URINARY SYSTEM - Weebly



URINARY

SYSTEM

LECTURE 1

URINARY SYSTEM ~ RENAL SYSTEM

KIDNEY

URINARY BLADDER

URINARY TRACT ~ URETERS & URETHRA

URINE & URINATION ~ Processes

Filtration

Reabsorption

Secretion

KIDNEY ~ Water purification plant

Major excretory organ ~ makes & excretes “urine”

Entire blood volume passes thru kidney 60x per day

50 gallons of blood filtered daily

99% of volume retained in blood

1% of volume eliminated as urine

Filters toxins, ions, nitrogen wastes ~ mostly urea ~ NH4

Regulates volume & composition of blood ~ controls BP

Maintains balance between water & salts ~ Na+ Cl- K+

Maintains acid & base balance ~ pH control

Endocrine Function: Erythropoietin & Renin

KIDNEY ~ ANATOMY

Bean shaped & paired

Left kidney slightly superior to right kidney ~ due to liver

Capped by adrenal glands

Located retroperitoneal in the lumbar abdominal cavity

Renal Hilus ~ Concave medial surface

Renal Artery enters ~ O2 & nutrients

Renal Vein exits ~ CO2 & purest blood in body

Ureter exits~ carries urine to bladder

Adipose Capsule ~ Adipose Tissue

Outer layer of fatty tissue ~ Holds kidney in place

Cushions against contusions & traumatic blows

Renal Fascia

Outermost layer of dense fibrous connective tissue

Completely surrounds kidney & adipose tissue

Also surrounds adrenal gland

Anchors kidney to surrounding structures

Renal Capsule

Fibrous supporting tissue capsule which adheres to surface of kidney

Provides strong barrier against infection

Renal Sinus

Internal cavity within kidney ~ covered by capsule

Surrounds entire urine collecting area

Renal Cortex

Superficial internal region ~ Light in color

Contains “Nephrons” ~ Structural & functional

units of kidney

Renal Medulla

Deep to cortex ~ Darker & reddish brown

Also contains part of Nephrons

Renal Pyramids ~ Medullary Pyramids

16 -18 cone shaped tissue within renal medulla

Bases point toward Renal Cortex

Apex Cones point toward urine collecting areas

Drains thru renal papilla into minor calyx

Renal Columns

Area of renal medulla between renal pyramids

Renal Lobe

Consists of pyramid, cortex, & column

Minor Calyces ~ initial urine collecting area

Encloses renal papillae of the pyramids

Collect urine & empty it into major calyces

Site of Kidney Stone Formation

Major Calyces

Branching regions of the renal pelvis

Collect urine draining from renal pyramids

Via Minor Calyx

Renal Pelvis

Large urine collecting area within the renal sinus

Continuous with ureters ~ urine flows to bladder

Ureters

Tubes ~ carry urine between kidney & bladder

Kidney Stones break off ~ block ureters ~ painful

KIDNEY - BLOOD SUPPLY

Kidneys receive 25% of total cardiac output each minute via Renal Arteries

90% of blood is “filtered” in nephrons - filters 50 gal/day

10% of blood supplies kidney tissue with O2 & nutrients

Abdominal Aorta Abdominal Vena Cava

( (

Renal Artery Renal Vein ~ “purest blood”

( (

Interlobar & Interlobular Peritubular Capillaries

“True Capillaries”

- - - - - - - -(- - - - - - - - - - - - - - - - - - - - - - - - -(- - - - - - - - - - - - - -

NEPHRON

“Afferent” Arterioles “Efferent” Arterioles

( (

( ( GLOMERULI ( (

(SPECIALIZED FILTERING CAPILLARIES)

RENAL NERVE SUPPLY ~ Supplied via renal nerves

Sympathetic Stimulation regulates renal blood flow & pressure via dilation/constriction of renal arterioles

“VASOMOTOR ACTIVITY”

