Final Flashcards
In what portion ofthe lungs does alveolar deadspace normally occur?
Apices
Airway Resistance Formula
Change in pressure/flow
Normal Airway Resistance
0.5-2.5 cmH2O/L/sec
Under resting metabolic conditions, how much carbon dioxide does a normal adult produce per minute?
200ml/min
What is the term for the opposition to ventilation caused by the movement of gas through the conducting airways?
Airway Resistance
Compliance Formula
- Volume/Pressure
- 1/elastance
Elastance Formula
- Pressure/Volume
- 1/compliance
Total Compliance Formula
Lung compliance x Chest wall compliance/ Lung compliance + chest wall compliance
Heart Pathway
Right Atrium->Right Ventricle->Pulmonary Artery->Pulmonary Capillaries->Pulmonary Vein->Left Atrium->Left Ventricle->Aorta->Systemic Capillaries->Vena Cava
What kind of blood does the Pulmonary Arteries and Veins carry?
Pulmonary Artery: deoxygenated blood. Only artery in body that carries deoxygenated blood.
Pulmonary Vein: oxygenated blood. Only vein in the body that carries oxygenated blood.
Whats the PaO2 in the pulmonary artery?
40 mmHg
Whats the PaCO2 in the pulmonary artery?
46 mmHg
Whats the PaO2 in the pulmonary vein?
100 mmHg
Whats the PaCO2 in the pulmonary vein?
40 mmHg
Time Constant Formula
Resistance x Compliance
Pseudoglandular Stage
- 6th, 7th-16th week
- lung resembles hollow tube like (glandular) structure surrounded by mesenchymal cells
- lined with cuboidal epithelial cells
- first type II pneumocytes appear
- terminal bronchioles begin to differentiate to form respiratory bronchioles and alveolar ducts
- cartilage begins to form around larger airways and smooth muscles forms around airways and major blood vessels
- production of fetal lung liquid
- NOT capable of extrauterine survival
Canalicular Stage
- canaliculi (canals) begin to branch out from terminal bronchioles
- all alveoli developed from a single terminal bronchiole form an acinus
- capillaries surround the acini in dense layer making gas exchange possible
- cuboidal Type II pneumocytes flatten into Type I pneumocytes
- alveolar septa start becoming thinner
Saccular Stage
- 26th week-birth
- peripheral air spaces have saclike appearance
- sacs distal to terminal bronchioles begin to lengthen
- 1st generation of sacs that will become alveoli are formed
- interstitial material compressed, capillary and alveoli move closer
- Type II cells produce and store pulmonary surfactant
Alveolar Stage
- 32nd week-8th or 10th year of life
- formation of the hexagonal shaped alveoli
- terminal saccule become enclosed in tissue sheath
- epithelial cells form crests that develop into alveolar septa
- septa separates individual alveoli and increase surface area for gas exchange
- number of alveoli provide 3-4m^2 of gas exchange surface area
- adult lung has a gas exchange surface area of 50-100m^2
Fick’s Law of diffusion
rate of diffusion of a gas through a tissue sheet is directly proportional to the surface area
Dead Space
1 cc or 1 ml per lb of body weight
-gas that doesn’t participate in gas exchange
physiological dead space= anatomical dead space + alveolar dead space
Inspiratory Expiratory Ratio
Total Cycle Time= 60/Respiratory Rate Inspiratory Time + Expiratory Time = TCT TI=TCTx I/ I+E End Expiratory Pause = 25% of TE TE/TI= I:E
Dead Space Tidal Volume Ratio
VD/VT= (PaCO2-PECO2)/PaCO2
VD=VT(PaCO2-PECO2)/PaCO2
Alveolar Minute Ventilation
V(with dot on top)A= (VT-VD) x RR
Minute Ventilation
V(with dot)= VT x RR
Hemoglobin Arterial Oxygen Saturation Equation
SaO2= HbO2/Total Hb x 100
Oxygen Carrying Capacity of blood
grams/dl of Hb x 1.34ml/g
Total Oxygen Content of the blood equation
CaO2=(0.003 x PaO2)+(Hb total x 1.34 x SaO2)
Hemoglobin Saturation
PaO2 (torr) | Saturation 27 torr - 50% 40 torr - 70% 50 torr - 80% 60 torr - 90% 100 > more torr - 97%-100%
Alveolar Air Equation
PAO2= FiO2(PB-PH2O)-(PACO2/0.8) PH2O= 47mmHg PaCO2= 40mmHg
Oxyhemoglobin Dissociation Curve to the RIGHT
- occurs in the SYSTEMIC capillaries
- pH decreases: blood picks up CO2 causes pH decreases, lowers affinity for Oxygen
- Temperature increases, affinity for oxygen decreases when exercising
- occurs during hypoventilation
- increased 2,3 DPG, promotes O2 unloading and reduces affinity for O2
- RBCs produces more 2,3DPG when metabolically active, more when temperature is high
Oxygen Dissociation Curve to the LEFT
- occurs in the PULMONARY capillaries
- pH increases, when venous blood returning to the lungs and CO2 diffuses out causes pH increase
- this increases affinity of Hb for O2 and enhances its uptake of Oxygen from alveoli
- body temperature goes down, Oxygen affinity goes up
- 2,3 DPG production decreases, O2 affinity goes up
- occurs during hyperventilation
- RBCs producing less 2,3DPG
Oxygen Delivery Formula
D(with dot)O2= CaO2 x Q
Oxygen minute delivery)=(oxygen content) x (Cardiac Output
Respiratory Exchange Ratio
R=V(with dot)CO2/V(with dot)O2
R=(minute CO2 production)/(minute O2 consumption)
Normal Respiratory Exchange Ratio
R= 200/250= 0.8
Under resting metabolic conditions, how much Oxygen does the body consume per minute?
