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Chapter 22— The Respiratory System. Ch. 22 (Respiratory Sys.) Study Guide. Critically read Chapter 22 pp. 864-886 right before 22.3 “Gas Exchange and Transport” section Comprehend Terminology (those in bold)

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Chapter 22— The Respiratory System

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Chapter 22— The Respiratory System

Ch. 22 (Respiratory Sys.) Study Guide

Critically read Chapter 22 pp. 864-886 right before 22.3 “Gas Exchange and Transport” section

Comprehend Terminology (those in bold)

Study-- Figure questions, Think About It questions, and Before You Go On (section-ending) questions

Do end-of-the-chapter questions:

Testing Your Recall— 1-5, 7, 10, 11-18

True or False– 1, 2, 4-6, 8

Testing Your Comprehension– 1, 4, 5


Breathe/Breath (1 or 2)

Fear less, hope more;

Whine less, breathe more;

Talk less, say more;

Hate less, love more;

And all good things are yours.

--Swedish proverb

Breathe/Breath (2 of 2)

Every day brings a chance

for you to draw in a breath,

kick off your shoes,

and dance.

--Oprah Winfrey

§ I. Anatomical Consideration

Self-Check Question: As we breathe in, what respiratory organs, in order, does air pass through?

Answer: Nose (mouth) . . .

Fig. 22.1

§ Organs of Respiratory System







General Aspects

  • Airflow in lungs

    • bronchi  bronchioles  alveoli

  • Conducting & Rspiratory (C/R) divisions--

    • (C) passages ONLY for airflow, nostrils to bronchioles

    • (R) distal gas-exchange regions and ________

  • Upper/lower (U/L) respiratory tracts

    • (U) organs in head and neck, nose through larynx

    • (L) organs of trachea through lungs

§ 1. Nose

  • Bony and cartilaginous; supported by:

    • superior half: nasal bones medially and maxillae laterally

    • inferior half: lateral and alar cartilages

    • ala nasi: flared portion shaped by alar cartilages and dense CT; forms lateral wall of each nostril

    • Fig. 22.2 a+b

Conn. tissues shape the nose

(Ala nasi)

External Anatomy of Nasal Region

Nasal Cavity (1)

  • Extends from nostrils to posterior nares

  • Vestibule: dilated chamber inside ala nasi (just inside the nostril)

    • stratified squamous epithelium and vibrissae (guard hairs)

  • Nasal septum divides cavity into right and left chambers called nasal fossae

    • Makes up of = Perpendicular plate of ethmoid bone + . . .

Nasal Cavity (2) - Conchae and Meatuses

  • Superior, middle and inferior nasal conchae

    • 3 folds of tissue on lateral wall of nasal fossa

    • mucous membranes lines the cavity

  • Meatuses:

    • narrow air passages beneath each conchae

    • narrowness and turbulence ensures most air contact the mucous membrane.

      Fig. 22.3


Figure 8.4b












Palatine bones

Functions of the nose

  • Nose (mouth)—air enters the body through here


    • Warm and moisten air

    • Produce nasal mucus– how much each day? By epi. cells

    • Cilia– push particles toward the throat

§ 2. Pharynx (throat)


  • Common entryway of . . .

  • Food and air diverge into two separate branches

  • Air  which organ next?

  • Food  which organ next?

    Which passage way (air or food) is at the anterior?

    Figure 22.3 b+c


Lower respiratory tract


Three Regions of Pharynx

Hyoid bone

Cricoid cartilage


§ 2. Pharynx (continued)

  • Nasopharynx(pseudostratified epithelium)

    • posterior to choanae, dorsal to soft palate

    • receives auditory tubes; houses _____ tonsil

    • 90 downward turn; traps large particles (>10m)

  • Oropharynx(stratified squamous epithelium)

    • space between soft palate and root of tongue, inferiorly as far as hyoid bone, contains palatine and lingual tonsils

  • Laryngopharynx(stratified squamous epi.)

    • hyoid bone to level of cricoid cartilage

§ 3. Larynx (Voice box)

  • Anatomy—anterior protrusion called ?

  • Functions—

  • Air passageway with cilia

  • Epiglottis– superior opening of larynx

  • Voice production by ____________

  • Laryngitis—Inflammation of the vocal cords; symptoms? Three major causes?