NEPHRONS > 1,000,000 in each kidney

Microscopic FILTERING units in Cortex & Medulla

FORM THE “FILTRATE” & MAKE URINE

Carries out the 3 processes of making URINE

1. Glomerular Filtration ~ filters blood

2. Tubular Reabsorption ~ primarily water & sodium

3. Tubular Secretion ~ secretes ions, H+, HCO3-, toxins,

drugs & nitrogenous wastes

“FILTRATE” = Water & solutes flowing thru the kidney prior

to urine formation

Same as blood plasma except NO PROTEINS

Proteins too large to pass filtration membrane

EMPTIES into “collecting ducts” as URINE

“URINE” = Mostly Water ~ 95%

Solutes ~ 5%

Includes: Toxins, drugs, ions, H+ & HCO3- &

NITROGEN WASTE

Elimintes Nitrogen Waste ~ UREA, Uric Acid, Creatinine

Regulates Blood Volume, Composition & pH

Regulates Water Retention & Blood Pressure

TYPES OF NEPHRONS

CORTICAL NEPHRONS ~ 85% of nephrons

Mostly in cortex ~ small portion dips into medulla

Mostly “THICK SEGMENTS” ~ NOT permeable to water

“Reabsorption” of solutes into blood ~ retains Na+

“Secretion” of solutes from blood into filtrate

Some “THIN SEGMENTS” ~ permeable to water

“Reabsorption” of H2O back into blood ~ retains H2O

JUXTAMEDULLARY NEPHRONS ~ 15% of nephrons

Located at mostly in medulla ~ LOH deep in Medulla

Many “THIN SEGMENTS” ~ Very permeable to water

MAJOR area for H2O reabsorption ~ retains H2O

Some reabsorption of solutes into blood ~ retains Na+

NEPHRON ~ Components & Specific Function

1. Renal Corpuscle ~ “Filtration” Only

2. Proximal Convoluted Tubule ~ Reabsorption Mostly

3. Loop of Henle ~ Reabsorption Mostly

4. Distal Convoluted Tubule ~ Secretion Mostly

Last Resort Reabsorption ~ ALDOSTERONE

5. Collecting Duct ~ Secretion Mostly

Last Resort Reabsorption ~ ADH

NEPHRON CAPILLARY BEDS ~ “Microvasculature”

Nephron surrounded by extensive special capillary beds

90% of blood filtered in renal corpuscle as FILTRATE

99% of filtrate is reabsorbed by the renal tubules

1% of filtrate goes to form final URINE

10% of blood goes to renal tissue as nutrients & O2

GLOMERULAR CAPILLARIES ~ in renal corpuscle

“Filtration Beds”

PERITUBULAR CAPILLARIES ~ surround tubules

“Reabsorption & Secretion Beds”

RENAL CORPUSCLE

GLOMERULUS

Glomerular Capillary Beds ~ “filtration membrane”

Form “initial” Filtrate via diffusion ~ “filtered blood”

Filtrate Passes into Bowman’s Capsule

BOWMANS CAPSULE ~ surrounds glomerulus

Continuous with & forms renal tubules

Collects the “initial filtrate” from blood

Passes “initial” filtrate into tubules for filtering

“Filtration Membrane” ~ Glomerulus Filtration Beds

Capillary Side ~ Endothelium with “fenestrations”

Tubule Side ~ Endothelium with “filtration slits”

Composed of large Podocyte Cells

Fenestrations & Filtration Slits ~ form filtrate

Permits free passage of water & solutes

smaller than plasma proteins via diffusion

Small particles pass ~ ions, H2O, small solutes

Blood, WBC, & proteins ~ too large to pass

FILTRATION dependent on “Net Filtration Pressure” ~ NFP

Movement from high pressure to low pressure

Movement from high solute conc. to low solute conc

Glomerular Capillaries

Only place with both afferent & efferent arterioles

Glomerulus ~ Fed by afferent arteriole ~ 100% in

Glomerulus ~ Drained by efferent arteriole ~ 10% out

Normal Capillaries = 40 mmHg in 20 mmHg out

Glomerular Capillaries = 60 mmHg in 30 mm Hg out

Efferent arterioles have smaller diameter

than afferent arterioles because of afferents & efferents

Causes “back pressure” into afferent arterioles

Higher blood pressure ( ( Capillary Hydrostatic Pres.

