.

Renal tubule*Proximal Convoluted tubule

Can be divided into an initial convoluted portion and a following straight (descending) portion.

Fluid entering the proximal convoluted tubule is reabsorbed into the peritubular capillaries, including filtered salt and water and all filtered organic solutes.

Renal Tubule*Loop of Henle

Also called the nephron loop, is a U-shaped tube that extends from the proximal tubule.

The primary role of the loop of Henle is to concentrate the salt in the interstitium, the tissue surrounding the loop.

It consists of a descending limb and ascending limb.

Renal Tubule*Loop of Henle

It begins in the cortex, receiving filtrate from the proximal tubule, extends into the medulla as the descending limb, and then returns to the cortex as the ascending limb (hairpin turn)to empty into the distal convoluted tubule.

The descending limb is permeable to water but completely impermeable to salt, and thus making the interstitium hypertonic.

The ascending limb is impermeable to water, a critical feature of the countercurrent mechanism. It actively pumps sodium out of the filtrate, because of this the fluid became more hypotonic.

Renal Tubule*Distal Convoluted Tubule

Cells lining the tubule have numerous mitochondria to produce enough energy (ATP) for active transport to take place.

Regulated by the endocrine system.

Renal Tubule*Distal Convoluted Tubule

In the presence of parathyroid hormone, the distal convoluted tubule reabsorbs more calcium and excretes more phosphate.

Aldosterone promotes more sodium to be reabsorbed and more potassium to be excreted.

Atrial natriuretic peptide causes the distal convoluted tubule to excrete more sodium.

In addition, the tubule also secretes hydrogen and ammonium to regulate pH.

Collecting Ducts The distal

convoluted tubules of several nephrons empty into a single collecting duct.

Collecting ducts then unite and converge to form papillary ducts.

Collecting Ducts As the filtrate moves through the renal tubule, the osmolarity of

the filtrate changes. 

As it moves deeper into the medulla, it increases, and when it ascends the loop of Henle, it decreases only to increase again while going down the collecting duct. 

It is this hyperosmotic condition in the medulla that allows passive transport to occur. 

Collecting duct is normally impermeable to water, it becomes permeable in the presence of antidiuretic hormone (ADH). Lower portions of the collecting duct are also permeable to urea..

Urine Formation*What is Urine?

The waste product secreted by the kidneys that in mammals is a yellow to amber-colored, slightly acid fluid discharged from the body through the urethra.

An aqueous solution of organic and inorganic substances, mostly waste products of metabolism.

It consists of water, carrying in solution the body's waste products such as urea, uric acid, creatinine, organic acids, and also other solutes such as Na+, K+, Ca2+, Mg2+, Cl-, the body fluid concentrations of which are regulated by the kidneys.

Urine formation The production of urine is vital to the health

of the body.

“Cleaning" of the blood takes place in the kidneys and, in particular, in the nephrons, where the blood is filtered to produce the urine.

The kidneys' 2 million or more nephrons form urine by three precisely regulated processes.

Urine Formation The three processes are the following:

A. Glomerulus Filtration

B. Tubular Reabsorption

C. Tubular Secretion

Expressed mathematically as:Urinary excretion rate = Filtration rate – Reabsorption rate + Secretion rate

Urine Formation*1.Glomerular Filtration

Urine formation begins with the process of filtration, which goes on continually in the renal corpuscles (glomerulus and Bowman’s capsule).

As blood courses through the glomeruli, much of its fluid soaks out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then flows into the Bowman's capsule.

The water, waste products, salt, glucose, and other chemicals that have been filtered out of the blood are known collectively as glomerular filtrate

Urine Formation*1.Glomerular Filtration

The glomerular filtrate consists primarily of water, excess salts (primarily Na+ and K+), glucose, and a waste product of the body called urea.

The total rate of glomerular filtration (glomerular filtration rate or GFR) for the whole body is normally about 125 ml per minute. That is, about 125 ml of water and dissolved substances are filtered out of the blood per minute.

