Comprehensive Human Anatomy and Physiology: Respiratory, Urinary, Fluid Balance, Reproduction, and Cardiovascular Systems

What is the primary function of the respiratory system?

To provide body cells with oxygen (O2) and remove waste carbon dioxide (CO2).

What are the two main zones of the respiratory system?

The Conducting Zone and the Respiratory Zone.

What structures are included in the Conducting Zone?

Structures from the nose to the bronchioles.

What is the role of the Respiratory Membrane?

It is the barrier across which gas exchange occurs, composed of alveolar type I cells, basement membranes, and endothelial cells.

What is Boyle's Law?

It describes the inverse relationship between pressure and volume of gas at constant temperature.

What is the driving force behind pulmonary ventilation?

Pressure gradients; gas moves from areas of high pressure to areas of low pressure.

What is Tidal Volume (TV)?

The amount of air inspired or expired during normal quiet ventilation, approximately 500 ml in healthy adults.

What is the Anatomical Dead Space?

The portion of Tidal Volume (150 ml) that does not participate in gas exchange.

What is Vital Capacity (VC)?

The total amount of exchangeable air, calculated as TV + Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV).

What is the role of surfactant in the alveoli?

It reduces surface tension, preventing alveolar collapse during expiration.

What is the difference between external respiration and internal respiration?

External respiration is the gas exchange between lungs and blood; internal respiration is the gas exchange between blood and tissues.

What is Dalton's Law?

The total pressure of a gas mixture is the sum of the partial pressures of its component gases.

What is Henry's Law?

The degree a gas dissolves in a liquid is proportional to its partial pressure and solubility in that liquid.

What is the significance of ventilation-perfusion (V/Q) coupling?

It ensures that air reaching the alveoli matches blood flow for efficient gas exchange.

What is the composition of oxygen transport in the blood?

Approximately 1.5% is dissolved in plasma, and 98.5% is bound to hemoglobin (Hb).

What happens during quiet inspiration?

The diaphragm contracts, increasing thoracic cavity height and lung volume, allowing air to flow in.

What is the role of the diaphragm in breathing?

It contracts during inspiration to increase thoracic cavity volume and facilitate air intake.

What is the typical range for Inspiratory Reserve Volume (IRV)?

Approximately 2100-3300 ml.

What is the purpose of the spirometer?

To measure and record the volumes of air inhaled and exhaled.

What is the effect of inadequate surfactant in infants?

It leads to Infant Respiratory Distress Syndrome (RDS), making alveolar inflation difficult.

What is the typical range for Expiratory Reserve Volume (ERV)?

Approximately 700-1200 ml.

What is the Residual Volume (RV)?

The amount of air remaining in the lungs after a forceful expiration.

What is Total Lung Capacity (TLC)?

The sum of all pulmonary volumes: IRV + TV + ERV + RV.

What is the primary role of the tracheal epithelium?

It is pseudostratified ciliated columnar epithelium that helps filter and moisten air.

What is the significance of the steepness of the pressure gradient in gas exchange?

It determines the rate of gas diffusion between alveoli and blood.

What are the signs of impaired gas exchange?

Hypoxemia (low blood O2) and Hypercapnia (high blood CO2).

What process occurs when O2 binds to hemoglobin in the pulmonary capillaries?

Loading

What is the term for hemoglobin releasing O2 to tissues in systemic capillaries?

Unloading

What does the hemoglobin saturation curve depict?

Hb saturation at varying PO2 levels.

What is the normal saturation percentage of arterial hemoglobin?

Approximately 97-100%.

What is the saturation percentage of venous blood hemoglobin at rest?

Approximately 75%.

What shape is the hemoglobin saturation curve?

S-shaped.

How does fetal hemoglobin differ from adult hemoglobin?

Fetal hemoglobin has a greater affinity for oxygen.

What factors affect hemoglobin's affinity for O2?

