Transcript Chapter 13 The Respiratory System

Chapter 13 The Respiratory
System
Biology 112
Tri-County Technical College
Pendleton, SC
System Essentials
Supply cells with oxygen
Pick up carbon dioxide from the body
Eliminate carbon dioxide from the body
Organs of respiratory system include:
Nose, pharynx, larynx, trachea, bronchi
and its branches, and the alveoli of the
lungs
Respiratory System Visual
A nose for this…or that
Only externally visible part of system
Air enters nose through external nares
(nostrils)
Interior consists of nasal cavity divided
by midline nasal septum
Olfactory receptors in mucosa in
superior part of cavity just below
ethmoid bone
Nose, cont.
Rest of mucosa lining called respiratory
mucosa rests on network of thin-walled
veins that warms air flowing past

Mucosa moistens inhaled air & traps
incoming debris
Ciliated cells move contaminated mucus
posteriorly toward throat (pharynx)
swallowed & digested by stomach acid
Nose, cont.
Three mucosa-covered lobes called nasal
conchae increase surface area exposed to air

Also increase turbulence in nasal cavity
Nasal cavity separated from oral cavity by
partition called the palate
Anterior palate supported by hard bone =
hard palate
Posterior palate is unsupported by bone =
soft palate
Paranasal Sinuses
Nasal cavity surrounded by paranasal
sinuses located in frontal, sphenoid,
ethmoid, and maxillary bones
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Lighten the skull
Resonance chambers for speech
Produce mucus that drains into nasal cavity
Nasal mucosa continuous throughout RT
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Nasal infections can spread throughout mucosa
Sinusitis difficult to treat & can cause marked
change in voice quality
Pharynx
Muscular passageway for food and air
commonly called throat
Naso-; Oro-; and laryngopharynx
Air enters superior portion (naso) from nasal
cavity anteriorly
Air descends through oropharynx and
laryngopharynx to enter larynx below
Food from mouth travels with air through oroand laryngopharynx but directed posteriorly to
esophagus instead of entering larynx
Pharynx, cont.
Auditory tubes that drain middle ear open into
nasopharynx
otitis media (ear infection) may follow sore
throat/pharyngeal infections
Clusters of lymphatic tissue called tonsils
found in pharynx
Pharyngeal: (adenoids) located high in naso
Palatine: oropharynx at end of soft palate
Lingual: at base of tongue
Respiratory Visual
Larynx and Associated
Structures
Larynx (voicebox) routes air/food into proper
channels and plays role in speech
Formed by 8 rigid hyaline cartilages and
elastic cartilage called epiglottis
Largest of hyaline cartilages is THYROID
cartilage (Adam’s apple)
Epiglottis protects superior opening of larynx
Larynx, cont.
Not swallowing, epiglottis does not restrict
passage of air into respiratory passages
Swallowing, larynx pulls forward and
epiglottis tips forming lid over opening of
larynx
Routes food/drink into esophagus posteriorly
Cough reflexunconscious person
Larynx, cont.
Part of mucous membrane of larynx
forms pair of folds called vocal folds
(true vocal cords) which vibrate with
expelled air
Allows speech
Slitlike passages between folds called
glottis
Larynx leads to trachea (windpipe)
Trachea
Extends from larynx to level of 5th
thoracic vertebra (~ midchest)
Lined with ciliated mucosa
Walls reinforced with C-shaped rings of
hyaline cartilage
Open parts of rings abut esophagus and
allow it to expand anteriorly when one
swallows
Trachea, cont.
Solid portions support walls and keep it
patent (or open) in spite of pressure changes
during breathing
Tracheal obstructions are LIFE-threatening
Heimlich maneuver can unclog trachea

