Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
158 Cards in this Set
- Front
- Back
|
Properties of blood-gas barrier |
Extremely thin Large surface area Increase pressure can damage |
|
|
Ficks law |
The gas passing through a tissue is proportional to its area and inversely proportional to its thickness |
|
|
Conducting zone |
NO ALVEOLI = area where no gas exchange occurs Anatomic dead space = 150ml Consists of: trachea, bronchi, bronchioles, terminal bronchioles |
|
|
Respiratory zone |
Does contain alveoli = gas exchange does occur Takes up the largest amount of space in the long - 2.5-3L Consists of: respiratory bronchioles, alveolar ducts, alveolar sacs |
|
|
Airways |
Divided into conducting and respiratory zones Volume of anatomic dead space = 150ml Volume of alveolar region = 2.5-3L Gas movement is chiefly by diffusion |
|
|
Airways (cont.) |
During inspiration = volume of the thoracic cavity INCREASES and air is drawn into the lungs Inspired air flows down to about the terminal bronchioles by bulk flow Increased air volume = increased cross sectional area Rate of diffusion = rapid |
|
|
Series of branching tubes by the pulmonary blood vessels |
Pulmonary artery —> capillaries —> pulmonary veins Pulmonary artery receives the WHOLE output of the right heart Resistance is small |
|
|
What is the additional blood system in the lung? |
Bronchial circulation = supplies conducting airways down to about the terminal bronchioles |
|
|
What is the additional blood system in the lung? |
Bronchial circulation = supplies conducting airways down to about the terminal bronchioles |
|
|
How long does blood spend in the capillaries at rest? |
0.75 seconds Transverses 2 or 3 alveoli |
|
|
What is the additional blood system in the lung? |
Bronchial circulation = supplies conducting airways down to about the terminal bronchioles |
|
|
How long does blood spend in the capillaries at rest? |
0.75 seconds Transverses 2 or 3 alveoli |
|
|
Typical lung volumes |
1) tidal volume = 500ml 2) anatomic dead space = 150ml 3) alveolar gas = 3000ml 4) pulmonary capillary blood = 70ml |
|
|
What is the additional blood system in the lung? |
Bronchial circulation = supplies conducting airways down to about the terminal bronchioles |
|
|
How long does blood spend in the capillaries at rest? |
0.75 seconds Transverses 2 or 3 alveoli |
|
|
Typical lung volumes |
1) tidal volume = 500ml 2) anatomic dead space = 150ml 3) alveolar gas = 3000ml 4) pulmonary capillary blood = 70ml |
|
|
Typical lung flows |
1) total ventilation = 7500 2) frequency = 15 3) alveolar ventilation = 5250 4) pulmonary blood flow = 5000 |
|
|
5 lung volumes |
Tidal volume Residual volume Vital capacity Functional residual capacity Total lung capacity |
|
|
5 lung volumes |
Tidal volume Residual volume Vital capacity Functional residual capacity Total lung capacity |
|
|
Tidal volume |
Normal breathing = eupnoea |
|
|
Vital capacity |
Exhaled volume after a mac inhalation |
|
|
Residual volume |
Air left in the lung after a max exhalation |
|
|
Functional residual capacity |
Air left in lungs after a normal exhalation |
|
|
Total lung capacity |
Volume of air in the lungs after a max inspiration |
|
|
2 ways of measuring FRC or residual volume |
1) helium dilution 2) body plethysmograph |
|
|
Helium dilution |
Helium = insoluble in blood After some breaths the helium in the lungs and in the spirometer become the same Measures communicating gas or ventilated lung volume |
|
|
Body plethysmograph |
Lung volume INCREASES, box pressure INCREASES, gas volume DECREASES |
|
|
Boyles law |
Pressure x volume = constant (at a constant temperature) |
|
|
What lung capacities can be measured by a simple spirometer? |
Tidal volume Vital capacity |
|
|
What lung volumes need additional measurement? |
Total lung capacity Functional residual capacity Residual volume |
|
|
Ventilation |
Volume of air entering the lung is slightly LARGER because more 02 is used than C02 is produced |
|
|
Alveolar ventilation |
The amount of air available for gas exchange Of each 500ml about 150ml remains in the anatomic dead space Alveolar ventilation can be increased by either increasing tidal volume or respiratory frequency —> increasing tidal volume is more effective |
|
|
Alveolar ventilation equation |
