Respiratory System

Pleura

Separate the lungs from the chest cavity; intrapleural space = thin layer filled with fluid and sandwiched by 2 pleura

Relationship between pressure and volume

Pressure and Volume are inversely related

How do the lungs perform thermoregulation?

-Nasal and Tracheal capillaries will vasoconstrict (conserve heat) or vasodilate (dissipate heat) -Water evaporation from mucous membranes (i.e. dogs pant to cool themselves off)

Exhalation

-diaphragm relaxes, and the recoil force of the thoracic wall and elastic force of the alveoli produce a positive pressure change on the air in the lungs -this pressure exceeds that of atmospheric air, and thus air flows outward.

Hypercapnia

Partial pressure of CO2 rising in blood (increased CO2 concentration)

What is the pressure of gas within the alveoli at the peak of inspiration, just before expiration, relative to that of atmospheric air?

Peak of inspiration/expiration = air flow momentarily stops and the pressure inside the lungs is the same as atmospheric air During inspiration = Lung P < Atm P During expiration = Lung P > Atm P

Elastic recoil

rebound of the lungs after having been stretched by inhalation; the ease with which the lung rebounds patho: emphysema = reduced recoil makes breathing difficult

Medulla oblongata

regulates breathing rate via chemoreceptors which are sensitive to blood levels of CO2 and pH CNS chemoreceptors can't respond to fluctuating O2 levels - peripheral chemoreceptors )aortic and carotid arteries) do this

Tidal Volume

volume of air inhaled or exhaled during a normal breath

Inspiratory/Expiratory Reserve Volume

volume of air that can be forcibly inhaled or exhaled, respectively

Function of nasal cavity (2)

-air's entry point -mucous membranes filter air to remove dirt and unwanted particles -warm air

Is the diaphragm under somatic or autonomic control?

Diaphragm contraction/relaxation is under somatic

How do the lungs regulate pH?

Bicarbonate buffer system

Is breathing under somatic or autonomic control?

Autonomic

Larynx

-air only pathway -contains vocal cords -capped by epiglottis during swallowing

How does RR change with acidemia? alkalemia?

Acidemia: RR increases (excess H+ converted to CO2 and exhaled) Alkalemia: RR decreases (convert excess CO2 to make blood LESS basic)

Inhalation

Active process; diaphragm (flattens) + external intercostal muscles (ribs) both CONTRACT = cause expansion of the thoracic cavity; this negative pressure system draws in the air

How do pressure gradients in the lungs drive gas exchange?

Alveoli: Partial Pressure of O2 is HIGH; Partial Pressure of CO2 is LOW Capillaries: Partial Pressure of CO2 is HIGH; Partial Pressure of O2 is LOW Net Flow: O2: Alveoli to Capillaries CO2: Capillaries to Alveoli ALL is PASSIVE!

How do the lungs maximize SA for gas exchange?

Bronchi divide into Bronchioles which further divide into Alveoli (grape sacs); Alveoli have thin walls for sufficient gas exchange

In a situation where the respiratory bronchioles become inflamed and narrowed, such as is seen in asthma, which aspect of respiration would be most mechanically impaired?*

Bronchiole radii are susceptible to negative pressure (inhalation, radius increases) & positive pressure (exhalation, radius decreases). In the case of inflammation, forced exhalation would be most impaired. This is because bronchiole radius decreases during this process - inflammation compounds the radius decrease thereby leaving the lungs sensitive to collapse. A forced expiration generates additional force on the air within the lungs; this pressure is not only a greater magnitude than normal exhalation, but also occurs much more rapidly. Therefore, an inflamed airway would collapse much sooner in this setting, and more air would be trapped.

The partial pressures of carbon dioxide (pCO2 and oxygen (pO2) in the atmosphere at sea level are 0.3 mmHg and 160 mmHg respectively, but the partial pressures of these gases in blood leaving the lungs are 40 mmHg (pCO2) and 95 mmHg (pO2). What factor most likely accounts for this difference?*

CO2 more soluble in blood than O2 Henry's law states that the amount of gas that dissolves in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with that liquid. If the only factor influencing dissolved gas concentrations is the partial pressure of the gas in the air in contact with the liquid, then we would assume that the ratio of oxygen to carbon dioxide would be equal both within and outside of the liquid. However, if a given gas were more soluble in a given liquid, a greater proportion of the gas could be dissolved within that liquid.

