The Respiratory System

Function of the Respiratory System

• To provide a constant supply of oxygen (O₂) to keep your body cells functioning

​

• To remove carbon dioxide (CO₂) from the body cells

​

​

Organs of the Respiratory System (Structure)

• Nose
• Mouth
• Nasal cavity
• Pharynx
• Epiglottis
• Larynx

​

​

• Trachea
• Bronchus (bronchi)
• Bronchioles
• Alveoli
• Pleura
• Diaphragm

​

Lungs

http://www.bbc.co.uk

Nasal Cavity

Nose

Mouth

Bronchus

Bronchiole

Alveolus

Diaphragm

Throat

(pharynx)

Windpipe

(Trachea)

Left Lung

Ribs

Mouth & Nose

• Brings air (O₂) into the body
• Carbon Dioxide leaves the body through the mouth and nose
• Nasal hairs in nostrils filter and trap dust.
• Air is not filtered as much when it enters in through your mouth.

Nasal Cavity

• Warms and moistens air
• Glands that produce sticky mucus line the nasal cavity
• traps dust, pollen, and other materials that were not trapped by nasal hairs
• cilia sweep mucus and trapped material to the back of the throat where it can be swallowed

Pharynx (Throat)

• 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

epiglottis

Larynx

• “Voice box”
• The airway to which two pairs of horizontal folds of tissue, called vocal cords, are attached

Trachea (Windpipe)

• Air-conducting tube
• Connects the larynx with the bronchi
• Lined with mucous membranes and cilia
• Contains strong cartilage rings which hold the trachea open. Without these rings your trachea might close off and air would not be able to get to and from your lungs.

Bronchi

• Two short tubes that branch off the lower end of the trachea
• Carry air into the lungs.
• Singular - bronchus

Bronchioles

• bronchi tubes split up, like tree branches, and get smaller and smaller inside your lungs.
• The tiny branches of air tubes in the lungs are bronchioles
• Connect bronchi to alveoli

Alveoli

• Tiny, thin-walled, grapelike clusters at the end of each bronchiole
• Surrounded by capillaries
• Where carbon dioxide and oxygen exchange take place
• Singular - alveolus

Bronchi and Alveoli Picture

http://mhln.com

Pleura

• Membrane lining the lungs and chest cavity

Diaphragm

• Muscle wall between the chest and the abdomen that the body uses for breathing

​

• Lungs expand and contract in response to changes in pressure inside the chest cavity.

​

• The diaphragm flattens to cause the chest to expand and air is pulled into the lungs.

​

• When the diaphragm relaxes, the chest collapses and the air in the lungs is forced out.

Diagram of Diaphram

Respiratory System Animation

Inhalation

• Breathing in
• Body gets oxygen from the air
• Rib muscles contract to pull ribs up and out
• Diaphragm muscle contracts to pull down the lungs
• Tissue expands to force (pull) in air.

Exhalation

• Breathing out
• Get rid of carbon dioxide
• Rib muscles relax
• Diaphragm muscle relaxes
• Tissue returns to resting position and forces (pushes) air out

Breathing and Respiration are NOT the same thing!

Breathing

• Moving air in and out of the lungs

Respiration

• Chemical reaction that releases energy

​

C₆H₁₂O₆  +  6O₂  →   6CO₂  +  6 H₂O  +  Energy

​

Relationship to Digestive System

• Cellular respiration requires glucose and oxygen to release energy to the body
• C₆H₁₂O₆  +  6O₂  → 6CO₂  +  6 H₂O  +  Energy
• Oxygen is provided by the respiratory system
• Glucose is provided by the digestive system
• (glucose is made during photosynthesis)

Relationship to Nervous System

• The respiratory system is under the control of the involuntary and voluntary nervous system.

●We don’t think about breathing.

●The autonomic nervous system controls breathing in response to the amount of carbon dioxide in the blood.

​

Relationship to Nervous System

●Humans can decide to hold their breath.

●The respiratory system is then controlled by the somatic nervous system.

●If you pass out from holding your breath, your autonomic nervous system will take over and return the blood gasses to normal.

​

​

​

Respiratory Information

Each lung is about the size of a football.

The lungs fill the area from the collarbone to the bottom of the ribs.

Lungs are the only organ in the body light enough to float.

There are 300-500 million alveoli having a total surface area or about 75 m² in adults (about the size of three living rooms).

Respiratory Information

• If all the capillaries that surround the alveoli were unwound and laid end to end they would extend about 620 miles.
• At rest, the body takes in and breathes out about 10 liters of air each minute.
• The right lung is slightly larger than the left.
• The highest recorded "sneeze speed" is 165 km per hour.

Respiratory Information

• The surface area of the lungs is roughly the same size as a tennis court.
• We lose half a liter of water a day through breathing. This is the water vapor we see when we breathe onto glass.
• A person at rest usually breathes between 12 and 15 times a minute.
• The breathing rate is faster in children and women than in men.