( capillary hydrostatic pressure ( ( filtration thru

Filtration membrane in glomerular capillaries(

( GLOMERULAR FILTRATION RATE (GFR)

URINE FORMATION PROCESSES

GLOMERULAR FILTRATION ~ measured as “GFR”

Forms the “initial” filtrate in the glomerulus

Glomeruli efficiently filters of blood ~ BY DIFFUSION

Passive, non-selective process ~ no ATP required

Materials move from high pressure to low pressure

Filtrate (solutes & fluid) forced into Bowman’s Capsule by HYDROSTATIC PRESSURE (BHP)

Determined by Net Filtration Pressure (NFP) ~ 10 mmHg

Glomerular Hydrostatic Pressure ↓ 60 mmHG

Blood Colloid Osmotic Pressure ↑ 32 mmHG

Capsule Hydrostatic Pressure ↑ 18 mmHG

Glomerular Hydrostatic Pressure ~ most significant

Blood Colloid Osmotic Pressure ~ in glomerulus

Pressure generated by blood to draw water in to it

Depends on solute concentration of blood

H2O moves from low to high solute concentration

Capsule Hydrostatic Pressure ~ in Bowman’s Capsule

Pressure exerted by fluids within Capsule

URINARY

SYSTEM

LECTURE 2

RENAL TUBULES ~ Further Process the Filtrate

1. Proximal Convoluted Tubule ~ PCT

2. Loop of Henle ~ LOH

3. Distal Convoluted Tubule ~ DCT

4. Collecting Ducts ~ CD ~ not really a renal tubule

“Peritubular Capillaries” ~ True Capillaries

Continuation of efferent arterioles which drain glomeruli

Surround & and closely follow renal tubules

Supply nephrons & renal tissue with O2 & Nutrients

Highly specialized for reabsorption & secretion ~ pores

Area of “reabsorption” of selected filtrate into blood

Area of “secretion” from blood into filtrate

Empty into Venules - - -> Renal Vein - - - > Vena Cava

Vasa Recta ~ surround Juxtamedullary Nephrons only

Mesh of thin straight vessels around Loop of Henle

Deep within the medulla

A major area for H2O & solute reabsorption in LOH

Further Concentrates Filtrate (Urine)

TUBULAR REABSORPTION & SECRETION

Movement of solutes & H2O between blood & tubules

Via “peritubular capillaries

Blood “reabsorbs” substances from tubule filtrate

Blood “secretes” substances back into tubular filtrate

Movement maintains equal concentration with blood

Tubular Reabsorption ~ “Reclaimation” Process

Movement of solutes or H2O from filtrate into blood

Transport may be “Active or Passive”

PASSIVE Tubular Reabsorption ~ NO ATP

Diffusion of ions & water into blood

Solutes (Na+ Cl- K+) move from high to low conc.

H2O moves from low solute to high solute conc.

Passive transport follows active transport of Na+

Na+ ~ establishes concentration gradient

Na+ pulls other solutes with it . . . H2O follows

Solutes first diffuses from filtrate into tubule cells

Then solutes diffuse into peritubular capillaries

Filtrate is concentrated as H2O is reabsorbed into blood

ACTIVE Tubular Reabsorption ~ requires ATP

Movement against concentration gradient

Na+ passively diffuses into tubule cells . . . then

Na+ is “ACTIVELY” pumped into peritubular capillaries against a gradient

Na+ K+ exchange pump

OTHER “Actively” Transported Solutes

Glucose, some other ions, & vitamins

Secondary Active Tubular Reabsorption

Protein carriers co-transport Na+ & GLUCOSE

100% of GLUCOSE is reabsorbed into blood

TUBULAR SECRETION ~ ACTIVE process ~ requires ATP

Adds solutes back to filtrate from blood

Removes undesirable Nitrogens & waste from blood

UREA (most prevalent solute in urine) ~ ammonia

Creatinine ~ nitrogen from muscle metabolism

Drugs . . . Toxins . . . Other Metabolites

Other Ions ~ Na+, K+, Cl- secreted as needed

Excess H+ or HCO3- ~ to maintain acid-base balance

RENAL TUBULE FUNCTIONS

Proximal Convoluted Tubule ~ PCT

Coiled tubule ~ continuous with Bowman’s Capsule

Confined to Renal Cortex

60-70% OF All FILTRATE IS REABSORBED IN PCT

65 % of Na+ ~ reabsorbed

65 % of water follows Na+ in PCT ~ Reabsorbed

100% Glucose Reabsorbed

50% Urea Reabsorbed

50% Urea Secreted

Loop of Henle ~ LOH

Proximal Convoluted Tubules Dip Down into Medulla

Descending Limb

Proximal ~ Thick Segment ~ Na+ Reabsorbed

Distal ~ Thin Segment ~ 15% H2O Reabsorbed

Ascending Limb

Thin Segment ~ 15 % H2O Reabsorbed

Thick Segment ~ 25 % Na+ & 40% K+ Reabsorbed

Distal Convoluted Tubule ~ DCT

Confined to Renal Cortex only

Reabsorption of Na+ & H2O Only ~ Aldosterone

Secretion of ions, H+, drugs, Urea, Creatinine

Has specialized cells that monitor filtrate concentration & hydration needs of body ~ regulates blood volume

