Unit #3: Transportation and Respiration

“Respiration”

Structures of the Respiratory

System:

Nasal Passage

Sinuses

• 1st structure of the system (assuming that you are breathing through your nose)

• Walls are lined with Nasal Concliawhich are ridges that warm and moisten air before it travels to the lungs

• Cavities that warm and moisten incoming air

• Cilia and Mucous on the walls of the Sinuses traps foreign material

Pharynx

Larynx

• Controls the opening and closing of the Trachea (wind pipe) by opening and closing the Epiglottis

• Entry point of the Trachea protected by the Epiglottis

• Contains Vocal Chords (“voice box”)

• Air movement crossing the vocal chords creates sound

• Tighter the chord higher the pitch

• Greater volume of air passing greater the volume

• Vocal Chords are protected by the “Adam’s Apple”

• Thick cartilage (easier to see in males)

Trachea

Primary Bronchi

Bronchial Trees

• The Windpipe

• Passageway of air from the mouth to the lungs

• Protected by rings of cartilage

• At the top of the Lungs, the trachea branches into these 2 passageways that extend into the lungs

• Branch like tubes made of smooth muscle and held open by rings of cartilage

• These lead to smaller alveolar ducts (located at the end of the bronchial trees) and then to the lungs

Lungs • Soft spongy cone shaped structures that occupy most of the thoracic cavity

• They are separated by the heart and a central region of the thoracic cavity called the mediastinum

• Lung activity (expansion and contraction) is controlled by a dome shaped muscle called the Diaphragm

• The Lungs are protected by the following bones: the ribs, the sternumand the clavicles

The Pleura The Pleura is the outer lining of the Lungs

• This lining has 2 layers:1. The Visceral Pleura

– This part of the pleura is attached to the lung cavities

2. The Parietal Pleura– This is the outer layer of the Pleura which

attaches to the rib cage, diaphragm and heart (keeps the lungs in position)

• The Pleural Cavity is the space between the 2 layers of the Pleura• The pleura secretes a thin film into this

cavity which allows the lungs to move within the “sac” without friction

The Mechanics of Breathing:

1. Exhalation • CO2 levels increase in the blood

• Deoxygenated Blood (containing high concentrations of CO2) is pumped to the capillaries surrounding the alveoli of the lungs

• CO2 diffuses from capillaries into the alveoli.

• Increases CO2 levels cause the Diaphragm contract (Diaphragm moves up)

• Volume of the Thoracic Cavity decreases

• The decrease in volume causes an increase in pressure in the cavity which forces air out (through bronchioles, primary bronchi and trachea)

2. Inhalation • Intercostal Muscles (c) receive a nerve impulse and then contract

• The nerve impulse also causes the Diaphragm to relax and then contract in the opposite direction (moves down)

• This creates an increase in the volume of the thoracic cavity which lowers the air pressure in the lungs

• Air (containing higher concentrations of O2) moves from areas of high pressure to low pressure and moves in through the Trachea, bronchioles and into the Alveoli of the Lungs

• O2 diffuses from the alveoli into the capillaries surrounding the alveoli and eventually flows into the pulmonary vein and is carried to the heart.