3: Respiratory System Flashcards
What are the functions of the respiratory system?
- conducts air into and out of lungs
- exchanges gases between air and blood
- humidifies air
- warms air
- filters air
What does humidifying inspired air do?
prevents damage to membranes due to drying out
What does warming inspired air do?
helps maintain body temperature
What does filtering inspired air do?
- mucus traps airborne particles
- cilia move mucus toward oral cavity to be expelled
What are the saclike structures surrounded by capillaries in the lungs?
alveoli
What are alveoli attached to?
respiratory bronchioles
What do alveoli do?
site of exchange of oxygen and carbon dioxide (provide a tremendous surface area for diffusion)
How many alveoli are there?
300 million in lungs
What are the respiratory membranes that aid diffusion?
membrane of alveolar cells, membrane of cells of capillary wall
What is the pleural sac?
double-layered membrane that encases each lung
Where is the visceral (pulmonary) pleura located?
outer surface of lungs
Where is the parietal pleura located?
inner surface of thoracic cavity and diaphragm
Where is the pleural fluid location?
lubrication between to 2 membranes
What is the pressure in the pleural cavity between 2 membranes? what is it less than?
Intrapleural pressure, less than atmospheric pressure
How are the lung attached to the inner walls of the thorax?
Not directly… they are connected by a thin film of fluid (serous fluid) that is secreted by the inner surfaces of the two thin serious membranes (plurae)
What happens to lung volume when there is an increase of volume in the intrathoracic cavity?
increases
What happens to intrapumonic pressure when there is an increase of volume in the intrathoracic cavity?
decreases
What does an increase of volume in the intrathoracic cavity cause?
inspiration (causes air to rush into lungs)
What happens to lung volume when there is a decrease in volume of the intrathoracic cavity?
decreases
What happens to intrapulmonic pressure when there is a decrease in volume of the intrathoracic cavity?
increases
What does an decrease of volume in the intrathoracic cavity cause?
expiration (causes air to rush out of lungs)
What is the most important inspiratory muscle?
diaphragm
What happens to the diaphragm as it contracts?
flattens
What does contraction of the diaphragm do to abdominal contents?
Pushes them forward and downward
Which muscles elevate the ribs?
external intercostals, scalenes, sternocleidomastoid, pectoralis minor
What causes expiration?
passive recoil of the diaphragm and other muscles
What accessory muscles pull the ribs downward (voluntary forced expiration, exercise, etc.)
Internal intercostals
Rectus abdominis
Internal oblique muscles of abdominal wall
Airflow =
airflow = p1-p2/resistance
How can airflow be increased?
amplifying pressure difference between two areas or decreases resistance to airflow
What is the biggest factor affecting airflow at rest?
diameter of airway
What decreases resistance to flow during exercise?
bronchodilation
What is the amount of air moved in and out of the lungs in a given time period?
Pulmonary ventilation
What is the tidal volume?
the amount of air moved per breath?
How do you calculate the volume of air moved per min?
VE = VT x f
volume of air expired per min = tidal volume x breathing frequency per min
How is VE affected in athletes?
greater
How is pulmonary ventilation determined?
PV = anatomical dead space + alveolar ventilation
What is the residual volume?
the air left in lungs after max exhalation
What is the tidal volume defined as?
the volume inspired or expired per breath
What is the inspiratory reserve volume (IRV)?
maximum inspiration at end of tidal inspiration
What is the expiratory reserve volume (ERV)?
maximum expiration at the end of tidal expiration
What is the total lung capacity (TLC)?
volume of air in lungs after maximum inspiration
What is the residual lung volume (RLV)?
volume in lungs after maximum expiration
What is the forced vital capacity (FVC)?
maximum volume expired after maximum inspiration
What is the inspiratory capacity (IC)?
maximum volume inspired following tidal expiration
What is the functional residual capacity (FRC)?
volume in lungs after tidal expiration
What happens to tidal volume (TV) during exercise?
increases
What happens to inspiratory reserve volume (IRV) during exercise
decreases
What happens to expiratory reserve volume (ERV) during exercise?
decreases
What happens to total lung capacity (TLC) during exercise?
slightly decreases
What happens to residual lung volume (RLV) during exercise?
slightly decreases
What happens to Forced Vital Capacity (FVC) during exercise?
slightly decreases
What happens to inspiratory capacity (IC) during exercise?
increases
What happens to functional residual capacity (FRC) during exercise?
decreases
What happens to inspiratory and expiratory reserve volumes with age? why?
