A & P Chapter 3: Physiology of Respiration

The Primary Goal of Respiration

- Oxygenation of blood.
- Elimination of carbon dioxide & waste products.

Respiration Secondary Function

- Humans using respiration for communication is a side effect/biproduct.

Types of Respiration

- Inspiration
o Quiet
o Forced
- Expiration
o Quiet
o Forced

Quiet Inspiration

- Involves diaphragm and intercostals.

Forced Inspiration

- Requires accessory muscles.
- Diaphragm
o Contract and thorax lifts to allow more room.
o 60% of inspiration capacity.
- Costal levators (back muscles)

Quiet Expiration

- System is restored to a resting position after respiration using:
o The passive forces of gravity.
o De-torquing
o Elastic Recoil
- No muscle involvement.

Forced/Active Respiration

- Muscular effort enhances the act of expiration.
- Abdomen are compressed.
- Muscles reduce the size of the thorax.
- Rib cage is pulled down.
- Air is pulled out of the lungs.

De-torquing

- Return to normal position from an angle.

Elastic Recoil

- The ability for muscles to go back to their normal shape.

Measuring Respiration Tools

- Spirometer
- Manometer

Spirometer

- Rate of air flow in respiration.
- Measures Volume (how much air we can get out).
- Lung capacities.

Manometer

- Force produced when blowing in a tube.
- Measures Pressure.

Quick Bedside Assessment to Ensure There is Enough Pressure to Phonate

- Portable manometer.
- Using a straw, paper clip, cup of water, CM measuring tape.
- Place the straw 5 cm below surface of the water, secure with the paper clip, have patient blow bubble.
o If they can blow bubbles for 5 seconds, they have the ability to phonate.

Basic Processes of Respiration/Gas Exchange

- Ventilation
- Distribution
- Perfusion
- Diffusion

Ventilation

- The actual movement of air in the respiratory pathway.
- Air inhaled per unit of time.

Distribution

- The amount of air distributed to the 300 million alveoli.

Perfusion

- The migration of fluid through a barrier.
- Oxygen-poor blood is perfused to the 6 billion capillaries that supply the alveoli.

Diffusion

Gas exchange across the alveoli capillary membrane.

Efficiency of Respiration

- Efficiency of respiration depends on how individuals control their muscles of respiration.

What is the force behind speech production?

- Respiration
- Respiration provides energy for oral communication.

Respiratory Cycle

- 1 inspiration and 1 expiration

Respiratory Cycle Ages

- Adults: 12 and 18 cycles/minute
- Newborns: 40-70 breaths per minute.
- 5-year-old: 25 breaths per minute.
- 15-year-old: 20 breaths per minute.

Why are breaths per minute reduced in later years?

- Systems get bigger.
- Muscle control and coordination get better.

Alveoli Development

- Expand from 25 million at birth to more that 300 million by 8 years of age.
o Because thorax expands and lungs stretch to fill the cavity.

Why do adults breath more slowly?

- Because they have a volume of air that is never expelled, and infants do not have this reserve.

During work, demands for oxygen increases to:

- Up to 20 times more air required.
- Because muscles require more oxygen to contract.

To Breathe More We:

- Breathe deeper.
- Breath more often.

For breathing while speaking:

- We control the amount of air we let out.
- This takes muscular control.

Cycle of Tidal Respiration Time

- About 10 seconds.
- 4 seconds for inspiration and 6 seconds for expiration.

Volume

- Refers to the amount of air that will fit in a discrete compartment of your lungs.
- The amount of air in a specific system.

Capacities

- Refers to the combination of volumes that specify the physical limits of the lungs.

Tidal Volume (TV)

The volume we breathe in during a typical respiratory cycle.

Inspiratory Reserve Volume (IRV)

- Air inspired beyond tidal volume.

Expiratory Reserve Volume (ERV)

- Air expired beyond tidal volume.

Residual Volume (RV)

- Volume remaining in the lungs after maximum exhalation.

Why is Residual Air important?