Macula Densa ~ chemo . . . baro . . . osmoreceptors

Juxtaglomerular Apparatus ~ Secretes RENIN

Reabsorption of Na+ & H2O . . . depends on body needs

Nearly all water & Na+ can be reabsorbed if needed

Reabsorption is hormonal influenced

Aldosterone works here . . . ADH starts working here

Aldosterone ~ ( reabsorption of remaining Na+ ~ DCT

( water follows Na+

MAJOR SECRETION ~ DCT

UREA ~ MOST Creatinine

H+ if acidotic HCO3- if alkalotic

Ions . . . Toxins . . . Drugs

JUXTAGLOMERULAR APPARATUS ~ in DCT

Surround distal convoluted tubules

Macula Densa Cells

Epithelial cells around distal convoluted tubules

Chemoreceptors . . osmoreceptors . . baroreceptors

Resond to solute concentration of the filtrate

Cause Juxtaglomerular cells to secrete RENIN if. . .

Osmolarity of urine too low (urine is dilute) or

Blood pressure decreases or blood loss

Juxtaglomerular Cells

Special cells of the afferent arterioles mostly

Secretes: Renin & Erythropoietin

Renin converts angiotensin 1 to angiotensin 2

Angiotensin 2 stimulates release of aldosterone from adrenal cortex

Aldosterone stimulates reabsorption of sodium

Water follows sodium

Urine becomes more concentrated

Blood pressure increases (vasoconstriction & increased volume)

COLLECTING DUCTS ~ Part of “urine collecting” system

Located both in Renal Cortex & Renal Medulla ~ MANY

Receives Filtrate (not yet urine) from all nephron tubules

Last resort area to concentrate or dilute filtrate . . .

before it becomes urine

Makes final adjustments to concentration & volume of

urine ~ concentrates or dilutes urine . . . as needed

Reabsorption of water ~ Hormone Dependent ~ ADH

Anti-diuretic Hormone ~ ADH ~ posterior pituitary

( permeability of collecting ducts to water - - ->

( reabsorption of water - - - >

( fluid & vascular volume - - > increased BP

Final Reabsorption of Na+, K+, H+, HCO3- . . . as needed

MAJOR SECRETION of ions, acids, drugs, toxins

UREA Creatinine H+ HCO3-

Filtrate is now called “URINE”

Merges into Papillary Ducts for urine flow to bladder

PAPILLARY DUCTS ~ starts urine flow

Fusion of collecting ducts ~ delivers urine to Minor Calyx

---> Major Calyx ---> Renal Pelvis ---> Ureter ---> Bladder

REGULATION OF RENAL BLOOD FLOW

Intrinsic & Extrinsic Neural/Hormonal Feedback Mechanisms

Maintains constant renal blood flow & glomerular filtration

Blood Pressure ~ is the major regulating factor of GFR

Dilation or Constriction of renal arterioles affects GFR

Afferent Arteriole Dilation - - -> more flow >( GFR

UNIQUE

Afferent Arteriole Constriction - > less flow > ( GFR

REGULATING FACTORS: Have Opposite Effects

Systemic Vasodilation causes low BP ( GFR

Renal Afferent Arteriole Dilation causes ( GFR

Systemic Vasoconstrictors causes high BP ( GFR

Renal Afferent Arteriole Constriction causes ( GFR

RENAL AUTOREGULATION ~ “INTRINSIC” ~ kidney only

Controlled by macula densa baroreceptors of JXT (JGA)

( blood pressure ( decrease glomerular filtration ( GFR

( intrinsic reflex afferent arteriole dilation to ( GFR

SYMPATHETIC REGULATION~ “EXTRINSIC”

