I. Respiratory System A. Structures / Functions

1. Nasal Cavity – warm, moisten and filter air

Mucus, hairs = trap dust, dirt and pathogens 2. Epiglottis – prevents food from going into

windpipe when swallowing 3. Larynx – voice box, contains the vocal

chords 4. Trachea = wind pipe, passage for air to

the lungs

I. Respiratory System 5. Bronchi – main branches to the trachea,

lead to each lung 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 occurs 8. Diaphragm – large muscle that aids in

breathing

lung

larynx

trachea

Cartilage rings

bronchus

bronchioles

Page 40 Unit 13

Nasal cavity

epiglottislarynx

trachea

alveoli

bronchi

diaphragm

I. Respiratory System B. Mechanics 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

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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. CO2 / O2 exchange

Capillaries/Bloodstream = CO2 high Alveoli = O2 high O2 moves into blood, CO2 moves out

of blood 300 million alveoli in a healthy lung

Transport of O2 and CO2

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, O2 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 O2 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