Ex. Phys. Respiratory System Flashcards
main purposes of respiratory system and ventilation
delivery of O2 to blood
removal of CO2 from blood
maintain acid-base balance in blood
respiratory system structure
lungs
thoracic cavity
muscles
lungs
- contain
- -those contain
contain network of bronchiole branches with several alveolar sacs
sacs contain pulmonary alveoli, which is where gas exchange occurs
thoracic cavity
visceral pleura: membrane that covers lungs
parietal pleura: membrane that lines thoracic wall
pleural cavity: space between visceral and parietal pleura filled with serous fluid
serous fluid: found inside the pleural cavity; helps adhere lungs to thoracic wall
muscles
diaphragm: lowers and elevates the bottom wall of the thoracic cavity
external intercostals: elevate ribs
internal intercostals: depress ribs
ventilation of the lungs
- movement of air is dependent on…
- _____
- _____
dependent on pressure differences between the atmosphere and the spaces inside the lungs intrapleural pressure -air pressure within the pleural cavity intrapulmonary pressure -air pressure within the alveoli
Boyle’s Law
increased volume = decreased pressure
decreased volume = increased pressure
process of ventilation
-inspiration
- contraction of diaphragm and external intercostals to increase volume of the thoracic cavity
- intrapleural pressure decreases, which drops intrapulmonary pressure
- atmospheric air pressure is now HIGHER than intrapleural and pulmonary pressures, which creates a vacuum inside the lungs
- atmospheric air is sucked inside, inflating the lungs and supplying O2
expiration
- elastic nature of lungs and thoracic cavity, relaxation of diaphragm, and possible contraction of internal intercostals (and abdominals during exercise) decrease volume of the thoracic cavity
- intrapleural and intrapulmonary pressures increase…
- atmospheric pressure is now LOWER than intrapleural and pulmonary pressures…
- air is forced out of lungs – see ya CO2!
air composition
-inspired (ambient/atmospheric) air
N2 = 79 O2 = 20.9 CO2 = 0.03 H2O = the rest (around 0.5)
air composition
-expired
N2 = 75 O2 = 15-17 CO2 = 3-6 H2O = the rest (around 6)
total/atmospheric air pressure
760 mmHg
partial pressure inspired air (atmospheric air pressure)
PIO2 = 760 x .209 = 150 mmHg PICO2 = 760 x .0003 = 0 mmHg
alveolar blood PP
PAO2 = 102 PACO2 = 40
arterial blood PP
PaO2 = 102 PaCO2 = 40
venous blood PP
PvO2 = 40 mmHg PvCO2 = -46 mmHg
pertinent lung volumes
breathing frequency (f) tidal volume (VT) ventilation (VE) Total Lung Capacity (TLC) Residual Volume (RV) Forced Vital Capacity (FVC) Forced Expiratory Volume 1, 2, 3
breathing frequency
- what is it
- frequencies
number of breaths taken per minute
resting: 8-12 bpm
aerobic: up to 50-60 bpm
resistance: slightly elevated from rest
tidal volume
- what is it
- volumes
the volume of air inspired/expired each breath
resting: 0.5 L/breath
aerobic: up to 2-4 L/breath
resistance: slightly elevated from rest
ventilation
- what is it
- VE =
- volumes
the volume of expired air per minute VE = VT x f resting: 6 L/min aerobic: up to 150-200 L/min resistance: slightly elevated from rest
Total Lung Capacity
- what is it
- average
the maximun lung volume (not entirely usable)
average: 5-6 L
residual volume
- what is it
- average
amount of air left in the lungs after a maximum exhalation (reserve air supply)
average - 1.0 L
forced vital capacity
- what is it
- FVC =
- greatly affected by
largest volume of air you can possibly expire in a single exhalation
FVC = TLC - RV
greatly affected by gender, age, height, and restrictive pulmonary diseases
FEV 1, 2, 3
- what is it
- greatly affected by
the volume of your FVC that can be expired in 1, 2, or 3 seconds
FEV is greatly affected by gender, age, height, and obstructive pulmonary diseases
-asthma
-bronchitis
-emphysema
success of gas exchange is dependent upon
NOT ON TEST
adequate total ventilation (VE) and alveolar ventilation (VA)
VE vs. VA
NOT ON TEST
VE: it is the volume of air that enters the lungs each minute
VA: volume of air that enters the actual alveoli each minute
what accounts for the difference between VA and VE
NOT ON TEST
remember that EV = VT x f
about 150 ml of VT is dead space (DS)
-air in the bronchial pathways that does not participate in gas exchange
VA = (VT - DS) x f
VA is important, then, in terms of pulmonary function
depth of breathing has a large impact on VA
NOT ON TEST
shallow, rapid breathing minimizes VA
slow, deep breathing maximizes VA
aerobic exercise is a balance between the rate and depth of breathing to obtain an adequate VA
gas exchange and transport
-purpose
integrated processes that sustain metabolism
what processes are included in gas exchange and transport
- loading O2 into the blood on hemoglobin from the alveoli