VA = (VC02/PC02) x K If alveolar ventilation is HALVED, the alveolar and arterial PC02 will DOUBLE |
|
|
What method is used to measure anatomic dead space? |
Fowler’s method |
|
|
What method is used to measure physiologic dead space? |
Bohr’s method |
|
|
Physiologic dead space |
In normal subjects - the PC02 in alveolar gas and that in arterial blood are virtually IDENTICAL The LARGER the physiologic dead space = the GREATER the total ventilation |
|
|
Bohr’s method vs Fowler’s method |
Fowler’s: anatomic dead space - measures the volume of the CONDUCTING zone Bohr’s: physiologic dead space - measures volume of the lung that does NOT eliminate C02 In normal subjects - the volumes are nearly the same Patients with lung disease = larger physiologic dead space |
|
|
Total ventilation |
Tidal volume x respiratory frequency |
|
|
What region of the lung ventilates better? |
The LOWER regions of the lungs ventilate better than the upper regions Ventilation per unit volume is greatest near the bottom Subject on side = lung is best ventilated |
|
|
3 basic elements of the respiratory control system |
1) sensors: gather info and feed to central controllers 2) central controllers: coordinates info and sends impulses to the effectors 3) effectors: respiratory muscles which cause ventilation |
|
|
3 main groups of neutrons in the brainstem |
1) medullary respiratory centre 2) apneustic centre 3) pneumotaxic centre |
|
|
Respiratory centres |
Responsible for generating the rhythmic pattern of inspiration and expiration Located on the medulla and pons Major output is to the phrenic nerves |
|
|
Medullary respiratory centre |
Located in reticular formation Pre-botzinger complex Dorsal respiratory group: inspiration and basic rhythm of ventilation Central respiratory group: expiration |
|
|
Apneustic centre |
Located in lower pons Excitatory effect |
|
|
Apneustic centre |
Located in lower pons Excitatory effect |
|
|
Pneumotaxic centre |
Located in upper pons Inhibits inspiration = regulate inspiration volume and respiratory rate Provides “fine tuning” |
|
|
Cortex |
Breathing is under voluntary control and the cortex can override the functions of the brainstem If a gas mixture is inhaled that raises the arterial PC02 and lowers the P02 = a further period of breath holding is possible |
|
|
Effectors |
Respiratory muscles: Diaphragm, intercostals, abdominal muscles, accessory muscles Important for these muscles to work together in a coordinated manner |
|
|
Sensors: Central Chemoreceptors |
Located near the ventral surface of the medulla Surrounded by ECF and responds to changes in H+ concentration Increase in H+ concentration stimulates ventilation where a decrease inhibits it CSF is the most important ** C02 decreases CSF pH = stimulating the chemoreceptor C02 easily diffuses from blood vessels to CSF Sensitive to the PC02 but not P02 of blood Respond to change in pH of ECF/CSF when C02 diffuses OUT of cerebral capillaries |
|
|
Sensors: Peripheral Chemoreceptors |
Located on the carotid and aortic bodies 2 types of glomus cells: Type I: large content of dopamine and close apposition to carotid sinus nerve Type II: “supporting cells” (non-neural) Neurotransmitter released from glomus cell Respond to a DECREASE in arterial P02 and pH and an INCREASE in arterial PC02 |
|
|
Is arterial P02 or PC02 the most important stimulus to ventilation? |
PC02 |
|
|
Where does most of the stimulus come from? |
Central chemoreceptors BUT the peripheral chemoreceptors also contribute and their response is faster |
|
|
Where does most of the stimulus come from? |
Central chemoreceptors BUT the peripheral chemoreceptors also contribute and their response is faster |
|
|
Is the response magnified if the arterial P02 is higher or lower? |
Lower |
|
|
What chemoreceptors is involved in the ventilator response to hypoxia? |
Peripheral chemoreceptors |
|
|
Are the pressures in the pulmonary circulation high or low? |
Low And low resistance Walls of the pulmonary artery are thin |
|
|
Systemic circulation |
Delivers blood to various organs Direct blood from one region to the other |
|
|
Systemic circulation |
Delivers blood to various organs Direct blood from one region to the other |
|
|
Lung circulation |
Accepts entire cardiac output Arterial pressure is LOW |
|
|
Transmural pressure |
