Respiratory Quotient (RQ)

                              Carbon Dioxide Produced/Oxygen Consumed

varies depending on foods eaten

Carbs: 1 (1 molecule O₂ used)

Average: 0.8

If <1: CO₂ less CO₂ produced than O₂ used

inflammation of pleural sac (accompanied by painful breathing)

 Severe Chest pains (from parietal pleura)

iv.    Extra fluid in pleural space ( pleural effusion)

  >1 mL fluid more 

Lungs can’t expand

Treat: aspiration, intercostal drain, chem./surgical pleurodesis

 Activate B2-receptors

Stimulated by: epinephrine, isoproterenol

Relaxes & dilates airwaysà Increase diameterà Decreased airway resistance

PNS Cholinergic Neurons

Activate Muscarinic-receptors on bronchial smooth muscle

Activated by Muscarinic, carbachol

Causes contraction & constriction of airwaysà increase resistance

Fick’s Law of diffusion

Amount of gas moving across tissue is:

 Proportional to: area

Inversely proportional to: thickness

V_x= D x A x Press difference/ membrane thickness

D: diffusion coefficient

 Rate: Movement/ unit time

recessive genetic disorder

    Defect in gene encoding for dyneinà decreased support

Reduced mucus & increased respiratory infections

volume of air entering/leaving lungs during a single breath

                                 @ Rest normal, passive breathing

    V_t: volume of air that fills alveoli AND the airways (dead space)

  ~ 500mL

                                     Additional volume inspired Above V_T

  Usually during exercise

~3000mL

                                      Additional volume expired below V_T

                                ~1200mL

                                Volume of gas left in lungs after maximal forced expiration

 When you can’t exhale even more

                                        CAN’T MEASURE WITH SPIROMETRY

                                        V_T + IRV (Tidal & reserves)

     3.5 L

                       (3500mL)

                                     Volume of air in the lungs at the end of a normal passive expiration or normal V_T

   ERV + RV

Usually about 2.4 L

                                    Volume expired after maximal inspiration

=IC + ERV

=V_T + IRV + ERV

   About 4.7 L

   Increases with gender, body size, physical conditioning

 Sum of all 4 lung volumes

                                    Maximum volume of air the lungs can hold

VC + RV

                                    Normally < 0.25

RV (volume of air trapped in lungs): 25% of total lung volume 

                                Obstructive Lung Disease: Ratio increases because RV increases

                   Restrictive Lung Disease: Ratio increases because TLC decreases

Anatomical Dead space + Functional Dead Space in alveoli

or =Anatomical Dead space

or 

= Tidal Volume x ([PaCO2-PeCO2]/PaCO2)

PeCO2: expired

Tidal Volume X fraction representing dilution of alveolar PaCO2 by dead space air (no CO2)

Tidal Volume X Breaths/min

Total rate of air movement

(Tidal Volume-Dead Space) X breaths/min

or

=(VCO2 X K)/ PACO2

VCO2: rate of CO2 production (from aerobic metab)

K: given constant

Fraction of Vital capacity forcibly expired in 1 second

Normal: 0.8 (80% of vital capacity expired in 1st second)

Restrictive Disease:

 Both FEV₁ & FVC decrease

 Change in FVC is greater--

  FEV₁ / FVC ratio INCREASES

Obstructive:

Both FEV₁ & FVC decrease

 FEV₁ decreases more--ratio decreases

Alveolar Pressure - Intrapleural Pressure

Pressure that keeps lungs inflated

Change in Volume

Change in Pressure

  Inversely correlated with lung’s elastic properties (More elastic tissueà decreased compliance)

More elastic tissueà increased elastic recoil forceà increased tendency to return to original position

P=2T/r

P: collapsing pressure

T: surface tension

r: alveolar radius

 Determines airway resistance

R=8 X Viscosity inspired air X Length

∏ X r⁴

R: airway resistance

Centriacinar: central part of lobe

Panacinar: whole lobule

Paraseptal: Near the interlobular space

Bullous: Large cystic area

 Partial pressureof gas in mixture of gases is pressure gas would exert if occupied total volume of mixture