Become proportionally smaller (decrease in elastic components of lung tissue)
What happens to residual lung volume with age?
increases
What measurement assesses dynamic lung volume?
FEV-to-FVC ratio
What is a normal FEV-to-VC ratio?
85%
What is a typical FEV-to-FVC ratio for someone with obstructive lung disease (asthma or emphysema)?
less than 70%
What promotes diffusion at the lungs?
- Large surface area of alveoli
- Thinness of respiratory membrane (2 cells thick)
- Pressure differences of oxygen and carbon dioxide between air in alveoli and blood
What is partial pressure?
portion of pressure due to a particular gas in a mixture of gases
What is Dalton’s Law?
total pressure of a gas mixture = sum of partial pressures of each gas
What is Henry’s Law?
amount of gas dissolved in any fluid depends on temperature, partial pressure of gas, and solubility of gas
What must happen to the PO2 in order for diffusion to take place?
Must be higher in alveoli than in blood… and greater in blood than in tissue
What must happen to PCO2 in order for diffusion to take place?
must be higher in blood than alveoli…. and higher in tissue than in blood
What happens to blood flow during exercise and what does it cause?
Increases… causes increased gas diffusion
How does blood pressure in the pulmonary circulation compare to that in systemic circulation?
pulmonary < systemic
How long does equilibriation of oxygen between alveoli air and lung capillary blood take?
0.25 seconds
How much oxygen can be dissolved in plasma?
9-15 mL
RBCs containing hemoglobin transport ______% of oxygen
98%
What changes shift the oxyhemoglobin dissosciation curve to the right? what does this mean?
- increase in temp
- increase in acidity (Bohr Effect)
- increase in 2,3 DPG
This means there is a decreased affinity of hemoglobin for O2
What are the 3 methods of carbon dioxide transport? respective percentages?
- plasma (7-10%)
- bound to hemoglobin (20%)
- transported as bicarbonate (70%)
What is normal hemoglobin level for men?
16g
What is normal hemoglobin level for women?
14g (5-10% less)
Each gram of Hb can combine loosely with _______ O2
1.34 mL
What happens to Hgb concentration of blood during exercise? Why?
Increases anywhere from 5%-10% (hemoconcentration or movement of fluid from the blood into surrounding cells and tissue)
How is %SO2 calculated?
O2 content of Hgb / O2 capacity of Hgb x 100
What is normal O2 saturation in arterial blood?
97-98%
What is obesity hyperventilation syndrome and what does it cause?
poor breathing leads to too much CO2 and too little O2… causes low blood oxygen
What causes OHS?
- defect in brains control over breathing
- excessive fatty tissue against chest wall
- sleep apnea?
What happens to VO2 max with prolonged bed rest?
decreases up to 25%
What happens to blood plasma with prolonged bed rest?
reduced (red cell mass)
How does gas exchange at the muscle occur?
partial pressure differences between oxygen and carbon dioxide between tissue and blood
What is myoglobin?
oxygen transport molecule similar to hemoglobin found in skeletal and cardiac muscle
What else does myoglobin function as?
oxygen reserve at start of exercise
Where is the respiratory control center?
portion of medulla oblongata and pons
What are rate and depth of breathing modified by?
- higher brain centers
- chemoreceptors in medulla
- other peripheral inputs
What do central chemoreceptors respond to?
changes in CSF (esp H+ concentration)
Where are central chemoreceptors located?
in medulla, separate from respiratory control centers
What do peripheral chemoreceptors respond to?
changes in blood PCO2 and H+ concentration
Where are peripheral chemoreceptors located?
carotid arteries and aortic arch
Where are other receptors located?
stretch receptors in lungs and respiratory muscles….proprioceptors and chemoreceptors in skeletal muscle and joints
What is a ventilatory equivalent?
the amount of air ventilated needed to obtain 1 L of oxygen or expire 1 L of CO2
What is the ventilatory equivalent of oxygen?
VE/VO2
What is the ventilatory equivalent of CO2?
VE/VCO2
What is the ventilatory threshold (VT)?
technique using ventilatory equivalents to estimate lactate threshold
What is the respiratory compensation point?
the work intensity at which both VE/VO2 and VE/VCO2 increase
What can VT and RCP be used to do?
Create 3 training zones of exercise intensity:
What is light-intensity?
<VT
What is moderate intensity?
VT-RCP
What is high-intensity?
> RCP
