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Respiratory System
• Functions
– Large area for gas exchange
– Move air to & from lungs
– Protect respiratory surfaces
– Produce sounds
– Aiding sense of smell
Internal nares
Nasal cavity
Pharynx
Sphenoidal sinus
Esophagus
Frontal sinus
Nasal conchae
Nose
Hyoid bone
Larynx
Tongue
Bronchioles
Bronchus
Trachea
Diaphragm
LEFTLUNG
RIGHTLUNG
Stem cell
Mucous cell
Mucus layer
Laminapropria
Movementof mucus
to pharynx
Ciliated columnarepithelial cell
Respiratory Anatomy
• Respiratory Tract– Upper
• Conducting portion– External nares to larger bronchioles– Warms, moistens, filters
» Respiratory mucosa• Respiratory epithelium
• Ciliated columnar• Mucous (goblet) cells• Loose connective tissue
– Lower• Respiratory portion
– Smallest bronchioles & alveoli
Nasal cavity
Internal nares
Soft palate
Frontal sinus
Mandible
Nasal conchae
Nasal vestibule
External nares
Hard palate
Oral cavity
Tongue
Respiratory Anatomy
• Nose– External nares– Nasal cavity
• Flushed by– Mucus from …– Tears from …
– Nasal vestibule• Hairs
– What for?
– Nasal septum– Nasal conchae
• Folds – useful?• Turbulent air flow - useful?
– Hard palate• Floor of nasal cavity
– Soft palate• Floor of nasopharynx
Internal nares
Nasopharynx
Oropharynx
Soft palate
Laryngopharynx
Esophagus
Frontal sinus
Mandible
Hard palate
Tongue
Hyoid bone
Internal nares
Nasopharynx
Pharyngeal tonsil
Soft palate
Entrance toauditory tube
Frontal sinus
Hard palate
Oral cavity
Oropharynx
Soft palate
Palatine tonsil
Hyoid bone
Epiglottis
Laryngopharynx
Esophagus
Hyoid bone
Trachea
Respiratory Anatomy
• Pharynx– Internal nares to esophagus/larynx– 3 parts
• Nasopharynx (nose pharynx)– Internal naresedge of soft palate– Pharyngeal tonsil– Opening to auditory tube
» Which goes where?– Normal respiratory epithelium
• Oropharynx (mouth pharynx)– Soft palate edge of tongue (hyoid bone level)– Palantine tonsils
» Say ‘aaaaahhhhhh’
• Laryngopharynx (larynx pharynx)– Hyoid bone entrance to esophagus
• What about food?
Glottis
Vocal fold
Esophagus
Hyoid bone
Cricoid cartilage
Thyroid cartilage
Trachea
Vocal cords
Hyoid bone
Cricoid cartilage
Thyroid cartilage
Trachealcartilages
Epiglottis
Ligament
Extrinsic (thyrohyoid)
ligament
Ligament
Trachea
Larynx
Arytenoid cartilages
False vocal cords
Cuneiform cartilage
Corniculate cartilage
Anterior view Posterior view
Figure 15.4ce
Vocal cord
Epiglottis
False vocal cord
ANTERIOR
POSTERIOR
Root of tongue
Glottis(open)
Vocal cord
Epiglottis
False vocal cord
Root of tongue
Glottis (closed)
Respiratory Anatomy
• Larynx (voice box)– Starts at the glottis– What’s it made of
• 9 cartilages with associated ligaments & skeletal muscles
– The largest 3 cartilages• Epiglottis
– Projects above glottis– During swallowing covers glottis
» Why is this rather important?
• Thyroid cartilage– Forms much of lateral & frontal portions– Adam’s apple
» Yes, women can have them
• Cricoid cartilage– Posterior portion
Respiratory Anatomy
• Larynx (voice box)– 2 pairs of ligaments
• False vocal cords (top pair)– Rather inelastic
– Prevent stuff from entering glottis
• True vocal cords (bottom pair)– Elastic ligaments
– Small muscles change position & tension
» For what?
– Coughing reflex• Triggered by stuff on vocal cords
• Keep glottis closed while chest & abdomen contract
Respiratory Anatomy
• Vocal cords & sound production– Air passing over glottis vibrates vocal cords
– Pitch depends on …• Diameter & Length
– Kids small
– MEN! PUBERTY! LARGER!
