Acid Base Balance Flashcards
Describe respiratory acidosis and alkalosis. What are some causes?
respiratory acidosis - increase CO2 in arteriole blood
- anything that impeded movement of CO2 across respirate membrane
- pneumonia, hypoventilation, COPD
respiratory alkalosis - decrease in CO2 in arteriole blood
- hyperventilation, high altitude, panic attack
Describe metabolic acidosis and alkalosis. What are some causes?
metabolic acidosis - too much H+
- diabetic ketoacidosis, lactic acidosis/exercise, alcohol, diarrhea (losing too much HCO3-), aspirin overdoes
metabolic alkalosis: losing too much H+
- severe vomiting (losing too much H+), K wasting diuretics, antacid overdose
What is the range for normal pH for blood? What are the regular values of PCO2 and HCO3- mEq?
normal pH: 7.35-7.45
normal PCO2 : 40 mmHg arteriole
normal HCO3-: 24 mEq
What are some buffer systems used in the metabolic system?
phosphate buffers, protein buffers carbonic acid-bicarbonate system buffers
How can the body counteract metabolic and respiratory acid/base imbalances?
respiratory system cannot buffer acid/base imbalance if is it caused by a respiratory problem
- requires chemical buffers and urinary system
metabolic acidosis - too many H due to ketoacidosis/diarrhea
- can increase respiratory rate to decrease CO2 and H
metabolic alkalosis - not enough H, decrease respiration to retain CO2
- cannot stop breathing, limit to how much it can help
Describe how the urinary system responds to metabolic or respiratory acidosis
Increases secretion of H ions
Increases reabsorption of HCO3-
does this via proximal convoluted cells and intercalated cells type A in distal convoluted tubule and collecting duct
Describe the urinary response to metabolic or respiratory alkalosis
proximal convoluted tubule and intercalated cells type A in DCT and collecting duct:
- CEASE FUNCTION: decrease H+ secretion, decrease HCO3- reabsorption
Intercalated cell type B
- increase secretion of HCO3-: exchanged with Cl-, requires active transport
- increase reabsorption of H+
How can you tell if an acid-base disturbance is metabolic or respiratory?
Henderson-Hasselbalch
pH = 6.1 + log [HCO3-/PCO2x0.03]
ratio is 20/1
change to 20 - metabolic cause
change to 1 - respiratory cause
Describe the bladder. Where is it located? What are its muscles and what kind of ET lines it?
infraperitoneal - below peritoneum
- has peritoneum on top surface but not surrounded
detrusor muscle - smooth muscle that lines bladder
- contracts to increase pressure
internal urethral sphincter - smooth muscles
- relaxes to open lumen of urethra and expel urine
bladder lines with transitional epithelium that is folded into rugae
What is the trigone? Where is it located? What kind of ET? What are its openings?
trigone - triangle of transitional epithelium not in ruguae at botom of bladder
2 opening for each ureter: enter at angle
- as bladder fills, it makes natural closure so ureter cannot add more urine
1 opening for urethra
Describe the muscle of the ureter. What typer of innervation does it have?
tunica media of ureter
- inner longitudinal smooth muscle
- outer circular muscle
transitional epithelium
sympathetic: slows down movement of urine through bladder
parasympathetic: increases movement of urine, increases peristalsis
Describe the histology of the urethra. What kind of epithelium?
distal end of urethra has noncornified SSET
- 1.5 inch in male
- .5 inch in female
contains smooth muscle, but not as functional as ureter
Describe the sensory pathway of the bladder
part of the pudendal nerve
stretch receptors in the bladder send signals to the posterior gray horn
- some cross to innervate autonomic NS
- come ascend and synapse at spinal cord - sympathetic NS
- afferent neurons to the brain
Describe the sympathetic pathway of the micturition reflex
sympathetic - holding pee, inhibitory
origin in lateral gray horns in lumbar spine
preganglionic: descends into pelvic plexus and releases ACh for detrusor
postganglionic:
- detrusor - inhibitory: does not contract
- internal urethral sphincter: excitatory, contracts
- external urethral sphincter: lower motor neurons excite, contract
Describe the micturition reflex during parasympathetic stimulation
stretch receptors stimulate signal to pudendal nerve:
- inhibits sympathetic NS
- excites pontine and parasympathetic neurons directly
parasympathetic - splanchnic nerve:
- excitatory on detrusor muscle - contracts
- inhibitory to internal urethral sphincter - relaxes
pontine micturition center - inhibits pudendal nerve which inhibits the external urethral sphincter - relaxes
