The Respiratory System ● Pathway ● Nasal cavities Pharynx Trachea Bronchi Bronchioles Alveoli

Parts and Function of the Respiratory System ● Nasal cavities- hair lined, with mucus glands – filters particles - warms and moistens air ● Pharynx – crossover point between digestive and respiratory tract - epiglottis serves as the switching mechanism

● Trachea and Bronchi both have the same function ● - both are held open by cartilaginous rings ● - both have mucous glands and are lined with cilia to capture foreign particles and move them up to the pharynx to be swallowed or expelled. ● Trachea – airway 12 cm long ● The Larynx (voice box) is located at the ● upper end of the trachea – this contains ● the vocal chords ● Bronchi – extension of the trachea ● - carries air to the lungs

Lungs are made up of the bronchioles and the alveoli. Bronchioles -Air enters the bronchioles from the bronchi, smaller branches leading to the Alveoli ● Alveoli – Gas exchange (diffusion) happens here

Diffusion ● Diffusion is the tendency of particle to move from an area of high concentration to an area of low concentration. ● Oxygen will move from an area of high concentration (the alveoli) to an area of low concentration (capillaries). ● Oxygen will then move from the capillaries into the body cells for the same reason. ● Carbon dioxide will move from an area of high concentration (the capillaries) to an area of low concentration (the alveoli). ● Carbon dioxide will then move from the body cells into the capillaries for the same reason.

Mechanics of Breathing ● Respiratory movement is triggered by respiratory muscles, which include: 1. the diaphragm (a muscle located beneath the lungs) 2. the intercostal muscles (located between the ribs of the rib cage.

● Inhalation (Inspiration) 1. intercostal muscles contract, ribs move up and out 2. Diaphragm contracts and moves down. 3. Larger volume is created, pressure is lower in the lungs than outside the body. Air rushes in. ● Exhalation (Expiration) 1. intercostal muscles relax, ribs move down and up 2. Diaphragm relaxes and moves up. Volume is reduced 3. Pressure is higher in the lungs than outside the body. Air rushes out. Breathing Mechanism and Gas Exchange U

Fluids ● Fluid: a substance that flows and is able to take the shape of its container. ● Fluids are liquids and gases ● Gases are compressible fluids (indefinate volume) ● Liquids are incompressible fluids (definite volume)

Pressure ● Pressure is the result of a force applied perpendicularly on a surface. ● Pressure (in Pascals) = Force( in Newtons) Area (in square meters)

Pressure in a Gas ● Pressure in a gas is the result of collisions ● between particles and their container. ● To increase pressure: ● 1. increase the number of particles ● (same volume, same temp.) ● 2. decrease the volume of the container ● (same no. of particles and same temp.) ● ● 3. increase temperature ● (same volume, same no. of particles)

Pressure in a Liquid ● Pressure in a liquid will depend on: ● 1. the depth of the liquid above the object ● 2. the density of the liquid