Ch16 Pulmonary Ventilation

APK2105C @ UF w/ Dr. Nguyen | Module 4 | Ch16 Pulmonary Ventilation

external respiration

Exchange of gases b/t the atmosphere and body tissues

internal respiration

Use of O₂ at the mitochondria to generate ATP via oxidative phosphorylation and the resulting production of CO₂

ventilation; lung air; blood; lungs; tissues; blood; tissues

4 processes of external respiration:

1. Pulmonary ________ (i.e. breathing)

2. Exchange of gases b/t _____ ____ and ______ via diffusion

3. Transportation of gases b/t _______ and _______

4. Exchange of gases b/t _______ and ______ via diffusion

nasal/oral cavity, pharynx, larynx

What are the 3 main structures of the upper respiratory tract?

less; defense against pathogens

As you move down the conducting zone, do you find more or less cilia and goblet cells? What is their function?

more; bronchoconstriction/dilation

As you move down the conducting zone, do you find more or less smooth muscle? Why?

no; could impede gas exchange

Will you find other structures/tissues in the respiratory zone (i.e. respiratory bronchioles + alveolar sacs)? Why or why not?

conducting zone

The airways that transport air to the lungs w/o participating in gas exchange, including the trachea, bronchi, and bronchioles.

respiratory bronchioles; alveoli

The respiratory zone (i.e. where gas exchange occurs) is made up of _______ ______, alveolar ducts, alveolar sacs and _______.

anatomical dead space

Volume of air in the conducting zone that doesn’t make it to the respiratory zone for gas exchange.

150mL

What is the typical volume of the anatomical dead space?

capillary network, alveolar pores, elastic fibers

What are the 3 physical characteristics of alveoli?

respiratory membrane

The thin respiratory membrane that separates air from blood

Type I cell

Simple squamous epithelium that line the alveoli, forming the wall

Type II cell

Surfactant-secreting cell that helps in relieving surface tension

alveolar macrophages

Cells in the alveoli that act as a last line of defense

Move through pores → “eat” pathogens → go up resp. structures → get trapped by mucus → whisked away by cilia

capillary endothelium, alveolar epithelium, basement membrane

What are the 3 structures that make up the respiratory membrane?

diffusion

How does gas exchange occur in the pulmonary system?

thin; surface area

2 factors that make gas exchange (diffusion) a fast process:

1. _____ respiratory membrane (minimal barrier)

2. Huge ________ _____ (huge blood supply to alveoli)

visceral and parietal pleura; simple squamous epithelium

What are the 2 layers of the pleural sac? What tissue is the pleura made up of?

intrapleural space

Space that allows the lungs to expand w/o collapsing by creating a pressure gradient

serous fluid

What is found in the intrapleural space that lubricates the lungs as they expand and recoil, reducing friction?

diaphragm

• Inferior border of the thoracic cavity

• Separates the thoracic cavity from the abdominal cavity

lubrication; compartmentalization; pressure

Pleural functions:

• ________ b/t moving organs

• ___________ of the thoracic cavity

• Intrapleural ________ keeps the lungs partially expanded at all times

external intercostal muscles

Inspiratory muscles:

contract → pull ribs up/out → increase thoracic cavity volume

diaphragm

Inspiratory muscles:

inhalation → muscle flattens → increases thoracic volume (to accommodate for air coming in)

internal intercostal muscles and abdominal muscles

Expiratory muscles (2):

contract → press down on chest cavity → bring ribs down → decrease thoracic cavity volume

external intercostal muscles

In normal breathing, which muscles are the only ones being used?

forceful exhalation

Internal intercostal muscles get activated during _______ _______.

functional residual capacity (FRC)

Lung capacities:

• Volume of air in the lungs after normal exhalation (ERV + RV)

• All forces acting on the lung and chest wall are balanced (i.e. no pressure gradient)

inspiration; expiration

Intra-alveolar pressure (P_atm)

• At rest, P_alv = P_atm

• During _______, P_alv < P_atm

• During _______, P_alv > P_atm

intrapleural pressure (P_ip)

Lung pressures:

• Changes w/ phases of ventilation, but

• Is always less than P_atm (i.e. negative relative to P_atm)

transpulmonary pressure

Lung pressures:

Pressure difference across the entire lung, calculated by P_alv - P_ip

inflated; pneumothorax

A negative P_ip (relative to P_atm) allows the lungs to remain ________. What would happen if P_ip = P_atm?

in; 0; -4; bulk flow

Due to elasticity, the lungs naturally want to recoil ____. However, P_alv = ___ (FRC) and P_ip = ___, so _____ _____ grants the pleural sac enough force to prevent the lung from collapsing.

out; -4; bulk flow

Due to elasticity, the chest wall naturally wants to recoil ____. However, since P_ip = ____, _____ _____ grants the pleural sac enough force to keep the chest wall from expanding.

=; P_ip; collapses; expands

Pneumothorax (collapsed lung):

Trauma/puncture to pleural sac → air comes in → P_ip ___ P_atm → ___ unable to hold lungs and chest wall → lung ____ and chest wall _____

air flow; P_alv

What does this equation represent? P_atm - P_alv / R

Which of these terms determine the direction of air movement?

volume; thoracic; quantity

2 determinants of P_alv:

• Alveolar _______ (i.e. size)

  • Changes are produced by changes in the ________ cavity due to respiratory muscles expanding or compressing it.

