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101 Cards in this Set
- Front
- Back
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Where does the airway lie?
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Within the visceral pleura
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What do the bronchioles branch into?
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Terminal bronchioles
Respiratory bronchioles Alveoli |
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Where does respiratory gas exchange occur?
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Respiratory bronchioles
Alveoli |
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What is essential for gas exchange and how is made?
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Thin Layer of fluid.
Recall that this fluid is the result of ion secretion from interstitial fluid formed by ultrafiltration across capillaries. |
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Through what structure is oxygenated blood returned to the heart?
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Pulmonary Veins
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What does pulmonary edema do?
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Increases the diffusion distance for oxygen absorption
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What is the airway surrounded by?
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Bands of smooth muscle that can constrict air flow to the alveoli (relaxed by Beta2 stimulation by epinephrine)
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How many alveoli are found in the lungs and how much gas exchange do they provide?
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There are about 300 million alveoli providing about 140 m2 of gas exchange area for both lungs. About the area of a tennis court.
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What is the goal of ventilation?
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Exchanges air to maintain partial pressure gradients for oxygen delivery and CO2 removal from the blood
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What is the traditional methods of measuring lung volumes and how is it recorded?
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The traditional way of measuring lung volumes with a simple water seal spirometer. Lung volumes are recorded as an ink trace on a rotating drum
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What is the lung volume under resting conditions?
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The lungs are about half filled to the functional residual capacity
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During period of tidal or quiet breathing what volume of air is exchanged per breath and what is it called?
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500 ml of air above the functional residual capacity
Tidal volume |
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In respiration, what does "volume" refer to?
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Air movements due to specific changes in ventilation
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In respiration, what does "capacity" refer to?
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The sum of two or more volumes
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In respiration what is the functional residual capacity or FRC?
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2.4L
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Of the 500 ml/breath of tidal volume (Vt) what is the volume of air not taken into the alveoli and what is it called?
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150 ml
"Anatomical dead space" |
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What does the remainder of the tidal volume that is not associated with the anatomical dead space do?
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Expands the alveoli and exchanges with alveolar air
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What is equation for minute volume?
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minute volume = breaths/min x Vt
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What is the equation for alveolar ventilation (Va)?
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Alveolar ventilation (Va) = breaths/min x (VT - Vd)
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What is the state of expiration when inspiring air above the FRC?
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Expiration is passive due to elastic recoil of the chest wall and alveoli
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What does expiration that utilizes the Expiratory Reserve Volume (ERV) require?
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Active contraction of the expiratory muscles
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What are the muscles that raise the rib cage and which one is the most important?
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1. External intercostals (most important)
2. Sternocleidomastoid muscles 3. Anterior Serrati muscles 3. Scaleni |
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What do the sternocleidomastoid muscles do?
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Lift upward on the sternum
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What do the anterior serrati muscles do?
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Lift many of the ribs
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What do the scaleni muscles do?
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Lift the first two ribs
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What does contraction of the diaphragm result in?
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Lowers the floor of the thoracic cavity to similarly create a negative pressure
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What are the muscles that pull the rib cage downward during expiration?
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1) Abdominal recti
2)Internal intercostals |
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What do the abdominal recti do?
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Have the powerful effect of pulling downward on the lower ribs at the same time that they and other abdominal muscles also compress the abdominal contents upward against the diphragm
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What if any muscular structures are required in quiet breathing?
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Expiration results passive recoil of lungs
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What if any muscular structures are required in active breathing?
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Internal intercostals, except parasternal intercartilaginous muscles (depress ribs)
Abdominal muscles (depress lower ribs, compress abdominal contents) |
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What is the pressure in the alveoli after expiration of a tidal breath?
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The pressure in the alveoli is equal to the ambient atmospheric pressure
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What occurs when the thoracic cavity expands?
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Air is drawn into the airway when the thoracic cavity expands and creates a negative pressure in the alveoli
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what is the outer membrane of the lung?
