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Physio Exam 4
Respiratory System
41
Physiology
Graduate
11/09/2009

Additional Physiology Flashcards

 


 

Cards

Term

                               Respiratory Quotient (RQ)

Definition

                              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

Term
Pleurisy
Definition

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

Caused by: viral infections, pneumonia, TB, Cancer

Term
SNS Adrenergic Neurons
Definition


 Activate B2-receptors

 

Stimulated by: epinephrine, isoproterenol

Relaxes & dilates airwaysà Increase diameterà Decreased airway resistance

Term

PNS Cholinergic Neurons

Definition

Activate Muscarinic-receptors on bronchial smooth muscle

 

Activated by Muscarinic, carbachol

Causes contraction & constriction of airwaysà increase resistance

Term

Fick’s Law of diffusion

Definition

Amount of gas moving across tissue is:

 

 Proportional to: area

Inversely proportional to: thickness

Vx= D x A x Press difference/ membrane thickness

D: diffusion coefficient

 Rate: Movement/ unit time

Term
Pores of Kohn
Definition
 Walls between adjacent alveolià allows airflow between adjacent alveoli (collateral ventilation)
Term
Ciliary Dyskinesia
Definition

recessive genetic disorder

 

    Defect in gene encoding for dyneinà decreased support

 

Reduced mucus & increased respiratory infections

Term
Tidal Volume
Definition

volume of air entering/leaving lungs during a single breath

                                 @ Rest normal, passive breathing

                                   

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

                                   

  ~ 500mL

Term
Inspiratory Reserve Volume (IRV)
Definition

 

                                     Additional volume inspired Above VT

                                   

  Usually during exercise

                  

~3000mL

Term
Expiratory Reserve Volume (ERV)
Definition

 

                                      Additional volume expired below VT

                                ~1200mL

Term
Residual Volume (RV)
Definition

 

                                Volume of gas left in lungs after maximal forced expiration

                                   

 When you can’t exhale even more

                                        CAN’T MEASURE WITH SPIROMETRY

Term
Inspiratory Capacity (IC)
Definition

 

                                        VT + IRV (Tidal & reserves)

                                   

 

     3.5 L

                       (3500mL)

Term
Functional Residual Capacity (FRC)
Definition

 

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

                                   

   ERV + RV

Usually about 2.4 L

 

Term
Vital Capacity (VC)
Definition

 

                                    Volume expired after maximal inspiration

                                   

=IC + ERV

=VT + IRV + ERV

                                  

   About 4.7 L

                                   

   Increases with gender, body size, physical conditioning

Decreases with age

Term
Total Lung Capacity (TLC)
Definition

 Sum of all 4 lung volumes

 

                                    Maximum volume of air the lungs can hold

                                   

VC + RV

(VT + IRV + ERV + RV)

Term
 [RV/TLC ratio]
Definition

 

                                    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

 

 

Term
Physiological Dead Space
Definition

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)

Term
Minute Ventilation
Definition

Tidal Volume X Breaths/min

 

Total rate of air movement

Term
Alveolar Ventilation (rate)
Definition

(Tidal Volume-Dead Space) X breaths/min

 

or

 

=(VCO2 X K)/ PACO2

 

VCO2: rate of CO2 production (from aerobic metab)

K: given constant

Term
FEV1/FVC ratio
Definition

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

 


 

Term
Transmural Pressure
Definition

Alveolar Pressure - Intrapleural Pressure

 

Pressure that keeps lungs inflated

Term
Compliane
Definition

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

 

Term
Law of Laplace
Definition

P=2T/r

 

P: collapsing pressure

T: surface tension

r: alveolar radius

Term
Poiseille's Law
Definition

 Determines airway resistance

 

R=8 X Viscosity inspired air X Length

∏ X r4

 

R: airway resistance

Term
Emphysema Types
Definition

Centriacinar: central part of lobe

Panacinar: whole lobule

Paraseptal: Near the interlobular space

Bullous: Large cystic area

 

Term
Dalton's Law of Partial Pressures of Gas
Definition

 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

                         

    Px= PB x 0.21

 

   If  humidified: correct for water vapor pressure:

                                       Px= (PB-47mmH2O) X 0.21

 

F changes if supplemental O2 used

 

Term
Henry's Law
Definition

Concentration of dissolved O­2 is proportional to partial pressure of oxygen

  Cx= Px X Solubility  Solubility constant= 0.003mL O2 /100ml blood/mmHg

Dissolved O2 Concentration @ PaO2= 0.3mL O2/100mL blood

 

Term
Methemoglobin
Definition


·      Iron in Fe+3 state (ferric)

Does NOT bind oxygen

 

Term
Fetal Hb
Definition

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

 

 Higher affinity for O2 than adult Hb

 

Facilitates movement of oxygen from mom to fetus


 

Term
Hemoglobin S
Definition

 Valine instead of glutamic acid in beta chains

 

Oxygen affinity is less

 

Causes Sickle cell diseaseàfragile RBCs

 

Term
 P50
Definition

PO2 where 50% of Hb is saturated (2 heme groups bound by O2)

 

Term
Right Shift of Hb-Oxygen Curve
Definition

 

 Factors that shift right:

Increased PCo2 &

 

Decreased pH due to Increased metabolic activity (Bohr Effect

 Increased Temperature

 

  Increased 2,3-DPG

Binds Hbàdecreases affinity for O­2


 

Term
Factors that Increase Hb Affinity for Oxygen
Definition

Decreased PCO2 & Increased pH

   

Decreased temperature

 

Decreased 2,3 DPGà due to decreased metabolism

 

Term
High V/Q
Definition


Highly ventilated relative to perfusion

 Blood flow is decreased, but still ventilated

Pulmonary capillary blood has high PO2 & low PCO2

 

Term
Low V/Q
Definition

Low ventilation relative to perfusion

 Ventilation is low, but still have SOME BF

Pulmonary capillary blood has low PO2 & high PCO2

 

Term
Apneustic Center
Definition

 

 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

 

Term
Pneumotaxic Center
Definition

In upper pons

 

Turns off inspiration by limiting burst of APs in phrenic nerve

 

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

 

Normal breathing pattern exists without this center

 

Term
Inspiratory Centers
Definition

 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

 

 

Term
Expiratory Centers
Definition

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

 

Term
Central Chemoreceptors
Definition
1. Most important regulators
2. Control minute-minute breathing
3. Located on ventral surface of medulla, near exit point of CN IX (glossopharyngeal) & CN X (vagus)
a. Short distance from medullary inspiratory center
4. Communicate directly w/ inspiratory center
5. Senses change in pH of CSF

Respond directly to change in pH & indirectly to CO2 levels
Term
Peripheral Chemoreceptors
Definition

 

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

Send info about arterial PO2, PCO2, & 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

 

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