Urinary SystemUrinary System

Functions of Urinary System:Functions of Urinary System:

1.1. Excretion- removing nitrogenous Excretion- removing nitrogenous wastes, certain salts and excess wastes, certain salts and excess water from blood.water from blood.

2.2. Maintain acid-base balanceMaintain acid-base balance

3.3. Secrete waste products in the form of Secrete waste products in the form of urine – urine – remove waste from bodyremove waste from body

4.4. Eliminate urine from bladderEliminate urine from bladder

What if kidneys are not What if kidneys are not working properly?working properly?

Toxic wastes would Toxic wastes would accumulate in the cells, accumulate in the cells,

poisoning thempoisoning them

KidneysKidneys

Bean-shaped organsBean-shaped organs Located between peritoneum and the Located between peritoneum and the

back muscles (RETROPERITONEAL)back muscles (RETROPERITONEAL) Renal Pelvis- funnel shaped structure Renal Pelvis- funnel shaped structure

at the beginning of the ureterat the beginning of the ureter

                                                                                                                                                                                                        

                                        

MedullaMedulla

Inner, striated layerInner, striated layer Striated cones (divisions) are renal Striated cones (divisions) are renal

pyramidspyramids Base of each pyramid faces cortex, Base of each pyramid faces cortex,

while apex empties into cuplike while apex empties into cuplike cavities called calycescavities called calyces

CortexCortex

Composed of millions of microscopic Composed of millions of microscopic functional units called nephronsfunctional units called nephrons

NephronsNephrons Functional unit of the kidneyFunctional unit of the kidney Over 1 million in each kidney which comprise 140 Over 1 million in each kidney which comprise 140

miles of filters and tubesmiles of filters and tubes Parts include:Parts include:

1.1. Bowman’s capsuleBowman’s capsule

2.2. GlomerulusGlomerulus

3.3. Proximal convoluted tubuleProximal convoluted tubule

4.4. Loop of HenleLoop of Henle

5.5. Distal convoluted tubuleDistal convoluted tubule

6.6. Collecting tubuleCollecting tubule

Nephron structureNephron structure

Afferent arteriole Afferent arteriole – blood from renal artery – blood from renal artery enters through this…enters through this…

Bowman’s capsule – double-walled hollow Bowman’s capsule – double-walled hollow capsule – surrounds glomeruluscapsule – surrounds glomerulus

Glomerulus – knotty ball formed from afferent Glomerulus – knotty ball formed from afferent arterioles finely dividing – contains 50 arterioles finely dividing – contains 50 separate capillariesseparate capillaries

Proximal convoluted tubule Proximal convoluted tubule – twisted tubular – twisted tubular branch off Bowman’s capsulebranch off Bowman’s capsule

Nephron structure cont’dNephron structure cont’d

Loop of Henle Loop of Henle – proximal convoluted – proximal convoluted tubule descends into the medulla forming tubule descends into the medulla forming large looplarge loop

Distal convoluted tubule Distal convoluted tubule – ascending limb – ascending limb of Henle’s loopof Henle’s loop

Collecting tubule Collecting tubule – distal tubule opens – distal tubule opens into collecting tubuleinto collecting tubule

Urine Formation in the Urine Formation in the NephronNephron

1- Filtration1- Filtration

2. Reabsorption2. Reabsorption

3- Secretion3- Secretion

FiltrationFiltration• First step in urine formationFirst step in urine formation• Blood from renal artery enters glomerulusBlood from renal artery enters glomerulus• High blood pressure in glomerulus forces High blood pressure in glomerulus forces

fluid (Filtrate) to filter into Bowman’s fluid (Filtrate) to filter into Bowman’s capsule capsule (function of glomerulus is to filter (function of glomerulus is to filter substances from the blood)substances from the blood)

• Filtrate does not contain plasma proteins or Filtrate does not contain plasma proteins or RBCs- they are too bigRBCs- they are too big

• Bowman’s capsule filters out 125cc of Bowman’s capsule filters out 125cc of fluid/min. – 7500cc/hourfluid/min. – 7500cc/hour

• As filtrate continues through nephron, 90% As filtrate continues through nephron, 90% of water is reabsorbedof water is reabsorbed

ReabsorptionReabsorption Water and useful substances are reabsorbed Water and useful substances are reabsorbed

in proximal convoluted tubulein proximal convoluted tubule If blood levels of certain substances are high If blood levels of certain substances are high

(glucose, amino acids, vitamins, sodium) (glucose, amino acids, vitamins, sodium) then those substances will not be reabsorbedthen those substances will not be reabsorbed

Useful substances filter out of the renal Useful substances filter out of the renal tubules and back into the capillaries around tubules and back into the capillaries around the tubules = reabsorptionthe tubules = reabsorption

SecretionSecretion

Opposite of reabsorption Opposite of reabsorption Secretion transports substances from Secretion transports substances from

blood into collecting tubulesblood into collecting tubules Substances include creatinine, Substances include creatinine,

hydrogen ions, potassium ions, and hydrogen ions, potassium ions, and some drugssome drugs

Electrolytes are selectively secreted to Electrolytes are selectively secreted to maintain body’s acid-base balancemaintain body’s acid-base balance

Urinary OutputUrinary Output

Average= 1500 ml/dayAverage= 1500 ml/day Urinalysis- examination of urine to Urinalysis- examination of urine to

determine presence of blood cells, determine presence of blood cells, bacteria, acidity level, specific gravity bacteria, acidity level, specific gravity and physical characteristics (color, and physical characteristics (color, clarity and odor)clarity and odor)

Normal in urinalysis = Ammonia Normal in urinalysis = Ammonia not normal = glucose, blood, pusnot normal = glucose, blood, pus

UretersUreters

One from each kidneyOne from each kidney Carry urine from kidney to bladderCarry urine from kidney to bladder Smooth muscle tube with mucous Smooth muscle tube with mucous

membrane lining membrane lining Peristalsis pushes urine down uretersPeristalsis pushes urine down ureters

The tubes that connect the kidneys and The tubes that connect the kidneys and bladderbladder..

