lec 11-Control of Breathing and pH Flashcards

Vocabulary-style flashcards covering the neuroanatomical, chemical, and renal controls of breathing and extracellular pH based on the lecture material.

Phrenic Nerve

The nerve that stimulates the diaphragm, the main respiratory muscle, via signals from the brain stem.

Dorsal Respiratory Group (DRG)

A region in the Medullary Respiratory Centre containing inspiratory neurones that synapse with primary motor neurons to stimulate inspiratory muscles.

Ventral Respiratory Group (VRG)

A region in the Medullary Respiratory Centre containing expiratory neurons and pacemaker neurons that generate spontaneous rhythmic bursts to set the basal rate of breathing.

Pneumotaxic centre

A region located in the pons that helps smooth transitions between inspiration and expiration.

Apneustic centre

A region in the pons that regulates the duration of breath.

Lung stretch receptors

Receptors in bronchial smooth muscle that, when activated by deep inspiration, send impulses via the vagus nerve to the $DRG$ to inhibit further inspiration and prevent over-inflation.

Central chemoreceptors

Receptors located in the medulla that detect changes in $[H^+]$ in cerebrospinal fluid, which is in equilibrium with $CO_2$ in arterial blood.

Peripheral chemoreceptors

Receptors located in the carotid bodies that detect changes in $PO_2$ and $[H^+]$ in arterial blood.

Hypercapnia

A state of high arterial $PCO_2$, which acts as the main determinant of ventilation rate at rest in healthy individuals.

Hypoxia

A state of low arterial $PO_2$; its effect on ventilation becomes profound only when $PO_2$ drops below approximately $8\,kPa$.

Chemoreceptor Synergy

The combined effect where hypercapnia and hypoxia together produce a significantly larger increase in ventilation than either condition alone.

Respiratory Acidosis

A condition where $pH < 7.4$ due to impaired elimination of $CO_2$ in respiratory disease, also known as hypoventilation.

Metabolic Acidosis

A condition where $pH < 7.4$ caused by the gain of $H^+$ from organic acids (e.g., lactic acid) or the loss of $HCO_3^-$ from diarrhea or renal dysfunction.

Respiratory Alkalosis

A condition where $pH > 7.4$ caused by the excess elimination of $CO_2$, often due to anxiety-induced hyperventilation.

Metabolic Alkalosis

A condition where $pH > 7.4$ resulting from the loss of $H^+$ (e.g., through vomiting) or the increased utilization of $H^+$ in the metabolism of organic molecules.

Respiratory Compensation

A rapid response occurring within minutes to correct $pH$ by adjusting ventilation to change $PCO_2$ levels, though it is not a sustainable long-term solution.

Renal Compensation

A long-term solution for $pH$ control involving the excretion of excess $H^+$ as phosphate or ammonium and the reabsorption or production of $HCO_3^-$.

Glutamine

A molecule metabolized by the liver and kidney to produce $NH_4^+$ and new $HCO_3^-$ to help restore normal plasma $[H^+]$ and $[HCO_3^-]$ during metabolic acidosis.