Baroreceptors ~ sense changes in blood pressure

( blood pressure ~ stimulates systemic sympathetic

release of epinephrine / NE

( constriction of efferent arterioles ( ( GFR

HORMONAL REGULATION ~ Renin-Angiotensin-Aldosterone

Regulates fluid volume & blood pressure

START DROP in blood pressure sensed by Baroreceptors

( blood pressure ( decreased GFR (

RENIN released by Juxtaglomerular cells

( activates Angiotensin I ( Angiotensin II

Potent vasoconstriction ~ efferent arteriole

( Angiotensin I & II ( ALDOSTERONE release

from adrenal cortex

( Aldosterone ( Na+ retention in DT and CD

( Water & Fluid Retention

( Increases Blood Volume

( Increases Systemic Pressure

( Increases Glomerular Filtration Rate

URINE FORMATION ~ OSMOLALITY

OSMOLALITY of a solution determines OSMOSIS

Osmosis ~ movement of water from low solute

to high solute concentration when only

water can move across membrane

Dependent on # of particles in a liter of solution

Solute particles per liter ~ mili-osmoles/Liter

Kidneys ~ Maintain concentration of blood ~ at 300 mOsm/L

300 (mOsm) x 1000 = 300,000 particles per liter

Hyper-osmolality ~ more than 300 mOsm/L

Hypo-osmolality ~ less than 300 mOsm/L

Osmolality ~ increases as filtrate moves from

Glomerulus (300 mOsm/L) same as blood (

Descending Loop of Henle (400 – 1200 mOsm/L) ( HYPER

Ascending Loop of Henle (1200 – 100 mOsm/L) (

Distal convoluted tubule (100 mOsm/L) HYPO-osmolar

Collecting Duct ~ urine concentrates as solutes secreted

& H2O reabsorbed

Urine could have osmolalities range of 65 –1200 mOsm/L

URINE FORMATION PROCESS ~ SUMMARY

“Medullary Osmotic Gradient” ~ changes in Tubule mOsm

“Countercurrent Mechanism” ~ opposite movement

Fluids moving in opposite directions in LOH

Filtrate in descending loop moves toward renal pelvis

Filtrate in ascending loop moves toward renal cortex

Change in gradient ~ increases as filtrate moves

“MULTIPLIER EFFECT” ~ countercurrent multiplier

GLOMERULUS

Filtrate formed ~ Osmolality = to blood ~ 300 mOsm

PROXIMAL CONVOLUTED TUBULES

60% Na+ ion reabsorption from glomerular filtrate

65% water reabsorption

Net Effect = Blood & filtrate Osmolality remains

constant ~ 300 mOsm

DESCEDING LIMB~ Loop of Henle ~ “thin” portion

15% water reabsorption into blood

This concentrates filtrate (( mOsm) ( hyper-osmolality in Loop of Henle ~ 1200 mOsm

ASCENDING LIMB ~ Loop of Henle ~ “thick” portion

Impermeable to H2O

Na+ & Cl- actively reabsorbed into blood

Filtrate becomes more dilute as more Na+ and Cl- passively move out of filtrate since water cannot move

Filtrate becomes hypo-osmolar as it moves into distal tubules and collecting ducts

Filtrate ~ 100mOsm

DISTAL CONVOLUTED TUBULES ~ DCT

Starts process of Final Adjustments to filtrate

Many substances “actively” SECRETED into filtrate

UREA & Creatinine

Drugs & Toxins

Excess ions H+ HCO3- K+

Not much Na+ of Cl- or water movement normally

Unless stimulated by Renin & Aldosterone

Aldosterone enhances Na+ reabsorption

ADH ~ starts working here ~ H2O reabsorption

Both Aldosterone (mostly) & ADH (starts) in DCT

Filtrate ~ 100 – 300 mOsm

URINE FORMATION PROCESS ~ SUMMARY

COLLECTING DUCTS

Final Area to concentrate urine & make final adjustment

Last place to reabsorb Na+ & H2O

“Active” Secretion

UREA & Creatinine

H+ HCO3- K+

Drug Metabolites & Toxins

Aldosterone ~ last place to reabsorb Na+

Anti-Diuretic Hormone ~ ADH ~ Posterior Pituitary

Effects permeability of water in collecting ducts

Affects final concentration of urine & blood volume

( ADH ( dilutes urine ~ more urine ~ polyuria

No water reabsorbed ~ Diabetes Insipitus 1.010

( ADH ( concentrates urine ~ less urine

Water reabsorbed in response to stimuli requiring increased blood & tissue fluid volume

