Respiratory System 2.17.10
Jan 02, 2016
Respiratory System
2.17.10
Respiratory System
Mechanics of Breathing• Breath in…what muscle are you contracting or relaxing?
Mechanics of Breathing• Inspiration (breathing in):
– Diaphragm contracts downwards– Exterior intercostal muscles contract up, pulling ribs and sternum out– Both actions lower pressure in lungs by creating space in chest cavity– Air rushes in due to lower air pressure
Mechanics of Breathing
• Expriation (breathing out):– Diaphragm and other
associated muscles relax– Space inside chest cavity
decreases– Air rushes out due to rising
air pressure inside lungs
Air Pathway
• Air enters the pharynx, where a flap of skin known as the glottis blocks food and liquids
Air Pathway
• Trachea leads to two bronchi, which fork into many hundreds of bronchioles, leading to millions of alveoli
Alveoli
• ~600 million alveoli in human lungs
• Site of gas exchange• Single-cell walls allow
for O2 and CO2 to pass between blood and air inside alveoli
• Covered in capillaries
Respiration at a Glance
Blood Basics
• Plasma--fluid portion of the blood (55%)
• Cells (45%)– Erythrocytes--red blood cells; responsible for oxygen
distribution– Leukocytes--white blood cells; responsible for “cleaning”
the system of foreign invaders– Thrombocytes--platelets; responsible for blood clotting
• Serum--liquid that separates from the blood when a clot is formed
Human Blood
• Red blood cells - 5 to 6 million per mm3, no nucleus
• White blood cells - Larger but less numerous, 5 to 10,000 per mm3
• Platelets - Tiny, cellular fragments 350 to 500,000 per mm3
Animal Blood
• Animal blood has large red blood cells with nuclei
Circulation•Venules•Arteries•Capillaries•Arterioles•Veins
Circulation1. Arteries (blood
away from heart)2. Arterioles
(smaller, branched arteries)
3. Capillaries (smallest vessels, very thin to allow gas exchange)
4. Venules (collect blood from capillaries)
5. Veins (blood back towards the heart)