• ________ of air molecules in the alveoli.

increased; decreased; into; decreased; increased; leaves

Thoracic volume impacts alveolar volume:

1. Inspiration: Alveoli expand → _______ volume → _______ pressure

2. Bulk flow: Air moves ____ alveoli, until pressure reaches 0

3. Expiration: Compression of respiratory muscles → _______ volume → _______ pressure

4. Bulk flow: Air ______ alveoli, until pressure reaches 0

lung compliance; airway resistance

2 factors impacting pulmonary ventilation:

1. ______ ______: ease of alveolar distention

2. ______ ______: resistance of entire system of airways

smaller; larger; inspiratory

Larger compliance means that a ______ change in transpulmonary pressure results in a ______ volume of air brought in. (This requires less muscular work and thus less energy.)

Such a change in transpulmonary pressure means ________ muscles contracted but they didn’t have to put in a lot of effort to pull on pleura.

elasticity; surface tension

Lung compliance depends on:

1. _______ of lungs

2. _______ _______ of water lining the alveoli

high; more

______ surface tension requires _____ muscular work to decrease P_ip

directly; inversely

The pressure necessary to prevent alveolar collapse (P) is _______ proportional to surface tension (T) and _______ proportional to alveolar radius (r)

P = 2T / r

pulmonary surfactant; decreases; increases; decreases

Detergent-like substance secreted by Type II cells that helps counter the effects of the water in the alveoli

• Decreases/increases surface tension

• Decreases/increases compliance

• Decreases/increases muscular work

high; more; bulk flow

In a small alveolus, there is _____ surface tension, which generates _____ pressure (P_alv). Due to _____ _____, air wants to leave the alveolus into a larger one → alveolar collapse

small; greater

Surfactant molecules are more present in ______ alveoli b/c they have _______ P_alv.

increases

As resistance ________, a larger ΔP (i.e. P_atm - P_alv) is necessary to produce a given flow gradient.

transpulmonary; bronchoconstriction; bronchodilation; mucous

3 factors affecting airway resistance:

• Changes in _________ pressure

  • Inspiration → pressure increases

  • Expiration → pressure decreases

• _________ and _________

  • Can be extrinsically or intrinsically mediated

• _________ secretion

spirometry

Technique for measuring the volumes of inspired and expired air

tidal volume (V_T); 500mL

The amount of air inhaled or exhaled during a normal breath.

What is the typical volume?

inspiratory reserve volume (IRV)

The amount of air you can forcefully inhale after a normal breath

expiratory reserve volume (ERV)

The amount of air you can forcefully exhale after a normal breath

residual volume (RV)

the amount of air remaining in the lungs after a forceful exhalation

lung capacities

Two or more lung volumes together make up ______ ________

inspiratory capacity

All the volumes of air (V_T + IRV) as they relate to inspiration make up the ________ ________. Shows the overall ability to bring air into the lungs.

vital capacity (VC)

The max. volume of air that can be exhaled after a full, maximal inhalation

V_T + IRV + ERV

total lung capacity (TLC)

Total volume of air in the lungs after max. inhalation

VC + RV

minute ventilation (V_E)

Total amount of air that flows into or out of the respiratory system in one minute

V_E = V_T x RR

6000 mL/min (or 6L)

What is the normal minute ventilation (V_T x RR) in a healthy adult?

alveolar ventilation (V_A)

The volume fresh air that reaches the alveoli each minute

V_A = (V_T - DSV) x RR

dead space ventilation (DSV)

• The volume of inhaled air that does not participate in gas exchange.

• Usually about 150mL remains in the conducting zone.

obstructive pulmonary disease

Pulmonary disease characterized by increased airway resistance

restrictive pulmonary disease

Pulmonary disease characterized by decreased lung compliance

acute obstructive pulmonary disease

What type of pulmonary disease is asthma?

asthma

Pulmonary disease:

• inflammation of airway lining

• increased mucous production

• bronchospasm (smooth muscle wall of bronchi/oles contract)

asthma

Corticosteroids (anti-inflammatory) and bronchodilators (i.e. B₂-adrenergic receptor agonists; e.g. inhalers) are used to treat what pulmonary disease?

chronic obstructive pulmonary disease (COPD)

Pulmonary disease:

• Inflammation → airways narrow → decreased air flow

• Inflammation → excessive mucous production

• Increased RV due to decreased ability to expire

FRC and TLC

In COPD, the decreased ability to expire leads an increase in which two lung capacities?

lung expansion; TLC; VC

Restrictive pulmonary disease:

• Structural damage to the pleura, chest wall, interstitium (e.g. scar tissue increases barrier) or parenchyma restrict _____ ________ → decreased compliance

  • Need more muscular work for air flow

  • Decreased _____ and _____

forced vital capacity (FVC)

Max. amount of air that can be exhaled after taking a deep breath in

forced expiratory volume in 1 sec (FEV₁)

Max. amount of air that can be exhaled after taking a deep breath in in 1 sec

(volume exhaled in 1 sec / FVC) x 100%

80%

What is the normal FEV₁ in a healthy individual?

normal; low; low

In a pt w/ obstructive pulmonary disease…

• FVC may be _______,

• FEV₁ is ____, so

• FEV₁ ratio is very ____

low; low; normal

In a pt w/ restrictive pulmonary disease

• FVC is ____

• FEV₁ is ____, so

• FEV₁ ratio may appear _______