Unit 2 Study Guide: Respiratory and Endocrine Systems

Comprehensive vocabulary flashcards covering anatomical terminology, respiratory mechanics, gas laws, ventilatory control, endocrine glands, and hormone functions from the Unit 2 Study Guide.

Upper Respiratory Tract

The division of the respiratory system located above the vocal cords, consisting of the nose, nasal cavity, pharynx, and larynx.

Lower Respiratory Tract

The division of the respiratory system located below the vocal cords, consisting of the trachea, bronchi, and lungs.

Conchae (Turbinates)

Bony swellings on the lateral walls of the nasal cavity that protect the entrances to the paranasal sinuses.

Epiglottis

A leaf-shaped structure made of elastic cartilage that covers and closes the larynx during swallowing.

Arytenoid Cartilages

Paired laryngeal cartilages attached to the true vocal cords that aid in adjusting vocal cord tension and pitch.

Carina

An internal ridge of cartilage located at the bifurcation where the trachea splits into the primary bronchi.

Type I Alveolar Cells

Simple squamous epithelial cells lining the alveoli that form the primary site for gas exchange.

Type II Alveolar Cells (Septal Cells)

Specialized alveolar cells that secrete alveolar fluid containing surfactant to reduce surface tension.

Alveolar Dust Cells

Wandering macrophages residing within the alveoli that engulf and remove inhaled debris and particulate matter.

Respiratory Membrane

A $0.5\,\mu\text{m}$ (1/2 micron) thick barrier through which gas exchange occurs between the alveoli and blood, composed of Type I alveolar cells, a fused basement membrane, and capillary endothelial cells.

Pulmonary Ventilation

The mechanical process of breathing (inhalation and exhalation) wherein air flows between the atmosphere and alveoli driven by pressure gradients.

Boyle’s Law

A physical law stating that pressure and volume are inversely related; as thoracic volume increases, intrapulmonary pressure decreases, and as volume decreases, pressure increases.

Tidal Volume (TV)

The volume of air inhaled and exhaled during a single restful, quiet breath.

Inspiratory Reserve Volume (IRV)

The additional volume of air that can be forcibly inhaled during heavy or labored breathing beyond the resting tidal volume.

Expiratory Reserve Volume (ERV)

The additional volume of air that can be forcibly exhaled during heavy or labored breathing beyond the resting tidal volume.

Residual Volume (RV)

The $1200\,\text{mL}$ of air that perpetually remains inside the respiratory system and cannot be forcibly expelled.

Vital Capacity

The maximum volume of air that can be exhaled following a maximal inhalation, calculated as $\text{IRV} + \text{TV} + \text{ERV}$.

Dalton’s Law

A gas law stating that each individual gas in a mixture exerts its own independent partial pressure ($p$), directly proportional to its abundance in the mixture.

Henry’s Law

A gas law stating that gas diffusion from an area of higher partial pressure to lower partial pressure is governed by the gas's solubility and pressure gradient.

External Respiration

The diffusion of gases between the alveoli and pulmonary capillary blood, whereby $\text{O}_2$ enters the blood and $\text{CO}_2$ moves toward the alveoli.

Internal Respiration

The diffusion of gases between systemic capillary blood and tissue cells, whereby $\text{O}_2$ enters the tissues and $\text{CO}_2$ diffuses into the blood.

Dorsal Respiratory Group (DRG)

A division of the medullary respiratory rhythmicity center responsible for regulating quiet, resting ventilation.

Ventral Respiratory Group (VRG)

A division of the medullary respiratory rhythmicity center responsible for regulating forceful and heavy ventilation.

Pontine Respiratory Group

A collection of neurons located in the pons that modifies the rhythm and output of the DRG and VRG during speech, sleep, or exercise.

Inflation Reflex (Hering-Breuer Reflex)

A protective neural reflex triggered when a deep inhalation ($\text{TV} > 500\,\text{mL}$) stretches alveolar walls, initiating exhalation to avoid overinflating the lungs.

Hypophyseal Portal System

A specialized vascular network connecting the hypothalamus to the anterior pituitary, transporting releasing and inhibiting hormones directly to endocrine target cells.

Thyroid-Stimulating Hormone (TSH)

An anterior pituitary hormone that stimulates the follicle cells of the thyroid gland to produce and secrete $\text{T}_3$ and $\text{T}_4$.

Adrenocorticotropic Hormone (ACTH)

An anterior pituitary tropic hormone that targets the adrenal cortex to stimulate the synthesis and release of cortisol.

Antidiuretic Hormone (ADH)

A neurohypophyseal (posterior pituitary) hormone that acts on the kidneys to promote water reabsorption and conservation.

Oxytocin (OT)

A posterior pituitary hormone targeting the uterus and mammary glands to trigger smooth muscle labor contractions and milk ejection.

Calcitonin

A peptide hormone secreted by the parafollicular C cells of the thyroid gland that lowers elevated blood calcium levels by stimulating osteoblast activity.

Parathyroid Hormone (PTH)

A hormone produced by parathyroid chief cells in response to low blood calcium that activates osteoclasts to dissolve bone and release $\text{Ca}^{2+}$ into the bloodstream.

Zona Glomerulosa

The outermost cortical zone of the adrenal gland, responsible for synthesizing mineralocorticoid hormones such as aldosterone.

Aldosterone

The primary mineralocorticoid produced by the zona glomerulosa that promotes sodium and water retention and sharpens salt receptor sensitivity in taste buds.

Zona Fasciculata

The middle layer of the adrenal cortex, responsible for secreting glucocorticoids including cortisol.

Cortisol

A glucocorticoid that exhibits anti-inflammatory actions, dampens immune responses, and mobilizes amino acids and lipids into circulation via catabolism.

Zona Reticularis

The innermost layer of the adrenal cortex that forms a network of endocrine cells producing androgens, predominantly dehydroepiandrosterone (DHEA).

Dehydroepiandrosterone (DHEA)

An adrenal androgen secreted by the zona reticularis that can be peripherally converted to testosterone in men and estrogen in women.

Alpha Cells (Pancreatic)

Endocrine cells of the pancreatic islets that synthesize and secrete glucagon to mobilize glycogen stores and elevate blood glucose and lipids.

Beta Cells (Pancreatic)

Endocrine cells within the islets of Langerhans that produce insulin to stimulate cellular glucose uptake and decrease blood glucose and lipid levels.

Melatonin

An amine hormone secreted by pinealocytes in the pineal gland that promotes sleep by dampening cerebral cortex activity and coordinates the biological clock.