Respritory Physiology

Front 1

respiratory quotient (RD,R)

Back 1

is the ratio of the rate of CO2 produced/ rate of O2 consumed. Under normal diet conditions R= 0.8.

R= Vco2 / V o2

Front 2

The pleural sac lies between the chest wall and the lung. The intrapeural fluid in the sac is under a negative pressure referred to as the _________

Back 2

intrapleural pressure.

Front 3

The exchange of air occurs via bulk flow
1. Bulk Flow (F) =

Back 3

= (Palv - Patm)/R (eqn. 2.1)
R = airway resistance
Pav = alveolar pressure
Patm = atmospheric pressure

Front 4

Exchange of air between atmosphere and aveoli due to pressure differences between Patm and Pav

boyles law=?

Back 4

Exchange of air between atmosphere and aveoli due to pressure differences between Patm and Pav
1. Boyle's Law: P1V1 = P2V2

Front 5

Airway resistance (R)
1. By Poiseuille’s law

Back 5

1. By Poiseuille’s law, R is proportional to the length of the tube (L) divided by the radius of the tube (r):
R ∝ 8nL/πr4 (eqn 2.4, n=viscosity coefficient).
a. Changes in airway radius has large effects on air flow.

b. Ptp = keeps small airways open (decreasing R) (see below for description of Ptp)

c. lateral traction = connective tissues open alveoli tissues during respiration (decreasing R)

d. Asthma reduces airway openings (increasing R)

Front 6

The conducting zone

Back 6

The conducting zone is the region of the lung (i.e. trachea and bronchi) that function during air flow but do not participate in gas exchange. Equals ~ 150 mls.

Front 7

The respiratory zone

Back 7

The respiratory zone is the region of the lung that participates in gas exchange.

Front 8

The aveoli

Back 8

The aveoli are the primary site of gas exchange.

Front 9

The intrapleural fluid within the pleural sac is at a negative pressure (_________) which creates a pressure difference between the lung and the pleural sac (___________). There is also a pressure difference between the pleural sac and the chest wall (____________). These pressure differences are key for proper lung mechanics and ventilation.

Back 9

The intrapleural fluid within the pleural sac is at a negative pressure (intrapleural pressure = Pip) which creates a pressure difference between the lung and the pleural sac (transpulmonary pressure = Ptp ). There is also a pressure difference between the pleural sac and the chest wall (transmural pressure = Pcw). These pressure differences are key for proper lung mechanics and ventilation.

Front 10

Ptp = ?= +4 mmHg. This positive (outward) pressure holds the lungs open.

2. Pcw = ?= -4 mmHg. This negative (inward) pressure pulls the chestwall in. It is offset by the outward elastic recoil of the chest wall.

Back 10

Ptp = Pav - Pip= +4 mmHg. This positive (outward) pressure holds the lungs open.

2. Pcw = Pip - Patm = -4 mmHg. This negative (inward) pressure pulls the chestwall in. It is offset by the outward elastic recoil of the chest wall.

Front 11

Puncturing of the plueral sac is referred to as a __________

Back 11

Puncturing of the plueral sac is referred to as a pneumothorax. This event is characterized by the elimination of the pressure difference between the intrapleural pressure (Pip) and both the atmospheric (Patm) and alveolar (Palv) pressures resulting in collapse of the lung and expansion of the chest wall.

Front 12

Contraction of the diaphragm and intercostal muscles

Back 12

inspiration

Front 13

during inspiration Pav becomes _____

Back 13

more neg

Front 14

compliance

Back 14

"stretchability"
relationship between the volume of the lung and the transpulmonary pressure (Ptp)

Compliance (C) = slope of = ΔV (lung) / ΔPtp (eqn. 2.3). Low compliance equals increased lung stiffness.

Front 15

surface tension _____ compliance

Back 15

lowers

Front 16

surfactants _____ compliance

Back 16

increase

Front 17

a. The Law of Laplace
- Law of Laplace = ?

Back 17

a. The Law of Laplace states that the pressure within a soap bubble, balloon, or alveoli is defined by the tension (T) divided by the radius (r).
- Law of Laplace = P = 2T/r (eqn 2.4)

Front 18

The ______connects to a patient and can measure the volume or air displaced during breathing

Back 18

The spirometer connects to a patient and can measure the volume or air displaced during breathing

Front 19

TD= tidal volume

Back 19

amount of air inhaled or exhaled in one breath during relaxed quiet breathing

Front 20

FRC

Back 20

functional residual capacity

amount of air remaining in the lungs after a normal tidal expiration

Front 21

increase in compliance would _____ FCR

Back 21

increase

Front 22

. Using a spirometer, a patient is instructed to inspire maximally and then expire as hard and completely as possible. The volume expired in the first second is called the ___________and the total volume expired is called the_________

Back 22

1 forced expiration volume (FEV1.0)
2. forced vital capacity (FVC).

Front 23

________refers to the total ventilation of the lung per minute

Back 23

Minute Ventilation refers to the total ventilation of the lung per minute (VE).

VE = TV x f

f= frequency of breaths per min

Front 24

dead space

Back 24

Not all of the tidal volume participates in gas exchanges. The portion of the tidal volume that does not participate in gas exchange is referred to as Dead Space (VD)

Front 25

anatomic dead space

Back 25

volume of the conducting airways (~ 150 ml). This volume does not change during ventilation

Front 26

alveolar dead space

Back 26

lack of perfusion (i.e. blood flow) of some alveoli due to injury or disease. Local mechanisms minimize alveolar dead space by altering local blood flow help to alleviate the alveolar dead space. In a healthy individual this volume is ~ 0 mls.