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Basically the inner lining of the thoracic cavity - Parietal Pleura
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What fills the thin space between the parietal and visceral pleura?
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Lymphatic fluid
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What are the characteristics of the visceral pleura?
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Has elastic elements that tend to collapse the lung and exert an inward force (about + 5 cm H2O) that must be overcome by the inspiratory muscles to prevent collapse.
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What is pleural pressure?
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The outward force that overcomes the inward force by the elastic elements of the visceral pleura.
-5 cm H2O after expiration of a tidal breath (i.e. at the FRC) |
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At the FRC what are the pressures of the parts of the lungs?
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The pleural pressure is opposed by the relaxed thoracic muscles and there is no difference between alveolar air pressure and external atmospheric pressure. The transpulmonary pressure is the recoil pressure (positive) that tends to collapse the lung.
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What are the pressures that a tidal inspiration generates?
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A tidal inspiration generates an additional -2.5cm H2O pressure as inspiratory muscles contract. This generates -7.5 cm H2O pleural pressure and -2.5 cm H2O negative alveolar pressure (numbers variable)
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What occurs when inspiratory muscles relax?
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Recoil of elastic elements generates positive pressure to expire alveolar air to FRC. In that sense, transpulmonary pressure can be seen as a positive pressure.
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What is the tendency and pressure of the lungs?
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Lungs tend to collapse, +5 cm H2O
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What does the chest wall do to prevent collapse?
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Chest wall exerts pressure to prevent collapse
-5 cm H2O at FRC |
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What does expansion of the chest wall result in?
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Expansion of the chest wall pulls against the recoil pressure of the lungs at pleural pressures more negative than -5 cm H2O. An additional -2.5 cm H2O will fill lungs with a tidal volume.
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What do open chest wounds result in?
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Open chest wounds or surgical procedures produce a pneumothorax (air in the chest) that can lead to collapse of one or both lungs
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What is the mediastinum?
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Compartment between the lungs
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How can pulmonary diseases be evaluated?
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On the basis of how much lung volume can be exchanged per unit of pressure generated during inspiration or expiration.
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What is lung compliance?
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The amount of filling per unit of pressure (deltaV/deltaP).
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With normal compliance, reducing transpulmonary pressure by 2-2.5 cm H2O will result in what?
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Movement of 0.5 L of air
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What are four common diseases that affect Va?
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1. Asthma
2. Pulmonary Fibrosis 3. Emphysema 4. Respiratory Distress Syndrome |
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What is asthma?
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Airway smooth muscle constricts, increases airway resistance and thus Va
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What is pulmonary fibrosis?
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Loss of elastic elements of alveoli
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What is emphysema?
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Fusion of alveoli due to smoking or other irritation
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What is Respiratory Distress Syndrome?
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Present in premature infants. Lack of surfactin reduces alveolar compliance
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Why is it when respiratory distress syndrome is evident even with a large pressure very little inspiration occurs?
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Because the biggest factor in compliance (about 2/3) is the surface tension of the thin layer of fluid lining the alveoli. In small spaces surface tension is very large.
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How is surface tension in the alveoli overcome?
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By a secretion called surfactant that lowers the surface tension of this fluid layer and greatly increases compliance
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Where is surfactin produced?
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Type II alveolar cells in late gestation so premature infants may be lacking and experience respiratory distress syndrome
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What physical problems occur when surfactin is not present?
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Compliance is greatly reduced and ventilation is very difficult, especially for a newborn with weak inspiratory muscles (respiratory distress syndrome)
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What is the composition of surfactant?
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Lipid 85-90%
Protein 10-15% |
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Of the lipids present in surfactant what is the percentage of phospholipids, neutral lipids, and glycolipids present?
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Phospholipids 85-90%
Neutral lipids 5% Glycolipids 5-10% |
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Of the phosphoplipids present in surfactant what percentage is Phosphatidylcholine, Dipalmitoly phosphatidylcholine, Phosphatidylglycerol, Phosphatidylethanolamine?