  • Glottis – vocal cords and opening between them

  • Epiglottis

    • flap of tissue that guards glottis, directs food and drink to esophagus

  • Infant larynx; epiglottis touches soft palate

    • higher in throat, forms a continuous airway from nasal cavity to the larynx that allows breathing while swallowing

    • by age 2, more muscular tongue, forces larynx down to lower position

Nine Cartilages of Larynx

The superior three (large):

  • Epiglottic cartilage (1)- most superior

  • Thyroid cartilage (1)– largest; laryngeal prominence is the Adam’s apple

  • Cricoid cartilage (1)- connects larynx to trachea

  • Fig. 22.4

Views of Larynx






Nine Cartilages of Larynx

The other 3 small pairs of cartilages:

  • Arytenoid cartilages (2) - posterior to thyroid cartilage

  • Corniculatecartilages (2) - attached to arytenoid cartilages like a pair of little horns

    The above two pairs of cartilages function in speech

  • Cuneiformcartilages (2) - support soft tissue between arytenoids and epiglottis

Walls of Larynx

  • Interior wall has 2 muscular folds on each side, from thyroid to arytenoid cartilages

    • Vestibular folds (superior pair) and vocal cords/folds (inferior) (produce sound)

  • Intrinsic muscles (deep)- rotate corniculate and arytenoid cartilages (Fig. 22.6)

    • adducts (tightens: high pitch sound) or abducts (loosens: low pitch sound) vocal cords

  • Extrinsic muscles (superficial)- connect larynx to hyoid bone, elevate larynx during swallowing

low pitch

High pitch

§ 4.Trachea (windpipe)

Anatomy/Histology: Beginning of lower respiratory tract (Fig. 22.7 a-c +x)

  • Rigid tube 5 in. long and 1 in. diameter, anterior/posterior (?) to the esophagus

  • Supported by 16 to 20 C-shaped rings; openings facing anterior/posterior (?)

    • The lowermost cartilage called ________

  • A smooth m. (trachealis) spans opening in rings, adjusts airflow; facing (ant./post.?)

  • (Histology) Larynx and trachea lined with ciliated pseudostratified columnar epi. which functions as mucociliary escalator


See next three slides



Ciliated Pseudostratified Epi.


ID structures: Practice at home






§ 4. Trachea (continued)


  • Air passageway

  • Warm and moisten air

  • Remove particles & debris

    Clinical applications:

  • Trachea obstruction and Heimlich Maneuver

  • Tracheostomy (Insight 22.1) when the obstruction is superior to the level of the larynx; pitfall?

§ 5. Bronchi (supported by cartilages)

  • Primary bronchi (2); with C-shaped rings

    • from trachea; after 2-3 cm enter hilum of lungs

    • right bronchus slightly wider and more vertical

  • Secondary (lobar) bronchi (2 L. lung+ 3 R. lung); one secondary bronchus for each lobe of lung; cartilage plates

  • Tertiary (segmental) bronchi (8 L. lung + 10 R. lung); cartilage plates

    • bronchopulmonary segment: portion of lung supplied by each tertiary bronchus

      Fig. 22.7

All bronchi are supported by cartilages

§ 6. Bronchioles

Bronchioles(lack cartilage; 1 mm or less in diameter; ciliated simple columnar to ciliated simple cuboidal epi.)

  • Each divides into 50 - 80 terminal bronchioles

    • Mostly nonciliated simple cuboidal; end of conducting division

  • Each terminal bronchiole branches into respiratory bronchioles (respiratory div. now); smallest ones are nonciliated epi.

  • Each divides into 2-10 alveolar ducts (nonciliated simple squamous epi.); end in alveolar sacs

    • Fig. 22.11

§ Bronchial tree

Def. --Highly branched system of air tubes from the primary bronchi to about 65,000 terminal bronchioles

Resemble inverted trees

Fig. 22.0 + X

CO 22

Right lung; 10 segments

Left lung; 8 segments

Each broncho-pulmonary segment by a different color of resin

Right lung; 10 broncho-pulmonary segments

Left lung; 8 broncho-pulmonary segments

§ 7. Lungs (Fig. 22.9 a + b)

  • Concave base and blunt apex

  • Costal surface--

  • Concave mediastinal surface—

  • The hilum (hilus)– slits/depression where bronchi, blood vessels, nerves entering/leaving

  • The right lung– shorter; the left lung– narrower, with cardiac impression

  • L– 2 lobes separated by a fissure

  • R– 3 lobes separated by two fissures

§ 8. Alveoli meaning hollow

  • Def.– tiny air sacs where . . .

