Nitrogenous Waste

Creatinine

breaks down creatine phosphate

toxic but not as much as other 3

water soluble

creatinine clearance used to estimate GFR

80% - 90% transferred to tubules via filtration

Uric Acid

breaks down purines (adenine, guanine)

toxic but MUCH less than ammonia/urea

water solubility is limited

high concentrations can lead to saturation and crystals form, in joints (gout), in kidneys (kidney stones)

Ammonia

breaks down peptides/proteins

waste amino acids release ammonia

HIGHLY cytotoxic

HIGHLY soluble

liver detoxifies ammonia to urea (costs ATP)

kidney excretes through filtration/secretion

Urea

breaks down peptides/proteins

toxic but < ammonia

soluble but less so than ammonia

40% filtered urea excreted with urine

What is the normal pH for ECF?

7.35 - 7.45

Acidosis

ECF lower than 7.35

Alkalosis

ECF higher than 7.45

importance of pH balance

enzymes have optimal pH + temp, can be dangerous for enzymes when either are too low/high

pH

measure of concentration of H+ ions (protons)

Strong Acid

ionizes freely + gives up MOST H+ ions to lower pH, ex: HCl to H+ and Cl-

Weak Acid

ionizes slightly and keeps large portion of H+

ex: H2CO3 to H+ and HCO3-

Strong Base

strong tendency to bind H+ to raise pH

NaOH to Na+ and OH- (binds to H+ to make H2O)

Weak Base

weak tendency to bind with H+

Physiological Buffers

system that stabilizes body’s pH by controlling body’s output of acid/base/CO2

(kidneys/lungs)

Chemical Buffers

a substance that can bind/release H+ ions as concentrations falls/rises

Respiratory acidosis

lung ventilation reduced

CO2 excretion < CO2 production

body pH goes down

Respiratory alkalosis

lung ventilation increased

CO2 excretion > CO2 production

body pH goes up

Metabolic alkalosis

increase in pH

vomiting stomach contents (loss of chloride + increase of bicarbonate lvls)

Metabolic acidosis

decrease in pH

vomiting of duodenal contents (loss of MORE bicarbonate than chloride)

prolonged respiratory failure (adds and goes beyond respiratory acidosis)

chronic diarrhea

vigorous exercise

How does body respond to pH disturbance?

responds via acid-base regulatory mechanisms (physiological buffers)

Potassium in Acidosis

H+ cells diffuse into cells which drives out K+ to elevate K+ in ECF

Potassium in Alkalosis

H+ diffuses out of cells and K+ diffuses to replace it causing K+ to lower in ICF