Acid/Base balance by Kidneys Flashcards

1
Q

Buffering equation

A

HCO3- + H+ → H2CO3 <ca>⇒ CO2 + H2O</ca>

2
Q

Normal values:

pH

CO2

HCO3

A

pH: 7.4 (7.35-7.45)

CO2: 40 mmhg (35-45)

HCO3: 24 mM (20-28)

3
Q

acute respiratory acidosis

A

Increased CO2

decreased pH

increased HCO3-

normal BE

4
Q

chronic respiratory acidosis

A

increased CO2

close to normal pH

very increased HCO3-

> +2 BE

5
Q

acute metabolic acidosis

A

decreased CO2

decreased HCO3- or increased H+

decreased pH

negative

6
Q

Chronic metabolic acidosis

A

decreased CO2

decreased HCO3-

negative

7
Q

Acute respiratory alkalosis

A

decreased CO2

decreased HCO3-

increased pH

normal BE

8
Q

chronic respiratory alkalosis

A

decreased CO2

very decreased HCO3-

negative

9
Q

acute metabolic alkalosis

A

increased CO2

increased HCO3-

increased pH

positive >+2 BE

10
Q

chronic metabolic alkalosis

A

increased CO2

increased HCO3-

positive >+2 BE

11
Q

anion gap

A

Na+ - (Cl- + HCO3-)

high anion gap = addition of acid

normal anion gap = loss of base

12
Q

Where does bicarb reabsorption take place?

A

proximal tubule

thick ascending limb of Henle

Collecting duct

13
Q

Under normal conditions, do you excrete bicarb in urine?

A

No

14
Q

How many millimoles of bicarb in our ultrafiltrate?

How much do we reabsorb?

A

24 millimoles

100%

15
Q

Generally, diuretics work by

A

altering osmolality of the urine filtrate, preventing the reabsorption of the water, resulting in an increase of urine volume.

* usually lose Na, then water follows

16
Q

ACE inhibitors

A

Prevents Angiotensin from becoming Angiotensin II

17
Q

How do loop diuretics work?

A

block the Na-K-2Cl pumps in the ascending loop of Henle

18
Q

How do Thiazide-like diuretics work?

A

block Na reabsorption

19
Q

Which diuretics are potassium sparing?

A

aldosterone blocking agents

20
Q

At what age does kidney function begin to decline?

A

Kidneys begin to diminish in size and function in 50’s and dignificantly by 65

21
Q

What are some renal considerations for the elderly?

A
• loss of nephrons
• diminished renal blood flow
• decrease in the GFR
• decreased ability to conserve salt and water
• cannot concentrate urine
• more susceptible to fluid and electrolyte imbalances and renal damage
22
Q

What studies are helpful in evaluating kidney function?

A
• Urinalysis
• serum creatinine
• blood urea nitrogen levels
• high protein diet causes more urea and high BUN
• tests of GFR
23
Q

Types of urinalysis

A
• single sample- most common
• 24 hour- used to evaluate substances that are excreted in varying concentrations throughout the day
• culture and sensitivity- determine presence of microorganisms and which drugs they are sensitive to.
24
Q

What are abnormal substances to find in urine?

A
1. protein (small amt is accepted as normal)
2. glucose
3. excess epithelial cells, erythrocytes, leukocytes, and bacteria
4. cyrstals and stones
5. casts
1. WBC casts reflect infection
2. RBC casts indicate inflammation of glomerulus
3. epithelial casts indicate sloughing of tubular cells (acute tubular necrosis)
25
Q

Where does creatinine come from and what is normal value?

A
• creatine is spontaneously converted to creatinine and excreted exclusively by the kidney
• normal level: 0.7 to 1.5 mg/dl
26
Q

What affects the levels of creatinine?

What does an elevated level indicate?

A
• rate of creatinine produced from muscle, which is relative constant
• rate of creatinine excreted by the kidney, which is determined primarily by GFR
• Elevated levels indicat a decrease in renal function or an increase in muscle
27
Q

BUN test

normal

elevated level indicates?

A
• Urea is the end product of protein metabolism excreted primarily by the kidney
• normal level: 10-20 mg/dl
• elevated level indicates:
• decrease in renal function and fluid volume.
• increase in catabolism and dietary protein intake
28
Q

What is the most acurate way to measure GFR?

A

Inulin