  • Anatomy/physiology—

    • Each alveolus– single layer of epithelium surrounded by ____________________

    • Numerous alveoli (150 million) in each lung

      Figure 22.12

Alveolar Blood Supply

§ Alveoli—Pore of Kohn

Pore of Kohn

  • Location?

  • Function?

  • Analogy—

    Fig. x





A. Branch of



C. Branch of



2. Respiratory


(beginning of respiratory division)

B. Pulmonary


3. Alveolus

Alveolar sac

Pores of Kohn

§ Alveoli—Three types of cells

  • Squamous (Type I) alveolar cells—

    • Location?

    • Function--Gas exchange through these sites; What type of epi.?

    • Respiratory membrane– 0.5 micrometer; the barrier between alveolar air and _____

  • Great (Type II) alveolar cells—

    • Location? Embed within alveolar walls

    • Functions— secretes surfactant & repairs

      Figure 22.12

Fluid lining

With surfactant

C. Alveolar


B. Great alveolar cell





A. Squamous alveolar cell

Respiratory mem.


§ Alveoli—Three types of cells

  • Alveolar macrophages (dust cells)—

    • Most numerous of all cells in the lung

    • Large tissue-bound phagocytes

    • Location– within the alveolar lumen

    • Function-- Phagocytosis

Practice at home



What is respiratory membrane?



Fig. 22.11

b and c

Identify A, B, C, and D.

Respiratory mem.

Questions (muddiest points)?

§ II. Pulmonary Ventilation

  • Respiratory cycle– One complete cycle of inspiration and expiration

    • Breathing (pulmonary ventilation) – repeated cycles above

  • Quiet respiration vs. forced respiration –

  • Basic requirement of respiration:

    • Flow of air in and out of lung requires a ______________ between air pressure within lungs and outside body; why? (next slide)

§ Breathing- mechanical steps

  • Why flow of air into and out of the lungs during the breathing?

  • A rule of thumb—

    • PV = K (Boyle’s law) with Temp. is constant

    • For example, during inspiration: lung volume increases lung pressure decreases  therefore, air flow (from where to where? _____________________)

      Figure x (Boyle’s Law explained)

Figure 13.10Page 467


Each container with the same number of gas molecules





A. Volume = 1/2

Pressure = 2

B. Volume = 1

Pressure = 1

C. Volume = 2

Pressure = 1/2

PV = K

§ Breathing- mechanical steps

  • Mechanism of Inspiration (resting)—

    • Diaphragm contracts and move ______?

    • External intercostals muscles contract  the ribs move __________?

    •  Chest volume _________?

    •  Air pressure is _________? (Boyle’s law)

    •  Air flows inward

  • Deeper Inspiration—

    • Neck muscles (among others) are also involved

      5 Figures


A 2-dimentional figure

Quiet Inspiration

2. Contraction

of external



1. Contraction

of diaphragm

increases side-to-side

dimension (x)

increases vertical

dimension of (z)

increases front-to-back

Dimension (y)

A 3-dimentional figure


no net movement of air

Before inspiration

760 mmHg


size of thorax

760 mmHg


size of lungs

760 mm Hg

During inspiration

Size of thorax  on

contraction of

inspiratory muscles

Size of lungs  as they

are stretched to fill

the expanded thorax; pressure 

757-759 mm Hg (from 760)

Demonstration—lung model


of active/forced


Muscles of deeper


1. Sternocleidomastoid




2. Scalenus

1. External



2. Diaphragm




muscles of


§ Breathing- mechanical steps (students practice on this; KEY on next slide)

  • Mechanism of Expiration—

    • Diaphragm ________ and becomes ______

    • External intercostal muscles ____  the ribs move ______

    •  Chest volume _________?

    •  Air pressure is _________? (Boyle law)

    •  Air flows outward

  • Forced expiration: abdominal and internal intercostal muscles are involved

    Figures 22.13


of external




of internal



Contraction of internal intercostal

muscles flattens ribs and

sternum, further reducing

side-to-side and front-to-back

dimensions of thoracic cavity

A review slide on expiration


of abdominal muscles

Position of relaxed

abdominal muscles

Relaxation of


Contractions of abdominal

muscles cause diaphragm to

be pushed upward, further

reducing vertical dimension

of thoracic cavity

Passive expiration

Return of diaphragm, ribs, and sternum

to resting position on relaxation of

inspiratory muscles restores thoracic

cavity to preinspiratory size

Active expiration

During expiration

760 mm Hg

Size of thorax on

relaxation of

inspiratory muscles

761 mm Hg (from 760)

Size of lungs as

they recoil

§ Summary of respiratory muscles (This slide for review with Fig. x next)

  • Diaphragm (dome shaped)

    • contraction flattens diaphragm

  • External intercostals

    • increases X&Y diameter; stiffen thoracic cage

  • Scalenes - hold first 2 pair of ribs stationary

  • Pectoralis minor, sternocleidomastoid and erector spinae muscles

    • used in forced inspiration

  • Abdominals, internal intercostals, and latissimus dorsi

    • forced expiration (to sing, cough, sneeze)

    • Valsalva maneuver– raise abdominal pressure . . .