= Barometric Pressure x Fractional concentration of the gas

    P_x= P_B x 0.21

   If  humidified: correct for water vapor pressure:

                                       P_x= (P_B-47mmH₂O) X 0.21

F changes if supplemental O2 used

Concentration of dissolved O­₂ is proportional to partial pressure of oxygen

  C_x= P_x X Solubility  Solubility constant= 0.003mL O₂ /100ml blood/mmHg

Dissolved O₂ Concentration @ Pa_O2= 0.3mL O₂/100mL blood

·      Iron in Fe⁺³ state (ferric)

Does NOT bind oxygen

 2 alpha & 2 gamm chains (replaced in the 1^st year by 2 alpha & 2 beta)

 Higher affinity for O₂ than adult Hb

Facilitates movement of oxygen from mom to fetus

 Valine instead of glutamic acid in beta chains

Oxygen affinity is less

Causes Sickle cell diseaseàfragile RBCs

P_O2 where 50% of Hb is saturated (2 heme groups bound by O₂)

 Factors that shift right:

Increased P_Co2 &

Decreased pH due to Increased metabolic activity (Bohr Effect

 Increased Temperature

  Increased 2,3-DPG

Binds Hbàdecreases affinity for O­2

Decreased P_CO2 & Increased pH

Decreased temperature

Decreased 2,3 DPGà due to decreased metabolism

Highly ventilated relative to perfusion

 Blood flow is decreased, but still ventilated

Pulmonary capillary blood has high P_O2 & low P_CO2

Low ventilation relative to perfusion

 Ventilation is low, but still have SOME BF

Pulmonary capillary blood has low P_O2 & high P_CO2

 Prolong inspiratory gasps followed by brief expiratory movement (Ketamine)

 center in lower pons stimulated

Excites inspiratory center in medulla (DRG neurons)

Results in prolonged inspiration

Prolonged APs in phrenic nerveà prolonged diaphragm contraction

In upper pons

Turns off inspiration by limiting burst of APs in phrenic nerve

 Limits the size of tidal volume (V_T) & secondarily regulates the respiratory rate

Normal breathing pattern exists without this center

 Located in dorsal respiratory group

·      Controls basic rhythm for breathing by setting inspiration frequency

·      Receives input from peripheral chemoreceptors by the glossopharyngeal (IV) & vagus nerves (X)

·      Receives input from mechanoreceptors in lungs by the vagus nerve (X)

·      Sends motor output to diaphragm via phrenic nerveo   Activity Pattern: period of quiescence (quiet) followed by burst of action potentials that increase in frequency for few seconds, then returns to quiescence

·      Diaphragm activity follows same pattern

o   When APs reach peak frequency, diaphragm contracts

·      Inspiration shortened by inhibition of inspiratory center via pneumotaxic center

Located in ventral respiratory group

·      3 Cell groups: rostral nucleus retrofacialis/caudal nucleus retro ambiguous/nucleus ambiguous

o   Each group has a distinct roles-some in inspirations & others for expiration

·      Center primarily, but not solely responsible for expiration

·      Neurons generally inactive during normal breathing, which is why expiration is generally passive

·      Center becomes active when exercising—active expiration

In aortic bodies (aortic arch) & carotid bodies (bifurcation of common carotid artery)

Send info about arterial P_O2, P_CO2, & H⁺ to the medullary inspiratory center (via CN IX & X)

Increase Breathing Rate after detecting decrease in PaO₂

   Most important thing detect

 only respond if PaO₂ is less than 60mmHg

Breathing rate is constant if PaO₂= 60-100mmHg

                                  Increase Breathing rate after detecting increase in PaCO₂

       Increase breathing rate after detecting decrease in arterial pH

 ONLY IN CAROTID BODY NOT IN AORTIC BODY

   Stimulated in metabolic acidosis: arterial pH

 Decreased HCO₃- due to increased lactic acid production/diarrhea