The Respiratory SystemClass Starter Questions:

1) What is the purpose of the respiratory system?

2) Explain the difference between breathing and respiration.

3) What organs make up the respiratory system? Write them in order through which air passes during inhalation.

1) What is the purpose of the respiratory system?

• To provide a constant supply of oxygen to keep your body cells functioning

• To remove carbon dioxide from the body cells

2) Explain the difference between breathing and respiration.

Breathing is:

Moving air in and out of the lungs

Respiration is:

A chemical reaction that releases energy

reactants: glucose + oxygen

products: carbon dioxide + water + energy

What is the pathway air takes through the respiratory system?

Nose & mouth

Pharynx

Trachea

Bronchi

Bronchioles

Alveoli

Capillaries

http://www.bbc.co.uk

Mouth & Nose

• This is where the oxygen first enters your body and also where carbon dioxide leaves.

• When the air comes into your nose it getsfiltered by tiny hairs

• Your mouth does not contain these hairs therefore breathing by your mouth does not filter the air as well as breathing by your nose

Nasal cavity

• Warms & moistens air • Glands that produce sticky mucus line

the nasal cavity – traps dust, pollen, and other materials that

were not trapped by nasal hairs

Pharynx

• Tube-like passageway used by food, liquid, and air

• At the lower end of the pharynx is a flap of tissue called the epiglottis – covers the trachea during swallowing so

that food does not enter the lungs

Larynx

• “Voice box”• The airway to which two pairs of

horizontal folds of tissue, called vocal cords, are attached

• When we exhale, the vocal cords vibrate which produces sound

Trachea

• Air-conducting tube • Connects the larynx with the bronchi• Lined with mucus membranes and cilia• Contains strong cartilage rings to hold

the airway open at all times

Bronchi

• Two short tubes that branch off the lower end of the trachea

• Carry air into the lungs. • Singular - bronchus

Lungs

• The lungs are spongy organs which contain the bronchioles and alveoli.

• Where gas exchange occurs• There are 2 lungs (right and left)

Smoker’s Lung vs. Healthy Lung

Bronchioles

• Tiny branches of air tubes in the lungs • Connect bronchi to alveoli

Alveoli

• Tiny, thin-walled, grapelike clusters at the end of each bronchiole

• Surrounded by capillaries• Where exchange of carbon dioxide and

oxygen (via diffusion) takes place• Singular - alveolus

Pleura

• A double membrane that lines the lungs and adheres to the walls of the rib cage

Diaphragm• Dome shaped muscle between the chest and

the abdomen that the body uses for breathing

Gas Exchange- What is it?

• Two gases, O2 and CO2 switch places

• O2 moves from the alveoli to the capillaries

• CO2 moves in the opposite direction, from the capillaries to the alveoli

• This occurs by diffusion:– The movement of molecules from a region of

high concentration to a region of low concentration

Diffusion of Carbon Dioxide

• Blood arriving at the alveolus is deoxygenated:– Low in O2– High in CO2

• The concentration of CO2 inside the alveolus is lower than in the cappilary

• Thus, CO2 diffuses into the alveolus

Diffusion of Oxygen

• Blood arriving at the alveolus has a low concentration of O2

• But air entering the alveolus has a high concentration of O2

• Thus, O2 diffuses from the alveolus (high conc.) into the capillary (low conc.)

Oxygenated blood leaving the alveolus

How does breathing work?

• Breathing is an involuntary action meaning that it occurs without conscious thought

• However, breathing is in fact controlled by a structure in the brain called the medula

Breathing Rate

• Breathing rate = # of breaths (including inhalation AND exhalation) in 1 min

• Your brain controls your breathing rate by monitoring the level of CO2 in your body

• When CO2 levels are high, breathing rate increases

• When CO2 levels are low breathing rate decreases

Why does your breathing rate increase during and after exercise?• Physical activity requires increased energy

production • Thus, your muscles must consume more O2 to

release more energy • As a result of respiration, more CO2 is produced• The increased levels of CO2 in the blood flowing

to your brain is a signal to the medulla to increase breathing rate

• WHY?– To remove CO2 and replenish O2 at a faster rate– http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/hlw_

when.html