Forced Expiration

Forced Inspiration

Quiet Inspiration

§ III. Neural Control of Breathing

§ Neural Control of Breathing (1)

  • Breathing depends on repetitive stimuli from the brain—controlled at two levels (A & B below):

    • Neurons in medulla oblongata and pons control unconscious breathing

      • Ondine’s curse – brainstem damage

      • Causes– Poliomyelitis etc.

      • Symptoms– disabled automatic respiratory functions

      • Cure--

    • Voluntary control provided by motor cortex is cerebral and consciously controlled

§ Neural Control of Breathing (2)

  • Unconscious breathing:

    • Inspiratory neurons: fire during inspiration

    • Expiratory neurons: fire during forced expiration

    • Fibers of phrenic nerve go to diaphragm; intercostal nerves to intercostal muscles

§ Three Respiratory Control Centersin the brainstem (Fig. 14.4)

  • Ventral respiratory group (VRG) in medulla

    • Primary generator of respiratory rhythm

    • Having both inspiratory and expiratory neurons, taking turns to fire  spinal integrating centers

  • Dorsal respiratory group (DRG) in medulla

    • An integrating center– inputs from . . . (Fig. 22.4)

    • Output to the VRG modifying respiratory rhythm

  • Pontine respiratory group (PRG) in pons

    • Modifies the rhythm of the VRG

    • Making each breath shorter/shallower OR longer/ deeper– during sleep, exercise, etc.

  • Anterior

    1. from higher brain centers


    2. PRG


    3. Central Chemoreceptors


    4. CN IX and X


    Spinal integrating centers


    § Input to the respiratory centers

    • Central chemoreceptors (in medulla)

      • primarily monitor pH (and CO2) of CSF

  • Peripheral chemoreceptors (Fig. 22.15)

    • Monitor pH, O2 and CO2 and fibers synapse to the DRG

  • Stretch receptors (bronchi and bronchioles)

    • Excessive inflation triggers inflation reflex and stops inspiration

  • Irritant receptors (epithelial cells of the airway)

    • Respond to particles and trigger coughing etc.

  • § Voluntary Control of breathing

    • Neural pathways

      • motor cortex of frontal lobe of cerebrum sends impulses down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem

    • Limitations on voluntary control

      • blood CO2 and O2 limits cause automatic respiration overrides one’s will

    • Voluntary control is important in singing, speaking, breath-holding

    Check Point Questions

    Q--Where exactly are the medulla oblongata and the pons located, respectively?

    Answer: medulla oblongata is the most caudal part of the brainstem (stalklike lower portion of the brain), immediately superior to the spinal cord

    • The pons is a part of the brainstem located immediately superior to the medulla oblongata and ventral to the cerebellum

    § Next section--IV. Pressure, Resistance, and Airflow

    Q-- Is it possible that temperamental children may hold their breath until they die?

    § Pressure and Airflow (1)

    Introduction– (Mostly we have talked about)

    • Atmospheric (barometric) pressure--

      • 1 atmosphere (atm) = 760 mmHg

    • Intrapulmonary pressure and lung volume

      • pressure is inversely proportional to volume

        • for a given amount of gas, as volume , pressure  and as volume , pressure 

    • Pressure gradientsmatters to airflow--

      • difference between atmospheric and intrapulmonary pressure

      • Airflow (F) = ΔP (pressure gradient)

    § Pressure and Airflow (2)

    During inspiration; how lungs are expanded?

    • Ribs swing upward and outward  lungs expand with thoracic cage

      •  intrapulmonary pressure (-3 mm Hg; 3 mm Hg below atmospheric pressure)

      • 500 ml of air flows into the lungs (tidal volume)

    • Another force expands the lungs– warming of the inhaled air. Inhaled air expands, it helps to inflate the lungs. (Charles’s law)

      • Charles’s law– volume of given quantity of gas is directly proportional to its absolute temperature

    § Pressure and Airflow (3)

    Recoiling mechanisms during expiration:

    • During quiet breathing, expiration achieved by elasticity of lungs and thoracic cage etc.

