Chapter 17: Mechanisms of Breathing Flashcards
What are the 4 functions of the respiratory system
Gas exchange, regulation of body pH, protection from inhaled pathogens, vocalization
External Respiration
- Ventilation
2.exchange of O2 and CO2 by lungs and blood - transport of O2 and CO2 by blood
- exchange of gases between lungs and cells
Structure of upper respiratory tract
mouth, pharynx, larynx
Structure of lower respiratory tract
trachea, bronchi, branches, lungs
What is the function of Pleural Fluid
It lowers friction between membranes
holds lungs against the thoracic wall
Why are there no muscles in the lungs? How do they expand
Muscles would interfere with gas exchange. So lungs have muscles around the lungs to help expand and contract them
Type one alveoli cells
Used in gas exchange. They are large but thin and flat epithelial cells whose basement membrane binds to capillary endothelium. There is also a small amount of fluid present in the remaining area.
Type 2 Alveoli cells
These are cuboidal cells that secrete and synthesize surfactants. They also minimize the amount of fluid in alveolar space by transporting solutes and water out of the alveoli air space.
What do surfactants do
It mixes with the alveolar fluid to aid the lungs as they expand. They decrease the surface tension of alveolar fluid, and decreases resistance of the lung to stretch
Is the blood flow in the pulmonary arteries Low flow or high flow? Low pressure or high pressure? Why?
High flow, Low pressure. Lungs receive the entire cardiac output of the right ventricle causing the high flow. The low pressure is due to the right ventricle not having to pump as forcefully because resistance is low. The low resistance is attributed to the shorter total length of blood vessels.
Why do gases diffuse rapidly in the alveolar space?
The distance between alveolar air space and capillary endothelium is short.
Is blood flow through the pulmonary trunk greater than, less than, or equal to blood flow through the aorta?
About equal
If nitrogen is 78% of atmospheric air, what is the partial pressure of nitrogen (PN2) in a sample of dry air that has an atmospheric pressure of 720 mm Hg? Why?
720 mm Hg * 0.78 = 562 mm Hg
Because the problem states that nitrogen makes up 78% of atmospheric air. To convert this percentage into mmHg you would multiply the sample of dry air(720 mm HG) by the percentage (0.78) of nitrogen.
Side note: I like to think of this in cookies. So if you have a box of an assortment of 720 cookies, and 78% of them are chocolate chip. You would use the calculation above to figure out how many cookies makeup 78% of the box.
Does all venous blood leaving the bronchi, pleura, and part of the heart to go through pulmonary circulation?
No, some of it drains directly into the anatomic shunt which is on the left side of the heart.
What does Boyles law describe?
It describes the pressure-volume relationships of gas. P1V1=P2V2
What does Boyles law state?
if the volume of gas is reduced pressure increases, if the volume of gas is increased, then the pressure decreases.
Does pressure in the respiratory system decrease or increase when you breathe out?
It increases to push the air out.
Side note: Think of it like a balloon. When you blow up a balloon you add air making the inside of the balloon bigger aka, increasing its volume. When you let go of the balloon, the balloon gets smaller, decreasing the volume and air gets pushed out.
How do you calculate the partial pressure of gas in humid air?
You do the same as in dry air but subtract the water vapor pressure first before multiplying the gas’s contribution
What tool is used to test pulmonary function?
Spirometer
Tidal volume(V1)
the volume that moves during a respiratory cycle
Inspiratory Reserve Volume (IRV)
additional volume above tidal volume
Expiratory Reserve Volume (ERV)
exhaled after end of a normal expriation
Residual Volume (RV)
The volume of air in the respiratory system after maximum exhalation
total lung capacity
vital capacity + the residual volume
Inspiratory capacity
tidal volume + inspiratory reserve volume
Functional residual capacity
expiratory reserve volume + residual volume
For air to move into the alveoli, what must happen
pressure inside the lungs must become lower than atmospheric pressure
When your diaphragm contracts, are you inhaling or exhaling
inhaling
What is the law of LaPlace
P=2T/r
Pressure inside a bubble formed by a fluid film is a function of the surface tension(T) and the radius of a bubble (r)
according to the Law of Laplace if two bubbles have different diameters but are formed by fluids with the same surface tension, would the bigger one or smaller one have a greater inside pressure
The smaller one
What does the stimulation of b2-receptors in bronchioles
They respond to epinephrine and cause bronchodilation
What is anatomic dead space
place where gases are not exchanged. 150ml
What is the total pulmonary ventilation
The volume of air moved in and out of lungs per minute
ventilation rate x tidal volume
What is alveolar ventilation?
a more accurate way to measure how much fresh air reaches the alveoli
Ventilation rate x (tidal volume - dead space)
Define compliance
the measure of the ease with which the chest wall and lungs expand. Loss of compliance increases the work of breathing
Elastance
the ability of a lung to resist stretching or to return to its unstretched state.
What air passages of the respiratory system are collapsible
The bronchioles
