LINGUISTICS 330 Lecture #4

RESPIRATORY MECHANISM

TRACHEA

It starts immediately below the cricoid cartilage

• The trachea consists of a tube of irregular cartilage rings descending just in front of the esophagus • The bottom ends divide into two twin tubes or bronchi which pass directly to the lungs and further subdivide into small bronchioles which house numerous air sacks (= alveoli) Ø oxygen is exchanged for carbondioxide Study APPENDIX , p.2

RESPIRATION The production of all speech sounds is the result of manipulation of air from the lungs.

Methods used for making the air audible: a. VOICING: The creation of near-periodic (see later) sound waves by the rapid opening and closing of the vocal folds. The air from the lungs is chopped into tiny puffs of air which are audible. b. CONSONANT NOISE: Part of the speech mechanism is positioned in such a way that aperiodic sound waves (see later) are created in the vocal tract. c. COMBINED METHOD: Combinations of periodic and aperiodic sound waves are created (voiced consonants) RESPIRATORY MECHANISM: NEGATIVE PRESSURE BREATHING • Expanding the chest and lungs will cause the air to flow in to equalize the negative pressure; • Contracting the chest and lungs will cause the air flowing out to equalize the positive pressure created by contraction.

IT IS BY CHANGING THE VOLUME THAT WE CHANGE THE PRESSURE (= the lungs are not like two balloons which are blown up with air as we breath in). Ø Boyle’s Law: Volume and pressure are inversely related.

1 The THORAX (=breast) is bounded by the vertebrae in the back and the sternum (=breast bone) in the front. Completing the cylinder are 12 sets of ribs (the lowest two ribs are only attached to the vertebral column).

DIAPHRAGM:

• A dome-shaped muscle sheet; it separates the thorax from the abdomen; • Contraction of the diaphragm: The muscle fibres shorten, pulling the central part downward toward the edges, which are attached to the lower ribs. The effect is to flatten and lower the diaphragm Æ thoratic volume is increased vertically! • The extent of movement of the diaphragm is only slight during speech. The lungs rest on the diaphragm and because they are spongy, elastic masses of air cells and lack muscles, they change shape by assuming the form of their container. When the diaphragm is lowered or elevated, the lungs go along the ride.

Similarly, when the thorax expands or contracts because of rib elevation or depression, the lungs also expand and contract due to a LINKAGE they have with the ribs.

PLEURAL LINKAGE: between the lungs and the ribs; it enables the lungs to expand and contract as the thorax changes volume. COSTAL (or parietal) PLEURA: A membrane that lines the rib cage PULMONARY (or visceral) PLEURA: A membrane that covers the lungs PLEURAL CAVITY: The space between these two membranes; it contains fluid. Study APPENDIX, p.1 and p.2

TIDAL VOLUME: The amount of air exchange during quiet respiration (about 0.5 liter) Ø 12-20 breaths per minute

VITAL CAPACITY (VC): Maximum inspiration Maximum expiration Ø (about 5 liters)

VC is related to sex, size and breathing habits.

RESIDUAL VOLUME: Air that cannot be expelled (about 2 liters)

THE MUSCLES OF RESPIRATION: a. diaphragm (see above)

2 b. Intercostal muscles external intercostals internal intercostals

STUDY Figure 9.10

The external and internal intercostal muscles are opposed in direction in which the muscle fibers course.

Inspiration: The external intercostals (and the section of internal intercostals which lies between the cartilaginous portion of the rib) contract Æ the ribs elevate.

Expiration: Internal intercostals contract (only in maximum expiration!) Æ the ribs are pulled down.

External intercostals: During expiration they act to slow down the elastic recoil force of the lungs!

Accessory respiratory muscles:

1. SCALENE MUSCLES (muscles of the neck): They elevate the ribs during inhalation

2. ABDOMINAL MUSCLES:

a. rectus abdominis b. external and internal obliques c. transversus abdominis

The ABDOMINAL MUSCLES serve to pull in the abdomen. They are active in respiration as their contraction forces the diaphragm up.

Study APPENDIX, p.1

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