Lab Quiz 3 - PHYSIO

Urine volume

Amount of urine produced; used to calculate urine production rate

Urine production rate

Urine volume divided by time (mL/min); normal ~0.5–2 mL/min

Specific gravity

Measure of urine concentration compared to water (water = 1.000; urine ~1.005–1.030)

Urine pH

Measure of acidity/basicity of urine; normal ~4.5–8

Blood pH

~7.4 and tightly regulated

Why urine pH differs from blood

Kidneys regulate acid/base balance by excreting acids or bases

Clearance

Rate at which a substance is removed from blood by kidneys

GFR normal value

~125 mL/min

Clearance = GFR

Substance is filtered only (measures GFR)

Clearance < GFR

Substance is reabsorbed

Clearance > GFR

Substance is secreted

Protein in urine (proteinuria)

Abnormal; indicates kidney damage

Glucose in urine (glucosuria)

Abnormal; usually diabetes or high blood glucose

Ketones in urine (ketonuria)

Abnormal; fat breakdown from starvation or uncontrolled diabetes

Blood in urine (hematuria)

Abnormal; infection or damage

Bilirubin in urine (bilirubinuria)

Abnormal; liver disease

Glomerular filtration

First step of urine formation; blood filtered into nephron

Reabsorption

Movement of useful substances from tubules back into blood

Secretion

Movement of wastes from blood into tubules

Nephron function

Filters blood and forms urine

Urine formation processes

Filtration, reabsorption, secretion

Specific gravity meaning

Indicates urine concentration compared to water

Eupnea

Normal breathing

Hyperventilation

Fast/deep breathing; decreases CO₂ levels

Hypoventilation

Slow/shallow breathing; increases CO₂ levels

Spirometer

Measures lung volumes and capacities

Respirometer

Measures oxygen consumption

Vital capacity

Max air exhaled after deepest inhale

Percent predicted vital capacity

(Measured VC ÷ predicted VC) × 100

Tidal volume (TV)

Normal breath volume

Respiratory rate (RR)

Breaths per minute

Minute ventilation (VE)

VE = RR × TV

VO2

Oxygen consumption per minute

Breath holding time factors

Lung volume and CO₂ buildup

Main driver of breathing control

CO₂ levels

Secondary driver of breathing control

O₂ levels (only when low)

Chemoreceptors

Sense CO₂, O₂, and pH changes

Ventilation

Movement of air in and out of lungs

Medulla oblongata

Breathing control center in brainstem

Urine vs blood pH

Urine varies more; blood is tightly regulated