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