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Phosphatidylcholine 70-80%
Dipalmitoyl phosphatidylcholine 45-50% Phosphatidylglycerol 7-10% Phosphatidylethanolamine |
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What happens to the structure and function of the lungs in emphysema?
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The alveolar divisions are lost and the airspace is expanded. Also, the elasticity of the alveolar wall is lost. Thus, the lungs are more compliant but gas exchange is greatly reduced and expiration is difficult.
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What occurs to the structure and function of the lungs in asthma?
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Asthma results from airway constriction, lung compliance is near normal. Airway smooth muscle is constricted by parasympathetic stimultion or by various allergens/toxins. It is relaxed by sympathetic neurotransmitters binding to Beta2 (2 lungs receptors)
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How can obstructive pulmonary disease be evaluated?
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By measuring the percentage of a forced vital capacity expired in one second (forced expiratory volume at one second = FEV1)
It takes longer to expire air if there is an airway obstruction when compared to normal airway. |
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What occurs in the pulmonary capillary beds and what are the pressures of O2, CO2?
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Oxygen is loaded and CO2 is unloaded at the respiratory surface
PO2 = 100 mmHg PCO2 = 40 mmHg The blood flow to the lungs is 5 L/min |
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What occurs in the systemic capillary bed and what are the presures of O2, CO2?
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Oxygen leaves the blood and CO2 enters the blood
PO2 = 40 mmHg PCO2 = 45 mmHg Blood flow to the systemic capillaries is 5 L/min |
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What is the arterial pressure of O2 and CO2 of the capillary beds?
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PO2 = 100 mmHg
PCO2 = 40 mmHg |
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What is the venous pressure of O2 and CO2 of the capillary beds?
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PO2 = 40 mmHg
PCO2 = 45 mmHg |
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What is the equation for the respiratory quotient with respect to VCO2 and VO2?
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RQ = VCO2 / VO2 = 1
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what are the percentages and partial pressures of respiratory gasses ("ambient" values at sea level?
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21% O2: PO2 = 159 mmHg
0.04% CO2: PCO2 = 0.3 mmHg |
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Who developed the barometer?
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Torrichelli (mmHg = Torr)
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What occurs in alveolar ventilation?
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Mix of fresh air with residual air
Oxygen in alveolar air must become dissolved in fluid layer and diffuse into blood as a solute. Carbon dioxide must diffuse from the blood to the alveolar air and be expired. |
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How are gasses dissolved in blood?
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According to partial pressure gradient and solubility
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Why is alveolar ventilation regulated and how is it adjusted?
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Alveolar ventilation is regulated to maintain a relatively constant partial pressure for oxygen and CO2, i.e. Va is adjusted according to metabolic activity
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What occurs as air enters the airway?
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Air becomes humidified. This decreases the PO2. In the alveoli, O2 delivery to the blood and CO2 delivered by the blood lower PO2 and increase PCO2
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What does an increased Va cause and what is it called?
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A reduction of blood PCO2 = hypocapnia
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What does a decrease in Va cause and what is it called?
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A reduction in PO2 = hypoxia
An increase in PCO2 = hypercapnia |
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What occurs to the blood gasses in alveolar capillaries?
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Equilibriate with alveolar air
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When will the Va increase?
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As the vital capacity becomes utilized so alveolar gas composition is regulated during exercise
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How does the composition of alveolar air remain constant?
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The functional residual capacity is 2,300-2,400 ml and each tidal breath will exchange 350 ml of fresh air. As long as Va matches the requirement of the body for oxygen delivery and CO2 the composition of the alveolar air will remain relatively constant.
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When does alveolar ventilation increase and why?
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When oxygen uptake increases with exercise
To maintain alveolar PO2 and PCO2 |
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What is the first volume when a tidal breath is expired?