• Tension– Only one you can control
– Higher tension = higher pitch
– Voice NOT only vocal cords• Amplification & resonance in pharynx, oral cavity, nasal
cavity, sinuses
Trachea
Larynx
Hyoid bone
Tracheal cartilage
Primary bronchi
Secondary bronchi
RIGHT LUNGLEFT LUNG
Mucous gland
Tracheal cartilage
Respiratoryepithelium
Tracheal ligament
Trachealis muscle(smooth muscle)
Esophagus
Respiratory Anatomy
• Trachea– Tough, flexible tube– Begins @ C6 attached to cricoid cartilage– Ends in mediastinum @ L5
• Branches into rt & lt primary bronchi
– 15-20 tracheal cartilages• Prevent collapse/overexpansion• C shaped – posterior open portion
– Why?» Allow expansion of esophagus
– Trachealis muscle• Changes diameter – autonomic control
Trachea
Cartilage plates
Tertiary bronchi
Left primarybronchus
Secondarybronchus
Smaller bronchi
Visceral pleura
Respiratorybronchiole
Terminalbronchiole
Bronchioles
Bronchopulmonarysegment
Alveoli in apulmonary
lobule
Respiratory Anatomy
• Bronchi– Right & left primary bronchi
• Walls resemble trachea– Ciliated epithelium, C shaped cartilage
• Right is steeper
– Bronchial tree• Primary secondary tertiary smaller bronchi
bronchioles
• Cartilage gets smaller, then disappears
• Bronchiole walls - smooth muscle– Why?
» Bronchodilation & bronchoconstriction
Lymphaticvessel
Alveoli
Interlobularseptum
Alveolar sac
Parietal pleura
Pleural cavity
Visceral pleura
Arteriole
Alveolarduct
Smooth musclearound terminalbronchiole
Branch ofpulmonaryartery
Respiratoryepithelium
Bronchiole
Bronchial artery (red),vein (blue), and
nerve (yellow)
Respiratorybronchiole
Terminalbronchiole
Branch ofpulmonary
vein
Capillarybeds
Elastic fibers
Respiratory Anatomy
• Bronchioles
– Terminal bronchioles (.3-.5 mm)
• Supplies air to lobule of lung– Lobule
» segment bounded by connective tissue
» fed by single bronchiole
– Terminal bronchiole branches into respiratory bronchioles
» Deliver gas to exchange surfaces
Alveolar epithelialcell
Capillary
Alveolar structure
Alveolar macrophage
Endothelial cell of capillary
Alveolar macrophage
Septic cell (secretes
surfactant)
Elasticfibers
Respiratory Anatomy
• Alveoli– Respiratory bronchioles alveolar ducts alveolar sacs
• Alveolar sacs– Connected to multiple alveoli
– Each lung has about 150 million alveoli– About 140 m2 of surface area– Function?
• What type of tissue necessary?– Simple squamous
– Other cells• Alveolar macrophages• Septal cells
– Surfactant» Reduces surface tension of water
• Why necessary?
Alveolar epithelium
Red blood cell
Capillary lumen
EndotheliumNucleus of
endothelial cell
Fused basement
membranes
Surfactant
Alveolar air space
The respiratory membrane
0.5 m
Respiratory Anatomy
• Respiratory membrane– Gas exchange– 3 layers
• Squamous epithelium• Fused basement membrane• Endothelium in capillary
– About 1m thick– Diffusion muy rapidamente– O2 & CO2 diffuse
• Both lipid soluble
– Receive blood from …• Pulmonary arteries branch along bronchi• 1 lobule; 1 arteriole
– Each alveolus surrounded by capillary bed
– Blood pressure• Rather low – about 30 mm Hg• Easily blocked
– Pulmonary embolism
Apex
Superiorlobe
Middlelobe
Inferiorlobe
Superior lobe(costal surface)
Base
RIGHT LUNG
LEFT LUNG
Anterior view
Cardiac notch (inmediastinal surface)
Inferior lobe
Respiratory Anatomy
• Lungs– Right -3 lobes/Left – 2 lobes– Light, spongy consistency
• Like a twinkie before the filling … mmmmm• Why?
