Respiratory Physiology

List the three stages of respiration.

1) Ventilation→ mechanical

2) Gas Exchange→ diffusion of O2 and CO2

3) Cellular respiration→ utilization of O2

Name the respiratory zones.

1) Conducting zone

2) respiratory zone

List in order the sites of the conducting zone.

mouth

pharynx

larynx

trachea

primary bronchi

What is the function of the conducting zone?

1)raises temp

2)moistens air

Distinguish between terminal and respiratory bronchiole.

Respiratory bronchiole branch out from terminal bronchiole.

What blood vessels are found on the alveoli?

capilaries

How does air move?

From high pressure area to low pressure areas

What is breathing in called?

Inspiration.

Describe lung air pressure during inhalation?

Reduction of air pressure in lungs to below atmospheric pressure due to volume increase.

What’s Boyle’s law?

P inversely proportional to Volume.

Describe the pleural membranes.

1)visceral→ tightly covers the lunds

2)pariental→ lines the

Describe the relationship between the diaphragm and the thoracic cavity.

The diaphragm muscle lines the base of the thoracic cavity.

What holds the visceral and pariental pleura together?

Pleural fluid

Is there a space between the pleura?

There’s no interpleural cavity.

ONLY PLEURAL CAVITY!

Distinguish between forced and normal inspiration.

**Normal** is caused by the contraction of the __diaphragm__ and the __external intercoastal__ muscles.

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**Forced** inspiration is caused by secondary muscles → __scalenes__ and __pectoralis minor__

What’s the change in INTRAPULMONARY PRESSURE during normal inspiration?

\-3mmHg BELOW ATMOSPHERIC PRESSURE

What’s the change in INTRAPULMONARY PRESSURE during forced inspiration?

\-20mmHg

What contributes to normal expiration?

The elasticity of thorax and lungs that recoil after being stretched.

Is expiration passive or active?

Passive

What is the pressure increased to during normal expiration

\+3mmHg

What contributes to forced expiration?

Intercoastal muscles and abdominal muscles

What is the pressure change during forced expiration?

\+30mmHg

What type of mucles are respiratory muscles?

Skeletal- regulation of breathing!

What’s pleural pressure? Ppl

Pressure of pleural fluid

What’s the relationship between intrapleural and intra alveolar pressure?

intrapleural pressure is LOWER than intra-alveolar

In which way are pariental and visceral pluera pulled?

Visceral is pulled inward

Pariental pulled outward (part of thoracic cavity)

What’s the pressure gradient between intra-pleural and intra-alveolar pressure called?

Transpulmonary pressure

Why is transpulmonary pressure vital?

To keep pressure in lungs higher

Why is pressure in the intrapleural cavity so low?

The thoracic cavity stretches it outwards

The lunds stretch it in

Increase in volume due to

Describe the intra-pleural pressure during inspiration and expiration

\-6mmHg during inspiration

\-3mmHg during expiration

What happens to transpulmonary pressure when pleural membranes are damaged and air flows in?

The air unsticks the pleural membranes

Define pneumothorax.

Collapsed lung.

What happens to lung volume due to pneumothorax?

Volume decreases as the visceral pleura no longer stretches the lung outward.

What’s the compliance of the lung?

Ability of the lung tissue to stretch and expand.

Define lung compliance.

The change in lung volume resulting from a change in TRANSPULMONARY PRESSURE

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Equation for lung compliance

Cl= delta Volume / transpulmonary tissue

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What’s the elasticity of the lung.

Ability of the lung to return rapidly to its original size.

What protein is responsible for the elasticity of lungs?

Elastin.

What happens to intrapulmonary (same as intralveolar pressure) during expiration.

Increased.

What happens to lung compliance in lungs with fibrotic tissue?

Compliance is reduced.

Less air moves in during inspiration.

= restrictive pulmonary disease.

What is degenerated in a patient with emphysema?

alveolar septa and pulmonary capillaries

→ compliance is increased

→ volume increased but doesn’t snap back

→ elasticity lost

→ expirary diifult

What else generates resistance to lung expansion?

Surface tension

What creates this surface tension?

SPHERICAL alveoli secrete a thin layer of fluid

→ presence of air increases surface tesnion

→ water molecules pull in towards the alveoli

→ opposed the expansion of lungs during inspiration

→ lung compliance decreased

Do smaller or larger alveoli have a greater surface tension?

smaller

What’s the law of laplace?

P= 2\* T/r

→ divided by the radius

→ inward pressure

→more work needed to increase the volume of air in alveoli that are pulled inward due to surface tension

What does alveoli fluid contain to reduce surface tension?

Surfacts

What kind of biomolecule is a surfactant

Lipoprotein

What does the surfactant prevent?

Collapse ofsmaller alveoli during expiration

Do alveoli completely empty themselves?

No, there’s always residual volume

What type of alveoli produce surfactant?

Type II alveolar cells

When do type II alveolar cells develop?

Late foetal development

\-25th week

What do premature infants (before 34th week) suffer from due to low type II development?

Acute respiratory distress syndrome

Acute respiratory distress syndrome- what does that do to the lungs?

Decreases lung compliance

Collapses Alveoli