Biomedical Respiratory and Metabolism Review

Flashcards covering biochemistry basics, respiratory anatomy, lung volumes, spirometry, gas exchange factors, hemoglobin dynamics, and acid-base balance based on the lecture transcript.

Phosphofructokinase-1 (PFK-1)

The rate limiting enzyme of glycolysis.

Hexokinase

The enzyme that catalyzes the first step of glycolysis in most tissues.

Conducting zone

The air pathway that moves, warms, humidifies, and filters air, but does not perform gas exchange; it includes approximately $150\,mL$ of anatomic dead space.

Terminal bronchiole

The last part of the conducting zone.

Respiratory bronchiole

The first part of the respiratory zone where alveoli begin appearing in its wall.

Mucociliary escalator

A mechanism where mucus traps particles and cilia move the mucus upward.

Type I pneumocyte

A thin squamous cell covering approximately $95\%$ of the alveolar surface that performs gas exchange.

Type II pneumocyte

A cuboidal cell covering $3-5\%$ of the alveolar surface that secretes surfactant and helps remove alveolar fluid.

Alveolar macrophages

Dust cells that phagocytose particles and microorganisms reaching the alveoli.

Surfactant

A lipid–protein mixture (primarily DPPC plus apoproteins) that decreases alveolar surface tension, prevents collapse, and increases lung compliance.

Boyle's Law

The principle stating that pressure and volume move in opposite directions.

Atelectasis

Lung collapse that occurs when the pressure difference is lost, such as when air enters the pleural space during a pneumothorax.

Tidal volume ($TV$)

The amount of air moved during one normal breath.

Residual volume ($RV$)

The air remaining in the lungs after maximal expiration; it prevents collapse and cannot be measured by spirometry.

Functional residual capacity ($FRC$)

The volume of air remaining after a normal expiration, calculated as $ERV + RV$.

Vital capacity ($VC$)

The total volume of air that can be exhaled after a maximal inspiration, calculated as $IRV + TV + ERV$.

Obstructive lung disease

A category of disease (e.g., Asthma, Emphysema) characterized by difficulty getting air out, a greatly decreased $FEV_1$, and a decreased $FEV_1/FVC$ ratio.

Restrictive lung disease

A category of disease (e.g., Pulmonary fibrosis) characterized by difficulty expanding the lungs, decreased $FVC$, and a normal or increased $FEV_1/FVC$ ratio.

Minute ventilation

The total volume of gas entering the lungs per minute, calculated as $RR \times TV$.

Alveolar ventilation

The volume of gas that reaches the alveoli per minute, calculated as $RR \times (TV - \text{dead space})$.

T state

The state of hemoglobin with low $O_2$ affinity that promotes oxygen unloading.

R state

The state of hemoglobin with high $O_2$ affinity that promotes oxygen binding.

Bohr effect

The phenomenon where active tissues produce $CO_2$, acid, and heat, causing a right shift in the hemoglobin-O2 curve to promote oxygen unloading.

HbF (Fetal hemoglobin)

A form of hemoglobin that is left-shifted because it binds $2,3-DPG$ poorly, allowing it to take oxygen from maternal blood.

Shunt

A $V/Q$ mismatch condition where blood reaches the alveoli but there is no ventilation ($V/Q = 0$).

Dead space ($V/Q$ context)

A condition where alveoli receive air but there is no blood flow or perfusion ($V/Q = \infty$).

Dorsal respiratory group (DRG)

A structure in the medulla that generates the basic inspiratory rhythm.

Central chemoreceptors

Receptors in the medulla that detect increased $CO_2$ indirectly through a decrease in $CSF$ $pH$.

Peripheral chemoreceptors

Receptors in the carotid and aortic bodies that primarily detect decreased $PaO_2$, as well as increased $PaCO_2$ and decreased $pH$.

Hypoxemia

A condition characterized by low arterial $O_2$.

Hypercapnia

A condition characterized by high arterial $CO_2$.

Respiratory acidosis

A disorder characterized by increased $CO_2$ and decreased $pH$, often caused by hypoventilation.

Metabolic acidosis

A disorder characterized by decreased $HCO_3^-$ and decreased $pH$, which the body compensates for through hyperventilation to decrease $CO_2$.