- It maintains blood oxygen exchange.
o If we did not have residual air, blood oxygen would rise/fall with each breath.
- Keeps the lungs from collapsing.

Dead Space Air

- Air that cannot undergo gas exchange.
- Air within the passageway of the lungs.
- Not a discreet volume itself.

Vital Capacity (VC)

- Volume of air that can be inspired after maximal expiration.
- Capacity that is available for speech.
- VC = IRV + ERV + TV.

Functional Residual Capacity (FRC)

- Air that remains in the body after passive expiration.
- FRC = ERV + RV

Inspiratory Capacity

- Volume that can be inspired after tidal expiration.
- IC = TV +IRV

Vital Capacity is Affected By:

- Size, shape, gender.
- Strength of musculature.
- Health vs. Disease.
- Age.

Once You Reach Adulthood TLC is:

- The same across the lifespan.

Improper Laryngeal Habits:

- Waste breath.

What is the difference between breathing while yelling vs. breathing while projecting?

- Yelling is wasteful whereas projection requires good breath control.

Types of Pressure

1. Pulmonic
2. Intrapleural
3. Subglottal
4. Intraoral
5. Atmospheric

Pulmonic Pressure

- (alveolar pressure)
- Pressure within the lungs, specifically in alveoli.

Intrapleural Pressure

- (pleural-surface pressure)
- Pressure between the visceral (lung) and costal (rib) pleurae.

Subglottal Pressure

- Pressure below the level of the vocal folds.

Intraoral Pressure

- (oral pressure)
- Pressure within the mouth.
o Intraoral and subglottal pressure are the same if you vocal folds are open.

Atmospheric Pressure

- Pressure arising from the force of gravity on air molecules of the atmosphere.

Pressure: During Inspiration

- The thorax expands and decreases the negative intrapleural pressure.
- Increase lung volume results in a negative alveolar pressure.

Negative Alveolar Pressure

- Air will flow into the lungs as a result of the pressure difference between the lungs and the atmosphere.
The air will flow from the area of positive pressure to the area of negative pressure

Pressure: If the Respiratory Passage is Unrestricted

- Pressures are stable at rest (are equal)
- Atmospheric = intraoral = alveolar.

Pressure: During Expiration

- Pressure differential is reversed.
- Air escapes the lungs to equalize the positive alveolar with the relatively negative atmospheric pressure.

Recoil Forces

- During expiration, the tissue returns to the original dimension due to elasticity and gravity.

Relaxation Pressure Curve

- Pressure generated by the force of deeply breathing in.
- Relaxing the muscles after inspiration results in positive alveolar pressure.

Negative Relaxation Pressure

Negative relaxation pressure is found following forced expiration

Volumes and Body Posture

- Body position and posture play a significant role in respiratory volumes.

Volumes in the Reclining Position

- The abdomen is affected by the force of gravity resulting in the lung volume decreasing.
- The effort required for inspiration increases, meaning it is harder to breathe.

Two Levels of Pressure for Speech:

1. Constants supply of subglottal pressure to drive the vocal folds.
2. Rapidly changing pressure for syllabic stress.

Normal Respiratory Cycle

- Inspiration takes up 40% of cycle.
- Expiration takes up 60% of cycle.

Respiratory Cycle During Speech

- Inspiration takes up 10% of the cycle.
- Expiration takes up 90% of the cycle.

Speech Posture

- Rib cage is more expanded during speech.
- Abdomen is more compressed/tensed.
- Thoracic muscles put chest walls in an optimum space for rapid pressure changes.

Thoracic Muscles Influence Pressure in 2 Ways:

1. Long steady pressure to provide general loudness.
2. Short bursts of air pressure to provided emphasis, stress, and syllables.

Adding Pressure to Air Stream

- Add pressure by closing off or partially closing off airways.

Adding Pressure During Speech

- Close off larynx or mouth.
- Increase subglottal pressure by constricting glottis.
- Increase intraoral pressure by constricting articulators.

Air Pressure is Affected By:

- Thoracic Muscles
- Constricting the Air Passage.