Respiratory System Flashcards
What encompasses respiration?
all the body processed that accomplish movement of O2 and Co2 from the tissues to support cell metabolism
Define external respiration
the entire sequence of events in exchange of O2 and CO2 between the environment and tissue cells
Define cellular respiration
intracellular metabolic processes carried out within mitochondria that use O2 and produce CO2
What is the respiratory quotient?
ratio of CO2 produced to O2 consumed
Where is the diaphragm located?
the floor of the thoracic cavity
What organ takes up most of the thoracic cavity?
the lungs
What is the pleural sac?
double walled, closed sac
Where does gas exchange occur in the circulatory system?
alveoli
What cell type makes up most of the alveoli?
type I alveolar cells
What substance is secreted by Type II alveolar cells? What does this substance do?
pulmonary surfactant, facilitates lung expansion
What is the role of alveolar macrophages?
provide defense against inhaled microbes and debris
What are the pores of Kohn and what do they do?
connect adjacent alveoli, providing alternate air route if other airway is blocked
Where are the atmospheric pressures?
760 mm Hg; pressure exerted by the weight of gas in Earth’s atmosphere
Where are the intra-alveolar pressures?
760 mm Hg; pressure within alveoli
Where are the intrapleural pressures?
756 mm Hg; pressure within pleural sac, pressure exerted outside the lungs within the thoracic cavity
What keeps the intrapleural pressure below atmospheric pressure?
lung elasticity which tends to pull them inward, while the plural sac remains in the same place, lowering intrapleural pressure.
What is the transmural pressure gradient and how does it relate to lung function?
difference between intra-alveolar pressure and intrapleural pressure
What happens when the transmural pressure gradient is eliminated due to puncture of the pleural sac? What is this called?
collapsed lung; pneumothorax
What is the gist of Boyle’s law? How does it relate to air flow through the lungs?
At any constant temperature, the pressure of a gas varies inversely with the volume of the container; applies to how air moves into and out of lungs during expansion
What does the compliance of the lungs mean? How would an individual deal with less compliant lungs?
how much effort is required to stretch the lungs; greater transmural pressure and more forceful contraction of inspiratory muscles to expand thoracic cavity more to increase the transmural pressure gradient.
What factors impact the elastic recoil of lungs?
- elastin fibers in lung tissue
- alveolar surface tension in thin film of liquid lining alveoli (most important)
Why does surface tension affect elastic recoil?
- resists increases in surface area (resists expansion of alveoli)
- tends to shrink surface area (shrinks alveoli)
Role of pulmonary surfactant in surface tension
- break up cohesive bonds in the thin film and decrease surface tension
- prevents small alveoli from collapsing their air into larger alveoli
Law of LaPlace
𝑷=𝟐𝑻/𝒓
relates to how inward collapsing pressure in a bubble (P) is related to surface tension (T) and radius (r)
What does a spirometer measure?
changes in lung volume with different respiratory efforts
Do the lungs completely empty during passive expiration? How about after maximal expiration?
No, lungs never empty completely.
Define reserve volume
volume in lungs remaining after maximal expiration
What does tidal volume refer to?
volume exchanged during single breath, normally operating during quiet breathing at around half full
Does gas exchange occur during expiration?
since lungs don’t empty completely, gas exchange can occur even during expiration
How does anatomic dead space affect alveolar ventilation?
decreases it
What two factors determine pulmonary ventilation?
- increasing tidal volume
- increasing respiratory rate
Define pulmonary ventilation
Tidal volume (mL/breath) x Respiratory rate (breaths/min)
sympathetic stimulation causes broncho__________.
dilation (more air flow)
What is anatomic dead space?
volume of inspire air that does not reach alveoli- stuck in airways and not available for gas exchange
Is it possible for pulmonary ventilation and alveolar ventilation to be different?
yes, because alveolar ventilation is affected by dead space volume
In what context bronchiolar smooth muscle contract (large vs. small airflow)?
large airflow (small blood flow)
What parts of the lungs are wrapped in smooth muscle?
bronchioles
Parasympathetic stimulation causes broncho___________
constriction (less airf low)
How does bronchiolar smooth muscle react to a decrease in local CO2 concentration?
contraction of local airway smooth muscle
How does bronchiolar smooth muscle react to a increase in local CO2 concentration?
relaxation of local airway smooth muscle
In what context would bronchiolar smooth muscle relax? (large vs. small airflow)?