250ml/min
Hypoxemia
-when the PaO2 is lower than the predicted normal value based on age
Causes:
1. Inadequate amount of )2 is reaching the alveoli
-hypoventilation, tachypnea (rapid shallowing breathing)
2. Inadequate amount of O2 crossing A/C membrane
-low PB causing a low PO2, low FiO2
Haldane’s Effect
- describes how high levels of O2 in the lungs increase Hb’s affinity for O2 and decreases its affinity for CO2
- high O2 levels speed up loading of the O2 onto Hb at the lungs producing saturated Hb
- HbO2 has a low affinity for CO2 so unloading and loading of O2 are sped up at the lungs
- also works to a lesser degree in tissues
Bohr’s Effect
- describes how high levels of CO2 and H+ in the tissue decrease Hb’s affinity for O2 and increases affinity for CO2
- high CO2 and H+ speed up unloading of O2 to cells and producing deoxygenated Hb
- Deoxygenated Hb has high affinity for CO2 so loading of CO2 and unloading of O2 are sped up at the tissues
- also works to a lesser degree at the lungs
Hypoventilation
- CO2 levels increase, breathing too slow
- can cause hypoxemia and hypoxia
- can be caused by medication overdose causing the central chemoreceptors to become depressed
- shifts curve to the right
Hyperventilation
- O2 levels rise, CO2 levels fall
- breathing too fast causes exhaling of CO2 faster than cells are producing it
- shifts curve to the left
How does the changes in blood pH impact Hb affinity for O2? (Bohr’s Effect)
- low pH shifts curve to the right, saturation decrease and Hb affinity decreases
- high pH shifts curve to the left, Hb saturated and Hb affinity increases
Percent Relative Humidity Formula
%RH=content/capacity x 100
Normal Body Temperature alveolar capacity at body temp= 44 mg/L
Formula for Density of Air
Density=m/v
Density of Air= (FN2 x gmwN2) + (FO2 x gmwO2)/ 22.4 L
STP=22.4
F->C->K
- C= 5/9(F-32)
- K=C+273
- F=(9/5 x C) +32
Hydrostatic Pressure Formula
- PL= Height x Density
- density = 1 g/cm3
Hamburger Effect
- when chloride ions shift from plasma into RBC
- Chloride shift
- to maintain a concentration equilibrium across cell membrane
- reverse chloride shift occurs in pulmonary capillaries
Boyles Law
V1 x P1= V2 x P2
Charles Law
V1/T1 = V2/T2
Gay Lussacs Law
P1/T1 = P1/T1
Henry’s Law
The amount of dissolved gas is proportional to its partial pressure in the gas phase
Poiseuille’s Law
Fluid flowing through a tube looses pressure as energy is converted to heat while overcoming frictional resistance
Obstructive diseases
- high compliance and low elastance
- pressure becomes positive to get air out
- emphysema (COPD)
- takes longer to inhale and exhale
Restrictive Diseases
- low compliance, high elastane
- asthma, pneumonia
- shorter time inhaling and exhaling
What causes the baby to take it’s first breath?
- central chemoreceptor cells in the medulla signal the respiratory muscles to work in response to receptor stimulation by
- acidosis
Pump Handle movement of ribs
- muscle contraction rotates the rib heads around the costovertebral joints, pulls up the distal ends of the ribs, especially ribs 2-7
- lifting the sternum and displacing it anteriorly
- increases the anteroposterior dimension of thorax
Bucket Handle movement of ribs
- same muscle contraction rotates the long axis of the ribs and reduces their downward slant
- increases the lateral (transverse) dimension of the thorax
What muscles are the primary respiratory muscles?
- Diaphragm and external intercostals
- both used during quiet breathing and exercising
Maximal contraction for the diaphragm is?
- 10 cm
- normal contraction: 1.5 cm (1-2cm)
Internal intercostal muscles
- responsible for forced exhalation
- depress the ribs and decrease space in the chest cavity
External intercostal muscles
- responsible for forced and quiet inhalation
- raise the ribs and expand the chest cavity
What muscles are used when in the Tripod position?
Pectoralis muscles
-allows the patient to fix the head and the pectoral (shoulder) girdle allowing the pectoralis muscles to general some anterior thoracic lift
Trapezius Muscle Use
-produces visible clavicular lift where the clavicle rise > 5 cm with each inspiration
Retractions
- when airway resistance is high the patient must produce a large trans-chest wall pressure gradient
- causes atmospheric pressure to press the skin of the chest tightly against the ribs during spontaneous inspiration
Costophrenic Angles
-formed by the costophrenic recesses, the points where the hemidiaphragms meet the chest wall