The Respiratory System Inhale … Exhale …

How important is the Respiratory System? How long can you hold your breath?

2 different levels Cellular, or internal Organism level

Why Breath? Respiratory System is a group of organs working together to bring about the exchange of oxygen and carbon dioxide with the environment

Respiratory System consists of: Nose Nasal cavity Pharynx Larynx Trachea Smaller conducting passageways Lungs

air is about 21% Oxygen; 78% Nitrogen; 1% Carbon dioxide, water vapor, argon, and other trace gasses (neon, helium, krypton, hydrogen, and ozone are a few)

Air enters through the nose or mouth Into the nasal cavity – warms and moistens air Enters pharynx – back of throat – serves as passageway for food and air Trachea – windpipe – leads to lungs

Direct connection to outside – must filter dust, dirt, smoke, bacteria and other contaminants When air goes through the mouth, it doesn’t get filtered as much as when it goes through the nose and nasal cavities Lined with mucous secretions and hair

Top of trachea is Larynx Made of cartilage (largest is the Adam’s Apple) Also known as Voice box Inside is two folds of tissue – the vocal cords

Trachea C – shaped rings of cartilage Protect the trachea Make it flexible Keep it from collapsing

Cells that line the trachea produce mucus Lined with cilia Particles are trapped in the mucus and carried to upper trachea – swept down into digestive system Smoke = Sabotage to system Cilia stop working after a while When this happens, particles get lodged in the trachea – SMOKER’S COUGH

Trachea divides to bronchi Bronchi divide into smaller and smaller passageways and lose the cartilage rings to become bronchioles Bronchioles divide further and further until they end in small clusters of hollow air sacs – alveoli Gas exchange occurs in alveoli

Mechanics of Breathing Inhalation and Exhalation Air pulled into the lungs and air pushed out of the lungs 10 – 15 X in a minute Diaphragm – large flat muscle along bottom of rib cage and Intercostal (between ribs) muscles

Makeup of air we breath GasChemical Symbol Air Entering Lungs Air Leaving Lungs Oxygen O2O %16% Carbon Dioxide CO %4.00% Nitrogen N2N2 80%

3 million alveoli in a healthy lung

Blood enters capillaries around the alveoli Carbon dioxide rich blood enters, Carbon dioxide diffuses out, Oxygen diffuses in – concentrations are unequal across the alveolar membrane of gasses

Phospholipids and protein produce a “surfactant” to coat the inside of the alveolus Keeps it open and makes it easier to exchange gasses

Hemoglobin – Found in red blood cells – iron containing compound – makes red blood cells red Without Hemoglobin, blood would only be able to carry about 2% of the oxygen needed by the body.

Control of Respiratory System Breathing is involuntary What makes you breath?

How does the nervous system control breathing? Sensory neurons check levels of gasses in your blood. One set in carotid arteries in the neck Other set in the aorta These are sensitive to levels of gasses in the blood – especially Carbon Dioxide

LUNG CAPACITIES Total Lung Volume – about 6 L Residual Volume – Following a normal exhalation, what is left (about 2 ½ L) Tidal Volume – Volume of air inspired or expired during a normal (at rest) breath (1/2 L per cycle) Inspiratory Reserve – additional air that can be breathed after a normal inspiration (4 ½ L) Vital Capacity – total volume of breathable air

Problems Hypoxia – High CO2 levels in the blood – provides greatest stimulus to breath Influenced by oxygen partial pressure, increased gas density, and emotional states Asphyxia – existence of both hypoxia (oxygen shortage) and Carbon Dioxide excess Suffocation – stoppage of breathing for any cause resulting in asphyxiation Strangulation – stoppage of breathing due to obstruction

Asthma Restriction of airways due to inflammation May cause –Shortness of breath –Wheezing –Coughing Can be triggered by –Cold –Allergies – dust, pet hair, smoke, pollen, etc… –Exercise

Asthma Medicines include –Long acting to prevent attacks –Short acting during attacks (bronchodilators)

Lung Caner

Emphysema COPD – Chronic Obstructive Pulmonary Disease –Lung tissue destroyed – cannot function fully –Irreversible condition –Steroids and other drugs –May need Oxygen permanently