Chapter 12 – Renal and Acid-Base Physiology

1. Kidneya. Maintains constancy of ECF volume (extra cellular fluid volume)b. Absorption means those substances come back to blood vessel – capillaryc. Excretion means releases into urine – elimination from bodyd. Kidney produces urine which avoids high level of blood volume and excretes extra fluid from body

as urinee. But first, renal system has filtrationf. Water filtration, the capillary again absorbs many ions, substances, glucose, and water

2. Structure of kidneya. Has two parts

i. Renal cortexii. Renal medulla in center

b. There are millions of nephrons and capillary surrounds nephronsc. Nephron

i. Consists of nephron and renal tubuled. Glomerulus

i. Glomerular capillary network emerges from afferent arteriolee. Renal tubule

i. Made of…1. Proximal tubule2. Loop of Henle3. Distal tubule4. Collecting ducts

3. Blood supplya. Renal artery enters kidney which is branch of aortab. Becomes interlobar artery becomes arcuate artery then cortical radial artery. c. After radial, becomes efferent arteriald. Then becomes glomerular capillary which is inside bowman capsulee. This becomes afferent arterial then peritubular capillary which surrounds tubules of nephrons. f. Peritubular becomes renal venule then renal veing. This releases content into inferior vena cava

4. Body fluidsa. Total body water (TBW) – 60% of body water

i. 40% inside cell – intracellular fluidii. 20% in blood vessels – extracellular

b. TBWi. Highest in newbornsii. Highest in adult males

iii. Lowest in adult femalesiv. Lowest in person with large amount of adipose tissue

5. Glomerular filtration rate (GRF)

a. Depends on size of bodyi. Male and female – know these numbers

1. 180 liters per day2. After filtration of 180 liters of blood, the capillary again absorbs that amount of fluid

b. Function of kidneyi. 180 liters of fluid is filtered into kidneyii. Sodium chloride, potassium, glucose, hydrogen ion, bicarbonate – HCO3

-, amino acid, phosphate are all in fluid. These exist in the fluid to be filtered.

iii. Filtered into nephron tubule but again the peritubular capillary reabsorbs most of these ions…

1. 100% of glucose reabsorbed2. 67% of fluid or more by capillary3. We need sodium, chloride, potassium

a. Deficiency of sodium affects action potential – depolarizationb. Deficiency of K leads to no repolarization – relaxation phase

c. Measuring renal filtration ratei. Inulin is filtered but not absorbedii. After filtration of inulin into nephron which is not absorbed

iii. Measure of inulin helps calculate renal filtration rated. Glucose in urine

i. After filtration of glucose, everything should be absorbed by capillaryii. Healthy person urine cannot have glucose

iii. Glucose in urine means nephron problem or kidney problem or hormonal problem like type I and 2 diabetes

e. NaCl/Glucose Absorption in Nephroni. Proximal tubule

1. 67% of sodium is absorbed by capillary of proximal tubule2. Helps 100% of glucose absorption3. Absorbs potassium, Cl, amino acids, and phosphate.4. Excretes H+ ion into urine

ii. Loop of Henle1. 25% of sodium is absorbed in loop of Henle2. Symports Cl, K3. Diluting segment i n ascending limb of Henle

a. This is where water remains in tubule, not absorbed in capillaryiii. Distal and Collecting tubule

1. 8% of sodium absorbed in distal tubule and collecting tubule together2. Sodium absorption in collecting tubule depends on aldosterone hormone effect

a. After binding of aldosterone to receptor on collecting tubulei. Absorption of NaCl and H2O into capillaryii. Excretion of K and H+ ion into urine

1. In hyperaldosteronism Conns disease

a. Hypernatremia --> excess Nai. Because of high level of aldosterone so excess

absorption of sodium into capillaryb. Hypokalemia less K

i. Because excess excretion of potassium into urine, less potassium in blood

iv. Glucose absorption1. Proximal tubule

a. After filtration of glucose 100% of glucose absorbed by sodium symport in proximal tubule capillary

