Maintaining Chemical Homeostasis. The Urinary System

Transcription

1 The Urinary System

2 Function 1. Remove nitrogenous wastes 2. Maintain electrolyte, acid-base, and fluid balance of blood 3. Homeostatic organ 4. Acts as blood filter 5. Release hormones: calcitriol & erythropoietin

3 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 liters are reabsorbed back into blood Excrete a protein free filtrate

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5 Maintaining Chemical Homeostasis The Urinary System

6 The Urinary System

7 blood filtration General Functioning of the Kidney tubular reabsorption and secretion urine refreshed blood

8 Nitrogenous urea Wastes uric acid ammonia

9 kidneys Organs of the Urinary ureters urinary bladder System urethra

10 Kidney Anatomy renal pyramids renal pelvis ureter renal cortex renal capsule renal medulla

11 nephron renal artery renal vein Kidney Anatomy

12 blood Nephron Functioning filtration tubular reabsorption and secretion urine refreshed blood

13 efferent arteriole afferent arteriole artery peritubular capillaries loop of Henle glomerulus vein Bowman s capsule proximal convoluted tubule distal convoluted tubule collecting duct

14 Each kidney contains over 1 million nephrons and thousands of collecting ducts Glomerulus DCT renal cortex PCT renal medulla Collecting duct Loop of Henle

15 efferent arteriole afferent arteriole Glomerular Filtration Bowman s capsule glomerulus Filters blood; proteins can t pass through

16 Composition of Glomerular Filtrate Water Small Soluble Organic Molecules Mineral Ions

17 Proximal Convoluted Tubule Reabsorbs: water, glucose, amino acids, and sodium. 65% of Na + is reabsorbed 65% of H 2 O is reabsorbed 90% of filtered bicarbonate (HCO 3- ) 50% of Cl - and K +

18 Loop of Henle Creates a gradient of increasing sodium ion concentration towards the end of the loop within the interstitial 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

19 Distal Convoluted Tubule Under 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

20 Collecting Duct Allows for the osmotic reabsorption of water. ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine

21 Urine Water- 95% Nitrogenous waste: urea uric acid creatinine Ions: sodium potassium sulfate phosphate From the original 1800 g NaCl, only 10 g appears in the urine

22 Hormonal Control of Kidney Function

23 Hormonal Control of Kidney Function high plasma solute concentration low blood volume heart receptors hypothalamus

24 Hormonal Control of Kidney Function hypothalamus posterior pituitary antidiuretic hormone collecting ducts

25 Hormonal Control of Kidney Function

26 Hormonal Control of Kidney Function reduced blood pressure and glomerular filtrate juxtaglomerular apparatus renin

27 Hormonal Control of Kidney Function angiotensinogen renin angiotensin I angiotensin II

28 Hormonal Control of Kidney Function angiotensin II adrenal cortex aldosterone convoluted tubules

29 Urinalysis Why do doctors ask for a urine sample? characteristics: smell- ammonia-like ph , ave 6.0 specific gravity more than 1.0; ~ color- affected by what we eat: salty foods, vitamins

30 Odor odor- normal is ammonia-like diabetes mellitus- smells fruity or acetone like due to elevated ketone levels diabetes insupidus- yucky asparagus---

31 ph- range ave 6.0 vegetarian diet- urine is alkaline protein rich and wheat dieturine is acidic

32 Infection- cloudy Color 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

33 Specific Gravity Water: s.g. = 1g/liter; Urine: s.g. ~ to Pyelonephritus- urine has high s.g.; form kidney stones Diabetes insipidus- urine has low s.g.; drinks excessive water; injury or tumor in pituitary

34 Abnormal Constitutes of Urine Glucose- when present in urine condition called glycosuria (nonpathological) [glucose not normally found in urine] Indicative of: Excessive carbohydrate intake Stress Diabetes mellitus

35 Abnormal Constitutes of Urine Albumin-abnormal in urine; it s a very large molecule, too large to pass through glomerular membrane > abnormal increase in permeability of membrane Albuminuria- nonpathological conditionsexcessive exertion, pregnancy, overabundant protein intake-- leads to physiologic albuminuria Pathological condition- kidney trauma due to blows, heavy metals, bacterial toxin

36 Abnormal Constitutes of Urine Ketone bodies- normal in urine but in small amts Ketonuria- find during starvation, using fat stores Ketonuria is couples w/a finding of glycosuria-- which is 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

37 Bile pigments- Bilirubinuria (bile pigment in urine)- liver pathology such as hepatitis or cirrhosis WBC- Abnormal Constitutes of Urine Pyuria- urinary tract infection; indicates inflammation of urinary tract Casts- hardened cell fragments, cylindrical, flushed out of urinary tract WBC casts- pyelonephritus RBC casts- glomerulonephritus Fatty casts- renal damage

38 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?