RESPIRATORY SYTEM Anatomy & Physiology

BACKGROUND-Cellular Respiration Oxygen is used by cells Oxygen is needed to convert glucose to ATP Carbon dioxide is a waste product Body cells die if respiration fails

FUNCTIONS Supplies body with oxygen and removes carbon dioxide Filters, warms, and humidifies air Helps with producing sound Regulates blood pH

DIVISIONS OF THE RESPIRATORY SYSTEM Upper respiratory tract Nose/nasal cavity/sinuses/pharynx/larynx Lower respiratory tract Trachea/bronchial tree/lungs

STRUCTURES/ORGANS Conducting Zone- passages that let air in Respiratory Zone- gas exchange Larynx- voice box; made of cartilage; false and true vocal cords; attached to hyoid bone Speech Breathing airway Switching mechanism for food and air→ epiglottis

Structures/organs Trachea- windpipe; smooth cartilage with C shaped rings that divides into 2 bronchi; flexible but does not collapse despite pressure changes Bronchi- tubes enter lungs; branch into microscopic alveolar ducts that end in sacs Lungs- extend from diaphragm to clavicle; lobes (2 left lobs and 3 right lobes) Alveoli- site of gas exchange

STRUCTURES/ORGANS Nose- airway; moisten and warms air; filters; resonating chamber for speech; olfactory receptors; nasal cavity=floor=palate (anterior is hard and posterior is soft) Paranasal sinus- open into nasal; lighten the skull; infection=sinusitis Pharynx- throat; houses tonsils; 3 parts (naso,oro,laryngo); uvula closes nasopharynx (no food in the nose)

RESPIRATORY MUCOSA Goblet cells Secrete mucus; watery fluid with lysozyme Produce about a quart a day of liquid with dead junk (dead junk is swallowed)

GAS EXCHANGE Air fills alveoli and accounts for most of the lung volume (1500 sq feet) Wall of alveoli→ 2 cell thick (thinner than tissue paper); external wall is covered with cobweb of capillaries air/blood barrier- gas exchange; oxygen diffuses from air in alveoli to blood in capillaries; carbon dioxide diffuses from blood (capillaries) into alveoli Moves from a high to low concentration through diffusion

RESPIRATION INCLUDES: Pulmonary ventilation- replaces gases External respiration- gas exchange in the lungs Transport- gases by the blood and heart Internal respiration- gas exchange into the tissues

VENTILATION Breathing is pulmonary ventilation 2 phases Inspiration- inhalation of air/air goes in Diaphragm flattens when contracted (high height of thoracic cavity) Intercostal muscles contract to raise the ribs (increases circumference of the thoracic cavity, keeps thorax stiff so sides don’t collapse) Expiration- exhalation of air/air goes out Rib cage drops under the force of gravity Relaxed diaphragm → moves up (curved shape) Volume decreases which increases the pressure  

Ventilation Mechanical forces causes movement of air Gases flow from high to low pressure Diaphragm and intercostal muscles accomplish this Pressure is established by changes in the thoracic cavity High (size) thorax → low pressure = air moves in Low (size) thorax → high pressure = air moves out

VOLUMES OF AIR EXCHANGE Vital capacity: largest volume of air a person can move in and out Depends on the size of the cavity, posture, diseases/condition