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

Gas Chemical Symbol

Air Entering

Lungs

Air Leaving Lungs

Oxygen O2 19.97% 16%

Carbon Dioxide

CO2 0.03% 4.00%

Nitrogen N2 80% 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