Lecture 58 - Lung Volumes & Mechanics Flashcards by Eleanor Nicklason

Compare the angels of the left and right main bronchi

Right main bronchus: more vertical

Left main bronchus: more horizontal

How well did you know this?

Not at all

Perfectly

Where is the largest surface area in the lung located?

Most of the surface are is at the alveoli (ie where exchange is occurring)

How well did you know this?

Not at all

Perfectly

Describe the structure of the trachea

Cartilage rings

Trachelis muscle

How well did you know this?

Not at all

Perfectly

What keeps the lungs inflated?

Pleural sac attaching to thoracic cavity

How well did you know this?

Not at all

Perfectly

Describe the structure of the pleura

Parietal

Visceral

How well did you know this?

Not at all

Perfectly

What is the pressure in the lungs?

1 atm

How well did you know this?

Not at all

Perfectly

What is the pressure in the pleural cavity?

Less than 1 atm

Keeps the lungs stuck to the pleura

How well did you know this?

Not at all

Perfectly

What happens when the intercostal muscles contract?

The ribs pull together and increase the volume inside

How well did you know this?

Not at all

Perfectly

What happens when there is a puncture through the ribs?

Lung collapses down because the seal has been broken

How well did you know this?

Not at all

Perfectly

What is Boyle’s law?

P1V1 = P2V2

How well did you know this?

Not at all

Perfectly

What happens when volume in a cavity decreases?

Pressure increases

and vice versa

How well did you know this?

Not at all

Perfectly

What happens to make inhalation happen?

Chest wall gets bigger
Pressure decreases in the thoracic cavity
Negative pressure → air flows into the lungs

How well did you know this?

Not at all

Perfectly

What happens to make expiration happen?

Chest wall gets smaller
Pressure increases in the thoracic cavity
Positive pressure → air expelled

How well did you know this?

Not at all

Perfectly

When pressure is higher in the lung than the atmosphere, where does air move?

Out of the lung

How well did you know this?

Not at all

Perfectly

Describe the volume of air moved during the respiratory cycle

How well did you know this?

Not at all

Perfectly

Describe which muscles are responsible for inspiration

Diaphragm
External intercostals
Scalenes
Mastoids

How well did you know this?

Not at all

Perfectly

Which muscles are responsible for expiration

Normally passive

Internal intercostals for forced expiration

How well did you know this?

Not at all

Perfectly

Describe Poiseuille’s law

Resistance proportional to length an viscocity

and inversely proportional to radius of the tube

How well did you know this?

Not at all

Perfectly

What parameters of poiseuille’s law are varibale?

Radius of the bronchi

Viscosity and length of bronchi not variable

How well did you know this?

Not at all

Perfectly

How is the diameter of the airways altered?

Upper airways: physical obstruction
• mucous

Lower airways
• ANS
• CO2
• epinephrine
• histamine
• leukotrienes

How well did you know this?

Not at all

Perfectly

What happens as diameter of the airways deccreases?

Resistance increases

More work required

How well did you know this?

Not at all

Perfectly

What is lung compliance?

The ability of the lung to stretch

How well did you know this?

Not at all

Perfectly

What happens as compliance of the lung increases?

More work required to inflate the lungs

How well did you know this?

Not at all

Perfectly

What factors affect lung compliance?

Surface tension in alveoli

How well did you know this?

Not at all

Perfectly

What is surface tension due to?

Attraction of hydrogen molecules They are trying to pull in close

What is the Law of LaPlace?

Pressure in smaller bubbles is greater (if surface tension is the same)

What does small alveoli mean?

Higher resistance to stretch | Greater inward pressure causing collapse

What prevents the alveoli from collapsing?

1. Surfactant | 2. Alveolar interdependence

What does Surfactant stand for?

Surface Active Agents

What does surfacant do?

Reduces surface tension (Radius is the same) → pressure is reduce H+ are happy to be further apart

Where is surfactant more concentrated?

In small alveoli

According to Law of LaPlace, what is pressure proportional to?

Proportional to surface tension Inversely proportional to radius

Describe alveolar interdependence

1. An alveolus collapses 2. Surrounding alveoli stretched 3. Recoil of stretched surrounded alveoli 4. Collapses alveolus pulled back open

What is the measurement of lung volumes?