Pressure difference between the inside and outside if the capillaries |
|
|
What are the 3 blood pressures |
Systolic blood pressure Diastolic blood pressure Mean arterial pressure |
|
|
Systolic blood pressure |
The HIGHEST pressure in the vascular system generated during CONTRACTION |
|
|
Systolic blood pressure |
The HIGHEST pressure in the vascular system generated during CONTRACTION |
|
|
Diastolic blood pressure |
The LOWEST pressure in the vascular system during RELAXATION |
|
|
Systolic blood pressure |
The HIGHEST pressure in the vascular system generated during CONTRACTION |
|
|
Diastolic blood pressure |
The LOWEST pressure in the vascular system during RELAXATION |
|
|
Mean arterial pressure |
Average pressure MAP = 2/3DBP + 1/3SBP MAP = DBP + [0.33(SBP-DBP)] |
|
|
What is a pressure gradient? |
Gas moves from a high pressure to a low pressure within the vessel |
|
|
Alveolar and extra-alveolar vessels |
Alveolar vessels are exposed to alveolar pressure and are compressed if this increases Extra-alveolar vessels are exposed to pressure LESS than alveolar and are pulled open by the radial traction of the surrounding parenchyma |
|
|
Alveolar and extra-alveolar vessels |
Alveolar vessels are exposed to alveolar pressure and are compressed if this increases Extra-alveolar vessels are exposed to pressure LESS than alveolar and are pulled open by the radial traction of the surrounding parenchyma |
|
|
What can change blood flow? |
Pressure and resistance Changing resistance has a larger effect on blood flow Resistance to blood flow equation * nL /r4 |
|
|
Vasoconstriction and vasodilation |
Vasoconstriction: radius of the vessel DECREASES so blood flow DECREASES Vasodilation: radius of the vessel INCREASES so blood flow INCREASES |
|
|
Poiseuille’s Law |
(Delta P)(r4)(Pi)/(nL)(8) P = pressure R = radius L = length N = viscosity |
|
|
Pulmonary vascular resistance |
Resistance to flow that must be overcome to push blood through the circulatory system Typically very LOW |
|
|
Pulmonary vascular resistance |
Resistance to flow that must be overcome to push blood through the circulatory system Typically very LOW DECREASE on exercise because of recruitment and distention of capillaries INCREASE at high and low lung volumes |
|
|
PVR: recruitment and distention |
Recruitment: closed vessels conduct blood Distention: vessels increase in caliber |
|
|
3 zones of distribution of blood flow |
Zone 1: PA > Pa > Pv Zone 2: Pa > PA > Pv Zone 3: Pa > Pv > PA |
|
|
Measurement of pulmonary blood flow - what principle? |
The volume of blood passing though the lungs each minute can be calculated using the Ficks principle |
|
|
Hypoxia pulmonary vasoconstriction |
Contraction of smooth muscles in the walls of the small arterioles Direct effect of the low P02 on vascular smooth muscle Vessel wall becomes hypoxic Directs blood flow away from hypoxic regions Critical at birth in the transition from placental to air breathing |
|
|
Water balance in lung obeys what law? |
Starlings law —> fluid exchange across the capillary endothelium Force pushing the fluid OUT minus the hydrostatic pressure in the interstitial fluid (Pc-Pi) |
|
|
Metabolic functions of the lung |
Important = arachidonic acid metabolites Only organ except the heart that receives entire circulation |
|
|
Metabolic functions of the lung |
Important = arachidonic acid metabolites Only organ except the heart that receives entire circulation |
|
|
What is the pressure of H20 molecules in humidified air? Use in an equation? |
0.2093(760-47) = 149mmHg This is PI02 Pressure of 02 molecules in humidified air = 47mmHg |
|
|
Average air pressures |
Oxygen: 14.4% C02: 5.5% Nitrogen: 80% Alveolar P02: 0.145(760-47)=103 Alveolar PC02: 0.055(760-47)=39 |
|
|
4 causes of hypoxemia |
1) hypoventilation 2) diffusion limitation 3) shunt 4) ventilation-perfusion inequality |
|
|
Hypoventilation |
If alveolar ventilation is abnormally LOW = alveolar P02 FALLS therefore PC02 RISES PC02 = VC02/VA x K If VA is HALVED, PCO2 is DOUBLED |
|
|
Alveolar gas equation |
Relationship between the fall in P02 and rise in PC02 PA02 = PI02 - (PAC02/R) + F R = respiratory exchange ratio |
|
|
Alveolar gas equation |
Relationship between the fall in P02 and rise in PC02 PA02 = PI02 - (PAC02/R) + F R = respiratory exchange ratio |
|
|