Front 27

physiologic dead space

Back 27

Anatomic + Alveolar dead space

Front 28

alveolar ventilation

Back 28

(VA) refers to the ventilation of only the areas of the lungs that participate in gas exchange. This is determined by subtracting the volume of the dead space (VD) from the tidal volume (TV).

Va= (TV-Vd) x f

. A normal healthy person ventilates 4 liters every minute resulting in the 250 mls of oxygen diffusing into the blood and the elimination of 200 mls of carbon dioxide.

Front 29

ficks law

Back 29

can help describe the parameters that change the rate of diffusion across a barrier such as the alveolar membrane.

Diffusion is proportional to: - concentration difference across membrane
- area of the membrane
- diffusion coefficient
- inversely with membrane thickness

Front 30

All of these parameters, except the __________ change under certain physiologic conditions resulting in changes to gas exchange.**

Back 30

diffusion coefficient,

Front 31

Dalton’s law

Back 31

Dalton’s law states that in a mixture of gases, the total pressure is determined by the sum of the individual pressures of each gas in the mixture. These are referred to as partial pressures.
: Ptot = P1 + P2 + P3 + … + Pn

Front 32

Henry’s law of solubility

Back 32

states that in a closed system, the gas content in liquid is proportional to the partial pressure of the gas dissolved in the air that is in contact with the liquid. Furthermore, at equilibrium the partial pressure of the gas in the air and liquid will be equal. This is accomplished via diffusion of gas between the air and liquid driven by differences in partial pressures. The diffusion of O2 and CO2 across the alveolar membrane during gas exchange is due to differences in the partial pressures of O2 and CO2 (PO2 and PCO2, respectively) between the blood and the alveolar air (see below).

Front 33

Factors that determine alveolar PO2 are:

Back 33

1-PO2 of atmospheric air (160 mmHg)
2-Rate of alveolar ventilation
3-Rate of metabolism

Front 34

determining alveolar PCO2 (PAVCO2)

Back 34

alveolar ventiltion equation demonstrates the inverse relationship between ventilation and alveolar PAVCO2

PAVCO2= Vco2 / Va x K

VCO2= rate of co2 produced
Va= alveolar ventilation
K= constant BTBS

Va= Vco2 / Pavco2 x K
Va= (TV- dead space) x f (breaths per min )

Front 35

determinig alveolar PO2 (Pavo2)

Back 35

PAVO2= Po2 (inspired) - Pavco2 / R

R= respritory exchange quotient (CO2 produced/ O2 consumption)

Front 36

ventilation perfusion inequalities

Back 36

V- alveolar ventilation (l/min)
Q= pulmonary blood flow (l/min)

V/Q = .8 in normal

airway obstruction(shunt)(blood flow but no ventilation) V/Q= 0 pulmonary Po2 = 40 Pco2 = 46

pulmonary embolism(dead space) (ventilation but no blood circulation ) V/Q= infinity Pavo2= 150 Pavco2 = 0

Front 37

The Bohr effect

Back 37

The Bohr effect describes the effect of an increase CO2 concentration on oxygen binding of Hb.

Front 38

Increased PCO2 due to hypoventilation or disease results in increase arterial H+ called

Back 38

respiratory acidosis

Front 39

Decreased PCO2 and arterial H+ due to hyperventilation results in

Back 39

respiratory alkalosis.

Front 40

Within the pons, the __________sends inhibitory signals and the __________sends excitatory signals to the __________within the medulla.

Back 40

pneumotaxic center sends inhibitory signals and the apneustic center sends excitatory signals to the respiratory rhythmicity centers within the medulla.

Front 41

respriatory center in medulla

Back 41

Dorsal respiratory group which is the location of the inspiratory neurons and the Ventral respiratory group which is the location of Pre-Botzinger complex which makes connections with both inspiratory and expiratory neurons. This area sends connections to the inspiratory and expiratory motor neurons within the spinal cord.

Front 42

Peripheral chemoreceptors

Back 42

monitor blood gas content and provide excitatory synaptic input into the respiratory centers within the medulla that control the rate and depth of breathing.

they stimulate ventilation

Front 43

Stimuli of peripheral chemoreceptors:

Back 43

Stimuli of peripheral chemoreceptors: PCO2 , pH, PO2

Front 44

Central chemoreceptors

Back 44

Central chemoreceptors are located within the medulla and monitor the pH of the cerebral/spinal fluid (CSF).

Front 45

As arterial PO2 falls, the rate of breathing_______due to the stimulation of peripheral chemoreceptors.

Back 45

increases

Front 46

Both peripheral and central chemoreceptors are involved

Back 46

reflex responding to change in H+, witht he help of pco2, or non co2 acid production

Front 47

As arterial PO2 falls, the rate of breathing increases due to the stimulation of

Back 47

peripheral chemoreceptors.

Front 48

Effects of exercise on ventilation

Back 48

1. Arterial PCO2 decreases (hyperventilation)
2. Arterial PO2 does not change
3. Arterial H+ increases (lactic acid)

Front 49

Hypoxia:

1. Hypoxemia -
2. Anemic/CO hypoxia -
3. Ishemic hypoxia -
4. Histotoxic hypoxia -

Back 49

Hypoxia: Oxygen deficiency at the level of the tissue

1. Hypoxemia - decreased arterial PO2
2. Anemic/CO hypoxia - normal PO2 , reduce oxygen content
3. Ishemic hypoxia - low blood flow
4. Histotoxic hypoxia - cellular defect in oxygen usage

Front 50

_________is a major cause of hypoxia.

Back 50

Emphysema is a major cause of hypoxia.

. Increased resistance, decreased gas diffusion, and ventilation-perfusion inequality

Front 51

High altitude results in hypoxia due to a chronic reduction in

Back 51

High altitude results in hypoxia due to a chronic reduction in arterial PO2