Urine Formation*Glomerular Filtration

The GFR per hour is: 125 ml/min X 60min/hr= 7500 ml/hr.

The GFR per day is:7500 ml/hr X 24 hr/day = 180,000 ml/day or

180 litres/day.

Urine Formation*2.Tubular Reabsorption

Reabsorption is the movement of substances out of the renal tubules and collecting ducts back into the blood capillaries located around the tubules (called the peritubular copillaries).

Substances reabsorbed are water, glucose and other nutrients, and sodium (Na+) and other ions.

Reabsorption begins in the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules, and collecting tubules.

Urine formation*2.Tubular Reabsorption

Large amounts of water about 99% of the 180 liters of water that leave the blood each day by glomerular filtration returns to the blood from the proximal tubule through the process of passive reabsorption.

The nutrient glucose (blood sugar) is entirely reabsorbed back into the blood from the proximal tubules. In fact, it is actively transported out of the tubules and into the peritubular capillary blood.

Urine Formation*2.Tubular Reabsorption

Sodium ions (Na+) and other ions are only partially reabsorbed from the renal tubules back into the blood.

Sodium ions are actively transported back into blood from the tubular fluid.

The amount of sodium reabsorbed varies from time to time; it depends largely on how much salt we take in from the foods that we eat.

Urine Formation*3.Tubular Secretion

Secretion is the process by which substances move into the distal and collecting tubules from blood in the capillaries around these tubules.

Secretion is reabsorption in reverse.

Whereas reabsorption moves substances out of the tubules and into the blood, secretion moves substances out of the blood and into the tubules where they mix with the water and other wastes and are converted into urine.

Urine Formation*3.Tubular Secretion

These substances are secreted through either an active transport mechanism or as a result of diffusion across the membrane.

Substances secreted are hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs.

Kidney tubule secretion plays a crucial role in maintaining the body's acid-base balance

Summary of Urine Formation

Characteristics of Normal UrineCharacteristic Description

Amount 1–2 liters per 24 hours; highly variable depending on fluid intake and water loss through the skin.

Color Straw or amber; darker means more concentrated; should be clear, not cloudy.

Specific Gravity 1.010–1.025; a measure of the dissolved material in urine; the lower the value, the more dilute the urine.

pH Average 6; range 4.6–8.0; diet has the greatest effect on urine pH

Composition 95% water; 5% salts and waste products

Nitrogenous Wastes Urea—from amino acid metabolismCreatinine—from muscle metabolismUric acid—from nucleic acid metabolism

Abnormal Constituents in UrineCharacteristics Reasons

Glycosuria (presence of glucose) In an untreated diabetic, for example, blood glucose is too high; therefore the filtrate glucose level is too high. The kidneys reabsorb glucose up to their threshold level, but the excess remains in the filtrate and is excreted in urine.

Proteinuria (presence of protein) Most plasma proteins are too large to be forced out of the glomeruli, and the small proteins that enter the filtrate are reabsorbed by pinocytosis. The presence of protein in the urine indicates that the glomeruli have become too permeable, as occurs in some types of kidney disease.

Hematuria (presence of blood-RBCs)

Another possible cause might be bleeding somewhere in the urinary tract. Pinpointing the site of bleeding would require specific diagnostic tests.

Bacteriuria (presence of bacteria) Bacteria give urine a cloudy rather than clear appearance; WBCs may be present also. The presenceof bacteria means that there is an infection somewhere in the urinary tract. Further diagnostic tests would be needed to determine the precise location.

Ketonuria (presence of ketones) Higher levels of ketones indicate an increased use of fats and proteins for energy. This may be the result of malfunctioning carbohydrate metabolism (as in diabetes mellitus)or simply the result of a high-protein diet.

Osmoregulation

OsmoregulationRegulation of the concentration of

dissolved substances in the cells and body fluids (e.g. blood) of an animal.

