Respiratory and Kidney Physiology: Gas Exchange, Regulation, and Filtration
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87 Terms
Q: What is the conducting zone?
The portion of the respiratory tract that transports, humidifies, warms, and filters air; no gas exchange occurs.
Q: What structures belong to the conducting zone?
Nose, pharynx, larynx, trachea, bronchi, bronchioles.
Q: What is the respiratory zone?
The region where gas exchange occurs, including respiratory bronchioles, alveolar ducts, and alveoli.
Q: What are Type I alveolar cells?
Thin epithelial cells forming most of the alveolar wall; primary site of gas exchange.
Q: What are Type II alveolar cells?
Cells that produce surfactant to reduce surface tension in alveoli.
Q: What is the mucociliary escalator?
System of mucus and cilia that traps and moves debris out of the airways.
Q: What is Boyle's law?
Gas pressure is inversely proportional to volume; governs ventilation.
Q: Describe the rest phase of breathing.
Alveolar pressure equals atmospheric pressure; no air movement.
Q: Describe inspiration.
Diaphragm contracts, thoracic volume increases, alveolar pressure drops, air flows in.
Q: Describe expiration.
Diaphragm relaxes, thoracic volume decreases, alveolar pressure increases, air flows out.
Q: What is tidal volume?
The amount of air inhaled or exhaled during quiet breathing.
Q: What determines air flow?
Pressure gradients created by changes in thoracic volume.
Q: What affects airway resistance?
Bronchiole diameter; constriction increases resistance and dilation decreases it.
Q: What affects lung compliance?
Elasticity of tissue and surface tension; reduced compliance seen in fibrosis.
Q: Function of surfactant?
Reduces alveolar surface tension and prevents collapse.
Q: Law of Laplace in alveoli?
Smaller alveoli require more pressure unless surfactant reduces surface tension.
Q: What is Dalton's law?
Total pressure of a gas mixture equals the sum of partial pressures.
Q: What is Henry's law?
Gas dissolved in a liquid depends on solubility and partial pressure.
Q: Why does CO2 dissolve more easily than O2?
CO2 is 20× more soluble in water than O2.
Q: What drives pulmonary gas exchange?
Partial pressure gradients between alveoli and blood.
Q: Where does systemic gas exchange occur?
Systemic capillaries deliver O2 to tissues and pick up CO2.
Q: What percentage of O2 is carried on hemoglobin?
About 98.5%.
Q: What percentage of O2 is dissolved in plasma?
About 1.5%.
Q: What forms of CO2 transport exist?
Dissolved (7%), carbamino compounds (23%), bicarbonate (70%).
Q: What is the chloride shift?
Exchange of Cl- and HCO3- across RBC membrane during CO2 transport.
Q: What is the Bohr effect?
High CO2/H+ decreases hemoglobin affinity for O2.
Q: How does exercise affect pulmonary blood flow?
Increases lung perfusion and diffusion capacity.
Q: Primary functions of kidneys?
Regulate ECF volume, BP, osmolarity, ions, pH; excrete wastes; produce hormones.
Q: What is a nephron?
Functional unit of kidney performing filtration, reabsorption, secretion, excretion.
Q: What is the renal corpuscle?
Consists of glomerulus and Bowman's capsule; site of filtration.
Q: Components of the filtration membrane?
Fenestrated capillaries, basement membrane, podocyte filtration slits.
Q: What determines filtration?
Balance of hydrostatic and osmotic pressures across glomerular capillaries.
Q: What is glomerular hydrostatic pressure?
Blood pressure inside glomerular capillaries promoting filtration.
Q: What is Bowman's capsule pressure?
Hydrostatic pressure opposing filtration.
Q: What is plasma oncotic pressure?
Osmotic pressure from plasma proteins opposing filtration.
Q: What is GFR?
Amount of filtrate formed per minute (~180 L/day).
Q: What affects GFR?
Arteriole resistance, blood pressure, tubuloglomerular feedback.
Q: What is autoregulation of GFR?
Kidney maintains stable GFR via myogenic response and tubuloglomerular feedback.
Q: Describe tubuloglomerular feedback.
