Allied Science Physiology 09-10. Respiratory System. Lecture 6.
Allied Science Physiology. Respiratory System. Lecture 6.
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Mouth: Food masticated
(chewed) and mixed with
saliva: BOLUS
Pharynx (throat): Common
passageway for food and
air. Air to larynx; food to
esophagus. diverged
Esophagus: Conduct food
from the pharynx to the
stomach.
Figure 20.4
Allied Science Physiology. Respiratory System. Lecture 6.
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Muscular tube from pharynx to
stomach
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Upper 1/3 – skeletal muscle
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Lower 2/3 – smooth muscle
Upper esophageal sphincter
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Skeletal muscle
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Between pharynx and
esophagus
Lower esophageal sphincter
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Smooth muscle
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Between esophagus and
stomach
Figure 20.4
Allied Science Physiology. Respiratory System. Lecture 6.
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1.  Voluntary
–  Chewed food + saliva = bolus
–  Tongue moves bolus backwards and upwards the back of
the mouth to pharynx
2.  Pharyngeal phase (1 s)
–  Initiation of swallowing reflex
3.  Esophageal phase (9 s)
–  Continuation of swallowing reflex
–  Delivery of bolus to the stomach
Allied Science Physiology. Respiratory System. Lecture 6.
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Bolus descends in pharynx, pressing on epiglottis
Epiglottis covers glottis so food does not enter trachea.
Inspiration inhibited
Upper esophageal sphincter relaxes
Bolus enters esophagus
Sphincter closes behind bolus
Figure 20.29
Allied Science Physiology. Respiratory System. Lecture 6.
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•  Bolus stretches esophagus, triggering peristalsis
•  Peristalsis propels bolus to stomach
•  Travel time ~ 9 seconds
Figure 20.29
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Bolus arrives at stomach
Triggers relaxation of lower esophageal sphincter
Bolus enters stomach
If necessary, secondary peristalsis wave(s) comes to move
bolus into stomach
Figure 20.29
Allied Science Physiology. Respiratory System. Lecture 6.
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Allied Science Physiology. Respiratory System. Lecture 6.
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Larynx suspended from hyoid bone
Cartilages:
-  3 unpaired: Thyroid (Adam’s Apple), Cricoid, Epiglottis (leaf shape).
-  3 paired cartilages: Arytenoid (attached to vocal cords), Cuneiform and
Corniculate
Allied Science Physiology. Respiratory System. Lecture 6.
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Laryngeal muscles
a) Extrinsic (8)
- Suprahyoid group (4)
rise the larynx
- Infrahyoid group (4):
lower larynx & hyoid bone
b) Intrinsic (5)
- Adduct (close) vocal cords (4)
- Abduct (open) vocal cords (1)
Allied Science Physiology. Respiratory System. Lecture 6.
True vocal cords
- 2 elastic bands of tissue (R & L)
- Form entryway into the trachea
- Looking from above: “V” shape
- Open (abduct) when breathing
- Close (adduct) during voicing, coughing
and swallowing
False vocal cords (ventricular cords):
- Above and to the sides of true cords
- Do not usually vibrate during voicing
- Often close (adduct)
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a) Abduction (opening):
- Cricoarytenoid muscles contract
- Arytenoid cartilages and vocal folds
pulled laterally to open the glottis.
- Air flows to the respiratory track
a)
b)
b) Adduction (closing)
- Adductor muscles contract
- Pull vocal cords to center of glottis
(close).
- Very tight: during holding one’s
breath, swallowing or generating high
abdominal pressures
- Not-tightly closed: during voicing
Allied Science Physiology. Respiratory System. Lecture 6.
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Phonation: “process in which sound is produced for speech”
The edges of vocal folds lightly touching each other.
Air blown up from lungs past the edges of vocal cords
causing a repetitive cycle of vibratory movements:
a.  High pressure from below (subglottal pressure) blows
vocal cords apart
b.  Due to elasticity of cords vocal cords return to middle
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When cords are apart, puffs of air burst up and ‘excite’ air
within upper larynx and pharynx.
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This sequence of events repeated 100-200 times / sec.
When sequence of air bursts are repeated at high frequencies the
voice sounds like a tone (not series of mini explosions)
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•  Contraction of cricothyroid muscles stretch and
stiffened vocal cords: higher frequency of
vibration
•  The stiffer the cords the higher the frequency at
which they vibrate
•  The sound (voice) created in vocal cords is
shaped by muscular changes in pharynx
(throat) and oral cavity (lips, tongue, palate and
jaw) to create speech
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