Download The Respiratory System Two major tasks of the respiratory system:

The Respiratory System
Two major tasks of the respiratory system:
1. Internal Respiration: bringing of oxygen to the cells and the removal of carbon
dioxide from them
-oxygen is exchanged from the alveoli
(in lungs) into the capillaries of the
bloodstream and carbon dioxide is
sent from the capillaries into the
alveoli
-oxygen is then delivered to the body’s
other cells
2. External Respiration, or breathing: exchange of air between
the body and the outside environment.
Relationship between PRESSURE and VOLUME
INHALATION
• intercostal muscles contract, pulling the ribs upward and outward
• diaphragm contracts and moves down (flattens)
• thoracic cavity is enlarged
• increase in lung volume
• Decrease in pressure in the thoracic cavity
• Air moves into the lungs (from high pressure outside to low pressure
inside the lungs)
EXHALATION
• intercostal muscles relax; ribcage falls down and inward
• diaphragm relaxes and moves up
• thoracic cavity decreases in volume
• decrease in lung volume, increase in pressure in the lungs
• Air moves from high pressure in lungs to the outside
• exhale waste (CO2)
Parts of the Respiratory System
A. The Upper Respiratory System
NOSE
• divided into two nasal cavities by a piece of cartilage called the
“nasal septum”
• air is warmed by blood in the mucous membranes that line the
cavities
• cilia (small hairs) in nasal cavity filter out foreign bodies
PHARYNX
• passageway for both air and food
• bottom section is called the laryngopharynx – at this point the
respiratory tract divides into the esophagus and larynx
Parts of the Respiratory System
B. The Lower Respiratory System
LARYNX (Voicebox)
• contains vocal cords – size and thickness determines the pitch of
sound
• males have thicker and longer cords, thus a lower pitch
• supported by various structures, one of which consists of two disks
joined at an angle to form the Adam’s apple (thyroid cartilage)
• epiglottis (flap of cartilage) covers opening of larynx (glottis) when
swallowing food
TRACHEA (windpipe)
• tube that connects the larynx to the right and left bronchi
BRONCHI (BRONCHUS)
• passageways through which air enters the right and left lungs
• divide and get smaller and smaller until they reach their smallest size – known as
bronchioles
BRONCHIOLES
• network of smaller tubes
• smooth muscles in the walls
• continue to branch until reach alveoli
ALVEOLI (ALVEOLUS)
• air sacs with thin walls
• capillaries surround each cluster of alveoli
• exchange of gases between alveoli and blood (O2 goes into blood, CO2 goes out)
LUNGS
• main organ of respiratory system
• -outside is a moist, double layer of membrane called the pleura
• visceral pleura: inner layer
• parietal pleura: outer layer
• pleural cavity: space between the two pleura
• -pleura protect the lungs and provide the moisture that allows
movement
• -right lung: 3 lobes
• -left lung: 2 lobes