Respiratory System

Passages filter air and transport it Passages filter air and transport it from outside body to lungs. from outside body to lungs.

Microscopic air sacs are sites for gas Microscopic air sacs are sites for gas exchangeexchange

Respiration

1.    1.    Pulmonary ventilation Pulmonary ventilation – movement of – movement of air in and out of lungsair in and out of lungs

2.    Exchange of gases between air in lungs 2.    Exchange of gases between air in lungs and bloodand blood

3.    Transport of gases by blood between 3.    Transport of gases by blood between lungs and body cellslungs and body cells

4.    Exchange of gases between blood and 4.    Exchange of gases between blood and body cellsbody cells

Cellular respiration

Aerobic - Aerobic - utilization of oxygen and utilization of oxygen and production of carbon dioxide by the cells production of carbon dioxide by the cells while forming ATPwhile forming ATP

Organs of respiratory system

NoseNose – bone & cartilage, 2 nostrils (nares), – bone & cartilage, 2 nostrils (nares), internal hairs to filter large particlesinternal hairs to filter large particles

Nasal cavityNasal cavity – hollow space behind nose; lined – hollow space behind nose; lined with a mucous membrane that filters, warms and with a mucous membrane that filters, warms and moistens incoming air. Particles trapped in mucus moistens incoming air. Particles trapped in mucus are carried to the pharynx by cilia and swallowedare carried to the pharynx by cilia and swallowed Nasal septum – divides nasal cavityNasal septum – divides nasal cavity Nasal conchae – curls of bone that increase Nasal conchae – curls of bone that increase

surface area, support mucous membranesurface area, support mucous membrane

SinusesSinuses – spaces within the bones of the – spaces within the bones of the skull that open into nasal cavity; lined with skull that open into nasal cavity; lined with mucous membranemucous membrane

PharynxPharynx – (throat) behind oral cavity and – (throat) behind oral cavity and between nasal cavity and larynx. between nasal cavity and larynx. Passageway for air. Aids in producing Passageway for air. Aids in producing speech.speech. Nasopharynx – superior portionNasopharynx – superior portion Oropharynx – middle portionOropharynx – middle portion Laryngopharynx – inferior portion Laryngopharynx – inferior portion

LarynxLarynx – contains vocal cords which – contains vocal cords which produce sound by vibrating when air passes produce sound by vibrating when air passes over themover them Glottis – triangular opening in between Glottis – triangular opening in between

vocal cords. Can close to prevent food vocal cords. Can close to prevent food from enteringfrom entering

Epiglottis – cartilage flap that covers Epiglottis – cartilage flap that covers glottis opening during swallowingglottis opening during swallowing

TracheaTrachea – (windpipe) tube in the front of – (windpipe) tube in the front of the neck; extends into thoracic cavity where the neck; extends into thoracic cavity where it branches into left and right bronchiit branches into left and right bronchi Held open by cartilage rings. Held open by cartilage rings. Inner wall is lined with ciliated mucous Inner wall is lined with ciliated mucous

membrane. Filters air and moves trapped membrane. Filters air and moves trapped particles upward to pharynx to be particles upward to pharynx to be swallowedswallowed

Bronchial TreeBronchial Tree – branched airways leading from – branched airways leading from trachea to alveoli in lungs. Get progressively trachea to alveoli in lungs. Get progressively smallersmaller Primary bronchi – cartilage in walls similar to Primary bronchi – cartilage in walls similar to

trachea; right and left divide intotrachea; right and left divide into Secondary bronchi – continue to divideSecondary bronchi – continue to divide Bronchioles – no more cartilage, smooth Bronchioles – no more cartilage, smooth

muscle instead; lead tomuscle instead; lead to Alveolar ducts – no muscle; lead to Alveolar ducts – no muscle; lead to Alveolar sacs – made of clusters of Alveolar sacs – made of clusters of Alveoli – microscopic air sacs surrounded by Alveoli – microscopic air sacs surrounded by

capillaries where gas exchange with blood takes capillaries where gas exchange with blood takes placeplace

Lungs

soft, spongy, right lung has 3 lobes, left lung has 2 soft, spongy, right lung has 3 lobes, left lung has 2 lobeslobes

Occupy the pleural cavitiesOccupy the pleural cavities Made of elastic tissue that stretches and recoils as Made of elastic tissue that stretches and recoils as

we breathewe breathe Tissues must be moist to allow gas exchangeTissues must be moist to allow gas exchange Surfactants – keep alveolar surfaces from sticking Surfactants – keep alveolar surfaces from sticking

togethertogether

Breathing mechanism - ventilation

Inspiration – (inhalation) dome shaped Inspiration – (inhalation) dome shaped diaphragm muscle contracts which diaphragm muscle contracts which decreases air pressure inside the lungsdecreases air pressure inside the lungs Air moves into the lungs because outside Air moves into the lungs because outside

pressure is higherpressure is higher External intercostal muscles can also External intercostal muscles can also

raise the ribs which further decreases raise the ribs which further decreases internal pressure internal pressure

Expiration (exhalation)

Diaphragm relaxes returning to its dome Diaphragm relaxes returning to its dome shapeshape

Elastic recoil of lung tissue forces air outElastic recoil of lung tissue forces air out Internal intercostal muscles which pull ribs Internal intercostal muscles which pull ribs

down and abdominal muscles which push down and abdominal muscles which push up on the diaphragm can contract to exhale up on the diaphragm can contract to exhale more forcefullymore forcefully

Air volume

Tidal volume – the amount of air that enters Tidal volume – the amount of air that enters and leaves during a respiration cycleand leaves during a respiration cycle

Residual volume – air that remains in the Residual volume – air that remains in the lungs even after exhaling the maximum lungs even after exhaling the maximum amountamount

Vital capacity – the maximum amount a Vital capacity – the maximum amount a person can exhale after taking the deepest person can exhale after taking the deepest breath possiblebreath possible

Respiratory center

Located in medulla oblongataLocated in medulla oblongata Sensitive to the concentration of carbon dioxide, Sensitive to the concentration of carbon dioxide,

causes the urge to breathecauses the urge to breathe Hyperventilation – breathing fast and deep, can let Hyperventilation – breathing fast and deep, can let

you hold your breath longer, but may make you you hold your breath longer, but may make you pass out. Don’t do it while swimming.pass out. Don’t do it while swimming.

Hypoxia – low oxygen levels reaching tissuesHypoxia – low oxygen levels reaching tissues