Macula densa senses NaCl; high NaCl → afferent arteriole constriction → reduced GFR.
Q: What are macula densa cells?
Cells in distal tubule that regulate GFR through paracrine signaling.
Q: What are juxtaglomerular (JG) cells?
Afferent arteriole cells that release renin.
Q: What stimulates renin release?
Low BP, low NaCl at macula densa, sympathetic activity.
Q: What is renin's role?
Converts angiotensinogen to angiotensin I.
Q: What is ACE?
Enzyme converting angiotensin I to angiotensin II.
Q: Effects of angiotensin II?
Vasoconstriction, increased aldosterone, ADH release, thirst.
Q: What does aldosterone do?
Increases Na+ reabsorption and K+ secretion in distal nephron.
Q: What are principal cells?
Distal nephron cells that reabsorb Na+ and secrete K+.
Q: What are intercalated cells?
Cells that regulate acid-base balance through H+ and HCO3- handling.
Q: Where does most reabsorption occur?
Proximal tubule (~65% of water/solutes).
Q: What is obligatory water reabsorption?
Water following solutes in proximal tubule and descending limb.
Q: What is facultative water reabsorption?
ADH-regulated water reabsorption in collecting duct.
Q: Descending limb permeability?
Permeable to water only.
Q: Ascending limb permeability?
Permeable to ions only; creates dilute filtrate.
Q: What is countercurrent multiplication?
Loop of Henle process creating medullary osmotic gradient.
Q: What is countercurrent exchange?
Vasa recta balancing solute/water to preserve gradient.
Q: What is urine concentration dependent on?
ADH controlling collecting duct water permeability.
Q: What is clearance?
Measure of how quickly a substance is removed from plasma.
Q: Why is inulin used for GFR?
Filtered but neither reabsorbed nor secreted.
Q: Glucose renal handling?
Normally fully reabsorbed until transport maximum is reached.
Q: Transport maximum (Tm)?
Maximum rate of reabsorption for a substance.
Q: Renal threshold?
Plasma concentration at which Tm is reached and substance appears in urine.
Q: Urea handling?
50% reabsorbed; helps maintain medullary gradient.
Q: Penicillin handling?
Actively secreted; clearance exceeds GFR.
Q: What is micturition?
Process of urination controlled by reflex and voluntary mechanisms.
Q: Steps of micturition reflex?
Stretch receptors → parasympathetic activation → bladder contraction → sphincter relaxation.
Q: Total body water percent?
55-60% of body mass.
Q: ICF vs ECF distribution?
ICF ~2/3, ECF ~1/3 of total body water.
Q: Major ECF ions?
Na+ and Cl-.
Q: Major ICF ions?
K+ and phosphate.
Q: Water gain sources?
Ingestion and metabolic water.
Q: Water loss routes?
Urine, sweat, lungs, feces.
Q: What triggers thirst?
Osmoreceptors, low BP, angiotensin II.
Q: ADH role in water balance?
Increases collecting duct permeability to water.
Q: ANP role?
Promotes Na+ and water excretion; inhibits RAAS.
Q: Aldosterone role?
Increases Na+ retention and K+ loss.
Q: What is osmolarity?
Measure of solute concentration; regulated mainly by water balance.
Q: Buffer systems?
Bicarbonate, phosphate, protein buffers.
Q: Respiratory compensation?
Changes ventilation to regulate CO2 and thus pH.
Q: Renal compensation?
Adjusts H+ excretion and HCO3- reabsorption.
Q: What is acidosis?
Blood pH below 7.35 due to excess H+.
Q: What is alkalosis?
Blood pH above 7.45 due to low H+.
Q: Respiratory acidosis cause?
Hypoventilation increasing CO2.
Q: Respiratory alkalosis cause?
Hyperventilation decreasing CO2.
Q: Metabolic acidosis cause?
Loss of HCO3- or gain of acids.
Q: Metabolic alkalosis cause?
Loss of acid (vomiting) or excess antacids.
Q: Severe dehydration responses?
RAAS activation, ADH release, sympathetic stimulation, thirst, reduced GFR.
Q: Volume vs osmolarity changes?
Volume changes affect BP; osmolarity affects cell size and ADH levels.