EG: Blood Loss, dehydration, ( BP

URINARY

SYSTEM

LECTURE 3

RENAL CLEARANCE & FUNCTION TESTS

Provides information ONLY about renal function & the

course of renal disease

Glomerular Filtration Rate ~ GFR

Volume flow rate ~ ml/min

Measures 24 hr. kidney clearance of plasma solutes

BUN ~ Blood Urea Nitrogen

Nitrogen waste ~ UREA most solute in urine

Normally secreted ~ small amounts reabsorbed

Indicates reversible glomerular problems ~ retained

Serum Creatinine & Urine Creatinine

Nitrogen waste product from muscle metabolism

Normally secreated & not reabsorbed ~ serum creatinine

May indicate irreversible glomerular problems if serum creatinine is high & urine secretion is low

Must compare serum creatinine & urine creatinine clearance

Good = low serum creatinine high urine creatinine

OK = high serum creatinine high urine creatinine

Bad = high serum creatinine low urine creatinine

URINE COMPOSITION

Urinalysis ~ analysis of urine ~ Covered in Laboratory

Aid to diagnose body condition . . . not just renal system

Significant indicators: Proteins Bacteria

Glucose pH

Acetone Specific Gravity

Blood Pus

URINE CHARACTERISTICS

93-97% Water 5% Solutes

Volume ~ 1200 ml/day to 1800 ml/day

Color ~ clear to pale yellow

Yellow pigment ~ urochrome

Due to hemoglobin/bile destruction

( concentration ( ( yellow color

Foods, pus, blood ~ may change color

Odor ~ Slightly ammonia due to urea & Nitrogen

Fruity if acetones present ~ diabetes mellitus

pH ~ Slightly acid ~ pH~ 6.0 (Range 4.4-8)

High protein diet causes more acid urine

Bacterial infection causes more alkaline urine

Specific Gravity ~ 1.003-1.030 (water = 1.000)

Slightly heavier than water ~ due to “solutes”

1.010 indicates inability to concentrate urine

“isosthanuria” ~ Diabetes insipitus ~ NO ADH

> 1.035 characteristic of Diabetes mellitus or severe dehydration ~ glucose adds weight to H2O

Normal Solutes Present in Urine

Nitrogenous Waste Products

Urea Uric acid Creatinine

Sodium, Potassium, Sulfate & Phosphate

Abnormal Urine Components Cause

Glucoseuria Glucose (trace ok) D. Mellitus

Proteinuria Protein (trace ok) Diet

Ketonuria Ketones (none) Wasting

Hemoglobinuria Hemoglobin (none) Hemolysis

Bilirubinuria Bilirubin (none) Liver

Hematuria Erythrocytes (none) Trauma/Stones

Pyuria Leukocytes (none) Infection

Bacteuria Bacteria (none) Infection

OTHER RENAL SYSTEM ORGANS & Structures

URETERS ~ Transitional Epithelium Mucosa

Two Slender tubes ~ carry urine from each kidney to

urinary bladder

Move urine by peristalsis ~ contraction of muscle layers

Full bladder causes compression of ends of ureters

Prevents back flow of urine into ureter

“Urolithiasis” ~ Extreme pain during movement of sand

or calculi from kidney to bladder

URINARY BLADDER

Distendable muscular sac posterior to pubic symphasis

Stores Urine ~ 500 to 1000ml in LUMEN (opening)

Two inlets: 2 ureters ~ one in from each kidney

One outlet: 1 urethra out through penis

Bladder Wall: Transitional Epithelium ~ Mucosa

Detrusor Muscle ~ “involuntary” & powerful

Longitudinal & Circular smooth muscles layers

Contraction Compresses & empties bladder

Trigone ~ funnel area for urine ~ connects to urethra

Prostate Gland ~ surrounds urethra below “trigone”

URETHRA

Thin Muscular tube ~ moves urine from bladder out of body

Male: Through penis

Female: Empties into vulva in front of cervix

Anterior to vaginal opening ~ posterior to clitoris

Internal Urethral Sphincter

Extension of bladder detrusor smooth muscle

Involuntary smooth muscle sphincter ~ surrounds urethra at bladder / urethra junction

