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Lecture

Respiratory Function and Structures Introduction to the respiratory system anatomy and functions

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Department
Physiology
Course
PSL201Y1
Professor
Michelle French
Semester
Winter

Description
Respiratory System: Function and Structure Professor French, January 10, 2011 What are the functions of the respiratory system? → Allows for exchange of gases b/w air and blood → Regulation of blood pH → Defense from inhaled pathogens and foreign particles → Vocalization What structures make up the respiratory system? → Epiglottis prevents food from entering the lungs, vocal cords also close → Diaphragm contracts allow for lungs to expand during inspiration o Intercostal muscles raises ribcage to increase lung capacity → Internal intercostals contract to draw ribcage closer, reducing thoracic cavity o Abdominal muscles contract to reduce volume → Pleural sacs (pleural fluid within pleural membranes enclose the lungs o Allows for lungs to remain inflated against the walls of the thoracic cavity → Air is fully humidified and warmed to body temperature by arrival at the lungs Bifurcation: division into two branches → 1st division produces left and right main bronchi → 2nd-4th division produces lobar bronchi o Have cartilage to maintain shape o Cartilage ensures it remains open in presence of pressure → 5th-11th division produces segmental bronchi → 12th-16th division produces terminal bronchioles, stabilized by bronchiolar muscles → Total of about 22 branches No gas exchange occurs in all of these conducting airways, forming anatomical dead space → Between breaths of air, “stale air” is breathed in first Gas exchange occurs at the primary lobule in alveoli via passive diffusion to capillaries → Epithelium of Type I alveolar cell is thin enough for gas exchange (300 million) o Both alveoli epithelium and capillaries endothelium are one-cell thick → Type II alveolar cell produces surfactant to reduce surface tension, prevent implosion of alveoli → Macrophages engulf any foreign particles in alveoli How is blood transported to and from the lungs? → Arteries carry away from the heart, veins carry towards → DeoxyHb travels from right ventricle -> pulmonary trunk (main vessel prior to branching) -> pulmonary arteries -> pulmonary arterioles -> capillaries (becomes HbO 2 → HbO tr2vels to pulmonary venules -> pulmonary veins to left atrium to aorta to rest of the body → Overlapping of capillary bed in the lungs ensures blood is fully oxygenated → Systemic arterioles branch into capillaries and only serve a pa
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