It works or my side would be gone…for good
Sometimes emergency trachesostomy is
required
Bronchi Divisions
Trachea divides into right and left primary
bronchi
Each primary bronchi plunges into medial
depression (the hilus-depressed area where
vessels enter/leave an organ) of lung
Right pulmonary bronchus is wider, shorter,
and straighter than left
Smaller subdivisons of primary bronchi within
lung deliver air to alveoli
Bronchi Visual
Lungs and more…
Occupy most of thoracic cavity except for
mediastinum (houses heart, great blood
vessels, bronchi, esophagus, thymus, and
trachea)
Narrow superior portion is APEX; located just
deep to clavicle
Broad area resting on diaphragm is BASE
Each lung divided into LOBES by fissures
Left lung = 2 lobes; right lung = 3 lobes
Lungs, cont.
Surface covered by visceral (pulmonary)
pleura and walls of thoracic cavity lined by
parietal pleura
Membranes produce pleural fluid which
allows lungs to glide easily over thorax wall
during breathing
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Also causes 2 pleural layers to cling together
Glide easily but resist being pulling apart
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Absolutely essential for normal breathing
Lungs, cont.
PLEURISY (inflammation of pleura) can be
caused by decreased secretion of pleural
fluid
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Surfaces become dry and roughfriction and
stabbing pain with each breath
Another kind of pleurisy results in excess fluid and
pressure on the lungs
Primary bronchisecondary & tertiary
bronchibronchiolesterminal bronchioles
(conducing zone structures)respiratory
zone structures
Lungs, cont.
RZ structures include respiratory
bronchiolesalveolar ductsalveolar
sacsalveoli and is ONLY site of gas
exchange
Exchange of Gases
Alveoli composed largely of single layer of
layer of squamous epithelial cells
External surface of alveoli covered with
cobweb of pulmonary capillaries
Alveolar and capillary walls construct
respiratory membrane (air-blood barrier)
Blood flowing on one side; air on the other
Gases diffuse across air-blood barrier by
simple diffusion
Gas Exchange, cont.
Surface area of lungs = size of racquetball
court (70-80 sq. meters)
Macrophages (dust cells) wander in and out
of alveoli to pick up bacteria/debris
Cuboidal epithelial cells scattered throughout
alveolar walls secrete surfactant (lipid that
coats gas-exchange alveolar surfaces and is
important in lung function
Gas Exchange Visual
Events of Respiration
Pulmonary ventilation (breathing)
External respiration (gas exchange
between pulmonary blood and alveoli)
Respiratory gas transport (gas must be
transported to/from lungs and tissue
cells via bloodstream
Internal respiration (gas exchange
between blood and tissue cells at
systemic capillaries
Mechanics of Breathing
Pulmonary ventilation depends on volume
changes in thoracic cavity
Volume changes lead to pressure
changes flow of gases to equalize the
pressure
Gas always fills its container

