The Respiratory System Flashcards
Conduction Zone
Portion of the respiratory system that includes the: nose, pharynx, larynx, trachea, bronchi, and bronchioles. Their function is to filter, humidify, and conduct air into the lungs.
Alveoli
Small sacs that interface with the pulmonary capillaries, allowing gases to diffuse across a one-cell-thick membrane. The branching and minute size of the alveoli allow for a larger surface area for gas exchange -> approx.
100 meters square
Pharynx
Organ that is a part of both the digestive and respiratory tracts. The pharynx is divided into the nasopharynx, oropharynx, and laryngopharynx.
Nasopharynx
Upper portion of the pharynx that extends from the base of the skull to the upper surface of the soft palate. Site of adenoids (or pharyngeal tonsils), that are lymphoid tissue structures in the posterior wall.
Oropharynx
Middle portion of the pharynx that extends from the uvula to the hyphoid bone. Site of the palatine tonsil and epiglottis. The oropharynx is lined by non-keratinised squamous stratified epithelium.
Epiglottis
A flap of connective tissue which closes over the glottis when food is swallowed to prevent aspiration. Superior side is a part of the pharynx while the inferior side is considered part of the larynx.
Laryngopharynx
The lower portion of the pharynx that extends from the inferior portion of the epiglottis to the location where this common pathway diverges into the respiratory (larynx) and digestive (esophagus) pathways.
Note: also called the Hypopharynx
Pulmonary Surfactant
Surface-active lipoprotein complex (phospholipoprotein) formed by type 2 alveolar cells. It coats the alveoli and acts as a detergent by lowering the surface tension and preventing the alveolus from collapsing on itself.
Lungs
Located in the thoracic cavity and encapsulated by membranes called pleurae.
- Left lung: 2 lobes; slightly smaller to compensate for the heart (cardiac notch)
- Right Lung: 3 lobes; slightly larger than left lung
Pleurae
Membranes that surround each lung and line the chest wall.
- Visceral Pleurae: lies adjacent to the lung itself
- Parietal Pleurae: lines the chest wall
Intrapleural Space
Lies between the visceral and parietal pleura and contains a thin layer of fluid, which lubricates the two pleural surfaces.
Inhalation (Negative-Pressure Breathing)
Active process; Expansion of diaphragm and external intercostal muscles increases intrathoracic/intrapleural space volume, thus decreasing intrapleural pressure. Air is then drawn from a higher-pressure environment (e.g. outside world) into a lower-pressure environment (e.g. the lungs).
Passive Exhalation
Relaxation of diaphragm and external intercostal muscles, decreases intrathoracic/intrapleural space volume, thus increasing intrapleural pressure. Air is then drawn from a higher-pressure environment (e.g. lungs) to a lower pressure environment (e.g. the outside world).
Active Exhalation
When both internal intercostal and abdominal muscles, which oppose the external intercostal muscles, pull the rib cage downward, thus decreasing the volume and increasing the pressure of the thoracic cavity. Air is then drawn out from a higher-pressure environment to a lower-pressure environment.
Pathway of Air
Nasal Cavity/ Oral Cavity -> Pharynx -> Larynx -> Trachea -> Primary Bronchi -> Secondary Bronchi -> Tertiary Bronchi -> Bronchioles ->
Alveoli (site of gas exchange)
Total Lung Capacity (TLC)
The maximum volume of air in the lungs when one inhales completely; between 6-7 liters.
Residual Volume (RV)
The minimum volume of air in the lungs when one exhales completely; between 0-2 liters.
Vital Capacity (VC)
The difference between the minimum and maximum volume of air in the lungs (TLC - RV).
Tidal Volume (TV)
The volume of air inhaled or exhaled in a normal breath.
Expiratory Reserve Volume (ERV)
The volume of additional air that can be forcibly exhaled after a normal exhalation.
Inspiratory Reserve Volume (IRV)
The volume of additional air that can be forcibly inhales after a normal inhalation.
Ventilation Center
Site of ventilation regulation by a collection of neurons in the medulla oblongata. Responds to both high CO2 levels in the blood (hypercarbia) and low O2 levels in the blood (hypoxia).
Chemoreceptors
Respond to CO2 concentrations, increasing the respiratory rate when there are high concentrations of CO2 in the blood (hypercarbia or hypercapnia).
Hypercapnia
Condition of abnormally elevated CO2 levels in the blood.
Other names include CO2 retention, hypercapnea and hypercarbia
Gas Exchange Steps
- ] Deoxygenated blood is carried from the right ventricle thru the pulmonary artery to the capillary bed of the alveoli.
- ] Alveoli facilitate diffusion of CO2 from blood to lungs and O2 into blood.
- ] Oxygenated blood is carried from capillary bed of the alveoli thru the pulmonary venule to the left atrium.
Pressure Differential of Gases
The driving force behind gas exchange. Upon arrival at alveoli, blood has a low partial pressure of O2 and a high partial pressure of CO2, facilitating each down its respective concentration gradient.
Note: Gas exchange does not require input of ATP (energy).
Function of O2 and CO2 in Respiration
O2: flows down its partial pressure gradient from alveoli into pulmonary capillaries, where it can bind to hemoglobin for transport.
CO2: flows down its partial pressure gradient from the capillaries into the alveoli for expiration.
Thermoregulation
The large surface area of interaction between the alveoli and capillaries allows the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction.
Note: Humans predominantly regulate temperature using capillaries and sweat glands in the skin or rapid muscle contraction.
Vasodilation in Thermoregulation
The process in which blood vessels widen due to the relaxation of smooth muscle cells within the vessel walls. As a result, the flow of blood is increased due to a decrease in vascular resistance and therefore lowers blood pressure.
End result: lowers body temperature
Vasoconstriction in Thermoregulation
The process in which blood vessels narrow due to the contraction of smooth muscle cells within the vessels walls. As a result, the flow of blood is decreased due to an increase in vascular resistance and therefore raises blood pressure.
End result: raises/conserves body temperature