2. Normal blood glucose range is 70 to 110 mg/dl3. Blood glucose is 250 mg/dl sodium is able to symport all glucose into capillary.

a. Patient has hyperglycemia4. Blood glucose is 300-350 mg/dl sodium is not able to symport glucose

a. Hyperglycemia and glycosuria glucose in urinei. Glucose in urine is harmful to nephron leads to nephropathy and

in long term can cause renal failure and hypertension (can’t control blood volume)

5. Conditions of glycosuriaa. Nephropathyb. Destruction of renal arteryc. Type I or type II diabetes

v. Potassium absorption1. Proximal tube

a. 67% of K is absorbed by sodium symport in proximal tubule2. Loop of Henle

a. 20% is absorbed again by sodium symport in loop of Henle 3. Collecting tubule and distal tubule

a. Depends on 3 factorsi. Diet

1. Eating too much potassium kidney excretes extra potassium by urine

ii. Aldosterone1. Excess aldosterone increases excretion of potassium into

urine. Hyperaldosteronism in Conns leads to hypokalemia and having potassium in urine

iii. Acid/base1. Acidosis decreases potassium excretion2. Alkalosis increases potassium excretion

vi. Urea absorption1. Proximal tubule

a. 50% reabsorbed into capillary

b. Rest is impermeable2. Antidiuretic hormone (ADH)

a. Increases permeability in medullary collecting ductsvii. Phosphate absorption

1. Proximal tubulea. 85% reabsorbed by Na symport

2. Leftover 15% excreted by urine3. Parathyroid hormone (PTH)

a. Inhibits phosphate reabsorptionviii. Calcium absorption

1. 60% of blood plasma Ca is filtered through glomerular capillaries2. Proximal tubule and Ascending loop of Henle

a. More than 90% reabsorbed by Na symport3. Distal and collecting tubule

a. 8% reabsorbed4. PTH increases Ca reabsorption in distal tubule

ix. Magnesium absorption1. Reabsorbed in…

a. Proximal tubule most absorption of Mgb. Ascending loop of Henlec. Distal tubule

2. Mg and Ca compete for reabsorptiona. Hypercalcemia increase Mg excretion since Mg can’t be reabsorbed

f. ADH functioni. Stimulation of osmoreceptors secretes ADH ii. ADH is for fluid retention in nephron tubule

iii. Dilutes concentrated bloodg. Aldosterone function

i. Sensitive to low blood sodium and low blood pressure (exam questions)

6. Urine osmolaritya. Proximal tubule

i. 67% of sodium and 67% of water in proximal tubuleii. This causes urine osmolarity of about 300 milliosmoles/liter

b. Loop of Henlei. Diluting segment (ascending limb) so more water that can’t be absorbed ii. Urine osmolarity should be lower than 300 milliosmoles/L maybe 100 milliosmoles/liter

c. Distal tubulei. Same level as proximal tubule

ii. 300 milliosmoles/literd. Collecting tubule

i. Epithelia cell of collecting tubule has receptors for two hormones

1. ADHa. Retention of fluid fluid comes back to capillary

2. Aldosteronea. Sodium chloride and water absorption into capillary

ii. ADH and aldosterone 1. Cause final urine osmolarity which means more H2O absorption in blood2. We have about 1200 milliosmoles/liter really concentrated urine

iii. Final fluid absorbed iv. Collecting tubule opens in ureter Final urine is about 1200 milliosmoles /literv. Clinical point

1. If final urine is less than 1200 (maybe 500) a. Really low. Means we have more fluid, or water, in urine could be

deficiency of ADH

7. Glomerulonephritisa. Could be infection or noninfectiousb. Noninfecting autoimmune disease

i. Bowman capsule destroyed by antibodiesii. Signs and symptoms

1. Blood may have….a. Bacteriab. Virusc. Antibody positive sign for autoimmune disease

i. Because of autoimmune disease infiltration of antibody in abdominal cavity and joints Gives pain in joints and abdominal cavity.

