Rnwk4- 5-2 Physio H+ Regulation

Front 1

molecules that can release H+?

molecules that accept H+?

what protein in particular?

relationship of pH and H+:

Range of pH compatible with life:

Back 1

HCl (stong), H2CO3 (weak) (acid- molecule capable of releasing an H)

HCO3-, HPO4, Proteins

hemoglobin

inverse- lower pH = higher [H+]

6.8-8.0

Front 2

Extracellular K is maintained at ____mEq/L?

Extracellular H is maintained at ____mEq/L?

pH of venous vs arterial blood?

Back 2

4.2


.00004

venous- 7.35
arterial= 7.4

Front 3

What is the dissociation constant (K)?

What is the equivalent to measuring CO2?

Back 3

tendency for an acid to release the H+ described by its dissociation constant (K')

- CO2 is proportional to H2CO3

Front 4

Control of H+
Instantaneous:

minutes:

long-term:

Buffers often contain _______ acids that can easily _____, ________ with H+

Enzyme: CO2 + H2O --> H2CO3 --> H+ + HCO3 --> What would removal of H+ cause?

Back 4

instantaneous: buffers

respiratory

renal

weak acids, disassociate/reassociate

-removal of H would cause more H2CO3 to dissociate, more water to combine with CO2 and depress ventilation

Front 5

Explain how more H+ affects ventilation, respiration:

Explain how less H+ affects respiration:

Henderson-Hasselbach equation? Why is this calculation important?

Back 5

H+ + HCO3- --> H2CO3 --> H2O + CO2, stimulates respiration to get rid of CO2

removal of H+ --> more disassociation of H2CO3, and H2O combines with CO2, so less respiration

pH = 6.1 + log (HCO3-)/(0.03xPCO2) this is important because it allows the calculation of pH by knowing HCO3- and PCO2 of solution

Front 6

Why is HCO3- an effective buffer system?

Phosphate buffer system?

adding acid drives system toward ________.

adding base drivers system toward ________.

Why is this not an efficient system? Where is it effective?

Back 6

CO2 changes compensated by ventilation, HCO3- compensated by kidneys

H2PO4- <--> H+ + HPO4--

acid --> H2PO4-

base --> HPO4--

low extracellular concentrations - effective in kidney, higher concentrations

Front 7

Intracellular proteins and hemoglobin account for ______% of buffering capability of fluids.

Proteins as a raw buffer...

As ventilation decreases, pH goes ____.

increased metabolic pH = _______ PCO2 and ventilation

decreased metabolic pH = ?

Back 7

60-70%

Proteins as a raw buffer are the most effective but are slow

down

increased pH = lower PCO2, ventilation

decreased pH = higher PCO2, ventilation

Front 8

Explain renal control of H+:

Back 8

HCO3- filtered into and reabsorbed from tubules
H+ secreted into tubules

if urine is acidic, then net removal has occurred, increased blood pH; urine is basic, then decreased blood pH

Front 9

HCO3- must form _______ to be reabsorbed in the kidney.

For each HCO3- absorbed, ____ is secreted.

Explain the Na+/H+ pump:

What other buffers does H+ get involved in?

Explain H/HCO3- ammonia/ium relationship

Back 9

H2CO3

H+ secreted

Na+ into cell, H+ into tubular lumen

HPO4-, NH4+, NH3

Ammonia/ammonium = 50% of excreted amount of H+ and HCO3- retention

Front 10

Phosphate buffer: Explain how this system keeps H+ bound.

Breakdown of glutamine --> ?

Relationship of H+ and HCO3- excretion/retention (as free ion or associated with NH4‐ or phosphate)?

Effect of increased PCO2 on pH, H+ excretion, HCO3 retention?

Back 10

NaHPO4- keeps H+ bound in the buffer system

2 HCO3- reabsorbed, 2 NH4+ excreted in exchange for Na

amount of H+ secretion = HCO3- retained, vice versa

increased PCO2 --> lowered pH, --> more H+ out, more HCO3 in

Front 11

Effect of ang II, aldosterone, hypokalemia on H+ secretion? What do they each affect?

general effect of volume depletion on acid-base balance?

Hypo/hyperkalemia?

Back 11

all favor secretion of H+ (all could cause alkalosis)
ang II - Na+/H+ exchanger
aldosterone - H+ pump
hypokalemia - proximal tubule

depletion --> more H+ secretion (ang II, ald), more HCO3- absorption --> alkalosis

hypokalemia - same

hyperkalemia - HCO3- excretion --> acidosis

Front 12

CO2 retention effect on H+, HCO3-?

How to check the relatinoship between metabolic/respiratory in acidosis/alkalosis?

Back 12

CO2 = H+ retention, so metabolic compensation = increased excretion of H+, increased retention of HCO3-

Is the change on PCO2 normal for the change in HCO3-? If not, then resp. component

Front 13

Respiratory acid/base changes are changes in ______.

Metabolis acid/base changes are changes in ______.

Some causes of respiratory acidosis?

Back 13

PCO2 - high in acidosis, low in alkalosis

HCO3- - high in alkalosis, low in acidosis

respiratory center damage
airway obstruction (asthma, bronchitis, emphysema), diffusion area loss (pneumonia, emphysema)_

Front 14

Causes of respiratory alkalosis?

Causes of metabolic acidosis?

Causes of metabolic alkalosis?

Back 14

increased CO2 elimination, so low environment PO2, hyperventilation

renal failure, Addison's (no aldosterone), diarrhea, vomiting of intestinal contents, DM, ASA ingestion

diuretics, excess aldosterone, antacid ingestion, vomiting of gastric contents

Front 15

Normal values for pH, PCO2, HCO3-?

Explain acidosis, and levels of PCO2, HCO3.

Explain alkalosis, PCO2, HCO3-:

Back 15

pH = 7.4, PCO2 = 40, HCO3- = 24

pH < 7.4; if PCO2 greater than predicted (respiratory); if HCO3- less than predicted, then metabolic.

alkalosis - pH >7.4, PCO2 less than predicted (resp), HCO3 greater than normal (meta)

Front 16

Anion gap = ?

If Cl- replaces HCO3-, then _______ anion gap. If not all HCO3- is replaced by Cl- the anion gap is ?

What are some causes of AG metabolic acidosis? (MUDPILES)

Back 16

Determines possible origin of disturbance
[Na+] - ([HCO3-] + [Cl-])

normal, increased

methanol, uremia, DKA, paraldehyde, INH, lactic acid, ethylene glycol, salicylate

Front 17

For respiratory alkalosis describe the CO2 in blood..
a. H+ in blood
b. metabolic response
c. results in?

Back 17

a. – Depletion of H+ in blood
b. – Metabolic compensation causes increased HCO3‐ excretion and decreased H+ secretion
c. – Causes decrease in blood HCO3‐

Front 18

For metabolic (non-respiratory) acidosis describe
a. basic findings
b. HCO3- in fluids
c. compensated by?

Back 18

a. • Decrease in blood pH
b. • Less HCO3‐ and/or more H+ in circulating fluids
c. normally compensated for by:
– Renal reflex (if not the cause) – Increased ventilation – Decreased PCO2

Front 19

For metabolic (non-respiratory) alkalosis.
a. general definiton
b. cause
c. normal compensation

Back 19

a. increase blood pH
b. more HCO3- and less H+
c. normally compensated by – Renal reflex (if not the cause)
– Decreased ventilation – Increased PCO2