ABG's Flashcards
(54 cards)
What is carbonic anhydrase reaction
CO2 + H2O ←CA→ H2CO3 ↔ H+ + HCO3- CO2 combines with H2O and using carbonic anhydrase makes carbonic acid Carbonic acid then dissociates into H+ and bicarbonate Occurs in the Red blood cells This equation occurs in the tissues/capillaries the reverse occurs in thelungs
What happens to the charge when HCO3- leaves the red blood cell
a Cl- ion enters to balance the charge
Known as chloride shift
What is chloride shift
when a HCO3 leaves a red blood cell and a cl- enters in order to balance the charge
where does this equation occur?
CO2 + H2O ←CA→ H2CO3 ↔ H+ + HCO3-
in the tissue/capillaries
Forward in lungs,
backwards in tissues
the reverse equation occurs in the lungs
Where does this equation occur?
H+ + HCO3- ↔ H2CO3 ←CA→ H2O + CO2
In the lungs
Forward in lungs,
backwards in tissues
the reverse occurs in the tissus/capillaries
What is reverse chloride shift
the HCO3 enters the red blood cell while a cl ion leaves
describe neural reflexes in the control of breathing
as CO2 goes up, minute vetilation goes up
(linear relationship, straight line)
CO2 is powerful stimulus for ventilation
O2 is not the same, it needs to drop a really long ways to have any changes in ventilation
(to around 40mmhg)
Central and peripheral chemoreceptors detect the changes
they respond to changes in arterial blood gases
and
H+ ion concentrations
Talk about the blood brain barriers role in ventilation
The BBB is impermeable to H+ and HCO3
It is permeable to CO2
this can cause rapid changes in acid base status
The more CO2, the more ventilation
CO2 in relation to ventilation
the more CO2 the more ventilation
A 9-ycar-old boy decided to find out for how long he could continue to breathe
into and out of a paper bag. After approximately 2 minutes, his friends noticed
that he was breathing very rapidly so they forced him to stop the experbnent.
What change in arterial blood gas composition was the most potent stimulus
for this boy’s hyperventilation?
A. Dcacased Pco2 B. Decreased Po2 C. Decreased pH D. Increased Pco2 E. Increased Po2 F. lncrcaacd pH
D. Increased Pco2
A 22-year-old man was involved in a fight in which he received a severe blow
to the head. On arrival at the emergency department. he was unconscious and
initially received assisted ventilation via a manual bag-valve device. An analysis
of his arterial blood gases shows:
Po2 =45mmHg
Pco2 = 80 mm Hg
pH=7.05
HC0,-=27 mM
In what form was most col being transported in his arterial blood?
A. Bicarbonate ions
B. Carbaminohemoglobin comp
A. Bicarbonate ions
A 3-month-old infant presented with persistent vomiting and was lethargic.
Arterial blood gas analysis shomd the following results:
Pao2 = 88 mm Hg
Pacoi = 44 mm Hg
pH = 7.60
[HCO,-J = 36 mEq/L
Base excess = + 12 mEq/L
Which of the following primary acid-base disturbances is present?
A. Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Metabolic acidosill
C. Metabolic alkalosis
The results of an arterial blood gas analysis of a 56-year-old man with a history of heavy smoking are as follows: Pao2 = 60 mm Hg Paco2 = 60 mm Hg pH = 7.33 [HCO,-J = 32mEq/L Base excess = + 8 mEq/L The patient has a partially compensated
A. mpiratory alkalosis
B. respiratory acidosis
C. metabolic alkalosis
D. metabolic acidosis
B. respiratory acidosis
What is an acid
any chemical that gives up a H+
What is a base
Any chemical that accepts a H+
What happens at ph of 6.8 and below
CNS depression
coma
death
What happens at ph of 8.0 or above
excitation of the nercous system muscle tetany convulsions respiratory arresst death
what are 2 sources of acid
Respiratory Acid
CO2
H2co3
Nonvolatile acid / nonrespiratory acid
Lacric acid
ketones
What are 2 major buffering systems
Chemical buffering system
Bicarbonate (CO2) most importatn
phosphate
protein
Physiological buffering system
Respiratory CO2 excretion (quick)
Renal hydrgogen ion excretion (slow)
How do chemical buffers maintain the normal blood ph
respiratory
disposes of CO2
if we start to get acidic, we blow off CO2
Kidneys elimniates H+ ions if we start to get acidic we excrete H+ ions form bicarb put bicab bak into blood
Diet can effect ph
What do the kidneys excrete to help maintain acid base balance
acid
H+ ions
What are alpha intercalated cells for
they secrete H+ to the blood
a for acid
What are Beta intercalated cells for
they secret bicarb
b for bicarb
How do the kidneys play a general role in maintaining acid base homeostasis
the kidneys excrete excess acid
the kidneys regulate blood ph by reabsorbing filtered bicarbonate
