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Respiratory System 1 - L09 - 10/08

Terms in this set (29)

Structure and function of the lungs
- Major Lobes
- Airways
- Major Vessels
Right lobe: Superior, middle, and inferior

Left lobe: Superior and inferior

Trachea > Bronchioles

Blood enters the lungs from pulmonary artery which pushes blood from the right ventricle into the lungs
What is the pleural space?
10 um thick space between the lungs and the chest wall contains fluids that allows the lungs to slide against the chest wall
What is the order of branching of the lungs? In what zones are they found?
Conducting Zone
Trachea > bronchi > bronchiole > terminal bronchiole

Respiratory Zone
Respiratory bronchiole > alveolar duct > alveolar sac
How does the cross-sectional area of the respiratory tree change as it branches out? How is resistance affected?
Increases the total cross-sectional area and reduces the resistance
Describe the innervation of capillaries around the alveolar sacs
Capillaries surround the air sacs to maximize the surface area for diffusion of gases
Alveolus Structure
1. Type 1 Alveolar Epithelial Cells
2. Type 2 Alveolar Epithelial Cells
1. Barrier formation; participate in gas exchange

2. Surfactant secretion; alveolar fluid lining with pulmonary surfactant
Mechanics of ventilation

What muscles/ structures are involved in inspiration & expiration? Pressure?
Inspiration
- Diaphragm contracts
- Scalene, Sternocleidomastoid, and external intercostal muscles contract
- Thoracic cavity expands
- Negative pressure

Expiration
- Diaphragm relaxes
- Obliques contract
- External intercostal muscles relax
- Positive pressure
Mechanics of Ventilation - Pressures

1. Paw
2. Ppl
3. PA
4. Pta
5. PL
1. Airway Pressure

2. Pleural Pressure

3. Alveolar Pressure

4. Transairway Pressure
- Pta = Paw - Ppl

5. Transpulmonary Pressure
- The pressure that keeps the lungs inflated and prevents them from collapsing
- PL = PA - Ppl
What is the main muscle that controls ventilation?
The diaphragm
1. What structures create the pleural pressure? How?

2. What is the normal intrapleural pressure?
1. The chest wall has an outward force and the lung tissue has an inward force. Since they are sealed in vacuum they are held together and the forces offset creating the negative pleural pressure

2. -3 to -5 mmHg
What happens to the pleural pressure during inspiration?
Goes down to about -7 mmHg
What happens to the pleural pressure in pneumothoracic lungs?
Presence of air or gas in the pleural space through puncture brings the pleural space to atmospheric pressure causing the lung to collapse
1. Alveolar Pressure
2. Transpulmonary Pressure
3. Lung Compliance
1. The pressure of the air inside the lung alveoli

2. The difference between the alveolar pressure and the pleural pressure

3. The extent to which the lungs will expand for each unit increase in transpulmonary pressure
Describe the changes in alveolar pressure with respect to pleural pressure during inspiration and expiration
During inspiration the expansion of the chest cavity lowers the pleural pressure to -7 mmHg, causing the alveolar pressure to decrease below atmospheric pressure, allowing for air flow into the lung.

During expiration the reduction in chest cavity space causes the pleural pressure to increase back to its normal pressure, which causes alveolar pressure to increase back to atmospheric pressure pushing air out of the lungs.
Describe what happens to the volume of air in the air sacs with each breath
Air in the sacs diffuse and gets mixed with new air with each breath
Define the following terms associated w/ volumes of respiration:

1. Tidal Volume
2. Anatomical Dead Space
3. Alveolar volume
1. The amount of air inhaled in each breathe. Typically 0.5L

2. Comprised of airways that don't partake in respiration. Any air in this volume is considered "wasted"

3. Amount of tidal volume that makes it to the alveolar space and takes part in gas exchange
What is a spirometer?
instrument used to measure respiratory volumes and flow of air.
Define each of these lung volumes and their values in both males and females

1. TLC
2. VT
3. IRV
4. IC
5. ERV
6. RV
7. VC
8. FRC
1. Total Lung Capacity (TLC)
- Male: 5.8 L
- Female: 4.2 L
- Volume at end of max inhalation

2. Tidal Volume (TV)
- Both: .5L
- Passive respiration

3. Inspiratory Reserve Volume (IRV)
- Male: 3.1L
- Female: 1.9L
- Max inspiratory volume

4. Inspiratory Capacity (IC)
- IRV + TV
- Volume b/w FRC and TLC

5. Expiratory Reserve Volume (ERV)
- Male: 1.2 L
- Female: .7 L
- Volume b/w FRC and RV

6. Residual Volume (RV)
- Male: 1.2L
- Female: 1.1L
- Volume at end of max expiration

7. Vital Capacity (VC)
- Male: 4.8L
- Female: 3.1L
- TLC - RV

8. Functional Residual Capacity (FRC)
- Residual volume after passive expiration
Draw and Label Lung Volumes
On ya board
Pulmonary Function Tests (PFTs)
Define: FVC & FEV1
What can these values tell us
FVC: Functional Vital Capacity
FEV1: Force Expiration in 1 sec

These values can tell us information about how well a patient is breathing
Obstructive Lung Disease
Condition which causes an obstruction to the airway. Typically this causes air to become trapped in the lung (hyperinflated) and allows for very poor expiration
Restrictive Lung Disease
Condition where infiltration of particles or damage to the lung has caused macrophage infiltration into the interstitial space. Leads to fibrotic tissue that doesn't expand during inspiration (less elastic)
What does the FEV1/ FVC ratio tell us?

Compare obstructive and restrictive ratios to normal FEV1/FVC ratios.
Obstructive vs Restrictive disease

Normal
- FEV1 = 4.0
- FVC = 5.0
- % = 80

Obstructive
Ratio lower than normal
Ex:
- FEV1 = 1.3
- FVC = 3.1
- % = 42

Restrictive
Ratio is higher than normal
Ex:
- FEV1 = 2.8
- FVC = 3.1
- % = 90
How are Total Ventilation (minute ventilation) & alveolar ventilation calculated?
Minute Ventilation: total amount of air moved into or out of the lungs in volume per time (rate)

VE = VT * f, where f is the respiratory rate per minute

Alveolar Ventilation: rate at which new air reaches the alveoli
VA = (VT-VD) *f, where VD = physiological dead space volume
Describe the relationship between alveolar ventilation and arterial PCO2
They are inversely proportional

↓ in VA (hypoventilation) > ↑ PCO2

↑ in VA (hyperventilation) > ↓ PCO2
Given tidal volume, determine the alveolar ventilation during hyper and hypoventilation
How does the surface tension affect lung compliance?
Compliance decreases because inflation force must overcome surface tension resulting in greater transpulmonary pressure
Describe the relationship between surface tension and Laplace's law. How is this overcome?
P = 2T/r, where T = tension & r = radius

Smaller airways are more susceptible to collapse due to high surface tension.

Surfactant is secreted by alveolar type II cells to line the alveolar sacs and reduce surface tension at low volumes by altering the fluid-gas interface b/w inspired air and lung tissue.
Describe airway resistances and how it changes throughout the lung with different lung volumes
Terminal bronchioles and alveoli have very high compliance and are arranged in large segments of parallel flow, which increases total cross-sectional area decreasing the resistance.

Resistance ↓ as volume ↑, b/c more work needed to inflate compressed alveoli at lower volumes. At higher volumes the lungs are already inflated so less work is needed.
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