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Flashcards in Renal A+P Deck (50)
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1

What are the 3 functions of the kidney?

1) Excretory
2) Regulatory (Electrolytes, acid base, BP, glucose)
3) Hormone production (Erythropoietin, renin)

2

What is the significance of erythropoietin?

Produced in peritubular capillaries, stimulates bone marrow to increase production of erythrocytes which increases RBCs.

When O2 perfusion decreases to kidneys, kidneys produce erythropoietin or enzymes that catalyze erythropoeitin formation.

Erythropoietin deficiency is primary cause of anemia in CKD pts

3

What two types of nephrons are in the cortex?

1) Cortical nephrons (85%), entire nephron located in the cortex. Includes BC, PCT, DCT, LOH. Function to produce urine

2) Juxtamedullary nephrons (15%), some parts in cortex but LOH in medulla. Concentrates urine

4

What happens in the major and minor calyx?

Contains urine from collecting ducts

5

What happens in the medulla regarding renal function?

Houses LOH, concentrates urine

6

What does the renal pelvis do?

Uses peristalsis to move urine onwards

7

How does the bladder function?

As bladder fills, stretch receptors and PSNS nerves stimulate spinal reflex causing bladder contraction in relaxation of internal sphincter (involuntary). We are in control of the external sphincter which lets urine out

8

What is the normal range for Na+ and how is it regulated?

Normal: 135-145mmol/L

Mostly reabsorbed at PCT, throughout nephron

Increased aldosterone increases Na+ reabsorption

Decreased GFR leads to increased Na+ reabsorption and H2O follows

Loop diuretics block Na+ reabsorption

9

What is the normal range for K+ and how is it regulated?

Normal: 3.5-5.5 meq/L

Mostly secreted at DCT and reabsorbed in PCT

In metabolic alkalosis/acidosis, both K+ and H+ removed at DCT.

Flow rates can effect secretion in DCT

Increased serum K+ increases aldosterone and increases K+ secretion

Loop diuretics lead to Na+ loss, causes aldosterone to reabsorb Na leading to K+ s secretion and loss as a result of trade

10

How is K+ affected by metabolic acidosis and alkalosis?

In acidosis, K+ excretion decreased as H+ excretion is preferential.

In alkalosis, K+ excretion increased as holding on to H+ is preferential ​

11

How do loop diuretics affect K?

Loop diuretics lead to Na+ loss, causes aldosterone to reabsorb Na leading to K+ s secretion and loss as a result of trade

12

What is the normal range of calcium and how is it regulated?

Normal: 2.2 - 2.6 mEq/L

Filtered at glomerulus, most reabsorbed in PCT

In acidosis, inhibition of parathyroid hormone causes Ca++ excretion and decreased reabsorption from bone, GIT, kidneys

Decreased serum PO4 (required to bind Ca++ to be stored in bone) causes Ca++ excretion

13

What is the normal range of urea and how is it regulated?

Normal: BUN 3.0 - 7.0 mmol/L

Waste product of protein metabolism, filtered at glomerulus, reabsorbed in PCT, CD, secreted in LOH

14

Is BUN a reliable indicator of GFR?

No. Increased protein intake, pregnancy, DM can increase urea excretion

15

What is normal range of creatinine and why is it significant?

Normal: 60-110 umol/L for males, 50-90 umol/L for females

Filtered at glomerulus with rate of GFR, not reabsorbed or secreted. Great indicator of renal function as long as no muscle breakdown exists *rhabdomyolysis)

16

What is urine creatinine clearance?

Urine clearance should be proportional to serum creatinine

17

What is the function of the afferent arteriole?

Divisions from the renal arteries, brings oxygenated blood to nephron (to glomerulus)

18

Which arteriole is wider, afferent or efferent?

Afferent to allow easy blood flow to glomerulus

19

What is the function of the bowmans capsule?

Cup shaped structure in the cortex for cortical and juxtamedullary nephrons. Glomerulus to one side and proximal convoluted tubule on the other, allows filtration

20

What is the function of the glomerulus?

Tuft of capillaries nested in the BC, glomerular filtration forces fluids and solutes through the glomerular capsular membrane into the BC

21

What is the glomerular filtration rate?

Clinical measure of renal function, reflects CO. Comparison of serum and urine Cr.

22

What is eGFR?

Estimation used to screen early kidney damage

<60 ml/min/1.73m2 = kidney disease
< 15 = kidney failure

23

What is the function of the efferent arteriole?

Blood leaves glomerulus via efferent arteriole and into capillary network. Are smaller in diameter, increasing glomerular pressure and creating more effective filtration at BC.

Cortical nephrons go to peritubular capillary

Juxtamedullary nephrons go to vasa recta

24

What is the function of the proximal convoluted tubule (PCT)?

REABSORPTION

Drains BC with hundreds of microvilli. 65% of glomerular filtrate is reabsorbed here, mainly H2O but also electrolytes, glucose, etc. Fluid leaves the PCT in an ISOTONIC state

25

What happens at the PCT if serum glucose > 10.5?

Active glucose reabsorption transport maxes out and glucose spills into urine

26

What is the function of the loop of henle (LOH)?

CONCENTRATION

Concentrates urine primarily by juxtamedullary nephrons. Goes deep into the hypertonic medulla region and H2O moves from tubule to interstitium

Has a descending and ascending limb

27

What is the function of the descending limb of LOH?

H2O permeable, allows for movement of H2O

28

What is the function of the ascending limb of LOH?

H2O impermeable, actively transports Cl-, and Na+ passively follows maintaining concentration gradient

29

What is the counter current mechanism in the LOH?

Filtrate going down one arm of the loop interacts with blood going up the other arm in opposing direction, increases diffusion

30

What do the NKCC2 transporters do and where are they?

Located in ascending LOH, actively reabsorb Na, K, and CL. Entire transporter blocked by loop diuretics (lasix)

Lasix causes Na, K, and 2Cl to remain in LOH causing filtrate to become hypertonic. This increases excretion of H2O along with all lytes that don't get reabsorbed.