– Lots of elastic fibers• Why?
• Pleural cavities– 2 – one for each lung
• Parietal & visceral– Separated by pleural cavity
» Which is filled with …• Which does what?
– Separated by mediastinum– Pnuemothorax
• Air in pleural cavity – bad?
Respiration
• Internal Respiration– exchange of CO2 & O2 between IF & cells
• External Respiration– All activities in exchange of CO2 & O2 between IF &
outside • Pulmonary respiration
– Movin’ air in & out of lungs
• Gas diffusion– Respiratory membrane & capillary cell membrane
• Transport of CO2 & O2– Between alveoli & capillary
– Hypoxia & anoxia
Respiration
• Pulmonary ventilation– Physical movement of air into & out of lungs
• Respiratory cycle– A single breath
• Respiratory rate– Breaths per minute
• 12-18 adults/18-20 kids
• Alveolar ventilation– In & out of alveoli
• Prevent CO2 buildup
Ribs andsternumelevate
Diaphragmcontracts
MediastinumPleuralspace
Diaphragm
Pressure outside andinside are equal, so no
movement occurs.
Po Pi
AT REST
Diaphragm
Volume increases;Pressure inside falls,
and air flows in.
Po Pi
INHALATION
Externalintercostal
Serratusanterior
Pectoralisminor
Scalenemuscles
Sternocleido-mastoid
Volume decreases;Pressure inside rises,
so air flows out.
Po Pi
EXHALATION
Rectusabdominis(otherabdominalmusclesnot shown)
Internalintercostals
Transversusthoracis
Respiration
• Pressure & airflow
– Air flows from … to …
– If you increase volume, then pressure …
– Inhalation
• The volume of the thoracic & pleural cavities …
• Therefore the pressure …
• Therefore the external pressure is …
• Therefore air moves …
Respiration
• Pressure & air flow– Diaphragm
• Relaxed – dome up into thoracic cavity– Lungs compressed
• Contracted – flattens out– Lungs expanded
– Rib cage• Elevation of rib cage
– External intercostals
• Lowers rib cage– Internal intercostals
Respiration
• Compliance– Resilience & ability to expand
• Lower compliance = greater force to ventilate
• Modes of Breathing– Quiet breathing
• Muscular inhalation– 75% diaphragm, 25% ext. intercostals
• Passive exhalation
– Forced breathing• Both inhalation & exhalation require muscular contraction
– Which muscles?
Inspiratoryreserve volume
(IRV)
Pulmonary volumes
Inspiratorycapacity
Restingtidal volume (VT 500 mL)
Functionalresidual capacity
Expiratoryreserve volume(ERV)
Volume(mL)
Residualvolume
Minimal volume(30–120 mL)
Totallung
capacity
Vitalcapacity
Time
Residual volume
Vitalcapacity
Inspiratorycapacity
Functionalresidualcapacity
IRVVT
ERV
3300500
10001200
1900500700
1100
6000 mL 4200 mL
Males Females
Respiration
• Lung Volume & Capacities
– Tidal volume
• Amt of air moved in/out during single cycle
• Can be increased/decreased– How?
