022 urinary system

7/28/2019 022 Urinary System

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The Urinary System


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Function

1. Remove nitrogenous wastes

2. Maintain electrolyte, acid-base,

and fluid balance of blood3. Homeostatic organ

4. Acts as blood filter

5. Release hormones: calcitriol &erythropoietin


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Kidneys as Filters

Diuretic- loose water; coffee, alcohol

Antidiuretic- retain water; ADH Aldosterone- sodium & water reabsorption,

and K+ excretion

GFR= 180 liters (50 gal) of blood/day

178-179 liters are reabsorbed back intoblood

Excrete a protein free filtrate


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Maintaining

ChemicalHomeostasis

The

Urinary

System


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The Urinary System


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urine

blood

filtration

tubularreabsorptionand secretion

GeneralFunctioning

of the Kidney

refreshed blood


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Nitrogenous

Wastes

ammonia

urea

uric acid


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Organs

of theUrinary

System

kidneys

ureters

urinarybladder

urethra


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renal

capsule

renalcortex

renal

medulla

renalpelvis

renalpyramids

ureter

Kidney

Anatomy


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KidneyAnatomy

renal artery

renal vein

nephron


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urine

blood

filtration

tubularreabsorptionand secretion

Nephron

Functioning

refreshed blood


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vein

artery

afferentarteriole

efferentarteriole

glomerulus

peritubularcapillaries

Bowmanscapsule

proximalconvolutedtubule

distalconvolutedtubule

loop ofHenle

collectingduct


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renalcortex

renalmedulla

Each kidney contains over 1 million nephrons and thousands

of collecting ducts

Collecting duct

Loop of Henle

PCT

DCTGlomerulus


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Glomerular

Filtration

afferent

arteriole

glomerulus

efferentarteriole

Bowmanscapsule

Filters blood; proteins cant pass through


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Composition of

Glomerular Filtrate

Water

Small Soluble OrganicMolecules

Mineral Ions


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Proximal Convoluted

TubuleReabsorbs: water, glucose,

amino acids, and sodium.

65% of Na+ is reabsorbed

65% of H2O is reabsorbed

90% of filtered bicarbonate (HCO3

-)

50% of Cl- and K+


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Loop of Henle

Creates a gradient of increasing

sodium ion concentration towards

the end of the loop within theinterstitial fluid of the renal pyramid.

25% Na+ is reabsorbed in the loop 15% water is reabsorbed in the loop

40% K is reabsorbed in the loop


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Distal Convoluted

TubuleUnder the influence of the hormone

aldosterone, reabsorbs sodium and

secretes potassium. Also regulates

pH by secreting hydrogen ion when

pH of the plasma is low.

only 10% of the filtered NaCl and 20% of water

remains


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Collecting Duct

Allows for the osmotic

reabsorption of water.

ADH (antidiuretic hormone)- makes

collecting ducts more permeable to

water-- produce concentrated urine


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From the original 1800 g NaCl, only 10 g appears in

the urine

Urine

Water- 95%

Nitrogenous waste:

urea

uric acid creatinine

Ions:

sodium

potassium sulfate

phosphate


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Hormonal

Control ofKidney

Function


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Hormonal Control

of Kidney Function

low blood volumehigh plasmasolute

concentration

hypothalamus

heart receptors


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Hormonal Control

of Kidney Function

hypothalamus

posterior pituitary

antidiuretic hormone

collecting ducts


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HormonalControl of

Kidney

Function


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Hormonal Control

of Kidney Function

reduced blood pressure and

glomerular filtrate

juxtaglomerular apparatus

renin


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Hormonal Control

of Kidney Function

reninangiotensinogen

angiotensin I

angiotensin II


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Hormonal Control

of Kidney Function

adrenal cortex

aldosterone

angiotensin II

convoluted tubules


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Urinary Bladder

ureters internalsphinctersexternal

sphinctersurethra


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Bladder

1. Mucosa (transitional epithelium)

2. Muscular layer (detrusor muscle):3 layers of smooth muscle

3. Fibrous adventia


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Internal urethral sphincter:

Smooth muscle

Involuntary control

More superiorly located

External Urethral sphincter:

Skeletal muscle Voluntary control

Posteriorly located

Sphincter Muscles on Bladder


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When bladder fills with 200 ml of urine,

stretch receptors transmit impulses to

the CNS and produce a reflex

contraction of the bladder (PNS)

Diuresis (Micturition)

When is incontinence normal?


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Distensionof the

Urinary

Bladder


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Why do doctors ask for a urine sample?

Urinalysis

characteristics: smell- ammonia-like

pH- 4.5-8, ave 6.0

specific gravity more than 1.0; ~1.001-

1.003 color- affected by what we eat: salty foods,

vitamins


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odor- normal is ammonia-like

diabetes mellitus- smells fruity oracetone like due to elevated ketonelevels

diabetes insupidus- yucky

asparagus---

Odor


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pH- range 4.5-8 ave 6.0

vegetarian diet- urine is alkaline

protein rich and wheat diet-urine is acidic


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Color- pigment is urochrome

Yellow color due to metabolic breakdown of

hemoglobin (by bile or bile pigments)

Beets or rhubarb- might give a urine pink or

smoky color

Vitamins- vitamin C- bright yellow

Infection- cloudy

Color


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Water: s.g. = 1g/liter;

Urine: s.g. ~ 1.001 to 1.030

Pyelonephritus- urine has high s.g.;

form kidney stones

Diabetes insipidus- urine has low

s.g.; drinks excessive water; injury or

tumor in pituitary

Specific Gravity


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Glucose- when present in urine condition

called glycosuria (nonpathological)

[glucose not normally found in urine]

Indicative of:

Excessive carbohydrate intake Stress

Diabetes mellitus

Abnormal Constitutes of Urine


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Albumin-abnormal in urine; its a very large

molecule, too large to pass through glomerular

membrane > abnormal increase in permeability

of membrane

Albuminuria- nonpathological conditions-

excessive exertion, pregnancy, overabundant

protein intake-- leads to physiologic albuminuria

Pathological condition- kidney trauma due to

blows, heavy metals, bacterialtoxin



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Ketone bodies- normal in urine but in small amts

Ketonuria- find during starvation, using fat stores

Ketonuria is couples w/a finding of glycosuria-- whichis usually diagnosed as diabetes mellitus

RBC-hematuria

Hemoglobin-

Hemoglobinuria- due to fragmentation or hemolysis of

RBC; conditions: hemolytic anemia, transfusion

reaction, burns or renal disease



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Bile pigments-

Bilirubinuria (bile pigment in urine)- liver pathology such as

hepatitis or cirrhosis

WBC-

Pyuria- urinary tract infection; indicates inflammation ofurinary tract

Casts- hardened cell fragments, cylindrical, flushed out of

urinary tract

WBC casts- pyelonephritus

RBC casts- glomerulonephritus

Fatty casts- renal damage



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INQUIRY

1. List several functions of the kidneys.

2. What does the glomerulus do?3. What are several constitutes you should not find in urine?

4. What is specific gravity?

5. What two hormones effect fluid volume and sodium

concentration in the urine?6. Where are the pyramids located in the kidney?

7. What vessel directs blood into the glomerulus?

8. Where does most selective reabsorption occur in the

nephron?


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Moment of Zen

KIDNEY

022 urinary system

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