Sympathetic ~ constricts ~ bladder filling

Parasympathetic ~ relaxes ~ bladder emptying

External Urethral Sphincter

Voluntary skeletal muscle surrounds urethra

Voluntary control to complete urine release

Male Urethra ~ travels entire length of penis

Prostatic Urethra ~ passes through prostate ~ 1”

Membranous Urethra ~ from prostate to penis ~ 1”

Spongy Urethra ~ penile urethra ~ 5”

External Urethral Orifice ~ Meatus ~ tip of penis

MICTURATION ~ URINATION

“Process of Emptying Bladder”

Bladder Volume ~ 200 ml causes stretch of bladder wall

Distension in bladder stimulates visceral reflexes

Storage Reflex ~ sympathetic “filling reflex”

Sympathetic Reflex ~ via lumbar spinal nerves

Internal & external sphincters contract~CLOSE

Detrusor Muscles Relax ~ ALLOWS FILLING

Voiding Reflex ~ parasympathetic “emptying reflex”

Awareness when stimuli reach sensory cortex

Parasympathetic Reflex ~ via sacral “pelvic nerves”

Stimulates Detrusor Muscle Contraction

Inhibits or relaxes internal sphincters

Inhibits sympathetic outflow to external sphincter

causing relaxation

MICTURATION ~ can be delayed voluntarily since external

sphincter is voluntarily controlled . . . to a point

Control lost when urine bladder volume reaches 500 ml

Children < 2yrs old ~ NO voluntary control

Spinal cord not fully developed until age 4

RENAL SYSTEM ABNORMALATIES

Glomerulonephritis

Inflammation of the glomeruli ~ clogged glomeruli

Many causes ~ could be an autoimmune disease

Hemolytic Anemia ~ E.coli toxins in petting zoo

Damaged filtration & increased permeability to proteins

Polycystic Kidneys

Inherited condition

Swollen cysts occur along renal tubules

Compresses adjacent nephrons and vessels

Deteriorated renal function ~ insidious symptoms

Treat: nephrectomy . . . dialysis . . . kidney transplant

Bladder Cancer

3% of all cancer ~ 3x more common in men

Incidence highest among cigarette smokers

85% cure rate if local & non-metastatic

Usually terminal if generalized & metasticized

Spreads via regional lymph nodes

Renal Failure & Insufficiency ~ common with age

Kidneys unable to perform excretory function

Reduced Filtration ~ reduces adequate normal urine

production . . . nitrogens build

All systems affected ~ many symptoms ~ many causes

Acute Failure ~ filtration stops abruptly ~ SERIOUS

Chronic Failure ~ gradual deterioration ~ irreversible

Treatment: Remove Causes

Dialysis

Kidney transplant ~ best in long term

Kidney & Bladder Stones ~ Calculi ~ very common in FLA

Nephrolithiasis ~ kidney stones ~ pain ??? ~ blood

Urolithiasis ~ stones in ureters ~ extremely painful

Cystolithiasis ~ Bladder Stones ~ pain??? & blood

Usually: calcium deposits, magnesium salts, others

Diagnosis: Blood in urine ~ painful in urolithiasis

Could cause urinary blockage ~ SERIOUS

Treatment: Most pass on own

Lithotripsy ~ ultrasound

Surgery

Removal via catheter

Diabetes insipidus

Inability of kidneys to concentrate urine ~ SG < 1.010

1.010 = isosthanuria

Little or no ADH release No Glucose in Urine

Cause: Tumor or trauma to hypothalamus

Diuresis ~ elimination of excess volume of urine

Diuretics ~ Chemicals that enhance urinary output

Frequently used drugs for hypertension ~ Lower

blood pressure

Most inhibit Na+ and K+ retention & reabsorption

Alcohol ~ inhibits ADH causing profuse water loss

Caffeine ~ is hypertensive, stimulates glomerular

filtration, & elimination of Na+

Aging

30-40% loss of nephrons between ages 25-85

Urinary Incontinence ~ lost muscle tone ~ CAN’T HOLD

Urinary Retention ~ prostate enlargement ~ CAN’T GO

Incontinence

Inability to “voluntarily” control micturation

Urine leaks out after coughing or sneezing

Caused by: Trauma ~ childbirth

Spinal or neural injury ~ paralysis

Stress

Lost muscle tone with age

Urinary Retention

Bladder unable to expel its contents

Prostate Enlarged ~ most common cause

Sympathomimetic Drugs ~ cold medications

Following Anesthesia

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