Biology I - Lungs
How does Fick's Law of Diffusion relate to Flux?
(V/A) = [(P1-P2)/T] x D Flux = Gradient x Diffusion Constant - Flux = net rate of particles moving through an area - Gradient = change in pressure over a distance (particles in a volume)
What does the thorax consist of?
- rib cage - diaphragm - lungs - heart
What type of muscle is the diaphragm?
Skeletal muscle
How does O2 move from the alveoli to the capillaries?
O2 travels through... 1. Layer of fluid (alveoli) 2. Epithelial cells (alveoli) 3. Basement membrane (alveoli) 4. Connective tissue (between alveoli and capillary) 5. Basement membrane (capillary) 6. Endothelial cells (capillary) 7. Plasma 8. Red blood cell 9. Hemoglobin
What occurs in the alveoli?
Oxygen is picked up by the bloodstream and carbon dioxide is released into the lungs to be expelled from the body through exhalation
What is the measure pressure in air?
P = 760 mmHg
What does surfactant do?
Reduces surface tension of fluid lining the alveoli and decreases the pressure needed to inflate alveoli during inhalation. Prevents the alveoli from collapsing on themselves during exhalation.
What muscles are motor nerves T1-T11 responsible for?
Intercostal muscles.
What is the role of the diaphragm?
When this contracts, it will move down, flattening. The lungs and heart will move down. The lungs will expand with volume.
Fick's Law of Diffusion: How to maximize the amount of particles that move from point 1 to point 2 in a period of time?
1. Less thick wall (decrease travel distance) 2. Small molecular weight molecules (will move faster) 3. Increase pressure (more molecules) 4. Increase area (expand surface area) Fick's Law Equation: V = [(P1-P2) x A x D]/T *V → rate of particles moving (moles, volume) *(P1-P2) ← (3) * A → surface area ← (4) * D → diffusion constant ← (2) * T → thickness ← (1)
What occurs during inhalation in terms of pressure?
1.) ↑ volume 2.)↓ pressure: fewer collisions, negative pressure 3.) air molecules move in 4.) ↑ pressure
What occurs during exhalation in terms of pressure?
1.) ↓ volume 2.) ↑ pressure: more collisions, positive pressure 3.) air molecules move out 4.) ↓ pressure
What is pulmonary surfactant composed of?
90% phospholipids and 10% protein Contains polar and nonpolar regions
Describe the alveolar sac structure.
A bronchiole intertwined with smooth muscle brings in O2 to the alveolar sac that travels to the alveoli. A pulmonary vein and artery surround the sac as one takes oxygenated blood and one brings deoxygenated blood, respectively.
What muscles are motor nerves C1-C3 responsible for?
Accessory muscles.
Henry's Law
At a given temperature the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. Partial pressure is used when talking about pressure from one molecule. As partial pressure increases, more gas molecules will go into the liquid. --- Concentration of dissolved oxygen is proportional to partial pressure of O2 in gas. CO2 is 22 times more soluble than O2 when in contact with plasma. Henry's Law Equation: P/K(H) = concentration of molecules in the surface layer P = Partial pressure K(H) = value determined by solute, solvent, and temperature http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/henry.html
What motor nerves serve our diaphragm?
C3-C5
What is the chemical equation for the bicarbonate buffer system?
CO2 + H2O ⇄ H2CO3 ⇄ H+ + HCO3-
Differentiate cellular respiration and respiration.
Cellular respiration - cells use oxygen to produce ATP Respiration = ventilation = breathing
How might central and peripheral chemoreceptors compare with regard to their role in the detection of respiratory gases resulting from a prolonged period of hypoventilation?
Central chemoreceptors and peripheral chemoreceptors may both respond to the resultant increase in pCO2, but only the peripheral chemoreceptors could respond to the decrease in pO2. Hypoventilation = decreased ventilation = build up of CO2 without proper exhalation.
Describe exhalation.
Decrease in volume. - Muscles relax. - Diaphragm and intercostal muscles begin to relax and return to their original shape. - Alveoli recoil as they are elastic (potential energy) - As muscles relax, they decrease in space and volume. This decreases the volume of the intrapleural space, and thus increases pressure. - When intrapleural pressure > atmospheric pressure, the pressure difference forces air to move out of the lungs.
How does gas exchange take place inside the alveolus?
Deoxygenated blood brought into alveolus by an arteriole contains a relatively low partial pressure for O2 (40 mmHg) and a high partial pressure for CO2 (45 mmHg). This pressure difference results in O2 diffusing into the capillary and CO2 will diffuse out of capillary. This diffusion will continue until the partial pressure of O2 is the same inside and outside the capillary.
Compare diffusion & bulk flow.