• Resting tidal volume (VT)– About 500 mL
– Expiratory reserve volume (ERV)
• Amt of air that could be expelled at end of cycle– About 1000 mL
Respiration
• Lung Volume & Capacities
– Inspiratory Reserve Volume (IRV)
• Amt of air inhaled above VT
– Vital Capacity
• Max amt of air moved in/out in one cycle
– Residual volume
• Amt of air left after max exhale
– Minimal volume
• Amt of air left after lungs punctured
Respiration
• Lung Volume & Capacities
– Inspiratory Reserve Volume (IRV)
• Amt of air inhaled above VT
– Vital Capacity
• Max amt of air moved in/out in one cycle
– Residual volume
• Amt of air left after max exhale
– Minimal volume
• Amt of air left after lungs punctured
Alveolus
Systemiccircuit
Interstitial fluid
Pulmonarycircuit
Systemiccircuit
Externalrespiration
Internalrespiration
Alveolarcapillary
Respiratorymembrane
PO2 40PCO2 45
PCO2 40PO2 100
PCO2 40PO2 100
PO2 40PCO2 45
Systemiccapillary
PCO2 45
PCO2 40PO2 95
PO2 40
PO2 159
PCO2 30.4
Gas Exchange
• Partial Pressure– Air is mixture of gases
• 78% N2; 21% O2; wee bit of H2O & CO2
– Total pressure equal to the sum of the pressures of each gas separately• PN + PO2
+ PH2O + PCO2= 760 mmHg
– PO2= (.209)760 mmHg = 159 mmHg
– Oxygen will go down its own partial pressure gradient• Outside air = 159 mmHg
• Alveolar air = 100 mmHg
• Blood = 40 mmHg
Red blood cells
Systemiccapillary
Alveolar
capillary
Plasma
Alveolar
air space
O2 pickup
Cells in
peripheral
tissues
O2 delivery
O2
O2O2
O2
Hb
Hb O2
O2
O2O2
Hb
Hb
Gas Transport
• Oxygen transport
– 1.5% dissolved in plasma
– 98.5% hemoglobin
• Bind to iron ion in heme group
– Amt O2 bound/released depends on
• PO2 of surroundings– Normal conditions (PO2 = 40 mmHg) only about 25% released
– Active tissue (PO2=15 mmHg)
– What are the conditions of active tissue?
– Temp? pH?
23% binds toHb, forming
carbaminohemoglobin,
HbCO2
CO2 diffusesinto bloodstream
H removedby buffers, especially
Hb
93% diffusesinto RBCs
7% remains dissolvedin plasma (as CO2)
H2CO3 dissociates into H and HCO3
–
70% convertedto H2CO3 by
carbonic anhydrase
HCO3– moves out of RBC
in exchange for CI–
(chloride shift)
CI–
Systemiccapillary
Alveolar
capillary
CO2 pickupCO2 delivery
CO2
CO2CO2
CO2
Hb
Hb
H
Hb
Hb
H HCO3–
H2CO3
H2O
HCO3–
CI–
H HCO3–
Hb
Hb H
CO2Hb
HCO3–
CI–
CO2Hb
H2O
H2CO3
Chloride
shift
CO2
Gas Transport
• Carbon dioxide transport– 7% Plasma– 23% Carbaminohemoglobin
– CO2 binds to amino acids in globulins of hemoglobin
– 70% Bicarbonate ions– Carbonic anhydrase
– CO2 + H2O H2CO3 H+ + HCO3-
– In peripheral tissue, moves to the right
– Chloride shift– H + binds to hemoglobin– HCO3
- leaves RBC, Cl- enters
– What happens in the lungs?
Control of Respiration
• Local Control
– In active tissues
• PO2? PCO2
?– Greater differences in partial pressure …
• Rising PCO2relaxes smooth muscles in arterioles
– In lungs
• Blood directed to alveoli with lots ‘o oxygen– Low O2 constricts alveolar capillary sphincters
» Is this the same response in peripheral tissues?
– Rising CO2 relaxes smooth muscle in walls of bronchioles
Control of Respiration
• Respiratory Centers– Medulla oblongata
• Respiratory rhythmicity centers– Dorsal respiratory group (DRG)
» Inspiratory centers• Functions EVERY cycle• What muscles does it control?• Quiet breathing
• Increasing stimulation for 2 sec• Silent for 3 sec
– Ventral respiratory group» Forced breathing only» Has both inspiratory & expiratory centers
• What muscles does it control?
Control of Respiration
• Reflex control– Mechanoreceptor reflexes
• Respond to changes in lung volume OR arterial pressure
• Inflation reflex– Prevent overexpansion of lungs
» Inspiratory center inhibited
» Expiratory center stimulated
• Deflation reflex– Prevents lungs from collapsing
» Inspiratory center stimulated
• NEITHER involved in quiet breathing– Why?
Control of Respiration
• Reflex control
– Chemoreceptor reflexes
• Respond to chemical changes in blood or CSF
• CO2 more effective than O2– Why?
• Free divers– 3 or 4 quick deep breaths
» What happens to CO2 levels in blood?