Temperature, PCO2, pH, and 2,3 BPG.

What does a right shift in the hemoglobin saturation curve indicate?

Decreased affinity for O2, facilitating unloading.

What causes a right shift in the hemoglobin saturation curve?

Increased temperature, acidity (decreased pH), PCO2, and 2,3 BPG.

What is the effect of carbon monoxide (CO) poisoning on hemoglobin?

Increases Hb's affinity for O2, decreasing O2 release to tissues.

What percentage of carbon dioxide is dissolved in plasma?

7-10%.

What percentage of carbon dioxide is bound to hemoglobin as carbaminohemoglobin?

20-23%.

What percentage of carbon dioxide is converted to bicarbonate (HCO3-) in the body?

70%.

Where does HCO3- conversion primarily occur?

In red blood cells (RBCs), catalyzed by Carbonic Anhydrase (CA).

What is the chloride shift?

Cl- diffuses into RBCs as HCO3- diffuses out to balance charge.

What occurs during the reverse chloride shift?

Cl- diffuses out of RBCs as HCO3- diffuses back in, forming CO2.

What characterizes restrictive lung diseases?

Decreased pulmonary compliance and reduced inspiration effectiveness.

What are examples of restrictive lung diseases?

Idiopathic pulmonary fibrosis and pneumoconiosis.

What characterizes obstructive lung diseases?

Increased airway resistance and decreased efficiency of expiration.

What is the primary risk factor for lung cancer?

Cigarette smoking.

What is the average Glomerular Filtration Rate (GFR)?

Approximately 125 ml/min (180 L/day).

What does the filtration membrane consist of?

Fenestrated glomerular capillary endothelial cells, basal lamina, and podocytes.

What is the formula for Net Filtration Pressure (NFP)?

NFP = GHP - (GCOP + CHP).

What is the role of the myogenic mechanism in GFR regulation?

It maintains GFR by constricting the afferent arteriole in response to increased systemic BP.

What is the function of the Renin-Angiotensin-Aldosterone System (RAAS)?

It maintains systemic BP primarily and GFR secondarily.

What effect does Atrial Natriuretic Peptide (ANP) have on GFR?

It increases GFR by dilating afferent arterioles and constricting efferent arterioles.

What is tubular reabsorption?

The process of reclaiming substances from tubular fluid back into the blood.

What is tubular secretion?

The active process of adding substances to filtrate from blood for excretion.

What is the Transport Maximum (TM)?

The maximum solute levels that can be transported; if reached, substances remain in filtrate.

What condition occurs when the tubular maximum for glucose is reached?

Glycosuria, commonly seen in diabetes mellitus due to hyperglycemia.

What is the primary function of the Proximal Convoluted Tubule (PCT)?

Reabsorbs approximately 100% of organic solutes (glucose, amino acids) and about 65% of water.

How does sodium reabsorption occur in the PCT?

The Na+/K+ pump transports 3 Na+ out of the cell and 2 K+ into the cell, creating a low Na+ gradient that drives Na+/H+ antiporters and Na+/glucose symporters.

What percentage of bicarbonate (HCO3-) is reabsorbed in the PCT?

Approximately 90%.

What is obligatory water reabsorption in the PCT?

About 85% of water is reabsorbed because it follows reabsorbed solutes by osmosis.

What role do aquaporins play in the kidneys?

Aquaporins are water channels that greatly increase water reabsorption.

What substances are secreted in the PCT?

H+ ions, drugs (like penicillin and morphine), and nitrogenous wastes (NH3, creatinine, urea).

What is the overall function of the nephron loop?

Reabsorbs approximately 20% of water and 25% of Na+/Cl-.

What is the permeability of the thin descending limb of the nephron loop?

Freely permeable to water but not to solutes.

What happens to filtrate osmolarity in the thin descending limb?

Filtrate osmolarity increases, reaching about 900 mOsm.