    • As volume of thoracic cavity , intrapulmonary pressure  (+3 mm Hg) and air is expelled

    • Pulmonary elasticity related disorders:

      • Atelectasis– The collapse of a lung

      • Causes– A) Pneumothorax (air in the pleural cavity; see next slide), B) airway obstruction (that part of lung collapses b/c it cannot be reventilated, for example inadequate surfactant, aspirated object etc.

    § Pneumothorax

    • Def.—abnormal condition of air entering the pleural sac

    • Causes— (see fig. x)

    • Consequences— transmural pressure gradient no longer exists and . . .

      Figure x


    Atelectasis (pneumothorax)





    760; intra-pulmonary pressure




    756; intrapleural pressure

    Collapsed lung

    A– Parietal pleura; B—pleural cavity (pleural fluid); C– Visceral pleura

    § Pulmonary surfactant (1)

    • A potential problem of breathing

      • In alveoli—tiny sacs . . .; why?

      • b/c surface tension of water— Fig. z

    • Solution-- pulmonary surfactant

      • What is it? Phospholipoproteins

      • Where does it from? By what cell type?

      • Functions?


    H2O molecules

    An alveolus

    § Pulmonary surfactant (2)

    • (Newborn/Infant) respiratory distress syndrome (IRDS)—

      • What is lacking in premature infants?

      • What are the problems?

        • When surfactant is produced?

        • Alveoli collapsed completely —

        • Newborn’s muscles--

      • Cure--

    Check Point Questions

    • What types of cells make up the wall of an alveolus? Function?

    • What type of cell in the lungs secrete pulmonary surfactant? Function?

    § V. Alveolar Ventilation

    § Alveolar Ventilation (1)

    Does all inhaled air enter the alveoli?

    • Dead air (150 ml per breath)

      • fills conducting division of airway, cannot exchange gases with the blood

    • Where is the dead air? In anatomic dead space:

      • It exists in conducting division of airway

      • Normally about _______mL

    • Physiological (total) dead space

      • sum of anatomic dead space and any pathological alveolar dead space

    § Alveolar ventilation (2)

    • Alveolar ventilation rate (AVR): body’s ability to get oxygen to the tissues per minute

      • alveolar ventilation rate (AVR) = (Tidal volume - dead space volume) x respiratory rate

      • AVR = (500-150mL) x 12 breaths/min = 4,200 mL/min

    § Measurements of Ventilation (1)

    • Spirometer – measures ventilation; specifically respiratory volumes and capacities

      Fig. x

    Floating drum





    with time





    Inspired air

    § Measurements of Ventilation (2)

    • Respiratory volumes:

      • Tidal volume (TV) - The air entering or leaving the lungs in a single breath.

      • Inspiratory reserve volume (IRV) - The extra air that can be maximally inspired over the typical resting TV.

      • Expiratory reserve volume (ERV) - The maximal volume of air that can be actively expired beyond a tidal volume.

      • Residual volume (RV) - air remaining in lungs after maximum expiration

        Fig. 22.17

    a capacity is the sum of more than two volumes





    § Measurements of Ventilation (3)

    • Respiratory capacities:

      • Inspiratory capacity (IC)- The maximum volume of air that can be inspired at the end of a normal quiet expiration. = TV + IRV

      • Functional residual capacity (FRC)– Amount of air remaining in the lungs after a normal tidal expiration; = RV + ERV

      • Vital capacity (VC)- The maximum volume of air that can be expired following a maximal inspiration. = TV + IRV + ERV

      • Total lung capacity (TLC)- maximum amount of air lungs can hold; = VC + RV

    ID the following respiratory volumes/capacities









    Work on this figure at home.

    Check Point Question

    • If you breathe in as deeply as possible and then exhale as much air as you can, which lung volume or capacity have you demonstrated?

    § Lung disorders and spirometry

    • Restrictive disorders– Those having reduce pulmonary compliance, limiting the amount to which the lungs can be inflated

      • Disorders- black lung disease, tuberculosis

      • Spirometry- reduced IC, VC, TLC

    • Obstructive disorders (COPD; Chronic Obstructive Pulmonary Disease) – those that interfere with airflow by narrowing or blocking the airway

      • Disorders– asthma, emphysema etc.

      • Detection: Forced expiratory volume (FEV)-- % of vital capacity exhaled/time; healthy adult - ___________% of VC in 1 sec(Fig. Y)


    1 sec interval

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