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Respiratory System. Structure of Respiratory System. 2 Lungs – light, soft, spongy organs located in thoracic region; R lung larger than L b/c heart takes up space on L. 2 regions : Conduction Zone - anatomical structures through which air travels before reaching (upside-down tree)
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Structure of Respiratory System • 2 Lungs – light, soft, spongy organs located in thoracic region; R lung larger than L b/c heart takes up space on L.
2 regions: • Conduction Zone - anatomical structures through which air travels before reaching (upside-down tree) • Respiratory Zone - region where gas exchange occurs (alveoli)
Pathway of Air • Nose/mouth – • trachea (windpipe) – • R & L bronchi – lungs – • bronchioles – • terminal bronchioles – • alveoli
Alveoli • functional units of system; 300 million tiny air sacs in which gas exchange occurs (little bubbles that are clustered like grapes) • Each alveolus is surrounded by network of pulmonary capillaries; gas diffusion (movement of molecules from high concentration to low concentration) occurs b/c of difference in concentration between O2 (alveoli) and CO2 (capillaries). O2 – heart; CO2 – exhaled
3 Phases of Human Respiration: • 1.Ventilation/breathing – inspiration & expiration • 2.Gas exchange • 3.Oxygen utilization by tissue for cellular respiration • Changes in thoracic cavity during ventilation occur due to activity of diaphragm & external intercostals muscles
Lung Volume Many factors influence the amount of air that moves in/out of the lungs: · - Body activities (sleeping vs. exercise) · -Individual differences (sex, height, age, weight) -State of the lungs/respiratory organs (health)
Measurements of Air Volume • Tidal volume (TV) = amount of air moved in/out of lungs with 1 breath (avg. = 500mL) • Inspiratory reserve volume (IRV) = amount of air that can be inhaled forcibly over the TV (avg. = 3100mL) • Expiratory reserve volume (ERV) = maximum amount of air that can be forcibly exhaled after a tidal expiration (avg. = 1200mL) • Residual volume (RV) = volume of air that remains in the lungs after a forced expiration (avg. = 1200mL)
Measurements of Air Volume • Vital capacity = total amount of exchangeable air; TV + IRV + ERV (avg. = 4800mL) • Total lung capacity = sum of vital capacity + residual volume (avg. = 6000mL) • Anatomic dead space = a portion of air that enters the respiratory tract never reaches the alveoli & remains in the air passageways (avg. = 150mL) • Avg. volume reaching alveoli in 1 breath = 350mL
Breathing • rhythmic, involuntary process controlled by respiratory centre of brain.
Factors that Effect Breathing • Chemical changes in blood– chemoreceptors monitor O2 & CO2 levels (hyperventilation results during emergency situations when CO2 levels have risen beyond normal) • Degree of stretch of lungs– stretch receptors in bronchi & bronchioles activated during inspiration & cause expiration; prevent lungs from over-inflating • Person’s mental state– stress, fear, or pain can rate of breathing automatically; some voluntary control over breathing but cannot stop breathing to the point of death (you’d pass out first)
Mechanics of Breathing • Brief demonstration of breathing mechanics • Respiration Lecture