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First volume is dead space and mixed alveolar and dead space air
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What occurs to the blood gasses in alveolar capillaries?
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Equilibriate with alveolar air
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When will the Va increase?
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As the vital capacity becomes utilized so alveolar gas composition is regulated during exercise
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How does the composition of alveolar air remain constant?
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The functional residual capacity is 2,300-2,400 ml and each tidal breath will exchange 350 ml of fresh air. As long as Va matches the requirement of the body for oxygen delivery and CO2 the composition of the alveolar air will remain relatively constant.
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When does alveolar ventilation increase and why?
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When oxygen uptake increases with exercise
To maintain alveolar PO2 and PCO2 |
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What is my name?
Other name? Category? Use? |
Army-Navy Retractor
U.S. Army retracting exposing supericial wound usually used in pairs |
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What occurs to the blood gasses in alveolar capillaries?
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Equilibriate with alveolar air
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When will the Va increase?
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As the vital capacity becomes utilized so alveolar gas composition is regulated during exercise
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How does the composition of alveolar air remain constant?
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The functional residual capacity is 2,300-2,400 ml and each tidal breat will exchange 350 ml of freash air. As long as Va matches the requirement of the body for oxygen delivery and CO2 the composition of the alveolar air will remain relatively constant.
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When does alveolar ventilation increase and why?
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When oxygen uptake increases with exercise
To maintain alveolar PO2 and PCO2 |
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What is the first volume when a tidal breath is expired?
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First volume is dead space and mixed alveolar and dead space air
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What does the last approximately half of the tidal volume represent?
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The alveolar air and thus the systemic arterial blood gas composition
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How is CO2 carried by the blood?
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Dissolved CO2 bicarbonate, carbamino CO2
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The partial pressure gradient for oxygen delivery is much greater than for carbon dioxide uptake even though with a carbohydrate diet, Oxygen consumption is equivalent to CO2 production (RQ = 1). Why?
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CO2 is about 20x more soluble than O2. Thus it has a much greater diffusion coefficient so that a much smaller partial pressure gradient can result in a net flux equivalent to that of O2.
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Which PO2 is lower, Systemic arterial or alveolar?
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Systemic arterial PO2 is lower than alveolar PO2 even though alveolar capillary blood equilibrates with alveolar air.
PO2 Ambient air = 160 Moist tracheal air = 150 Alveolar gas = 102 Systemic arterial blood = 90 Mixed venous blood = 40 |
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Why is arterial PO2 only 90mmHg when it was said to be 100 mmHg?
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Mixing of oxygen depleted blood with oxygen rich blood lowers systemic arterial PO2 below that of alveolar PO2
The reason is that lung tissue consumes oxygen as well and has its own arterial branch from the aorta. Venous blood with a reduced PO2 mixes with pulmonary blood from the alveoli. This is called an "anatomical shunt" |
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What are other "physiological shunts"?
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Patent ductus arteriosus
Cardiac septal defect |
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What is alveolar ventilation?
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The amount of air exchanged in the alveoli.
Calculated as: Ventilation rate (breaths/min) x alveolar volume (ml/breaths). For a person respiring at 12 breaths/minute Va = 12 x 350 = 4,200 ml/minute |
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What is the rate of pulmonary blood flow and at any given time what volume of blood is in the lungs?
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5,000 ml/min (=systemic blood flow)
500 ml of blood in the lungs (about 10% of the total) |
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Under resting conditions how much blood is in the alveolar capillaires?
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70 ml
(spread over a tennis court) |
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What is the stroke volume at rest and how often is alveolar capillary blood replaced?
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70 ml/beat
Alveolar capillary blood is replaced about once per second (with a pulse rate of 60/min) |
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What is the importance of the Va/q ratio (q = systemic blood flow)?
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Important for maintaining the alveolar (and arterial gas) composition constant. Disease processes that affect either parameter can compromise oxygen delivery and carbon dioxide removal from the tissues
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