Importance: Maintains homeostasis○ cells being bathed in tissue fluid which

has the correct amount of water, mineral salts, glucose and temperature.

Osmoregulation the physiological processes that an

organism uses to maintain water balance; that is, to compensate for water loss, avoid excess water gain, and maintain the proper osmotic concentration (osmolarity) of the body fluids

Most humans are about 55 to 60 percent water by weight (45 percent in elderly and obese people and up to 75 percent in newborn infants).

Procedure

Four subjects were asked to drink 500 ml of coffee, water, brine solution and

soft drinks

Amount of urine excreted was noted. Urine samples were collected thrice with

an interval of 30 minutes.

Physical characteristics of urine were noted.

Results and Discussions

Subject First collection

Second collection

Third collection

Total

Subject 1 (water)

150 mL 240 mL 200 mL 590 mL

Subject 2 (brine solution)

275 mL 225 mL 75 mL 575 mL

Subject 3 (soft drink)

150 mL 70 mL 200 mL 420 mL

Subject 4 (coffee)

40 mL 180 mL 110 mL 330 mL

Volume of Urine Produced

Results and Discussions

1st col 2nd col. 3rd col0

100

200

300

400

500

600

700

800

Chart Title

subject 4subject 3subject 2subject 1

Axis Title

Results and Discussions

Subject 1 Subject 2 Subject 3 Subject 40

100

200

300

400

500

600

700

590 575

420

330

Total volume

1(water)2(brine soln.)3(soft drink)4(coffee)

Total Volume of Urine Produced

Results and Discussions Diuretics

Increase urine output by the kidney

Promote diuresis

Results and Discussions Caffeine is a natural diuretic.

It makes you secrete more urine.It is found in coffee, tea, soft drinks, and

chocolate.

Results and Discussions

If caffeine promotes diuresis, then why does coffee and soft drinks which contain caffeine only ranked fourth and third respectively in volume of urine excreted?

Results and Discussions Subsequent studies have further shown

that the mechanism of caffeine diuresis is dubious in nature, as caffeine containing beverages did not impact urinary output any differently, when compared to other beverages that do not contain caffeine. However, this does not mean that caffeine does not increase your need or urge to urinate.

Results and Discussions The antidiuretic hormone (ADH) or

vasopressin stimulates the kidney tubules to absorb water from the filtered plasma that passes through the kidneys and thus regulates the amount of urine secreted by the kidneys

Sodium chloride is antidiuretic in a sense that it stimulates ADH production

Results and Discussions When the amount of salt and other

substances in the bloodstream becomes too high, the pituitary gland releases ADH into the bloodstream. When it enters the kidney, ADH makes the walls of the renal tubules and collecting ducts more permeable to water, so that more water is reabsorbed into the bloodstream decreased urine output

Conclusion Osmoregulation: control of the concentration of

dissolved substances in the cells and body fluids (e.g. blood) of an animal and is important because it helps maintain homeostasis.

Kidneys are delicate organs needed in the excretion of wastes.

Two types of substances that can affect osmoregulation: diuretics and antidiuretics

Diuretics, increases urine output Antidiuretics decreases urine output

Practical Application◦ Medicines: ◦ antidiuretics and diuretics (furosemide)

◦ Diuretics are administered to patients with diseases relating to high water retention and those with congenital heart diseases.

◦ Antidiuretics (synthetic vasopressin) is given to patients with Diabetes insipidus (deficiency of vasopressin)

Patients often experience increased thirst and urination. Treatment is with drugs, such as synthetic vasopressin, that help the body maintain water and electrolyte balance.

Practical Applications

Clinical tests: Measurements of the composition of urine are useful in the diagnosis of a wide variety of conditions, including kidney disease, diabetes, and pregnancy.

Routine Urinalysis

Routine Urinalysis Urinalysis, or examination of the urine, indicates

whether any abnormal substances are present in the urine.