Spirometry

Describe spirometry

Breathes in: bucket goes down Breathes out: bucket goes down This is recorded by a machine We can measure the volume going in and out

What is capacity?

More than one lung volume

What is tidal volume?

Volume of one breath in | 500 mL

What is the name for the total volume that we can expire if needed?

Expiratory reserve volume 1100 mL

What is the name for the total volume that we can inspire if needed?

Inspiratory capacity 3500 mL

What is the maximum volume we can expire

Vital capacity 4600 mL

What is the volume in the lung that we can't expel?

Residual volume 1200 mL

What does the Helium dilution method tell us?

Allows estimation of: • residual volume • functional residual volume

When is most of the air expired?

In the first second

What is FEV1?

Volume of air expired in the first second | • 4 L

What is FVC?

Forced vital capacity | 5L

What sort of diseases can occur in the lungs?

1. Obstructive lung disease • narrowed lungs • can't expire ``` 2. Restrictive lung disease • decrease in lung compliance due to scar tissue • can't inhale Pulmonary fibrosis (asbestos, smoking) ```

What things change in obstructive lung disease?

``` Decrease in FEV Decrease in FVC Decrease in the ratio Decrease in vital capacity Increase in residual volume ```

Why do people with Obstructive lung disease swim well?

More volume in the lungs | Increased residual volume

What changes occur in restrictive lung disease?

``` Decrease in FEV Decrease in FVC Ratio goes up Decrease in vital capacity No change in residual volume Decrease total lung capacity ```

What is dead space? - give examples of anatomical dead space

Part of the lungs that aren't involved in gas exchange Anatomical dead space • trachea • bronchi

Describe the effect of anatomical dead space

Air trapped in the trachea that is not refreshed This is taken back in during the next inspiration This stale air has reduced partial pressure of oxygen

What is the average tidal volume?

500mL

What is the average breathing rate

12 breaths / min

What is minute ventilation

Total ventilation over a fixed time period (usually a minute)

What is alveolar ventilation?

Volume of alveolar air exchanged per unit time Tidal vol - dead space

What happens if we breathe TV of 150 mL at f = 40?

Minute ventilation doesn't change Alveolar ventilation does! Pass out eventually, because of the dead space in the trachea

What is normal total pulmonary ventilation?

6 L/min

What is eupnea?

Normal quiet breathing

Describe the structure of the bronchioles. | Compare this with the bronchi

Bronchi: cartilage rings to keep them open Bronchioles: no cartilage • smooth muscle innervated by ANS

Describe what factors affect the resistance in the lungs

Resistance is proportional to: • length of airway • viscosity of air Inversely proportional to: • diameter

What is work of breathing? | What affects it?

Work of breathing is how much energy is required, ie how much resistance that needs to be overcome Resistance affects it. • airway diameter • lung compliance

What is the difference between lung compliance and elastance?

Compliance: ability to stretch Elastance: ability to spring back after stretching

What things can affect lung compliance?

Pulmonary fibrosis • causes decrease in compliance • scar tissue is stiff

What things can affect lung elastance?

Emphysema • decreases elastance • destroys elastin fibres

What is the effect of histamines and leukotrienes on the bronchioles?

Bronchoconstriction

What is the effect of epinephrine on the bronchioles?

Bronchodilation

What causes restrictive lung disease? How about obstructive lung disease?

Restrictive: decrease in compliance • asthma • emphysema Obstructive: narrowing of lower airways • pulmonary fibrosis

What is normal Va?

4.2 L/min

What is the name for increased respiratory rate?

Hyperpnea • due to increased metabolism Hyperventilation • no increase in metabolism

What is the apnea?

Cessation of breathing

What is dyspnea?

Difficulty breathing

What is tachypnea?

Rapid breathing | eg. panting

What parameters in alveoli would change if it weren't for surfactant?

Surface tension | Diameter of alveoli doesn't change

What would increased pressure in the alveoli result in?

* Decreased compliance | * Increased work of breathing

What is the important ratio?

• normally 80 FEV1 / FVC