Path of urine formationPath of urine formation

Afferent arteriole - Glomerulus – Afferent arteriole - Glomerulus – Bowman’s capsule – proximal convoluted Bowman’s capsule – proximal convoluted tubule – loop of Henle – distal convoluted tubule – loop of Henle – distal convoluted tubule – collecting tubule – renal pelvis - tubule – collecting tubule – renal pelvis - ureterureter

Urinary BladderUrinary Bladder Hollow, muscular organ – in the pelvic cavityHollow, muscular organ – in the pelvic cavity Made of elastic fibers and involuntary muscleMade of elastic fibers and involuntary muscle Stores urine- usually about 500ccStores urine- usually about 500cc Emptying urine (voiding) is involuntary but Emptying urine (voiding) is involuntary but

controlled through nervous system (voluntary)controlled through nervous system (voluntary) Function = store and aid in elimination of urineFunction = store and aid in elimination of urine Urine leaves through Urine leaves through urethraurethra to outside opening to outside opening

= Urinary Meatus= Urinary Meatus

Chemical ControlChemical Control Reabsorption of H2O in distal convoluted tubule Reabsorption of H2O in distal convoluted tubule

controlled by ADH (antidiuretic hormone) controlled by ADH (antidiuretic hormone) Secretion and regulation of ADH controlled by Secretion and regulation of ADH controlled by

hypothalamushypothalamus Diuretics inhibit reabsorption of H2ODiuretics inhibit reabsorption of H2O Medications can replace chemicals created by Medications can replace chemicals created by

body body i.e. renin = diuretici.e. renin = diuretic Production of urine is controlled by ADH and Production of urine is controlled by ADH and

aldosteronealdosterone

Nervous ControlNervous Control

Direct control through nerve impulses Direct control through nerve impulses on kidney blood vesselson kidney blood vessels

Indirect control through stimulation of Indirect control through stimulation of endocrine glandsendocrine glands

Disorders of the Urinary Disorders of the Urinary SystemSystem

Renal Calculi (Kidney Stones)Renal Calculi (Kidney Stones) Made of crystals of calcium phosphate and uric Made of crystals of calcium phosphate and uric

acidacid Gradually they get larger until they block Gradually they get larger until they block

ureters…can causey hydronephrosisureters…can causey hydronephrosis First symptom- severe painFirst symptom- severe pain Other symptoms- nausea and vomiting, Other symptoms- nausea and vomiting,

frequency, chills, fever, hematuriafrequency, chills, fever, hematuria Diagnosis- by symptoms, ultrasound, or x-rayDiagnosis- by symptoms, ultrasound, or x-ray Rx- increase fluids to flush out stone, Rx- increase fluids to flush out stone,

medications, and if needed- lithotripsymedications, and if needed- lithotripsy

LithotripsyLithotripsy

Surgical procedure to remove kidney Surgical procedure to remove kidney stonesstones

Shock waves hit dense stones and Shock waves hit dense stones and break them upbreak them up

Done on outpatient basisDone on outpatient basis

                                                              

                

NephritisNephritis

Inflammation of the kidney (kidney Inflammation of the kidney (kidney infection)infection)

Incontinence =Incontinence = Involuntary urinationInvoluntary urination

CystitisCystitis

Inflammation of the mucous membrane Inflammation of the mucous membrane lining of the urinary bladderlining of the urinary bladder

Most common cause- E. ColiMost common cause- E. Coli Symptoms- Dysuria Symptoms- Dysuria (painful urination), (painful urination),

lower abd pain, and frequencylower abd pain, and frequency Usually in females (shorter urethra)Usually in females (shorter urethra) Rx- antibioticsRx- antibiotics

  

  

  

                    

Dialysis (Hemodialysis)Dialysis (Hemodialysis)

Used for kidney failureUsed for kidney failure Involves the passage of blood through Involves the passage of blood through

device with semipermeable membranedevice with semipermeable membrane Dialysis serves as substitute kidney… Dialysis serves as substitute kidney…

replaces filtrationreplaces filtration Blood from patient flows through machine Blood from patient flows through machine

and is filteredand is filtered Can be done at home or in clinicCan be done at home or in clinic Takes 2-4 hours, 2-3 times a weekTakes 2-4 hours, 2-3 times a week

Kidney TransplantKidney Transplant

As a last resortAs a last resort Involves donor organ from someone Involves donor organ from someone

with a similar immune systemwith a similar immune system Main complication- rejectionMain complication- rejection

TerminologyTerminology Enuresis- bedwettingEnuresis- bedwetting Incontinence – involuntary urinationIncontinence – involuntary urination Gylcosuria- sugar in urineGylcosuria- sugar in urine Nocturia- frequent urination at nightNocturia- frequent urination at night Polyuria- large amounts of urinePolyuria- large amounts of urine Anuria- no urine producedAnuria- no urine produced Hematuria- blood in urineHematuria- blood in urine Diuretic- drug or substance to increase Diuretic- drug or substance to increase

urine productionurine production Oliguria – decreased urine production Oliguria – decreased urine production

(sign of kidney failure)(sign of kidney failure)