How do lungs help out the immune system?

Cilia lining the nasal cavity can trap and expel pathogens Alveoli contain innate immune cells like macrophages that can address any pathogen that has bypassed the nasal cavity

Is exhalation always passive?

No, sometimes extra air is forced out abdominal and intercostal muscles

Interstitial lung disease (ILD) refers to a set of conditions which affect the pulmonary interstitium-- the area of tissue and space which lies between the alveoli and alveolar capillaries. What factor in the setting of severe ILD, would NOT decrease the extent to which oxygen passes from the air sacs of the lungs into the blood? Choose 1 answer:

Decreased interstitial thickness* Increased lung elastic recoil Increased alveolar surface tension -BOTH would increase pressure of the alveolar wall on the gas; increased chances of lung collapse so no opp for gas exchange Decreased lung capacity -because of thick, scarred tissue the lungs cannot expand as well

What produces the force which drives normal exhalation, and is the process active or passive?

Elastic; Passive

4 Major functions of the respiratory system?

Gas exchange pH regulation Thermoregulation Immune function

How do ventilation patterns affect pH?

HYPOventilation = increased CO2; acidic pH HYPERventilation = decreased CO2; basic pH

Many respiratory diseases affect pulmonary function by altering the ability of alveoli to participate in gas exchange. What physical change would most greatly reduce the degree to which a particular alveolus is ventilated?

Increased alveolar elastic recoil

Describe the relationship between pressure and volume during inhalation vs. exhalation?

Inhalation: volume increased; pressure decreased Exhalation: volume decreased; pressure increased (byproduct of lungs recoiling)

Septic shock is a serious condition resulting from the body's response to systemic bacterial infections, which may impair oxygen uptake and delivery. What physiological change may result from septic shock which would decrease the ability of hemoglobin in the alveolar capillaries to become fully saturated with oxygen?

Two 'broad' categories must be considered which may affect hemoglobin saturation: 1. Is there enough oxygen present to saturate the hemoglobin, and 2. physiological factors which affect Hb's oxygen affinity. 2. An increase in temperature, pCO2 and 2,3-BPG concentration, or a decrease in pH will decrease O2 affinity. If pO2 in the afferent capillary is low (the capillary coming TO the alveoli), concentration gradients will favor greater diffusion of oxygen into the vessel, thereby increasing the amount of oxygen available to bind. 1. Factors affecting gas diffusion into the capillaries include wall thickness, wall surface area, partial pressure difference, and the ventilation-perfusion ratio. The longer blood 'hangs around' in the alveolar capillaries, the longer the hemoglobin has to recruit oxygen. If blood is flowing too quickly for ventilation to match it, the hemoglobin saturation will decrease.

If the mouth and nose are closed at the peak of a complete inspiration, but before expiration, and the breath is held, what is the pressure of gases within the alveoli relative to the pressure of atmospheric air?

With the airway closed (mouth and nose), the lungs and chest wall become a closed system, and are therefore isolated and unable to equilibrate with the atmosphere. Therefore, the elastic recoil force of the alveoli and chest wall cause alveolar pressure to be greater than atm pressure.

How does pleura help prevent lung collapse?

because of the pleura, the lungs are indirectly connected to chest wall...this prevents lung collapse during exhalation since the chest helps can pull the lungs + expand volume

Relationship between serum CO2 and Respiratory Rate

blood CO2 is directly proportional to Respiratory Rate (higher CO2 = greater RR = get CO2 out via exhalation)

How do surfactants prevent lung collapse?

breaks surface tension caused by water's tendency to H-bond

Trachea and Bronchi

ciliated cells lining these structures perform an added layer of filtration

Fick's Law

describes the rate of diffusion of particles across a membrane, and considers wall thickness, wall surface area, pressure gradient across the wall, and the diffusion constant of the molecule moving across the membrane

Total lung capacity

max volume of air in the lungs when one inhales COMPLETELY

Residual Volume

minimum volume of air in the lungs that remains post-exhalation