I. Respiratory System A. Structures / Functions 1. Nasal Cavity – warm, moisten and filter airNasal Cavity Mucus, hairs = trap dust, dirt and pathogens 2. Epiglottis – prevents food from going into windpipe when swallowingEpiglottisswallowing 3. Larynx – voice box, contains the vocal chordsLarynx 4. Trachea = wind pipe, passage for air to the lungs

I. Respiratory System 5. Bronchi – main branches to the trachea, lead to each lungBronchi Lined with cilia that move mucus up out of the lungs 6. Bronchioles – smaller branches of the bronchi 7. Alveoli – small grape-like clusters of air sacs where gas exchange occursAlveoli 8. Diaphragm – large muscle that aids in breathing

lung larynx trachea Cartilage rings bronchus bronchioles Page 40 Unit 13

Nasal cavity epiglottis larynx trachea alveoli bronchi diaphragm

I. Respiratory System B. Mechanics of BreathingMechanics of Breathing 1. Muscles = diaphragm, intercostals (between ribs) 2. Inhalation Intercostals contract pulling ribs up and out Diaphragm contracts pushing abdomen down Both muscular contractions increase volume of thoracic cavity lowers air pressure w/in lungs Outside air pressure > inside air pressure = air moves in

I. Respiratory System 3. Exhalation Intercostals relax Diaphragm relaxes Both decrease volume of thoracic cavity increases air pressure w/in lungs inside air pressure > outside air pressure = air moves out 4. Volumes of Breathing Vital capacity - maximum inhalation/exhalation Tidal volume - amount in “normal “ breath Respiratory reserve - amount that can be exhaled forcefully after normal exhalation

II. Exchange of Gases A. Diffusion movement of gases from high concentration to low concentration B. CO 2 / O 2 exchangeCO 2 / O 2 exchange Capillaries/Bloodstream = CO 2 high Alveoli = O 2 high O 2 moves into blood, CO 2 moves out of blood 300 million alveoli in a healthy lung

Transport of O 2 and CO 2 C. Hemoglobin – molecule in red blood cell Red colored, oxygen carrying molecule Without it, the blood only carries about 2% of O2 needed As blood flows through capillaries around alveoli, O 2 is picked up by the hemoglobin of RBCs Oxyhemoglobin: oxygen rich hemoglobin

III. Respiratory Control How is breathing rate controlled? N.S. needs way to figure out if there is enough O2 in the blood Controlled by the level of CO2 in the bloodstream CO2 is an acid High levels of CO2 stimulate nerve cells to send message to MEDULLA OBLONGATA, which sends messages to respiratory muscles to increase breathing rate Try it! Hold your breath! What’s happening?

IV. Respiration in Extreme Circumstances A. CO (carbon monoxide) = poison Similar chemical reactions as oxygen Attaches to hemoglobin more strongly than oxygen => RBC cannot deliver O 2 cells Symptoms of CO poisoning Flushed appearance, tired, nauseous, aches/pains

Extreme, contd. B. Extreme Altitudes At higher altitudes, atmospheric pressure drops Total amount of gases is much less, difficult to obtain enough oxygen (hypoxia) Try to compensate by hyperventilating or breathing more quickly or deeply Ex. Mountain climbers use oxygen masks to help them breathe Pulmonary edema: low pressure causes lung capillaries to leak fluid that drowns the person in own secretions Ex. Native Andeans: barrel shaped chests, large lungs, more capillaries around alveoli, strong diaphragms

Extreme, contd. C. Diving: At higher pressures below ocean’s surface, divers must carry tanks, which release oxygen-containing air at a pressure that matches the pressure of the ocean water on diver’s body Otherwise, it would be impossible for them to inhale/inflate lungs at such high external pressure D. Drowning Death from suffocation Water cuts off oxygen supply

Extreme, contd. Mammalian Diving Reflex Slowing of breathing and pulse, triggered by exposure of cold water to face Blood is shunted from gut, skin, muscles and sent to brain, heart, lungs When face removed from water, MDR shuts down and CPR must be administered for survival CPR is administered for underwater exposure up to one hour! Younger people more apt to recover Example, Jimmy T (UP 43)

V. Common Respiratory Diseases (UP 42) Bronchitis Emphysema Pneumonia Lung Cancer Asthma