RESPIRATORY SYSTEM

FUNCTION

• TO MOVE AIR IN AND OUT OF THE LUNGS

• EXCHANGE OF

OXYGEN AND

CARBON DIOXIDE

BETWEEN THE AIR

AND THE BLOOD

DIVISIONS• UPPER RESPIRATORY TRACT – THE

PART OUTSIDE THE CHEST CAVITY• INCLUDES NOSE, NASAL CAVITIES,

PHARYNX, LARYNX, AND UPPER TRACHEA

• LOWER RESPIRATORY TRACT – THE PART INSIDE THE CHEST CAVITY

• INCLUDES LOWER TRACHEA, LUNGS, BRONCHIAL TUBES, AND ALVEOLI

NOSE AND NASAL CAVITIES• AIR ENTERS AND LEAVES THE NOSE

• WARMS THE AIR

• CONTAINS MUCOUS

• HAIRS BLOCK THE ENTRY OF DUST

• OLFACTORY RECEPTORS FOR SMELL

PHARYNX – 3 PARTS• NASOPHARYNX – UPPERMOST

PORTION BEHIND THE NASAL CAVITIES• ALLOWS PASSAGE OF AIR• OROPHARYNX – BEHIND THE MOUTH• LARYNGOPHARYNX – INFERIOR

PORTION• ORO- AND LARYNGOPHARYNX ALLOW

THE PASSAGE OF AIR AND FOOD

LARYNX• AKA VOICE BOX• FUNCTIONS IN SPEAKING

AND THE AIR PASSAGEWAY BETWEEN THE PHARYNX AND TRACHEA

• MADE OF CARTILAGE THAT IS FIRM TO KEEP AIRWAY OPEN YET IT IS FLEXIBLE

• THE LARGEST CARTILAGE IS THE THYROID CARTILAGE

• EPIGLOTTIS - THE UPPERMOST CARTILAGE• IT CLOSES OVER THE TOP TO PREVENT THE ENTRY OF FOOD IN TO THE LARYNX• MUCOSA IS MADE OF CILIATED

EPITHELIUM TO REMOVE DUST AND MUCOUS

• VOCALS CORDS ARE ON EITHER SIDE OF THE GLOTTIS

TRACHEA• APPROXIMATELY 4-5 INCHES LONG

• EXTENDS FROM LARYNX TO THE PRIMARY BRONCHI

• MADE OF CARTILAGE THAT CONSISTS OF CILIATED EPITHELIUM

• DIVIDES IN TO RIGHT AND LEFT PRIMARY BRONCHI

BRONCHI• RIGHT AND LEFT PRIMARY BRONCHI• LEADS TO SECONDARY BRONCHI• LEADS TO BRONCHIAL TREES• BRANCHES FURTHER IN TO BRONCHIOLES TO THE ALVEOLI

LUNGS• RIGHT LUNG HAS 3 LOBES• LEFT LUNG HAS 2 LOBES• PROTECTED BY RIBS• BASE OF EACH LUNG RESTS ON THE

DIAPHRAGM AND THE APEX IS AT THE CLAVICLE

• INDENTATION ON THE MEDIAL SIDE OF LUNGS IS THE HILUS WHERE PRIMARY BRONCHUS AND ARTERIES/VEINS ENTER THE LUNG

PLEURA• PARIETAL PLEURA LINES THE CHEST

WALL

• VISCERAL PLEURA LIES ON THE SURFACE OF THE LUNGS

• SEROUS FLUID BETWEEN THE MEMBRANES PREVENTS FRICTION

ALVEOLI• FUNCTIONAL UNIT OF THE LUNGS• MADE OF SIMPLE SQUAMOUS EPITHELIUM• ELASTIC CONNECTIVE TISSUE BETWEEN

CLUSTER OF ALVEOLI WHICH IS IMPORTANT FOR EXHALATION

• DIFFUSION OCCURS BETWEEN ALVEOLI AND BLOOD VESSELS• MACROPHAGES ARE IN THE ALVEOLI• PULMONARY SURFACTANT DECREASES SURFACE TENSION AND PERMITS INHALATION

MECHANISM OF BREATHING• VENTILATION – MOVEMENT OF AIR TO AND FROM ALVEOLI• RESPIRATORY CENTERS – MEDULLA

(ALSO FOR COUGHING AND SNEEZING) AND PONS (2 BREATHING CENTERS)

• PHRENIC NERVE ACTIVATED FROM THE MEDULLA TO CONTRACT AND RELAX THE RESPIRATORY MUSCLES

RESPIRATORY MUSCLES• DIAPHRAGM – MOVES DOWN DURING

INHALATION AND UP DURING EXHALATION. MADE OF SKELETAL MUSCLE.

• EXTERNAL INTERCOSTAL MUSCLES – PULL THE RIBS UPWARD AND OUTWARD DURING INHALATION

• INTERNAL INTERCOSTAL MUSCLES – PULL THE RIBS DOWNWARD AND INWARD DURING EXHALATION

RESPIRATION• INHALATION IS AN ACTIVE PROCESS

LASTING 1-2 SECONDS

• EXHALATION IS A PASSIVE PROCESS LASTING 2-3 SECONDS

• NORMAL RESPIRATIONS ARE 8-12/MIN

RESPIRATION• EXTERNAL RESPIRATION - INVOLVES

THE EXCHANGE OF GASES BETWEEN THE ALVEOLI AND THE PULMONARY CAPILLARIES (EXTERNAL ENVIRONMENT)

• INTERNAL RESPIRATION – INVOLVES THE EXCHANGE OF GASES BETWEEN THE BLOOD IN THE SYSTEMIC CAPILLARIES AND THE TISSUES

DID YOU KNOW…• WE INHALE APPROX 21% OXYGEN

AND 0.04% CARBON DIOXIDE

• WE EXHALE APPROX 16% OXYGEN AND 4.5% CARBON DIOXIDE

TRANSPORT OF GASES• MOST OXYGEN IS CARRIED IN THE

BLOOD BONDED TO Hgb

• IRON IS NECESSARY

• GAS EXCHANGE IS CARRIED OUT BY DIFFUSION

PULMONARY VOLUMES• TV – TIDAL VOLUME – AMOUNT OF

AIR IN 1 NORMAL INHALATION/EXHALATION (500mL)

• MRV – MINUTE RESPIRATORY VOLUME – AMOUNT OF AIR INHALED AND EXHALED IN 1 MINUTE

TV x R = MRV (6000 mL or 6 L)

PULMONARY VOLUMES• IR – INSPIRATORY RESERVE –

AMOUNT OF AIR, BEYOND THE TV, THAT CAN BE TAKEN IN WITH THE DEEPEST POSSIBLE INHALATION (2000-3000mL)

• ER – EXPIRATORY RESERVE – AMOUNT OF AIR, BEYOND THE TV, THAT CAN BE EXPELLED WITH THE MOST FORCEFUL EXPIRATION (1000-1500 mL)

PULMONARY VOLUMES• VC – VITAL CAPACITY – THE SUM OF

THE TV, IR, AND ER (3500-5000 mL)• RESIDUAL AIR – THE AMOUNT OF AIR

THAT REMAINS IN THE LUNGS AFTER THE MOST FORCEFUL EXHALATION (1000-1500mL)

• VOLUMES ARE DETERMINED WITH A SPIROMETER THAT MEASURE THE MOVEMENT OF AIR