This is done to screen for possible presence of diseases that could be detected in the urine sample.

A complete urinalysis has three stages:1.Physical Examination2. Chemical Examination3. Microscopic Examination

Procedure I. Physical Examination of Urine

Fresh urine samples were placed in a

beaker.

Volume, color, transparency, odor of

urine were noted.

Using the ___, ph, specific gravity,

presence of glucose and protein were

noted.

Results Physical Examination of Urine Samples

Subject 1 Subject 2 Subject 3 Subject 4

Color Pale yellow Straw yellow Yellow orange Orange

pH Acidic (5.5) Acidic(6) Acidic(6) Acidic(5.5)

Transparency Clear Clear Cloudy Clear

Glucose 0 0 0 0

Protein +/-0.15 + 0.15 +1(0.3) 0

Specific Gravity 1.025 1.015 1.020 1.025

Refractory 1.02 1.00 1.021 1.033

Procedure Chemical Examination of Urine

Benedict’s test

5 mL of Benedict’s reagent was mixed

with 8 drops of uncentrifuged urine.

Mixed solution was heated for 5 minutes.

If positive: a precipitate will form with colors ranging from green, yellow,

orange to red.

Results

None of the urine samples is positive to Benedicts test, it simply implies that glucose is not present in the urine.

Procedure

The fresh urine sample was

centrifuged for 5 mins, then the

sediments were decanted

The upper half of the urine was heated using an alcohol lamp. The bottom

part was not heated for comparison

The presence of turbidity or cloudiness

was observedFew drops of 10 %

Acetic acid was added

Chemical Examination of Urine• Heat and Acetic Acid Test

Results and Discussions

Results Normally, only small plasma proteins filtered at the glomerulus are

reabsorbed by the renal tubule. The detection of protein in urine may indicate that the permeability of the glomerulus is abnormally increased.

May be caused by renal infections or it may be caused by other diseases that have secondarily affected the kidneys such as diabetes mellitus, jaundice, or hyperthyroidism.

Normal total protein excretion does not usually exceed 150 mg/24 hours or 10 mg/100 ml in any single specimen. More than 150 mg/day is defined as proteinuria.

Proteinuria > 3.5 gm/24 hours is severe and known as nephrotic syndrome.

Microscopic Examination

The sediment from the previous test

was utilized.It was then placed

in a glass slide

In HPO, bacteria, RBCs and WBCs

were observed

Microscopic ExaminationCasts

Urinary casts are formed only in the distal convoluted tubule (DCT) or the collecting duct (distal nephron).

Their presence indicates inflammation of the kidney, because such casts will not form except in the kidney.

Conditions which may lead to:1. lupus nephritis2. malignant hypertension3. diabetic glomerulosclerosis4. rapidly progressive glomerulonephritis

Microscopic Examination RBC (Red Blood Cells) Casts

RBC in urine - indicative of glomerulonephritis, with leakage of RBC's from glomeruli, or severe tubular damage.

Hematuria - the presence of red blood cells (erythrocytes) in the urine.

Microscopic Examination White blood cell casts

Sterile pyuria is urine which contains white blood cells while appearing sterile by standard culturing techniques. Sterile pyuria is listed as a side effect from some medications such as paracetamol (acetaminophen). Its occurrence is also associated with certain disease processes, such as Kawasaki Disease and renal TB

Microscopic ExaminationRenal Tubular Epithelial Cells usually larger than granulocytes, contain a large round or oval

nucleus and normally slough into the urine in small numbers. smaller and rounder than transitional epithelium

Transitional Epithelial Cells from the renal pelvis, ureter, or bladder have more regular cell

borders, larger nuclei, and smaller overall size than squamous epithelium.

Squamous Epithelial Cells from the skin surface or from the outer urethra can appear in urine.

Their significance is that they represent possible contamination of the specimen with skin flora.

