Respiratory Flashcards
Differentiate between internal and external respiration.
Internal Respiration: exchange of gases between tissues and blood
External Respiration: gas exchange between air and blood in lungs
Define: ventilation, gas exchange, oxygen utilization, inspiration, expiration, compliance.
Ventilation: process of moving air in and out of lungs
Gas Exchange: process where gases are transferred across a surface in the opposite direction (based on diffusion gradient; between air and blood in the lungs and between blood and tissues)
Oxygen Utilization: use of oxygen by tissue through cellular respiration
Inspiration: movement of air into lungs through contraction of diaphragm
Expiration: movement of air out of lungs through relaxation of diaphragm
Compliance: ability to distend/expand when stretched
Describe the anatomy of the lungs.
-lungs are located in the thoracic cavity, suspended in the pleural cavity
-open to the external environment via trachea
-have a series of tubes that systemically branch out into smaller and smaller airways that carry air to millions of interconnected sacs called alveoli, where gas exchange occurs
Identify: mouth, nose, pharynx, laryns, trachea, primary bronchus, carina, terminal bronchioles, respiratory bronchioles, alveolus, conducting zone, and respiratory zone.
Pharynx: moistens air to send to lungs, behind larynx
Larynx: connects pharynx to trachea, allows air to pass through it while keeping food from blocking pathway
Trachea: providing air flow to and from the lungs, hollow tube connect larynx to bronchi of lungs
Primary Bronchus: passage of airway in the respiratory system that conducts air into the lungs
Carina: separates left and right main bronchi
Terminal Bronchioles: divides to form respiratory bronchioles which contain a small number of alveoli
Respiratory Zone: site of gas exchange; includes respiratory bronchioles and alveolar sacs
Describe the morphology of the alveolus and identify the type I and type II alveolar cells and indicate their function.
-alveoli make up the majority of the lung and are the reason for the spongy texture
-clustered together in the shaped of a polyhedral, similar to a honeycomb
-alveoli are thin walled and their basement membrane fuse with the endothelial cells of capillaries; easy gas exchange
Type I: make up the majority of the surface area of the lungs and is the site for gas exchange
Type II: secrete surfactant to reduce surface tension caused by hydrogen bonds between water molecules at the water/air interface; this prevents the collapse of alveoli
Describe the relationship between lung alveoli and pulmonary capillaries.
-pulmonary capillaries and lung alveoli are closely associated with a large number of capillaries enveloping the entire alveolus
-capillaries and alveoli are only separated by a very small distance (0.3mm)
-both features allow for rapid gas exchange between air in the alveoli and blood in the pulmonary capillary
List the homeostatic functions of the conducting zone of the respiratory system.
Warming, humidification, filtration, cleaning.
Describe the diaphragm, mediastinum, thoracic cavity, pleural membranes, intrapleural space, lung lobes.
Diaphragm: separates the abdominal and thoracic cavity; it’s dome-shaped striated muscle that is used during inspiration/expiration
Mediastinum: group of structures located in the middle of the thoracic cavity (between the lungs)
Thoracic Cavity: region above the diaphragm that contains the heart and associated large vessels, the respiratory system (including the lungs, trachea) as well as the esophagus and thymus
Pleural Membrane: wet epithelium membrane that line the mediastinum; the parietal pleural line the inside wall of the thoracic cavity and the visceral pleura covers the surface of the lung
Intrapleural Space: very small space between the parietal and visceral membrane that contains a thin layer of fluid that lubricates lungs during ventilation
-visceral pleura is pushed against the parietal pleura with both membrane essentially stuck together, eliminating this space
-if lungs collapse, the intrepleural space would become a real space
Lung Lobes: right lung has 3 lobes, whereas the left lung has 2 lobes
Define: atmospheric pressure, intrathoracic pressure, intrapleural pressure, transpulmonary pressure and negative pressure.
Atmospheric Pressure: pressure in atmospheric air; remains constant
Intrapleural Pressure: pressure within the intrapleural space caused by contraction/recoil of diaphragm
-during inspiration, pressure within the intrapleural space is lower (negative) than atmospheric
-during expiration, pressure within the intrapleural space is higher than atmospheric
Transpulmonary Pressure: pressure difference between intrapulmonary (pressure within the lungs) and intrapleural pressures (pressure within the intrapleural space); causes lungs to stick to thoracic cavity wall
Negative Pressure: pressure that is less than atmospheric pressure
State Boyle’s Law.
Pressure of any given gas is inversely proportional to its volume.