Diffusion: material automatically flows from where its concentration is HIGH → LOW - good system but it can take A LOT of time for O2 in the air to diffuse through the various layers till it gets to the alveoli Bulk flow: moves large quantities of molecules quickly and the lungs help with this
Why does the left lung only have 2 lobes?
For the cardiac notch; it makes space for the heart.
An individual droplet of H2O on a table takes on a spherical shape. If we add a tiny drop of detergent, the water drop will lose its shape (flatten out). Why?
H2O has its spherical shape due to its strong hydrogen bonds. The spherical shape creates an optimal arrangement for maximum hydrogen bonding. Detergents have a polar and nonpolar region. When we add detergent to the H2O, the non-polar section of the detergent will try to orient itself far away from H2O resulting in the breakage of many H2O bonds.
Air molecules collide with each other. The more frequent the collisions, the ________________ the pressure in the air.
Higher
What is the role of the hypothalamus in the respiratory center?
In anxious, scary, or painful situations, our breathing changes and the hypothalamus sends info to the respiratory center regarding this.
Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?
In respiratory failure, ventilation slows, and less CO2 is blown off. As this occurs, the buffer equation shifts to the right and more H+ are generated. This results in a lower pH of the blood.
Describe inhalation.
Increase in volume. - Muscles contract using chemical energy (ATP) - Diaphragm contracts, it flattens and pulls the thoracic cavity downward. - External intercostal muscles contract, they also expand the thoracic cavity. - Alveoli stretch open with elastin - This expansion ↑ the volume within the thorax and the intrapleural space, which results in an ↓ in pressure; pressure drops in the pleural cavity below atmospheric pressure. - The pressure difference between the intrapleural space and outside environment causes the movement of air down its pressure gradient and into the lungs. - Once lungs fill w/ air, O2 is exchanged for CO2.
What muscles are involved in inhalation? Exhalation?
Inhalation uses the diaphragm and external intercostal muscles. Passive exhalation uses the recoil in the same muscles. Active exhalation uses the internal intercostal muscles and abdominal muscles.
What is the role of the Adam's apple?
It is your voice box; helps you control your voice
What is the role of the cerebrum in the respiratory center?
It provides us with voluntary control on our breathing.
Pure H2O has high surface tension. Adding detergent will decrease the surface tension. Why?
Surface tension - difficult to break the bonds that exist on the surface of a liquid. Surface molecules are restricted to certain movements as they don't interact well with air molecules. The smallest movement can cause them to lose hydrogen bonds. The molecules beneath the surface can move freely without fear of breaking hydrogen bonds. Adding detergent causes the molecules at the surface to reorient themselves due to the polar and nonpolar regions of detergent. This results in water molecules having more movement, lowering surface tension.
What motor nerves serve our abdominal muscles?
T6-L1
What does Fick's Law of Diffusion say regarding the diffusion of O2 at the alveolar sac?
The alveoli is a very effective gas exchange interface. http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/henry.html
How do maintain thermoregulation in our bodies?
The cool air we breath equilibrates with the temperature of the blood passing by the capillaries. The air we breathe in is a lot cooler than the air we breath out (98.6°F - body temp).
Layers of the lungs
The lungs are encased in the serous membrane that infolds on itself to form a 2-layer protective barrier known as the pleura. - inner membrane: visceral pleura - outer membrane: parietal pleura Between the two layers is a cavity = intrapleural space/pleural cavity. It contains a fluid used to decrease the amount of friction the lungs experience during breathing.
What is the respiratory center?
The respiratory center is located in the medulla oblongata and pons (brainstem). The center is responsible for generating and maintaining the rhythm of respiration. It is also responsible for adjusting breathing in response to homeostatic changes.
Compare the right and left lungs.
The right lung has three lobes: - upper/superior - middle - lower/inferior The right lung has two fissures: - horizontal fissure separates upper and middle lobes - right oblique fissure separates middle and lower lobes The left lung has two lobes: - upper/superior - lower/inferior The left lung has one fissure: - left oblique fissure
If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?
When CO2 levels become too low, the brain can decrease the respiratory rate in order to raise CO2 levels.
What is the term "negative pressure" used?
When the pressure in a system is negative relative to atmospheric pressure.
What does Boyle's law state?
When the temperature is constant, pressure and volume have an inverse relationship. PV = nRT
What may affect the amount of O2 diffusing over time from the alveolus to the capillary?
The starting point, the area, and the thickness may affect the amount of O2 diffusing over. The endpoint and diffusion constant tend to stay stable.
What is the role of the intercostal muscles?
These muscles will contract when you want to take a deep breath.
What do respiratory center peripheral chemoreceptors gather information on?