Diffusion limitation |
Rarely causes hypoxemia bc the red blood cells spend enough time in the pulmonary capillary to allow nearly complete equilibrium |
|
|
Shunt |
Blood that enters the arterial system without going through ventilated areas of the lung Depressed arterial P02 Hypoxemia CANNOT be abolished by giving the subject 100% 02 - bc shunted blood is never exposed to alveolar P02 Shunt equation ** |
|
|
Shunt |
Blood that enters the arterial system without going through ventilated areas of the lung Depressed arterial P02 Hypoxemia CANNOT be abolished by giving the subject 100% 02 - bc shunted blood is never exposed to alveolar P02 Shunt equation ** |
|
|
Ventilation-perfusion ratio/inequality |
Determines the gas exchange in any single lung unit Regional differences in the upright human lung cause a pattern of regional gas exchange VA/Q inequality impairs the uptake or elimination of all gases by the lung Hypoxia cannot be eliminated by increasing ventilation Measure using alveolar gas equation |
|
|
How is oxygen carried in the blood? |
1) dissolved 2) bound to hemoglobin |
|
|
Dissolved 02 obeys which law? |
Henry’s law = the amount dissolved is proportional to the partial pressure This way of transporting 02 is inadequate - additional method is required |
|
|
Dissolved 02 obeys which law? |
Henry’s law = the amount dissolved is proportional to the partial pressure This way of transporting 02 is inadequate - additional method is required |
|
|
02 dissociation curve: 02 capacity |
The maximum amount of 02 that can be combined with Hb Normal blood has around 15g or Hb 02 capacity is about 20.8ml02/100ml of blood |
|
|
Dissolved 02 obeys which law? |
Henry’s law = the amount dissolved is proportional to the partial pressure This way of transporting 02 is inadequate - additional method is required |
|
|
02 dissociation curve: 02 capacity |
The maximum amount of 02 that can be combined with Hb Normal blood has around 15g or Hb 02 capacity is about 20.8ml02/100ml of blood |
|
|
02 saturation equation |
(02 combined w Hb/02 capacity)x 100 |
|
|
How is carbon dioxide carried in the blood? |
1) dissolved 2) bicarbonate 3) carbamino compounds |
|
|
How is carbon dioxide carried in the blood? |
1) dissolved 2) bicarbonate 3) carbamino compounds |
|
|
Dissolved C02 |
Obeys Henry’s Law - C02 is 20x more soluble than 02 Dissolved C02 plays a significant role in its carriage |
|
|
How is carbon dioxide carried in the blood? |
1) dissolved 2) bicarbonate 3) carbamino compounds |
|
|
Dissolved C02 |
Obeys Henry’s Law - C02 is 20x more soluble than 02 Dissolved C02 plays a significant role in its carriage |
|
|
C02 carriage: bicarbonate |
When the concentration of ions increases within the RBC, HCO3 diffuses OUT but H+ cannot Haldane effect: deoxygenation of the blood increases the ability to carry C02 |
|
|
How is carbon dioxide carried in the blood? |
1) dissolved 2) bicarbonate 3) carbamino compounds |
|
|
Dissolved C02 |
Obeys Henry’s Law - C02 is 20x more soluble than 02 Dissolved C02 plays a significant role in its carriage |
|
|
C02 carriage: bicarbonate |
When the concentration of ions increases within the RBC, HCO3 diffuses OUT but H+ cannot Haldane effect: deoxygenation of the blood increases the ability to carry C02 |
|
|
C02 carriage: carbamino compounds |
Not very significant |
|
|
Transport of C02 |
Bicarbonate reactions are a major source of expired C02 C02 carriage is enhanced by deoxygenation if the blood |
|
|
Transport of C02 |
Bicarbonate reactions are a major source of expired C02 C02 carriage is enhanced by deoxygenation if the blood |
|
|
C02 dissociation curve |
C02 curve is steeper and more linear than the 02 curve Shifted to the right by an increase in S02 |
|
|
Acid-base status |
Transport of C02 has a profound effect on the acid-base status of the blood |
|
|
Acid-base status |
Transport of C02 has a profound effect on the acid-base status of the blood |
|
|
What do Davenport diagrams show? |
Changes in PC02, pH and HC03 |
|
|
Acid-base status |
Transport of C02 has a profound effect on the acid-base status of the blood |
|
|
What do Davenport diagrams show? |
Changes in PC02, pH and HC03 |
|
|
Respiratory Acidosis |
Caused by: 1) INCREASE in PC02 2) DECREASE in HCO3/PC02 ratio 3) DECREASE pH |
|
|
Acid-base status |