- removing CO2 from the blood to the alveoli
- transporting O2 to the tissues and unloading in onto myoglobin
- loading CO2 from the tissues into the blood and transporting it to the alveoli
roles of hemoglobin (Hb)
Hb is the iron-containing O2 transport protein found in all RBCs
- initially accepts O2 during gas exchange at the lungs
- also can transport CO2 from the tissues to the lungs for gas exchange
- each Hb molecule can bind up to 4 O2 molecules
- -with each O2 that binds, Hb’s affinity for O2 increases
roles of myoglobin
iron-containing O2 transport protein found in all muscle tissue
-accepts O2 during gas exchange at the muscles
oxygen transport process
O2 diffuses from alveoli into RBC
-within RBC, O2 binds to Hb
Hb carries 95% of all the O2 that diffuses into blood
remaining 5% of diffused O2 is dissolved in the blood (PO2)
-although small, this is important because it is used to monitor ventilation (primary)
once carried to the muscles, increases 2,3-Bisphosphoglycerate (2,3-BPG), H+, CO2, and temperature induce O2 loading into the muscles
O2 unloaded into muscles onto Mb for use in mitochondrial respiration
Bohr effect
describes how CO2 and H+ affect the affinity of Hb for O2
high CO2 and H+ concentrations decrease affinity for O2, while low concentrations increase affinity for O2
Bohr effect example
in active muscles, CO2 and H+ levels are high
oxygenated blood that flows past is affected by these conditions, and the affinity of Hb for O2 is decrease, allowing O2 to be more easily transferred to the muscles
carbon dioxide transport process
CO2 diffuses from the muscle into RBC
90% of CO2 is converted to H+ and bicarbonate (HCO3-) using the following reaction
-CO2 + H2O –> H+ + HCO3-
-HCO3- binds to Hb for transport to lungs
H+ “buffered” via binding to Hb in the RBC and to specific blood plasma proteins
-this reaction is important because sizeable amounts of CO2 can be transported in the blood to the lungs without substantially altering blood pH
-at lungs, the above reaction is reversed to produce CO2 and H2O, which diffuses into alveoli and is expired
CO2 transport cont.
5% of CO2 is directly bound to and carried by Hb
5% of CO2 is dissolved in blood (PCO2). again, this is very important because it is what is monitored for ventilation regulation
haldane effect
describes how O2 concentrations determine Hb affinity for CO2
ex.
-high O2 concentrations enhance the unloading of CO2
-converse is true: low O2 concentrations promote loading of CO2 onto Hb
in both situations, it is O2 that causes change in CO2 levels
haldene effect example
in the lungs, when Hb loaded with CO2 is exposed to high O2 levels, Hb’s affinity for CO2 decreases
important factors that affect gas exchange
partial pressure gradients barriers to diffusion RBC transit time Hb and Mb concentrations Bohr and Haldane effects ventilation/perfusion ratio
barriers to diffusion
surfactant alveolar epithelium interstitial space capillary basement membrane capillary endothelium
RBC transit time
within capillary, transit time is 0.75 sec at rest, down to 0.25 sec with maximal exercise
-at maximal exercise, Hb desaturation occurs, which can make the muscles ischemic
Hb and Mb concentrations
the more Hb that is present in the blood (typically due to increased RBC concentrations), the more O2 that can be carried to the muscles
the more Mb that is present in the muscle, the more O2 than can be accepted into the muscles
ventilation/perfusion ratios
- calculated as
- represents
- -ideal score
- score variation
calculated as VA/Q
represents the relative efficiency of gas exchange from the alveoli to the blood
-an ideal score is around 1.0
score variation
-lung blood flow varies from the base to the apex, so VA/Q changes depending on region
-really high or really low values typically imply some sort of ventilatory pathophysiology, such as chronic bronchitis, asthma, or COPD
ventilation regulation
ventilatory centers (medulla and pons) in the brain initially adjust ventilation via a feed forward system sensory receptors through the body adjust ventilation via feedback systems
ventilatory centers
- primary responsibility
- SNS function
primary responsibility for an anticipatory rise in VE
SNS dilates bronchioles to increase airflow into lungs
sensory receptors
- mechanoreceptors
- chemoreceptors
mechanoreceptors in muscles often elicit rapid rises and sudden drops in VE due to increases or absence of physical motion
chemoreceptors in the blood vessels are responsible for slow plateaus and gradual declines in VE during sustained exercise or periods of rest
main things monitored by chemoreceptors
-which is primary determinant of ventilation
PCO2, blood pH, LA, epinephrine and norepinephrine, temperature, etc.
-PCO2 is the primary
