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THE RESPIRATORY SYSTEM
Function of the lungs is gas exchange with the blood.
Facts:
5 liters of blood pass thru the lungs per minute
total lung surface area=80m sq. which is equivalent to a tennis court.
Functional terms to know:
Breathing: moving air in/out of lungs; 12-16 per min.
External respiration: in the lungs exchange of gas into the blood.
Internal respiration: exchange of O2 between blood and cells.
Therefore O2 in and CO2 out
TWO PARTS TO RESP SYS:
CONDUCTING
RESPIRATORY
Conducting portion:
• Nose
• Nasopharynx
• Larynx
• Trachea
• Bronchi
• bronchioles
FUNCTIONS OF CONDUCTINGPORTION:
• FILTRATION – BY HAIRS
• CLEANSING – BY MUCOUS AND CILIA
• MOISTENING – BY MUCOUS
• WARMING – BY HEAT EXCHANGE VIA BLOOD VESSELS
RESPIRATORY MORPHOLOGY
NASAL AREA: a nose is a nose is a nose!
1. Nares(nostrils)-have coarse hairs for filtering large particles.
2. Conchae-3 plates of bones lined with a rich vascular blood system for warming inspired air.
3. Pseudostratified columnar epithelium with goblet cells.
a. Cilia-propel dusts “insults” downward to nasopharynx.
B. Goblet cells-secrete mucus to filter dusts “insults”
Goblet cell
4. Nasopharynx-first part of pharynx(throat) provides a separation for the air route from feeding(oropharynx).
Naso-pharynx
Oro-pharynx
LARYNXSERVES AS A PASSAGEWAY FOR AIR, A VALVE TO CLOSE OFF THE AIR PASSAGEWAY FROM FOOD ENTERING AND A VOICE BOX.
COUGH REFLEXIF SOMETHING OTHER THAN AIR ENTERS THE LARYNX THERE IS A COUGH REFLEX TO PREVENT FOOD FROM ENTERING THE TRACHEA.
IN CASES OF DROWNING THE C.R. CAUSES LARYNGEAL SPASM PREVENTING O2 FROM ENTERING LUNGS. AUTOPSIES SHOW LUNGS FREE OF WATER.
Epiglottis
EPIGLOTTIS
FLEXIBLE FLAP-LIKE STRUCTURE FOUND NEAR OROPHARYNX (BEHIND TONGUE).
IT FLIPS OVER THE OPENING OF THE TRACHEA AND PREVENTS FOOD AND LIQUID FROM ENTERING THE TRACHEA.
TRACHEA
BRONCHUS
BRONCHIOLE
EACH BRONCHUS DIVIDES AND SUBDIVIDES INTO SMALLER BRANCHES.
BY THE TIME AIR REACHES HERE, WARMED UP AND FILTERED.
SMOOTH MUSCLE AND ELASTIC FIBER…NO CARTILAGE AND GOBLET CELLS
RESPIRATORY PORTION
• ALVEOLAR DUCTS
• ALVEOLAR SACS
• ALVEOLI
ALVEOLAR DUCTS
SHORT TUBES INTO WHICH OPEN THE ALVEOLI. CONSISTS OF ELASTIC AND COLLAGEN FIBERS.
ALVEOLUS
THE SAC-LIKE ALVEOLUS IS THE FINAL ELEMENT OF THE BRONCHIAL TREE SURROUNDED BY A RICH NETWORK OF BLOOD.
ALVEOLI-FOR GAS EXCHANGE
SURFACTANT PRODUCTION
SURFACTANT-SECRETED BY ALVEOLAR SECRETORY CELLS.
PHOSPHOLIPID WHICH REDUCES THE SURFACE TENSION OF ALVEOLI.
WITHOUT THIS CHEM. THE ALVEOLI WOULD COLLAPSE AND THEREFORE NOT FUNCTION.
PREMATURE BABIES LACK SURFACTANT TOWARDS THE END OF GESTATION AND SUFFER FROM RDS.
LUNGS
CROSS-SECTION OF LUNGS
LUNG GROSS SPECIMEN
LUNG
X-RAY
MECHANICS OF BREATHING
PONS
MEDULLA
NERVES- PHRENIC &
INTERCOSTAL
FACTORS-CO2, H+, O2.
760
755
750
765
500cc
mmHG
Vol.Mechanics of breathing
inspiration expiration
Tidal volume
Intrapulmonic P
Intrathoracic
Pressure
ATM P
Inspiration
• Muscles-intercostals & diaphragm• Thorax expands• Intrapulmonic P falls below ATM
(760)• = a “pressure gradient”• air moves into lungs & expands the
thorax until P is equal (ATP needed)
EXPIRATION
• INSPIRATORY MUS. RELAX• DIAPHRAGM MOVE UPWARD & RIBS
RETURN TO ORIGINAL POSITION• = “ELASTIC RECOIL”= NO ENERGY.• WHEN INTRAPULMONIC P INCREASES
ABOVE ATM P, AIR IS EXPELLED FROM THE LUNGS
• NOTE INTRATHORACIC P REMAINS BELOW ATM P.= A NEG P.
MUCOKINESIS
AEROSOL - GEL- SOL- GOBLET CELLS -BRONCHIAL-MUS
& EPITHELIUM
FACTORS THAT AFFECT THE MOVEMENT OF MUCUS
• CILIA• SOL-GEL LAYERS• VISCOSITY• PATENT AIRWAY• RATE OF AIR FLOW• COUGH• BODY POSITIONING
• NARCOTICS• ANESTHESIA• SMOKING• HIGH O2• STRESS• ALLERGIES• CHANGE IN PH
INTRINSIC EXTRINSIC
RESPIRATORY TERMS
• EUPNEA
• DYSPNEA
• TACHYPNEA
• HYPERPNEA
• APNEA
• ORTHOPNEA
• BRADYPNEA
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