They detect O2, CO2, and pH levels in the aortic body (cranial nerve 9 - glossopharyngeal) and the carotid body (cranial nerve 10 - vagus nerve).
What do central chemoreceptors from the respiratory center do?
They gather information on CO2 levels and pH levels but NOT O2 levels.
What do mechanoreceptors from the respiratory center detect?
They send information on pressure. - Nose: cranial nerve 5 - trigeminal nerve; pollen - Lungs: cranial nerve 10 - vagus nerve; smoke and stretch - GI tract: distention/expansion
How does lung volume change?
Through inhalation and exhalation
What are some of the mechanisms used in the respiratory system to prevent infection?
Vibrassae in nares Lysozyme in mucous membranes Mucociliary escalator Macrophages in the lungs Mucosal IgA antibodies Mast cells
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? [A] Alveolar pressure > Atmospheric air pressure [B] Alveolar pressure = Atmospheric air pressure [C] Alveolar pressure < Atmospheric air pressure [D] Cannot be predicted without more information
[A] Alveolar pressure > Atmospheric air pressure At the peak of inspiration (or expiration) airflow stops momentarily, even as the mouth and airway remain open. The lack of flow indicates that the pressure of air in the alveoli is equal to that 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. The elastic recoil force of the alveoli and the chest wall still exert a force on the air within the lungs.
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? [A] Decreased interstitial thickness [B] Increased lung elastic recoil [C] Decreased lung capacity [D] Increased alveolar surface tension
[A] Decreased interstitial thickness. [B] and [C] are very similar. Think back to Fick's Law of Diffusion.
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? [A] Increased alveolar elastic recoil [B] Decreased capillary flow [C] Increased alveolar volume [D] Decreased temperature
[A] Increased alveolar elastic recoil Increased elastic recoil of the alveolar wall would increase the inward force of the wall on the gas as the wall tried to collapse, which would increase the pressure of gases within an alveolus, which would hinder airflow into the space.
What produces the force which drives normal exhalation, and is the process active or passive? [A] Diaphragm, active. [B] Intercostal muscles, active. [C] Elastic force, passive. [D] Reflex arcs, passive.
[C] Elastic force, passive.
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? [A] Increased blood pH [B] Decreased afferent capillary pO2 [C] Increased capillary blood flow [D] Decreased alveolar wall thickness
[C] Increased capillary blood flow.
Bronchodilators are a class of drug often used in the treatment of asthma and COPD, which act on β-adrenergic receptors of the airways to induce smooth muscle relaxation. The anatomic distribution of these receptors is closely correlated to the function of each structural component of the lungs. What structural component(s) of the airway would be most affected by the use of a bronchodilator, and in what functional zone(s) are they found? [A] Lobar bronchi and alveoli would be affected equally, and they are both found in the respiratory zone. [B] Lobar bronchi and alveoli would be affected equally, and they are both found in the conducting and respiratory zones, respectively. [C] Lobar bronchi, which are found in the conducting zone. [D] Alveoli, which are found in the respiratory zone.
[C] Lobar bronchi, which are found in the conducting zone. The conducting zone is simply a series of tubes through which gases travel, while the respiratory zone directly participates in gas exchange. The walls of the airways contain smooth muscle. The alveoli are made of only a single layer of cells, and their walls do not contain smooth muscle.
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? [A] CO2 penetrates more deeply into smaller airways than O2. [B] CO2 is less soluble in the blood than O2. [C] O2 penetrates more deeply into smaller airways than CO2. [D] CO2 is more soluble in the blood than O2.
[D] CO2 is more soluble in the blood than O2.
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? [A] Normal expiration [B] Forced inhalation [C] Normal inhalation [D] Forced expiration
[D] Forced expiration. Contraction of the diaphragm produces a negative pressure within the intrathoracic cavity. The negative pressure gradient pulls air into the lungs, the lungs expand, and thus the radius of respiratory bronchioles increases during inspiration. If these airways are inflamed and smaller than usual, they would be much more prone to collapsing entirely. In fact, this is precisely what occurs during expiration in asthma; inflamed airways within the thoracic cavity collapse, interfering with expiration and trapping air within the lungs.
What is the pressure of gas within the alveoli at the peak of inspiration, just before expiration, relative to that of atmospheric air? [A] Less than atmospheric air [B] Greater than atmospheric air [C] Cannot be predicted without more information [D] The same as atmospheric air
[D] The same as atmospheric air. During inspiration, the diaphragm contracts which generates a negative pressure within the alveoli, which draws air into the lungs. During expiration, the elastic force of the thoracic wall and the alveoli themselves exert a positive pressure on the air within the alveoli. This pressure is greater than that of atmospheric air, and the air flows out of the lungs. At the peak of inspiration or expiration, the airflow momentarily stops.