Volume of container related to pressure of gas
Inspiration = gas flowing into lungs
Expiration = gas flowing out of lungs
Mechanics of Inspiration
Diaphragm & external intercostal muscles
contract
Size of thorax increaseslungs adhere tightly
to thorax wallsstretched to new, larger size
of thorax
Lung volume increases producing partial
vacuum (pressure less than atmospheric
pressure)
Air rushes in to fill space—inspiration is
always an active process
Mechanics Visual
Mechanics of Expiration
Usually passive process that essentially
reverse of inspiration
Active expiration (forced)—internal
intercostals activated and contracted to
depress rib cage and abdominal
muscles contract to help FORCE air
from lungs
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Asthma (spasms of bronchioles) or chronic
bronchitis/pneumonia can narrow
respiratory passageways
Mechanics, cont.
Actelectasis (lung collapse) renders
lung useless for ventilation
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air enters pleural space through chest
wound or rupture of visceral pleural (allows
air to enter pleural space from respiratory
tract)
Pneumothorax is term given presence
of air in intrapleural space (disrupts fluid
bond between pleura)
Mechanics, cont.
RESPIRATORY SOUNDS:
Bronchial sounds produced by air
rushing through large respiratory
passageways such as trachea and
bronchi
Vesicular breathing sounds occur as air
fills alveoli
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Soft and resemble muffled breeze
Modified Respiratory
Movements
Situations other than breathing move air in
and out of respiratory system
Most “nonrespiratory air movements” are
result of reflex activity
Cough, sneeze, crying, laughing, hiccups,
yawn, sighing….
External Respiration
Actual exchange of gases between alveoli
and blood (pulmonary gas exchange)
Oxygen leaves alveolus and enters blood
capillary
Carbon dioxide leaves blood capillary and
enters alveolus
Occurs by simple diffusion (movement occurs
toward area of lower [ ] of diffusing
substance)
Gas Transport
Very small amount of O2 dissolved in blood
Most transported as oxyhemoglobin
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Hb + O2  HbO2
Most CO2 transported as bicarbonate ion
20-30% carried inside RBCs bound to
hemoglobin (at different site than oxygen)
Very small amount transported in plasma
CO2 + H2OH2CO3H+ + HCO3For carbon dioxide to diffuse out of blood into
alveoli, reaction must be reversed
Gas Exchange Visual
Internal Respiration
Gas exchange process that occurs
between systemic capillaries and tissue
cells
Carbon dioxide leaves tissues and
enters blood
Oxygen leaves blood and enters tissues
All gas exchanges made according to
the laws of diffusion
Respiration Controls
Activity of respiratory muscles,
diaphragm, and external intercostals
regulated by brain impulses carried by
phrenic and intercostal nerves
Respiratory rhythm and depth control
center located in medulla and pons
Medulla contains self-exciting
inspiratory and expiratory centers
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Sets the rhythm of breathing
Controls, cont.
Pons contains apneustic and pneumotaxic
centers
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Smooth out basic rhythms of inspiration and
expiration
Work to maintain ~ 12-15 respirations/min.
EUPNEA= normal breathing rate
Inspiratory center active = inspire
Expiratory center active = expire
Apneustic center in pons=keeps inspiratory
center going
Pneumontaxic center in pons=limits length of
inspiration and promotes expiration
Rate/Depth Breathing Factors
PHYSICAL such as walking, coughing, and
exercise
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>body temp can > rate of breathing
CONSCIOUS such as singing, swallowing, or
holding breath while swimming
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voluntary control limited then involuntary takes
over
EMOTIONAL such as fright, surprise, or
“other”
Factors, cont.
CHEMICAL most important rate and depth
factors
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CO2 and O2 levels in blood
Increased levels of CO2 and decreased blood
pH MOST important stimuli leading to
increase in rate/depth of breathing
Changes in CO2 [ ] in blood act directly on
medulla centers
Changes in O2 [ ] in blood detected by
chemoreceptors in AORTIC ARCH and
CAROTID body in carotid artery
Factors, cont.
Chemoreceptors send impulses to medulla
when blood O2 levels are dropping
<s in O2 levels ONLY important when they are
dangerously LOW
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Increases rate/depth of breathing
Hypoventilation=accumulation of CO2 in
blood and >ed blood acidity
Hyperventilation=CO2 removed from blood
and <ed blood acidity
Acidosis or alkalosis can result
Respiratory Related Terms
Apena is cessation of breathing caused by
hyperventilation
Dyspnea is labored or difficult breathing
Emphysema=alveoli enlarge as walls of
adjacent chambers break through; chronic
inflammation promotes fibrosis of lungs
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Requires lots of energy to exhale
Chronic bronchitis=mucosa of lower
respiratory passages become severely
inflamed and produces extra mucus
Terms, cont.
Chronic bronchitis impairs ventilation
and gas exchange and increases risk of
lung infections
Pneumonitis=inflammation of alveoli of
the lungs resulting in them becoming
clogged with mucus and/or fluids
Volumes and Capacities
Tidal volume (TV) is amount of air
moved in and out of lungs with each
breath (500 ml)
Inspiratory Reserve Volume (IRV) is
amount of air that can be forcibly taken
in over tidal volume (2100-3200 ml)
Expiratory Reserve Volume (ERV) is
amount of air that can be forcibly
exhaled after tidal expiration (1200 ml)
Volumes, cont.
Residual Volume (RV) is amount of air left in
lungs that cannot be voluntarily expelled
Vital Capacity (VC) is sum of TV + IRV + ERV
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Total amount of exchangeable air
about 4800 ml in healthy young males
Dead space volume is air that remains in
conducting zone
Volume Visual