small air flow (large blood flow)
How does pulmonary arteriolar smooth muscle react to an increase O2 concentration?
relaxation of local pulmonary arteriolar smooth muscle
How does pulmonary arteriolar smooth muscle react to an decrease O2 concentration?
contraction of local pulmonary arteriolar smooth muscle
In what context would arteriolar smooth muscle relax (large vs. small blood flow)?
small blood flow (large airflow)
In what context would arteriolar smooth muscle contract (large vs. small blood flow)?
large blood flow (small airflow)
How do systemic arterioles respond to changes in local O2 in relation to pulmonary arteriolar smooth muscles?
systemic arterioles have an opposite response to pulmonary arteriolar smooth muscles
What is partial pressure?
individual pressure exerted by a particular gas within a mixture of gases
Is the PO2 in the alveoli greater than or less than that in the atmosphere?
PO2 in alveoli is lower than that breathed in from the atmosphere
Why is the PO2 in the alveoli greater than or less than that in the atmosphere?
- air is humidified (diluting air with the additional partial pressure of vaporized H2O)
- volume of freshly breathed in air is mixed with larger volume leftover in lungs— this old air has less O2
Is the PO2 of blood arriving to the systemic capillaries greater than or less than that in the body tissues? How about the PCO2?
PO2 is lower in body tissues than in systemic capillaries
PCO2 is greater in body tissues than in systemic capillaries
Is more O2 exchanged than CO2 in the lungs? How about at the systemic capillaries?
in lungs: more O2 exchanged
in systemic capillaries: more CO2 exchanged
Is the PO2 of blood coming in from the pulmonary arteries greater than or less than that in the alveoli? How about the PCO2?
PO2 is greater in alveolar sacs than in pulmonary capillaries
PCO2 is lower in alveolar sacs thant in pulmonary capillaries
Is hemoglobin more saturated at the pulmonary capillaries or at the systemic capillaries?
hemoglobin is more saturated with oxygen in the pulmonary capillaries (higher partial pressure (larger gradient), more O2 available in lungs)
How is most O2 transported in the blood?
98.5% of O2 is transported by hemoglobin (1.5% transported in blood as dissolved gas)
Does O2 bound to hemoglobin factor into the PO2?
No, O2 bound to hemoglobin does not contribute to the PO2 of the blood
What is percent hemoglobin saturation dependent on?
1.) PCO2
2.) pH
3.) temperature
4.) 2,3-bisphosphoglycerate (BPG)
How would a greater O2 demand in hard-working tissues change the percent hemoglobin saturation at the systemic capillaries in those tissues?
decrease; percent hemoglobin saturation at systemic capillaries would decrease (lower PO2, higher PCO2, higher temp, higher BPG)
What are the three ways in which CO2 is transported in the blood? Which transports the greatest amount?
1.) dissolved gas (10%)
2.) hemoglobin bound (to globin subunit) (30%)
3.) as bicarbonate (HCO3-) (60%)
What is the role does carbonic anhydrase play in CO2 transport? Where is it located?
catalyzes conversion of CO2 to bicarbonate ion (HCO3-)
carbonic anhydrase is located in erythrocytes
What are the two centers that generate the rhythmic pattern of breathing?
1.) medullary respiratory center (medulla)
2.) pons respiratory center (pons)
What is the pre-Bötzinger complex?
a network of neurons that creates self-induced action potentials that underlie the respiratory rhythm
Which group of neurons triggers inspiratory muscles?
Dorsal respiratory group
What neural center fine tunes inspiration and expiration?
pneumotaxic center and apneustic center
What signal is the main regulator of ventilation?
Co2-generated H+ in the brain
Which group of neurons triggers active expiratory muscles?
Ventral respiratory group
How does an increase in arterial CO2 increase this signal? What neural structure senses the signal?
increased PCO2 in the brain ECF leads to increased H+, which stimulates central chemoreceptors located in the medulla.
What are the peripheral chemoreceptors strongly sensitive to?
strongly sensitive to O2 when PO2 falls below 60 mmHg
What three diseases are considered types of chronic obstructive pulmonary disease?
1.) chronic bronchitis
2.) asthma
3.) emphysema
Define percent hemoglobin saturation
percentage of O2 binding sites from all hemoglobin molecules that are filled with O2
How many O2 binding sites does one hemoglobin have?
four O2 binding sites