Microscopic ExaminationYeast Yeast cells may be contaminants or represent a

true yeast infection. They are often difficult to distinguish from red cells and amorphous crystals but are distinguished by their tendency to bud. Most often they are Candida, which may colonize bladder, urethra, or vagina.

Microscopic ExaminationCrystals Common crystals seen even in healthy

patients include calcium oxalate, triple phosphate crystals and amorphous phosphates.

Very uncommon crystals include: cystine crystals in urine of neonates with congenital cystinuria or severe liver disease, tyrosine crystals with congenital tyrosinosis or marked liver impairment, or leucine crystals in patients with severe liver disease or with maple syrup urine disease.

Microscopic Examination Amorphous crystals

appear as aggregates of finely granular material without any defining shape

Amorphous urates of Na, K, Mg or Ca tend to form in acidic urine

Amorphous phosphates tend to form in alkaline urine

Microscopic Examination

Bacteria Bacteria are common in urine

specimens because of the abundant normal microbial flora of the vagina or external urethral meatus and because of their ability to rapidly multiply in urine standing at room temperature.

Therefore, microbial organisms found in all but the most scrupulously collected urines should be interpreted in view of clinical symptoms.

Results and Discussions Subject 1(water)

Under HPO Abundance

Red Blood Cells 1

White Blood Cells 1

Bacteria 10

Under LPO Abundance

Amorphous urates Some Epithelial Cells OccasionalMucus Threads Rare Renal Cells Rare Casts None Other crystals Rare

Results and DDcussions Subject 2(brine)

Under HPO Abundance

Red Blood Cells 0

White Blood Cells 1

Bacteria 15

Under LPO Abundance

Amorphous urates rareEpithelial Cells FewMucus Threads Occasional Renal Cells NoneCasts None Other crystals Rare

Results and DiscussionsResults and Discussions Subject 3(Softdrink)

Under HPO Abundance

Red Blood Cells 0

White Blood Cells 0

Bacteria 20

Under LPO Abundance

Amorphous urates Rare Epithelial Cells Few Mucus Threads Occasional Renal Cells noneCasts None Other crystals Rare

Results and DiscussionsResults and Discussions Subject 4( Coffee)

Under HPO Abundance

Red Blood Cells 1

White Blood Cells 1

Bacteria 24

Under LPO Abundance

Amorphous urates SomeEpithelial Cells Rare Mucus Threads Some Renal Cells Rare Casts None Other crystals Few

Results and DiscussionsWhite bloods cells

Results and DiscussionsRed bloods cells

Results and DiscussionsMucus Threads

Results and DiscussionsBacteria

Conclusion The presence of glucose in the urine usually

indicates that the individual has diabetes mellitus, a condition in which either the liver fails to store glucose as glycogen or the cells fail to take up glucose. In both cases, the blood glucose level is abnormally high.

This makes the filtrate level of glucose high, and because the proximal convoluted

tubule cannot absorb all of it, glucose appears in the urine.

Practical Applications Diabetes insipidus

Diabetes insipidus (DI) is a rare disease that causes frequent urination and excessive thirst.

DI is not related to diabetes mellitus (DM). excessive intake of fluid a defect in ADH production a defect in the kidneys’ response to ADH

Practical Applications Central DI results from damage to the

pituitary gland which disrupts the normal storage and release of ADH

Nephrogenic DI results when the kidneys are unable to respond to ADH

Dipsogenic DI, which is caused by a defect in the thirst mechanism.

Gestational DI results when an enzyme made by the placenta destroys ADH

Practical Applications Polyuria

The excessive passage of urine (at least 2.5 liters per day for an adult) resulting in profuse urination and urinary frequency (the need to urinate frequently).

Caused by DI, increase uptake of water, or uptake of diuretics

Practical Applications Anuria and oliguria

The absent or decreased urine production, respectively

failure in the function of kidneys severe obstruction like kidney stones or

tumours