What is the function of the thick ascending limb of the nephron loop?

Impermeable to water; actively transports Na+/Cl- out, decreasing filtrate osmolarity.

What is the countercurrent mechanism?

It creates and maintains the medullary osmotic gradient, involving juxtamedullary nephrons, urea recycling, and vasa recta.

What is the role of urea in the collecting ducts?

Urea is reabsorbed into interstitial fluid, contributing to the medullary gradient.

What regulates water reabsorption in the distal convoluted tubule (DCT) and collecting duct (CD)?

It is highly hormone-regulated to fine-tune water, electrolyte, and acid-base balance.

What is facultative water reabsorption?

Approximately 15% of water reabsorption adjusted according to the body's needs, occurring in the late DCT and CD.

What effect does antidiuretic hormone (ADH) have on water reabsorption?

ADH triggers the insertion of aquaporin (AQP2) water channels into the apical membranes of principal cells.

What is the effect of aldosterone on sodium and potassium?

Increases the number of Na+/K+ pumps, leading to increased Na+ reabsorption and K+/H+ secretion.

What does atrial natriuretic peptide (ANP) do?

Inhibits Na+ ion reabsorption, resulting in increased water and sodium excretion.

What is the average total body water percentage of body weight?

Approximately 60%.

What are the two main fluid compartments in the body?

Intracellular compartment (ICF) and extracellular compartment (ECF).

What is the osmotic pressure gradient?

Solutes pull water toward the solution with higher osmotic pressure (higher osmolarity).

What happens to cells in hypotonic ECF?

Cells gain water and swell.

What is hypernatremia?

A condition characterized by sodium levels greater than 145 mEq/l, commonly caused by dehydration.

What is hypokalemia?

A condition where potassium levels are less than 3.9 mEq/l, making the resting membrane potential more negative.

What is the normal pH range of blood?

7.35-7.45, which is slightly alkaline.

What is the role of bicarbonate ion (HCO3-) in acid-base balance?

It is the most common base that accepts H+.

What is the effect of hypercalcemia on neurons?

Neurons become less permeable to Na+, diminishing their ability to depolarize.

What is the most common base in the body?

Bicarbonate ion (HCO₃⁻)

What is a volatile acid and how is it eliminated?

Carbonic acid (H₂CO₃) from CO₂ gas; eliminated by kidneys and lungs.

What are fixed acids and how are they eliminated?

Fixed acids (e.g., lactic acid, uric acid, ketone bodies) must be eliminated by the kidneys.

What is the function of buffer systems in the body?

Buffer systems resist dramatic swings in H⁺ concentration.

Which buffer system is the most important in blood?

The Carbonic Acid Buffer System.

What is the reaction catalyzed by Carbonic Anhydrase?

CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻.

What percentage of the body's total buffering capacity is composed of protein buffer systems?

60-70%.

How does the respiratory system regulate volatile acids?

It controls CO₂ levels, which determine H₂CO₃ and HCO₃⁻ levels.

What happens during hyperventilation?

Increased respiratory rate/depth leads to decreased PCO₂ and increased pH (risk of Respiratory Alkalosis).

What happens during hypoventilation?

Decreased respiratory rate/depth leads to increased PCO₂ and decreased pH (risk of Respiratory Acidosis).

How does the urinary system regulate fixed acids?

It controls fixed acids and HCO₃⁻; compensation takes hours to days but is more effective.

What is the response of the urinary system to acidosis?

Increased reabsorption of HCO₃⁻ and secretion of H⁺.

What defines acidosis in terms of pH?

pH < 7.35.

What are the effects of acidosis on neurons?

Neurons become less excitable, leading to nervous system depression.

What defines alkalosis in terms of pH?

pH > 7.45.

What are the effects of alkalosis on neurons?

Increased excitability of neurons, which can lead to seizures or coma.

What is spermatogenesis?

The production of male gametes, occurring in seminiferous tubules.