Discuss how Boyle’s law impacts ventilation.
-movement of air into and out of the lungs is dependent on pressure differences between the atmosphere and lungs
-contraction and relaxation of the diaphragm during ventilation causes a change in lung volume, which ultimately changes transpulmonary pressure
Inspiration: contraction of diaphragm, increase lung volume, decrease transpulmonary pressure, which is less than atmospheric pressure, air moves into lungs
Expiration: relaxation of diaphragm, decrease lung volume, increase transpulmonary pressure, which is greater than atmospheric pressure, air moves out of lungs
List the physical properties of the lung and how they influence ventilation.
-compliance, elasticity and surface tension are physical properties that affect their functioning
Compliance: for a given transpulmonary pressure; will cause a greater or lesser expansion depending on compliance of lungs
Elasticity: ability for lungs to go back to original size after expansion
-tension increases during inspiration when lungs are stretched and is reduced by elastic recoil during expiration
Surface Tension: exerted by fluid in alveoli; allows for easy flow of Na+ and active transport of Cl- out of epithelial alveolar cells
State Laplace’s Law.
Pressure is proportional to surface tension and inversely proportional to the radius of alveoli.
P=2T/r
P=pressure; T=surface tension; r=radius
Discuss how Laplace’s law affects alveolar surface tension and pulmonary ventilation.
-as an alveolus decreases in size, its surface tension is decreased at the same time that its radius is reduced
-decreased surface tension prevent alveoli from collapsing
Describe the role of surfactant in maintaining normal alveolar function.
Surfactant: fluid made of lipoprotein complexes that is secreted on surface of alveoli
-decreases surface tension by disrupting the H binds between water molecules
-surfactant molecules become more concentrated as the alveoli get smaller; prevents the alveoli from collapsing during expiration, as would be predicted from the law of Laplace
Discuss the actions of the diaphragm, intercostals, rib cage, intrathoracic pressure, intrapleural pressures, and movement of air during inspiration and expiration.
Inspiration: contraction of diaphragm and intercostals muscles raises ribcage, increase in thoracic volume, decrease in intrapulmonary pressure, and movement of air into lungs
Expiration: relaxation of diaphragm and intercostals muscles cage, decrease in thoracic volume, increase in interpulmonary pressure and movement of air out of lungs
Define tidal volume.
Tidal Volume: volume of air expired in each breath
State Dalton’s Law.
Pressure air = sum of partial pressure of gases contained in the air mixture
Define pressure, partial pressure, atmospheric pressure.
Pressure: amount of force within a given area exerted against the surface
Partial Pressure: amount of pressure that a specific gas within a mixture exerts on its own
Atmospheric Pressure: sum of all partial pressures of gases in atmospheric air; consistent at sea level but as altitude increases, partial pressures of gases and atmospheric gases decreases
State specifically the partial pressure of oxygen in the atmosphere (PatmosphereO2), alveoli (PAO2), pulmonary arterial blood (PaO2) and pulmonary venous blood (PvO2).
PO2 in atmosphere = 159 mmHg
Alveoli (PAO2) = 105 mmHg
Pulmonary arterial blood (PaO2) = 100 mmHg
Pulmonary venous blood (PvO2) = 40 mmHg
Discuss how Henry’s Law predicts movement of O2 during alveolar gas exchange.
According to Henry’s Law, the maximum amount of gas dissolved in air or blood is dependent on:
1. solubility of gas in liquid
2. temperature of fluid
3. partial pressure of gas
Generally, solubility and temperature are constant; the movement of oxygen during gas exchange is driven by differences in partial pressure between air and blood.
Identify the major atmospheric gases and indicate the proportions relative to atmospheric pressure.
H2O: Inspired air = variable, Alveolar Air = 47 mmHg
CO2: Inspired air = 0.3 mmHg, Alveolar Air = 40 mmHg
O2: Inspired air = 159 mmHg, Alveolar Air = 105 mmHg
N2: Inspired air = 601 mmHg, Alveolar Air = 568 mmHg
Total Pressure = 760 mmHg
-notice that as air enters the alveoli its oxygen content decreases and its carbon dioxide content increases
Describe how oxygen is transported in the blood.
Oxygen is transported via hemoglobin; even though small amounts are dissolved into the blood.
Discuss how hemoglobin transports oxygen in the blood.
Hemoglobin is found in RBCs; made of 4 polypeptide chains each with a heme group that contains an iron molecule that can bind and transport O2.