2. Viral3. Fever4. Seizure5. Coma6. Weakness7. Headache8. Losing appetite9. Joint pain10. Edema because retro flow of fluid into body11. Puffy eyes12. Periorbital edema puffy eyes13. Puffy face shows extra fluid in body edema14. Edema in lower limb

iii. Treatment1. Always check cause2. Bacteria antibiotics3. Autoimmune cannot do anything

a. Only medicine in cortisol to control inflammation4. Control hypertension because of destruction of kidney

a. Needs antibiotic for possible infectionb. Antihypertensive control blood pressurec. Give pain killer for pain in joints

5. In sever condition kidney transplanta. Especially when case is autoimmune disease

8. Pyelonephritisa. Bacterial infection of kidneyb. Caused by E. coli infection

i. 99% of time it is by infection of E. coli in kidneyc. Signs and symptoms

i. Cause feverii. Back pain

iii. Seizureiv. Abdominal painv. Vomiting

vi. Pain in intercostal and vertebrald. Treatment

i. Antibiotic

9. Kidney stonea. Cause

i. Hypercalcemia . Excess calcium gives calcification and formation of stone from calcium (calculi)

1. Especially in hormonal disordersa. Like hyperparathyroidism

i. PTH increases blood calcium level over secretion leads to hypercalcemia

ii. Deficiency of citrate1. Natural calcium channel regulator2. Deficiency

a. Formation of kidney stoneiii. Treatment

1. Pain killer2. Verapamil calcium blocker3. if citrate problem replace citrate

10. Regulation of Reabsorption Bicarbonate and H+ in Nephron Tubule in kidneya. Box 1 Lumen of proximal tubule, box 2 epithelial cell of proximal tubule, box 3 blood

(capillary) or peritubular capillaryb. In cell respiration, cell releases CO2 into epithelial cell in PT tubule

c. CO2 combines with H20 form carbonic acidd. Some enzyme (carbonic anhydrase) converts carbonic acid to bicarbonate and hydrogen ione. Bicarbonate gets into blood by sodium symport into PT capillaryf. H+ gets into lumen of PT tubule by sodium antiport (urine pH is about 4.4, pretty acidic because of

H+ ion)g. Few bicarbonates secreted into lumen as wellh. H+ combines with bicarbonate in lumen reform carbonic acidi. Carbonic acid releases H2O which remains in urinej. CO2 comes back to the Pt cell for recycling and future bicarbonate absorption

11. Metabolic acidosisa. Acid level is high in blood

b. HCO3- used to buffer extra acid

i. More bicarbonate less acidicc. Extra acid increases CO2d. High level of CO2 gives high H+ ione. Respiratory system must eliminate extra CO2 to decreases H+ concentration

i. There is relation between CO2 and H+ii. Hyperventilating decreases CO2 and decreases acidity

12. Clinical problemsa. Really important

i. Signs and symptoms are hypersecretion of NE pheochromocytomaii. If you see any hypernatremia, hypokalemia, this is for Conns disease hyperaldosteronism

b. (1) 35-year female big spleen, big liver, hypertension, headache, high level of plateletsi. Diagnosis

1. Big spleen shows polyverac. (2) 55-year-old male has anemia. Blood test shows reduction of red blood cells and spleen is

enlarged splenomegaly. Signs and symptoms for anemia: weakness, pale color, sleep disorder, difficulty in respiratory system. And jaundice

i. Diagnosis1. Leukemia2. Sickle cell disease3. Myocardial infarction4. Polyvera

d. (3) 56-year-old male has back pain. Urine test shows fresh red blood cells in urine (pinkish color) and he has signs and symptoms for kidney infection because of obstruction

i. Diagnosis1. Problem is kidney stone because injured tissue by stone

e. (4) 65 female has weak immune system. Losing weight, headache, vomiting, general inflammationi. Diagnosis

1. Leukemia2. Sickle cell disease3. Myocardial infarction

f. (5) 35-year old female has difficulty in respiratory system. EKG shows several P waves which is sign for atrial fibrillation. She has risk for heart failure.

i. Diagnosis1. Mitral regurgitation2. Mitral stenosis3. Tricuspid regurgitation4. Tricuspid stenosis