Intro and Anatomy of the Respiratory System week 5 Flashcards
What are the 3 functions of the respiratory system?
- gas exchange: btwn a network of capillaries and the alveoli of the lungs (O2 acquisition from air, CO2 elimation from the body)
- host defense
metabolism
gas exhcnage is the primary fxn
How is respiration quantified using the respiration quotient (RQ)? What is the normal value for this parameter?
What is respiratory exchange ratio (RER)?
RQ is important in determining BMR.
RER is another method of quaintification of respiration. It is the rationof the rate of CO2 expired to the rate of O2 inspired. At steady state, this value is the same as the RQ.
True or false: Because the body consumes O2 faster than it produces CO2, the volume of air inspired is ~1% greater than the volume expired. Typcial values of the rate of CO2 production (v dot) is 200 ml/min and is 250 ml/min for rate of O2 consumption.
True.
What muscles are involed in inspiration and expiration? Which of these processes is active and which is passive at rest?
How is pressure in the lungs generated for respiration compared to pressure in the heart generated for circulation?
Inspiration is active contraction of the external intercostal muscles (pull ribs up and out) and the diaphragm (flattens which increases size of lungs). Expiration (at rest) is passive as it is involves relaxation of inspiratory muscles. Expiratory muscles (internal intercostals and other accesory muscles) only contract (pull ribs down) during exercise to increase ventilation.
Lungs use same tubes to get air in and out which is diff from CV system that has valves for unidirectional flow. Respiratory system doesn’t have valves bc it uses the same tubes for air moving in and out. The heart works by positive pressure. Contraction increases pressure which forces blood flow. Respiratory system: get air in through negative pressure. Contraction of inspiratory muscles lowers pressure in lungs below atmospheric so air flows in. If you poke a hole in a heart during contraction, blood shoots out. If you poke hole in lungs during contraction, air flows in bc pressure is lower in lungs- way to tell difference btwn positive and negative pressure.
Diffusion: Fick’s equation
diffusion works best over short distances!
How does Hb change the rate of
O2 delivery to tissues?
Matching ______ with ______ is the main point of the respiratory system.
in disease, the V/Q ratio can be disturbed
What parameters do chemoreceptors sense and in what vessels to control respiration? Which of these is most important in controlling respiration?
What parameters of respiratory system do the respiratory control centers change to change ventilation? What role does the CV control centers play in this control?
note: P represents partial pressure and lower case a represents arterial
How many levels of branching are present in the lung? At what levels are the conduction and respiratory portions contained?
By what process is air moved in each part? List the structures that air passes through begining with nasal/oral cavities.
How many alveoli are there in the lungs?
What is the functional unit of the lungs? What are its components?
Conductive Zone [16 generations]: (movement of air by convection = bulk flow)
- Nose/ mouth –> trachea –> primary main stem bronchi –> segmental bronchi –> bronchioles –> terminal bronchioles –>
Respiratory Zone (transitional + respiratory) [7 generations]: (movement of air by diffusion)
- Respiratory bronchioles –> alveolar ducts –> alveoli (~ 300 million alveoli that maximize the surface area for gas exchange. Business district where gas exchange occurs The alveolar unit, with its pulmonary capillaries, is the functional unit of the lung. Each alveolar unit consists of:
- Respiratory bronchioles
- Alveolar duct
- Alveolus
Lung parenchyma is mostly ___. The alveolar wall is packed with_____.
- air
- capillaries-getting air and blood as close togther as possible
The alveolar capillary network forms a sheet of blood flowing past the alveolus, maximizing gas exchange.
Alveolar surface area is in proportion to what parameter in animals?
Define the following lung volumes and their normal values (as well as how they are calculated if it applies):
tidal volume
residual volume
reserve volumes
functional reserve capacity (discuss importance of this parameter)
vital capacity
total lung capacity
When you inspire (breathe in), the amount of air that you add to your lungs is the tidal volume (VT). After you expire (breathe out) normally, by relaxing muscles of respiration, the air left in your lung is the functional residual capacity (FRC). If you forcibly inspire as much air as possible (maximal inspiration), you reach total lung capacity (TLC). Now when you expire as much air as possible (maximal expiration), the air you breathe out is the lung’s vital capacity (VC). After maximal expiration, the amount of air left in the lung is the residual volume (RV). This air stays in your lungs no matter how hard you try to breathe out, and keeps your alveoli from collapsing, as well as acting as a buffer so that the respiratory gases do not change very much during breathing. All of these volumes, except for FRC and RV, can be measured by spirometry.
Tidal volume: (VT). volume of a single inspiration. 0.6 L at rest (about 1/10 of total lung capacity). varies over a wide range depending on ventilation (exercise)
Residual volume (RV): volume in lungs after maximal expiration. 1.2 L
Reserve volumes:
- expiratory reserve volume (ERV): additional amount of air that could be expired after expiration
- inspiratory reserve volume (IRV): additional amount of air that could be inspired after inspiration
Functional residual capacity (FRC): 2.4 L. FRC is an important reference point. When all of the respiratory muscles are relaxed at the end of a passive expiration, the lungs are at their resting volume, or FRC. At FRC, the outward recoil of the chest wall exactly balances the inward recoil of the lungs. FRC is a functional, not an anatomical, measure.
Vital Capacity: maximal expiration. 4.8 L.
VC= VT + IRV + ERV
Total lung capacity (TLC): lung volume at maximum inspiration. 6.0 L.
TLC= VC + RV
How does the value of FRC change with position?
FRC= 1/2 TLC when stand erect-gravity pulls heavy abdominal contents down and allows for lungs to expand
FRC only 1/3 of TLC when reclined-gravity pushes abdominal contents against diaphragm and decreases lung space
Forced expired vital capacity (FEVC) is a parameter measured in spirometry as a test of pulmonary function. What parameters are measured in this type of test? What are low values of these parameters indicative of? What are limitations?
see slide 21 of PP and pg 43 of course notes