Transport of C02 has a profound effect on the acid-base status of the blood |
|
|
What do Davenport diagrams show? |
Changes in PC02, pH and HC03 |
|
|
Respiratory Acidosis |
Caused by: 1) INCREASE in PC02 2) DECREASE in HCO3/PC02 ratio 3) DECREASE pH Whenever PC02 increases the bicarbonate must also increase |
|
|
Respiratory Alkalosis |
Caused by: 1) DECREASE in PC02 2) INCREASE in HC03/PC02 ratio 3) INCREASE pH Decrease in PC02 is caused by hyperventilation |
|
|
Metabolic Acidosis |
The ratio of HC03 to PC02 decreases this depressing the pH Metabolic = primary change in HCO3 |
|
|
Metabolic Acidosis |
The ratio of HC03 to PC02 decreases this depressing the pH Metabolic = primary change in HCO3 |
|
|
Metabolic Alkalosis |
Increase in HC03 raises the HCO3/PC02 ratio and this the pH |
|
|
What are the 3 mechanisms that regulate pH? |
1) chemical buffers 2) ventilatory buffer 2) renal buffer |
|
|
Bar headed geese |
More effective breathing pattern Larger lungs Increased hemoglobin-02 affinity Larger hearts More blood vessels |
|
|
EIAH |
Significant threat to systemic 02 transport Reduction is Sa02 and Ca02 rather than PA02 Abnormal gas exchange Prevalence: 50% young, adult, highly fit males Causes: absence of hyperventilation and widened A-aD02 |
|
|
COPD |
Progressive condition characterized by lung and airway dysfunction |
|
|
COPD |
Progressive condition characterized by lung and airway dysfunction |
|
|
Symptoms of COPD |
Coughing and wheezing Excess sputum production Dyspnea during light exercise Dyspnea during rest in severe COPD |
|
|
COPD |
Progressive condition characterized by lung and airway dysfunction |
|
|
Symptoms of COPD |
Coughing and wheezing Excess sputum production Dyspnea during light exercise Dyspnea during rest in severe COPD |
|
|
COPD: emphysema and chronic bronchitis |
Emphysema: destruction of support tissue Chronic bronchitis: inflammation irritation |
|
|
COPD |
Progressive condition characterized by lung and airway dysfunction |
|
|
Symptoms of COPD |
Coughing and wheezing Excess sputum production Dyspnea during light exercise Dyspnea during rest in severe COPD |
|
|
COPD: emphysema and chronic bronchitis |
Emphysema: destruction of support tissue Chronic bronchitis: inflammation irritation |
|
|
Causes of COPD |
1) smoking = major risk factor (85-90%) 2) environmental = dust, gases, fumes, pollution 3) infection 4) genetic link Decrease Pv02 and increase PvC02 and CO |
|
|
The lung wants to (blank) and the chest wants to (blank) |
Collapse Expand |
|
|
The lung wants to (blank) and the chest wants to (blank) |
Collapse Expand |
|
|
Rest is a (blank) process Physical activity is a (blank) process |
Passive Active |
|
|
The lung wants to (blank) and the chest wants to (blank) |
Collapse Expand |
|
|
Rest is a (blank) process Physical activity is a (blank) process |
Passive Active |
|
|
Inspiration is: Expiration: |
Active Passive |
|
|
The lung wants to (blank) and the chest wants to (blank) |
Collapse Expand |
|
|
Rest is a (blank) process Physical activity is a (blank) process |
Passive Active |
|
|
Inspiration is: Expiration: |
Active Passive |
|
|
Most important muscle of inspiration |
Diaphragm = supplied by the phrenic nerve (from high cervical region) |
|
|
Elastic properties of the lungs |
Pressure-volume curve Compliance Surface tension |
|
|
What pressure are we changing when the diaphragm contracts? |
Intrathoracic = making lung space more negative relative to atmosphere |
|
|
Pressure-volume curve of lung |
Nonlinear - lung becomes stiffer at higher volumes Compliance is the slope of deltaV/deltaP Behaviour depends on both structural proteins (collagen and elastin) and surface tension |
|
|
Pressure-volume curve of lung |
Nonlinear - lung becomes stiffer at higher volumes Compliance is the slope of deltaV/deltaP Behaviour depends on both structural proteins (collagen and elastin) and surface tension |
|
|
Compliance |
Slope of the pressure-volume curve |
|
|
Reduced compliance |
Pulmonary fibrosis Alveolar edema Increased venous pressure |
|
|
Increased compliance |
Emphysema Normal aging |
|
|
Laminar flow obeys what law? |
Poiseuilles law Reynolds number |
|
|
Laminar flow |
Resistance is inversely proportional to the 4th power of the radius |
|
|
Turbulent flow |
Likely to occur at a HIGH Reynolds number |
